diff --git a/.gitignore b/.gitignore index 466fd6e..317532a 100644 --- a/.gitignore +++ b/.gitignore @@ -1,3 +1,8 @@ *.swp target tango.stamp + + +#Added by cargo + +/target diff --git a/Cargo.lock b/Cargo.lock new file mode 100644 index 0000000..6399955 --- /dev/null +++ b/Cargo.lock @@ -0,0 +1,5 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +[[package]] +name = "dnsguide" +version = "0.1.0" diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..088887f --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,9 @@ +[package] +name = "dnsguide" +version = "0.1.0" +authors = ["Emil Hernvall "] +edition = "2018" + +# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html + +[dependencies] diff --git a/README.md b/README.md index 4211c63..142a595 100644 --- a/README.md +++ b/README.md @@ -24,3 +24,18 @@ DNS server, starting from first principles. * [Chapter 3 - Adding more Record Types](/chapter3.md) * [Chapter 4 - Baby's first DNS server](/chapter4.md) * [Chapter 5 - Recursive Resolve](/chapter5.md) + +Samples +------- + +Each chapter has a corresponding sample which contains the full code up to +that point in the guide, named `sample1.rs` through `sample5.rs`. These can be +run using, for first chapter, `cargo run --example sample1`. + +Revision History +---------------- + + * June 2020 - Fixed a security vulnerability in `read_qname` which allowed for + a malicious packet to trigger an infinite loop. Modernized the code to + conform to current rust pratices. + * July 2016 - Initial version diff --git a/samples/sample1.rs b/examples/sample1.rs similarity index 58% rename from samples/sample1.rs rename to examples/sample1.rs index ea982ad..c677d2a 100644 --- a/samples/sample1.rs +++ b/examples/sample1.rs @@ -1,18 +1,20 @@ -use std::io::{Result, Read}; -use std::io::{Error, ErrorKind}; -use std::net::Ipv4Addr; use std::fs::File; +use std::io::Read; +use std::net::Ipv4Addr; + +type Error = Box; +type Result = std::result::Result; pub struct BytePacketBuffer { pub buf: [u8; 512], - pub pos: usize + pub pos: usize, } impl BytePacketBuffer { pub fn new() -> BytePacketBuffer { BytePacketBuffer { buf: [0; 512], - pos: 0 + pos: 0, } } @@ -34,7 +36,7 @@ impl BytePacketBuffer { fn read(&mut self) -> Result { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } let res = self.buf[self.pos]; self.pos += 1; @@ -44,61 +46,66 @@ impl BytePacketBuffer { fn get(&mut self, pos: usize) -> Result { if pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } Ok(self.buf[pos]) } fn get_range(&mut self, start: usize, len: usize) -> Result<&[u8]> { if start + len >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } - Ok(&self.buf[start..start+len as usize]) + Ok(&self.buf[start..start + len as usize]) } - fn read_u16(&mut self) -> Result - { - let res = ((try!(self.read()) as u16) << 8) | - (try!(self.read()) as u16); + fn read_u16(&mut self) -> Result { + let res = ((self.read()? as u16) << 8) | (self.read()? as u16); Ok(res) } - fn read_u32(&mut self) -> Result - { - let res = ((try!(self.read()) as u32) << 24) | - ((try!(self.read()) as u32) << 16) | - ((try!(self.read()) as u32) << 8) | - ((try!(self.read()) as u32) << 0); + fn read_u32(&mut self) -> Result { + let res = ((self.read()? as u32) << 24) + | ((self.read()? as u32) << 16) + | ((self.read()? as u32) << 8) + | ((self.read()? as u32) << 0); Ok(res) } - fn read_qname(&mut self, outstr: &mut String) -> Result<()> - { + fn read_qname(&mut self, outstr: &mut String) -> Result<()> { let mut pos = self.pos(); let mut jumped = false; let mut delim = ""; + let max_jumps = 5; + let mut jumps_performed = 0; loop { - let len = try!(self.get(pos)); + // Dns Packets are untrusted data, so we need to be paranoid. Someone + // can craft a packet with a cycle in the jump instructions. This guards + // against such packets. + if jumps_performed > max_jumps { + return Err(format!("Limit of {} jumps exceeded", max_jumps).into()); + } + + let len = self.get(pos)?; // A two byte sequence, where the two highest bits of the first byte is // set, represents a offset relative to the start of the buffer. We // handle this by jumping to the offset, setting a flag to indicate // that we shouldn't update the shared buffer position once done. if (len & 0xC0) == 0xC0 { - // When a jump is performed, we only modify the shared buffer // position once, and avoid making the change later on. if !jumped { - try!(self.seek(pos+2)); + self.seek(pos + 2)?; } - let b2 = try!(self.get(pos+1)) as u16; + let b2 = self.get(pos + 1)? as u16; let offset = (((len as u16) ^ 0xC0) << 8) | b2; pos = offset as usize; jumped = true; + jumps_performed += 1; continue; } @@ -111,7 +118,7 @@ impl BytePacketBuffer { outstr.push_str(delim); - let str_buffer = try!(self.get_range(pos, len as usize)); + let str_buffer = self.get_range(pos, len as usize)?; outstr.push_str(&String::from_utf8_lossy(str_buffer).to_lowercase()); delim = "."; @@ -120,21 +127,21 @@ impl BytePacketBuffer { } if !jumped { - try!(self.seek(pos)); + self.seek(pos)?; } Ok(()) } } -#[derive(Copy,Clone,Debug,PartialEq,Eq)] +#[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ResultCode { NOERROR = 0, FORMERR = 1, SERVFAIL = 2, NXDOMAIN = 3, NOTIMP = 4, - REFUSED = 5 + REFUSED = 5, } impl ResultCode { @@ -145,59 +152,61 @@ impl ResultCode { 3 => ResultCode::NXDOMAIN, 4 => ResultCode::NOTIMP, 5 => ResultCode::REFUSED, - 0 | _ => ResultCode::NOERROR + 0 | _ => ResultCode::NOERROR, } } } -#[derive(Clone,Debug)] +#[derive(Clone, Debug)] pub struct DnsHeader { pub id: u16, // 16 bits - pub recursion_desired: bool, // 1 bit - pub truncated_message: bool, // 1 bit + pub recursion_desired: bool, // 1 bit + pub truncated_message: bool, // 1 bit pub authoritative_answer: bool, // 1 bit - pub opcode: u8, // 4 bits - pub response: bool, // 1 bit + pub opcode: u8, // 4 bits + pub response: bool, // 1 bit - pub rescode: ResultCode, // 4 bits - pub checking_disabled: bool, // 1 bit - pub authed_data: bool, // 1 bit - pub z: bool, // 1 bit + pub rescode: ResultCode, // 4 bits + pub checking_disabled: bool, // 1 bit + pub authed_data: bool, // 1 bit + pub z: bool, // 1 bit pub recursion_available: bool, // 1 bit - pub questions: u16, // 16 bits - pub answers: u16, // 16 bits + pub questions: u16, // 16 bits + pub answers: u16, // 16 bits pub authoritative_entries: u16, // 16 bits - pub resource_entries: u16 // 16 bits + pub resource_entries: u16, // 16 bits } impl DnsHeader { pub fn new() -> DnsHeader { - DnsHeader { id: 0, + DnsHeader { + id: 0, - recursion_desired: false, - truncated_message: false, - authoritative_answer: false, - opcode: 0, - response: false, + recursion_desired: false, + truncated_message: false, + authoritative_answer: false, + opcode: 0, + response: false, - rescode: ResultCode::NOERROR, - checking_disabled: false, - authed_data: false, - z: false, - recursion_available: false, + rescode: ResultCode::NOERROR, + checking_disabled: false, + authed_data: false, + z: false, + recursion_available: false, - questions: 0, - answers: 0, - authoritative_entries: 0, - resource_entries: 0 } + questions: 0, + answers: 0, + authoritative_entries: 0, + resource_entries: 0, + } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - self.id = try!(buffer.read_u16()); + self.id = buffer.read_u16()?; - let flags = try!(buffer.read_u16()); + let flags = buffer.read_u16()?; let a = (flags >> 8) as u8; let b = (flags & 0xFF) as u8; self.recursion_desired = (a & (1 << 0)) > 0; @@ -212,17 +221,17 @@ impl DnsHeader { self.z = (b & (1 << 6)) > 0; self.recursion_available = (b & (1 << 7)) > 0; - self.questions = try!(buffer.read_u16()); - self.answers = try!(buffer.read_u16()); - self.authoritative_entries = try!(buffer.read_u16()); - self.resource_entries = try!(buffer.read_u16()); + self.questions = buffer.read_u16()?; + self.answers = buffer.read_u16()?; + self.authoritative_entries = buffer.read_u16()?; + self.resource_entries = buffer.read_u16()?; // Return the constant header size Ok(()) } } -#[derive(PartialEq,Eq,Debug,Clone,Hash,Copy)] +#[derive(PartialEq, Eq, Debug, Clone, Hash, Copy)] pub enum QueryType { UNKNOWN(u16), A, // 1 @@ -239,84 +248,85 @@ impl QueryType { pub fn from_num(num: u16) -> QueryType { match num { 1 => QueryType::A, - _ => QueryType::UNKNOWN(num) + _ => QueryType::UNKNOWN(num), } } } -#[derive(Debug,Clone,PartialEq,Eq)] +#[derive(Debug, Clone, PartialEq, Eq)] pub struct DnsQuestion { pub name: String, - pub qtype: QueryType + pub qtype: QueryType, } impl DnsQuestion { pub fn new(name: String, qtype: QueryType) -> DnsQuestion { DnsQuestion { name: name, - qtype: qtype + qtype: qtype, } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.read_qname(&mut self.name)); - self.qtype = QueryType::from_num(try!(buffer.read_u16())); // qtype - let _ = try!(buffer.read_u16()); // class + buffer.read_qname(&mut self.name)?; + self.qtype = QueryType::from_num(buffer.read_u16()?); // qtype + let _ = buffer.read_u16()?; // class Ok(()) } } -#[derive(Debug,Clone,PartialEq,Eq,Hash,PartialOrd,Ord)] +#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] #[allow(dead_code)] pub enum DnsRecord { UNKNOWN { domain: String, qtype: u16, data_len: u16, - ttl: u32 + ttl: u32, }, // 0 A { domain: String, addr: Ipv4Addr, - ttl: u32 + ttl: u32, }, // 1 } impl DnsRecord { - pub fn read(buffer: &mut BytePacketBuffer) -> Result { let mut domain = String::new(); - try!(buffer.read_qname(&mut domain)); + buffer.read_qname(&mut domain)?; - let qtype_num = try!(buffer.read_u16()); + let qtype_num = buffer.read_u16()?; let qtype = QueryType::from_num(qtype_num); - let _ = try!(buffer.read_u16()); - let ttl = try!(buffer.read_u32()); - let data_len = try!(buffer.read_u16()); + let _ = buffer.read_u16()?; + let ttl = buffer.read_u32()?; + let data_len = buffer.read_u16()?; match qtype { - QueryType::A => { - let raw_addr = try!(buffer.read_u32()); - let addr = Ipv4Addr::new(((raw_addr >> 24) & 0xFF) as u8, - ((raw_addr >> 16) & 0xFF) as u8, - ((raw_addr >> 8) & 0xFF) as u8, - ((raw_addr >> 0) & 0xFF) as u8); + QueryType::A => { + let raw_addr = buffer.read_u32()?; + let addr = Ipv4Addr::new( + ((raw_addr >> 24) & 0xFF) as u8, + ((raw_addr >> 16) & 0xFF) as u8, + ((raw_addr >> 8) & 0xFF) as u8, + ((raw_addr >> 0) & 0xFF) as u8, + ); Ok(DnsRecord::A { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::UNKNOWN(_) => { - try!(buffer.step(data_len as usize)); + buffer.step(data_len as usize)?; Ok(DnsRecord::UNKNOWN { domain: domain, qtype: qtype_num, data_len: data_len, - ttl: ttl + ttl: ttl, }) } } @@ -329,7 +339,7 @@ pub struct DnsPacket { pub questions: Vec, pub answers: Vec, pub authorities: Vec, - pub resources: Vec + pub resources: Vec, } impl DnsPacket { @@ -339,31 +349,30 @@ impl DnsPacket { questions: Vec::new(), answers: Vec::new(), authorities: Vec::new(), - resources: Vec::new() + resources: Vec::new(), } } pub fn from_buffer(buffer: &mut BytePacketBuffer) -> Result { let mut result = DnsPacket::new(); - try!(result.header.read(buffer)); + result.header.read(buffer)?; for _ in 0..result.header.questions { - let mut question = DnsQuestion::new("".to_string(), - QueryType::UNKNOWN(0)); - try!(question.read(buffer)); + let mut question = DnsQuestion::new("".to_string(), QueryType::UNKNOWN(0)); + question.read(buffer)?; result.questions.push(question); } for _ in 0..result.header.answers { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.answers.push(rec); } for _ in 0..result.header.authoritative_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.authorities.push(rec); } for _ in 0..result.header.resource_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.resources.push(rec); } @@ -371,12 +380,12 @@ impl DnsPacket { } } -fn main() { - let mut f = File::open("response_packet.txt").unwrap(); +fn main() -> Result<()> { + let mut f = File::open("response_packet.txt")?; let mut buffer = BytePacketBuffer::new(); - f.read(&mut buffer.buf).unwrap(); + f.read(&mut buffer.buf)?; - let packet = DnsPacket::from_buffer(&mut buffer).unwrap(); + let packet = DnsPacket::from_buffer(&mut buffer)?; println!("{:?}", packet.header); for q in packet.questions { @@ -391,4 +400,6 @@ fn main() { for rec in packet.resources { println!("{:?}", rec); } + + Ok(()) } diff --git a/samples/sample2.rs b/examples/sample2.rs similarity index 54% rename from samples/sample2.rs rename to examples/sample2.rs index d9afc50..9b31908 100644 --- a/samples/sample2.rs +++ b/examples/sample2.rs @@ -1,18 +1,19 @@ -use std::io::{Result, Read}; -use std::io::{Error, ErrorKind}; use std::net::Ipv4Addr; use std::net::UdpSocket; +type Error = Box; +type Result = std::result::Result; + pub struct BytePacketBuffer { pub buf: [u8; 512], - pub pos: usize + pub pos: usize, } impl BytePacketBuffer { pub fn new() -> BytePacketBuffer { BytePacketBuffer { buf: [0; 512], - pos: 0 + pos: 0, } } @@ -34,7 +35,7 @@ impl BytePacketBuffer { fn read(&mut self) -> Result { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } let res = self.buf[self.pos]; self.pos += 1; @@ -44,61 +45,66 @@ impl BytePacketBuffer { fn get(&mut self, pos: usize) -> Result { if pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } Ok(self.buf[pos]) } fn get_range(&mut self, start: usize, len: usize) -> Result<&[u8]> { if start + len >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } - Ok(&self.buf[start..start+len as usize]) + Ok(&self.buf[start..start + len as usize]) } - fn read_u16(&mut self) -> Result - { - let res = ((try!(self.read()) as u16) << 8) | - (try!(self.read()) as u16); + fn read_u16(&mut self) -> Result { + let res = ((self.read()? as u16) << 8) | (self.read()? as u16); Ok(res) } - fn read_u32(&mut self) -> Result - { - let res = ((try!(self.read()) as u32) << 24) | - ((try!(self.read()) as u32) << 16) | - ((try!(self.read()) as u32) << 8) | - ((try!(self.read()) as u32) << 0); + fn read_u32(&mut self) -> Result { + let res = ((self.read()? as u32) << 24) + | ((self.read()? as u32) << 16) + | ((self.read()? as u32) << 8) + | ((self.read()? as u32) << 0); Ok(res) } - fn read_qname(&mut self, outstr: &mut String) -> Result<()> - { + fn read_qname(&mut self, outstr: &mut String) -> Result<()> { let mut pos = self.pos(); let mut jumped = false; let mut delim = ""; + let max_jumps = 5; + let mut jumps_performed = 0; loop { - let len = try!(self.get(pos)); + // Dns Packets are untrusted data, so we need to be paranoid. Someone + // can craft a packet with a cycle in the jump instructions. This guards + // against such packets. + if jumps_performed > max_jumps { + return Err(format!("Limit of {} jumps exceeded", max_jumps).into()); + } + + let len = self.get(pos)?; // A two byte sequence, where the two highest bits of the first byte is // set, represents a offset relative to the start of the buffer. We // handle this by jumping to the offset, setting a flag to indicate // that we shouldn't update the shared buffer position once done. if (len & 0xC0) == 0xC0 { - // When a jump is performed, we only modify the shared buffer // position once, and avoid making the change later on. if !jumped { - try!(self.seek(pos+2)); + self.seek(pos + 2)?; } - let b2 = try!(self.get(pos+1)) as u16; + let b2 = self.get(pos + 1)? as u16; let offset = (((len as u16) ^ 0xC0) << 8) | b2; pos = offset as usize; jumped = true; + jumps_performed += 1; continue; } @@ -111,7 +117,7 @@ impl BytePacketBuffer { outstr.push_str(delim); - let str_buffer = try!(self.get_range(pos, len as usize)); + let str_buffer = self.get_range(pos, len as usize)?; outstr.push_str(&String::from_utf8_lossy(str_buffer).to_lowercase()); delim = "."; @@ -120,7 +126,7 @@ impl BytePacketBuffer { } if !jumped { - try!(self.seek(pos)); + self.seek(pos)?; } Ok(()) @@ -128,7 +134,7 @@ impl BytePacketBuffer { fn write(&mut self, val: u8) -> Result<()> { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } self.buf[self.pos] = val; self.pos += 1; @@ -136,58 +142,56 @@ impl BytePacketBuffer { } fn write_u8(&mut self, val: u8) -> Result<()> { - try!(self.write(val)); + self.write(val)?; Ok(()) } fn write_u16(&mut self, val: u16) -> Result<()> { - try!(self.write((val >> 8) as u8)); - try!(self.write((val & 0xFF) as u8)); + self.write((val >> 8) as u8)?; + self.write((val & 0xFF) as u8)?; Ok(()) } fn write_u32(&mut self, val: u32) -> Result<()> { - try!(self.write(((val >> 24) & 0xFF) as u8)); - try!(self.write(((val >> 16) & 0xFF) as u8)); - try!(self.write(((val >> 8) & 0xFF) as u8)); - try!(self.write(((val >> 0) & 0xFF) as u8)); + self.write(((val >> 24) & 0xFF) as u8)?; + self.write(((val >> 16) & 0xFF) as u8)?; + self.write(((val >> 8) & 0xFF) as u8)?; + self.write(((val >> 0) & 0xFF) as u8)?; Ok(()) } fn write_qname(&mut self, qname: &str) -> Result<()> { - let split_str = qname.split('.').collect::>(); for label in split_str { let len = label.len(); if len > 0x34 { - return Err(Error::new(ErrorKind::InvalidInput, "Single label exceeds 63 characters of length")); + return Err("Single label exceeds 63 characters of length".into()); } - try!(self.write_u8(len as u8)); + self.write_u8(len as u8)?; for b in label.as_bytes() { - try!(self.write_u8(*b)); + self.write_u8(*b)?; } } - try!(self.write_u8(0)); + self.write_u8(0)?; Ok(()) } - } -#[derive(Copy,Clone,Debug,PartialEq,Eq)] +#[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ResultCode { NOERROR = 0, FORMERR = 1, SERVFAIL = 2, NXDOMAIN = 3, NOTIMP = 4, - REFUSED = 5 + REFUSED = 5, } impl ResultCode { @@ -198,59 +202,61 @@ impl ResultCode { 3 => ResultCode::NXDOMAIN, 4 => ResultCode::NOTIMP, 5 => ResultCode::REFUSED, - 0 | _ => ResultCode::NOERROR + 0 | _ => ResultCode::NOERROR, } } } -#[derive(Clone,Debug)] +#[derive(Clone, Debug)] pub struct DnsHeader { pub id: u16, // 16 bits - pub recursion_desired: bool, // 1 bit - pub truncated_message: bool, // 1 bit + pub recursion_desired: bool, // 1 bit + pub truncated_message: bool, // 1 bit pub authoritative_answer: bool, // 1 bit - pub opcode: u8, // 4 bits - pub response: bool, // 1 bit + pub opcode: u8, // 4 bits + pub response: bool, // 1 bit - pub rescode: ResultCode, // 4 bits - pub checking_disabled: bool, // 1 bit - pub authed_data: bool, // 1 bit - pub z: bool, // 1 bit + pub rescode: ResultCode, // 4 bits + pub checking_disabled: bool, // 1 bit + pub authed_data: bool, // 1 bit + pub z: bool, // 1 bit pub recursion_available: bool, // 1 bit - pub questions: u16, // 16 bits - pub answers: u16, // 16 bits + pub questions: u16, // 16 bits + pub answers: u16, // 16 bits pub authoritative_entries: u16, // 16 bits - pub resource_entries: u16 // 16 bits + pub resource_entries: u16, // 16 bits } impl DnsHeader { pub fn new() -> DnsHeader { - DnsHeader { id: 0, + DnsHeader { + id: 0, - recursion_desired: false, - truncated_message: false, - authoritative_answer: false, - opcode: 0, - response: false, + recursion_desired: false, + truncated_message: false, + authoritative_answer: false, + opcode: 0, + response: false, - rescode: ResultCode::NOERROR, - checking_disabled: false, - authed_data: false, - z: false, - recursion_available: false, + rescode: ResultCode::NOERROR, + checking_disabled: false, + authed_data: false, + z: false, + recursion_available: false, - questions: 0, - answers: 0, - authoritative_entries: 0, - resource_entries: 0 } + questions: 0, + answers: 0, + authoritative_entries: 0, + resource_entries: 0, + } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - self.id = try!(buffer.read_u16()); + self.id = buffer.read_u16()?; - let flags = try!(buffer.read_u16()); + let flags = buffer.read_u16()?; let a = (flags >> 8) as u8; let b = (flags & 0xFF) as u8; self.recursion_desired = (a & (1 << 0)) > 0; @@ -265,40 +271,44 @@ impl DnsHeader { self.z = (b & (1 << 6)) > 0; self.recursion_available = (b & (1 << 7)) > 0; - self.questions = try!(buffer.read_u16()); - self.answers = try!(buffer.read_u16()); - self.authoritative_entries = try!(buffer.read_u16()); - self.resource_entries = try!(buffer.read_u16()); + self.questions = buffer.read_u16()?; + self.answers = buffer.read_u16()?; + self.authoritative_entries = buffer.read_u16()?; + self.resource_entries = buffer.read_u16()?; // Return the constant header size Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.write_u16(self.id)); + buffer.write_u16(self.id)?; - try!(buffer.write_u8( ((self.recursion_desired as u8)) | - ((self.truncated_message as u8) << 1) | - ((self.authoritative_answer as u8) << 2) | - (self.opcode << 3) | - ((self.response as u8) << 7) as u8) ); + buffer.write_u8( + (self.recursion_desired as u8) + | ((self.truncated_message as u8) << 1) + | ((self.authoritative_answer as u8) << 2) + | (self.opcode << 3) + | ((self.response as u8) << 7) as u8, + )?; - try!(buffer.write_u8( (self.rescode.clone() as u8) | - ((self.checking_disabled as u8) << 4) | - ((self.authed_data as u8) << 5) | - ((self.z as u8) << 6) | - ((self.recursion_available as u8) << 7) )); + buffer.write_u8( + (self.rescode.clone() as u8) + | ((self.checking_disabled as u8) << 4) + | ((self.authed_data as u8) << 5) + | ((self.z as u8) << 6) + | ((self.recursion_available as u8) << 7), + )?; - try!(buffer.write_u16(self.questions)); - try!(buffer.write_u16(self.answers)); - try!(buffer.write_u16(self.authoritative_entries)); - try!(buffer.write_u16(self.resource_entries)); + buffer.write_u16(self.questions)?; + buffer.write_u16(self.answers)?; + buffer.write_u16(self.authoritative_entries)?; + buffer.write_u16(self.resource_entries)?; Ok(()) } } -#[derive(PartialEq,Eq,Debug,Clone,Hash,Copy)] +#[derive(PartialEq, Eq, Debug, Clone, Hash, Copy)] pub enum QueryType { UNKNOWN(u16), A, // 1 @@ -315,119 +325,121 @@ impl QueryType { pub fn from_num(num: u16) -> QueryType { match num { 1 => QueryType::A, - _ => QueryType::UNKNOWN(num) + _ => QueryType::UNKNOWN(num), } } } -#[derive(Debug,Clone,PartialEq,Eq)] +#[derive(Debug, Clone, PartialEq, Eq)] pub struct DnsQuestion { pub name: String, - pub qtype: QueryType + pub qtype: QueryType, } impl DnsQuestion { pub fn new(name: String, qtype: QueryType) -> DnsQuestion { DnsQuestion { name: name, - qtype: qtype + qtype: qtype, } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.read_qname(&mut self.name)); - self.qtype = QueryType::from_num(try!(buffer.read_u16())); // qtype - let _ = try!(buffer.read_u16()); // class + buffer.read_qname(&mut self.name)?; + self.qtype = QueryType::from_num(buffer.read_u16()?); // qtype + let _ = buffer.read_u16()?; // class Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - - try!(buffer.write_qname(&self.name)); + buffer.write_qname(&self.name)?; let typenum = self.qtype.to_num(); - try!(buffer.write_u16(typenum)); - try!(buffer.write_u16(1)); + buffer.write_u16(typenum)?; + buffer.write_u16(1)?; Ok(()) } - } -#[derive(Debug,Clone,PartialEq,Eq,Hash,PartialOrd,Ord)] +#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] #[allow(dead_code)] pub enum DnsRecord { UNKNOWN { domain: String, qtype: u16, data_len: u16, - ttl: u32 + ttl: u32, }, // 0 A { domain: String, addr: Ipv4Addr, - ttl: u32 + ttl: u32, }, // 1 } impl DnsRecord { - pub fn read(buffer: &mut BytePacketBuffer) -> Result { let mut domain = String::new(); - try!(buffer.read_qname(&mut domain)); + buffer.read_qname(&mut domain)?; - let qtype_num = try!(buffer.read_u16()); + let qtype_num = buffer.read_u16()?; let qtype = QueryType::from_num(qtype_num); - let _ = try!(buffer.read_u16()); - let ttl = try!(buffer.read_u32()); - let data_len = try!(buffer.read_u16()); + let _ = buffer.read_u16()?; + let ttl = buffer.read_u32()?; + let data_len = buffer.read_u16()?; match qtype { - QueryType::A => { - let raw_addr = try!(buffer.read_u32()); - let addr = Ipv4Addr::new(((raw_addr >> 24) & 0xFF) as u8, - ((raw_addr >> 16) & 0xFF) as u8, - ((raw_addr >> 8) & 0xFF) as u8, - ((raw_addr >> 0) & 0xFF) as u8); + QueryType::A => { + let raw_addr = buffer.read_u32()?; + let addr = Ipv4Addr::new( + ((raw_addr >> 24) & 0xFF) as u8, + ((raw_addr >> 16) & 0xFF) as u8, + ((raw_addr >> 8) & 0xFF) as u8, + ((raw_addr >> 0) & 0xFF) as u8, + ); Ok(DnsRecord::A { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::UNKNOWN(_) => { - try!(buffer.step(data_len as usize)); + buffer.step(data_len as usize)?; Ok(DnsRecord::UNKNOWN { domain: domain, qtype: qtype_num, data_len: data_len, - ttl: ttl + ttl: ttl, }) } } } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result { - let start_pos = buffer.pos(); match *self { - DnsRecord::A { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::A.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(4)); + DnsRecord::A { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::A.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(4)?; let octets = addr.octets(); - try!(buffer.write_u8(octets[0])); - try!(buffer.write_u8(octets[1])); - try!(buffer.write_u8(octets[2])); - try!(buffer.write_u8(octets[3])); - }, + buffer.write_u8(octets[0])?; + buffer.write_u8(octets[1])?; + buffer.write_u8(octets[2])?; + buffer.write_u8(octets[3])?; + } DnsRecord::UNKNOWN { .. } => { println!("Skipping record: {:?}", self); } @@ -435,7 +447,6 @@ impl DnsRecord { Ok(buffer.pos() - start_pos) } - } #[derive(Clone, Debug)] @@ -444,7 +455,7 @@ pub struct DnsPacket { pub questions: Vec, pub answers: Vec, pub authorities: Vec, - pub resources: Vec + pub resources: Vec, } impl DnsPacket { @@ -454,85 +465,85 @@ impl DnsPacket { questions: Vec::new(), answers: Vec::new(), authorities: Vec::new(), - resources: Vec::new() + resources: Vec::new(), } } pub fn from_buffer(buffer: &mut BytePacketBuffer) -> Result { let mut result = DnsPacket::new(); - try!(result.header.read(buffer)); + result.header.read(buffer)?; for _ in 0..result.header.questions { - let mut question = DnsQuestion::new("".to_string(), - QueryType::UNKNOWN(0)); - try!(question.read(buffer)); + let mut question = DnsQuestion::new("".to_string(), QueryType::UNKNOWN(0)); + question.read(buffer)?; result.questions.push(question); } for _ in 0..result.header.answers { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.answers.push(rec); } for _ in 0..result.header.authoritative_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.authorities.push(rec); } for _ in 0..result.header.resource_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.resources.push(rec); } Ok(result) } - pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> - { + pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { self.header.questions = self.questions.len() as u16; self.header.answers = self.answers.len() as u16; self.header.authoritative_entries = self.authorities.len() as u16; self.header.resource_entries = self.resources.len() as u16; - try!(self.header.write(buffer)); + self.header.write(buffer)?; for question in &self.questions { - try!(question.write(buffer)); + question.write(buffer)?; } for rec in &self.answers { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.authorities { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.resources { - try!(rec.write(buffer)); + rec.write(buffer)?; } Ok(()) } } -fn main() { +fn main() -> Result<()> { let qname = "www.yahoo.com"; let qtype = QueryType::A; let server = ("8.8.8.8", 53); - let socket = UdpSocket::bind(("0.0.0.0", 43210)).unwrap(); + let socket = UdpSocket::bind(("0.0.0.0", 43210))?; let mut packet = DnsPacket::new(); packet.header.id = 6666; packet.header.questions = 1; packet.header.recursion_desired = true; - packet.questions.push(DnsQuestion::new(qname.to_string(), qtype)); + packet + .questions + .push(DnsQuestion::new(qname.to_string(), qtype)); let mut req_buffer = BytePacketBuffer::new(); - packet.write(&mut req_buffer).unwrap(); - socket.send_to(&req_buffer.buf[0..req_buffer.pos], server).unwrap(); + packet.write(&mut req_buffer)?; + socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)?; let mut res_buffer = BytePacketBuffer::new(); - socket.recv_from(&mut res_buffer.buf).unwrap(); + socket.recv_from(&mut res_buffer.buf)?; - let res_packet = DnsPacket::from_buffer(&mut res_buffer).unwrap(); + let res_packet = DnsPacket::from_buffer(&mut res_buffer)?; println!("{:?}", res_packet.header); for q in res_packet.questions { @@ -547,4 +558,6 @@ fn main() { for rec in res_packet.resources { println!("{:?}", rec); } + + Ok(()) } diff --git a/samples/sample3.rs b/examples/sample3.rs similarity index 50% rename from samples/sample3.rs rename to examples/sample3.rs index d012fda..2052475 100644 --- a/samples/sample3.rs +++ b/examples/sample3.rs @@ -1,18 +1,19 @@ -use std::io::{Result, Read}; -use std::io::{Error, ErrorKind}; -use std::net::{Ipv4Addr,Ipv6Addr}; use std::net::UdpSocket; +use std::net::{Ipv4Addr, Ipv6Addr}; + +type Error = Box; +type Result = std::result::Result; pub struct BytePacketBuffer { pub buf: [u8; 512], - pub pos: usize + pub pos: usize, } impl BytePacketBuffer { pub fn new() -> BytePacketBuffer { BytePacketBuffer { buf: [0; 512], - pos: 0 + pos: 0, } } @@ -34,7 +35,7 @@ impl BytePacketBuffer { fn read(&mut self) -> Result { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } let res = self.buf[self.pos]; self.pos += 1; @@ -44,61 +45,66 @@ impl BytePacketBuffer { fn get(&mut self, pos: usize) -> Result { if pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } Ok(self.buf[pos]) } fn get_range(&mut self, start: usize, len: usize) -> Result<&[u8]> { if start + len >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } - Ok(&self.buf[start..start+len as usize]) + Ok(&self.buf[start..start + len as usize]) } - fn read_u16(&mut self) -> Result - { - let res = ((try!(self.read()) as u16) << 8) | - (try!(self.read()) as u16); + fn read_u16(&mut self) -> Result { + let res = ((self.read()? as u16) << 8) | (self.read()? as u16); Ok(res) } - fn read_u32(&mut self) -> Result - { - let res = ((try!(self.read()) as u32) << 24) | - ((try!(self.read()) as u32) << 16) | - ((try!(self.read()) as u32) << 8) | - ((try!(self.read()) as u32) << 0); + fn read_u32(&mut self) -> Result { + let res = ((self.read()? as u32) << 24) + | ((self.read()? as u32) << 16) + | ((self.read()? as u32) << 8) + | ((self.read()? as u32) << 0); Ok(res) } - fn read_qname(&mut self, outstr: &mut String) -> Result<()> - { + fn read_qname(&mut self, outstr: &mut String) -> Result<()> { let mut pos = self.pos(); let mut jumped = false; let mut delim = ""; + let max_jumps = 5; + let mut jumps_performed = 0; loop { - let len = try!(self.get(pos)); + // Dns Packets are untrusted data, so we need to be paranoid. Someone + // can craft a packet with a cycle in the jump instructions. This guards + // against such packets. + if jumps_performed > max_jumps { + return Err(format!("Limit of {} jumps exceeded", max_jumps).into()); + } + + let len = self.get(pos)?; // A two byte sequence, where the two highest bits of the first byte is // set, represents a offset relative to the start of the buffer. We // handle this by jumping to the offset, setting a flag to indicate // that we shouldn't update the shared buffer position once done. if (len & 0xC0) == 0xC0 { - // When a jump is performed, we only modify the shared buffer // position once, and avoid making the change later on. if !jumped { - try!(self.seek(pos+2)); + self.seek(pos + 2)?; } - let b2 = try!(self.get(pos+1)) as u16; + let b2 = self.get(pos + 1)? as u16; let offset = (((len as u16) ^ 0xC0) << 8) | b2; pos = offset as usize; jumped = true; + jumps_performed += 1; continue; } @@ -111,7 +117,7 @@ impl BytePacketBuffer { outstr.push_str(delim); - let str_buffer = try!(self.get_range(pos, len as usize)); + let str_buffer = self.get_range(pos, len as usize)?; outstr.push_str(&String::from_utf8_lossy(str_buffer).to_lowercase()); delim = "."; @@ -120,7 +126,7 @@ impl BytePacketBuffer { } if !jumped { - try!(self.seek(pos)); + self.seek(pos)?; } Ok(()) @@ -128,7 +134,7 @@ impl BytePacketBuffer { fn write(&mut self, val: u8) -> Result<()> { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } self.buf[self.pos] = val; self.pos += 1; @@ -136,44 +142,43 @@ impl BytePacketBuffer { } fn write_u8(&mut self, val: u8) -> Result<()> { - try!(self.write(val)); + self.write(val)?; Ok(()) } fn write_u16(&mut self, val: u16) -> Result<()> { - try!(self.write((val >> 8) as u8)); - try!(self.write((val & 0xFF) as u8)); + self.write((val >> 8) as u8)?; + self.write((val & 0xFF) as u8)?; Ok(()) } fn write_u32(&mut self, val: u32) -> Result<()> { - try!(self.write(((val >> 24) & 0xFF) as u8)); - try!(self.write(((val >> 16) & 0xFF) as u8)); - try!(self.write(((val >> 8) & 0xFF) as u8)); - try!(self.write(((val >> 0) & 0xFF) as u8)); + self.write(((val >> 24) & 0xFF) as u8)?; + self.write(((val >> 16) & 0xFF) as u8)?; + self.write(((val >> 8) & 0xFF) as u8)?; + self.write(((val >> 0) & 0xFF) as u8)?; Ok(()) } fn write_qname(&mut self, qname: &str) -> Result<()> { - let split_str = qname.split('.').collect::>(); for label in split_str { let len = label.len(); if len > 0x34 { - return Err(Error::new(ErrorKind::InvalidInput, "Single label exceeds 63 characters of length")); + return Err("Single label exceeds 63 characters of length".into()); } - try!(self.write_u8(len as u8)); + self.write_u8(len as u8)?; for b in label.as_bytes() { - try!(self.write_u8(*b)); + self.write_u8(*b)?; } } - try!(self.write_u8(0)); + self.write_u8(0)?; Ok(()) } @@ -185,21 +190,21 @@ impl BytePacketBuffer { } fn set_u16(&mut self, pos: usize, val: u16) -> Result<()> { - try!(self.set(pos,(val >> 8) as u8)); - try!(self.set(pos+1,(val & 0xFF) as u8)); + self.set(pos, (val >> 8) as u8)?; + self.set(pos + 1, (val & 0xFF) as u8)?; Ok(()) } } -#[derive(Copy,Clone,Debug,PartialEq,Eq)] +#[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ResultCode { NOERROR = 0, FORMERR = 1, SERVFAIL = 2, NXDOMAIN = 3, NOTIMP = 4, - REFUSED = 5 + REFUSED = 5, } impl ResultCode { @@ -210,59 +215,61 @@ impl ResultCode { 3 => ResultCode::NXDOMAIN, 4 => ResultCode::NOTIMP, 5 => ResultCode::REFUSED, - 0 | _ => ResultCode::NOERROR + 0 | _ => ResultCode::NOERROR, } } } -#[derive(Clone,Debug)] +#[derive(Clone, Debug)] pub struct DnsHeader { pub id: u16, // 16 bits - pub recursion_desired: bool, // 1 bit - pub truncated_message: bool, // 1 bit + pub recursion_desired: bool, // 1 bit + pub truncated_message: bool, // 1 bit pub authoritative_answer: bool, // 1 bit - pub opcode: u8, // 4 bits - pub response: bool, // 1 bit + pub opcode: u8, // 4 bits + pub response: bool, // 1 bit - pub rescode: ResultCode, // 4 bits - pub checking_disabled: bool, // 1 bit - pub authed_data: bool, // 1 bit - pub z: bool, // 1 bit + pub rescode: ResultCode, // 4 bits + pub checking_disabled: bool, // 1 bit + pub authed_data: bool, // 1 bit + pub z: bool, // 1 bit pub recursion_available: bool, // 1 bit - pub questions: u16, // 16 bits - pub answers: u16, // 16 bits + pub questions: u16, // 16 bits + pub answers: u16, // 16 bits pub authoritative_entries: u16, // 16 bits - pub resource_entries: u16 // 16 bits + pub resource_entries: u16, // 16 bits } impl DnsHeader { pub fn new() -> DnsHeader { - DnsHeader { id: 0, + DnsHeader { + id: 0, - recursion_desired: false, - truncated_message: false, - authoritative_answer: false, - opcode: 0, - response: false, + recursion_desired: false, + truncated_message: false, + authoritative_answer: false, + opcode: 0, + response: false, - rescode: ResultCode::NOERROR, - checking_disabled: false, - authed_data: false, - z: false, - recursion_available: false, + rescode: ResultCode::NOERROR, + checking_disabled: false, + authed_data: false, + z: false, + recursion_available: false, - questions: 0, - answers: 0, - authoritative_entries: 0, - resource_entries: 0 } + questions: 0, + answers: 0, + authoritative_entries: 0, + resource_entries: 0, + } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - self.id = try!(buffer.read_u16()); + self.id = buffer.read_u16()?; - let flags = try!(buffer.read_u16()); + let flags = buffer.read_u16()?; let a = (flags >> 8) as u8; let b = (flags & 0xFF) as u8; self.recursion_desired = (a & (1 << 0)) > 0; @@ -277,47 +284,51 @@ impl DnsHeader { self.z = (b & (1 << 6)) > 0; self.recursion_available = (b & (1 << 7)) > 0; - self.questions = try!(buffer.read_u16()); - self.answers = try!(buffer.read_u16()); - self.authoritative_entries = try!(buffer.read_u16()); - self.resource_entries = try!(buffer.read_u16()); + self.questions = buffer.read_u16()?; + self.answers = buffer.read_u16()?; + self.authoritative_entries = buffer.read_u16()?; + self.resource_entries = buffer.read_u16()?; // Return the constant header size Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.write_u16(self.id)); + buffer.write_u16(self.id)?; - try!(buffer.write_u8( ((self.recursion_desired as u8)) | - ((self.truncated_message as u8) << 1) | - ((self.authoritative_answer as u8) << 2) | - (self.opcode << 3) | - ((self.response as u8) << 7) as u8) ); + buffer.write_u8( + (self.recursion_desired as u8) + | ((self.truncated_message as u8) << 1) + | ((self.authoritative_answer as u8) << 2) + | (self.opcode << 3) + | ((self.response as u8) << 7) as u8, + )?; - try!(buffer.write_u8( (self.rescode.clone() as u8) | - ((self.checking_disabled as u8) << 4) | - ((self.authed_data as u8) << 5) | - ((self.z as u8) << 6) | - ((self.recursion_available as u8) << 7) )); + buffer.write_u8( + (self.rescode.clone() as u8) + | ((self.checking_disabled as u8) << 4) + | ((self.authed_data as u8) << 5) + | ((self.z as u8) << 6) + | ((self.recursion_available as u8) << 7), + )?; - try!(buffer.write_u16(self.questions)); - try!(buffer.write_u16(self.answers)); - try!(buffer.write_u16(self.authoritative_entries)); - try!(buffer.write_u16(self.resource_entries)); + buffer.write_u16(self.questions)?; + buffer.write_u16(self.answers)?; + buffer.write_u16(self.authoritative_entries)?; + buffer.write_u16(self.resource_entries)?; Ok(()) } } -#[derive(PartialEq,Eq,Debug,Clone,Hash,Copy)] +#[derive(PartialEq, Eq, Debug, Clone, Hash, Copy)] pub enum QueryType { UNKNOWN(u16), - A, // 1 - NS, // 2 + A, // 1 + NS, // 2 CNAME, // 5 - MX, // 15 - AAAA, // 28 + MX, // 15 + AAAA, // 28 } impl QueryType { @@ -339,246 +350,267 @@ impl QueryType { 5 => QueryType::CNAME, 15 => QueryType::MX, 28 => QueryType::AAAA, - _ => QueryType::UNKNOWN(num) + _ => QueryType::UNKNOWN(num), } } } -#[derive(Debug,Clone,PartialEq,Eq)] +#[derive(Debug, Clone, PartialEq, Eq)] pub struct DnsQuestion { pub name: String, - pub qtype: QueryType + pub qtype: QueryType, } impl DnsQuestion { pub fn new(name: String, qtype: QueryType) -> DnsQuestion { DnsQuestion { name: name, - qtype: qtype + qtype: qtype, } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.read_qname(&mut self.name)); - self.qtype = QueryType::from_num(try!(buffer.read_u16())); // qtype - let _ = try!(buffer.read_u16()); // class + buffer.read_qname(&mut self.name)?; + self.qtype = QueryType::from_num(buffer.read_u16()?); // qtype + let _ = buffer.read_u16()?; // class Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - - try!(buffer.write_qname(&self.name)); + buffer.write_qname(&self.name)?; let typenum = self.qtype.to_num(); - try!(buffer.write_u16(typenum)); - try!(buffer.write_u16(1)); + buffer.write_u16(typenum)?; + buffer.write_u16(1)?; Ok(()) } - } -#[derive(Debug,Clone,PartialEq,Eq,Hash,PartialOrd,Ord)] +#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] #[allow(dead_code)] pub enum DnsRecord { UNKNOWN { domain: String, qtype: u16, data_len: u16, - ttl: u32 + ttl: u32, }, // 0 A { domain: String, addr: Ipv4Addr, - ttl: u32 + ttl: u32, }, // 1 NS { domain: String, host: String, - ttl: u32 + ttl: u32, }, // 2 CNAME { domain: String, host: String, - ttl: u32 + ttl: u32, }, // 5 MX { domain: String, priority: u16, host: String, - ttl: u32 + ttl: u32, }, // 15 AAAA { domain: String, addr: Ipv6Addr, - ttl: u32 + ttl: u32, }, // 28 } impl DnsRecord { - pub fn read(buffer: &mut BytePacketBuffer) -> Result { let mut domain = String::new(); - try!(buffer.read_qname(&mut domain)); + buffer.read_qname(&mut domain)?; - let qtype_num = try!(buffer.read_u16()); + let qtype_num = buffer.read_u16()?; let qtype = QueryType::from_num(qtype_num); - let _ = try!(buffer.read_u16()); - let ttl = try!(buffer.read_u32()); - let data_len = try!(buffer.read_u16()); + let _ = buffer.read_u16()?; + let ttl = buffer.read_u32()?; + let data_len = buffer.read_u16()?; match qtype { - QueryType::A => { - let raw_addr = try!(buffer.read_u32()); - let addr = Ipv4Addr::new(((raw_addr >> 24) & 0xFF) as u8, - ((raw_addr >> 16) & 0xFF) as u8, - ((raw_addr >> 8) & 0xFF) as u8, - ((raw_addr >> 0) & 0xFF) as u8); + QueryType::A => { + let raw_addr = buffer.read_u32()?; + let addr = Ipv4Addr::new( + ((raw_addr >> 24) & 0xFF) as u8, + ((raw_addr >> 16) & 0xFF) as u8, + ((raw_addr >> 8) & 0xFF) as u8, + ((raw_addr >> 0) & 0xFF) as u8, + ); Ok(DnsRecord::A { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::AAAA => { - let raw_addr1 = try!(buffer.read_u32()); - let raw_addr2 = try!(buffer.read_u32()); - let raw_addr3 = try!(buffer.read_u32()); - let raw_addr4 = try!(buffer.read_u32()); - let addr = Ipv6Addr::new(((raw_addr1 >> 16) & 0xFFFF) as u16, - ((raw_addr1 >> 0) & 0xFFFF) as u16, - ((raw_addr2 >> 16) & 0xFFFF) as u16, - ((raw_addr2 >> 0) & 0xFFFF) as u16, - ((raw_addr3 >> 16) & 0xFFFF) as u16, - ((raw_addr3 >> 0) & 0xFFFF) as u16, - ((raw_addr4 >> 16) & 0xFFFF) as u16, - ((raw_addr4 >> 0) & 0xFFFF) as u16); + let raw_addr1 = buffer.read_u32()?; + let raw_addr2 = buffer.read_u32()?; + let raw_addr3 = buffer.read_u32()?; + let raw_addr4 = buffer.read_u32()?; + let addr = Ipv6Addr::new( + ((raw_addr1 >> 16) & 0xFFFF) as u16, + ((raw_addr1 >> 0) & 0xFFFF) as u16, + ((raw_addr2 >> 16) & 0xFFFF) as u16, + ((raw_addr2 >> 0) & 0xFFFF) as u16, + ((raw_addr3 >> 16) & 0xFFFF) as u16, + ((raw_addr3 >> 0) & 0xFFFF) as u16, + ((raw_addr4 >> 16) & 0xFFFF) as u16, + ((raw_addr4 >> 0) & 0xFFFF) as u16, + ); Ok(DnsRecord::AAAA { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::NS => { let mut ns = String::new(); - try!(buffer.read_qname(&mut ns)); + buffer.read_qname(&mut ns)?; Ok(DnsRecord::NS { domain: domain, host: ns, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::CNAME => { let mut cname = String::new(); - try!(buffer.read_qname(&mut cname)); + buffer.read_qname(&mut cname)?; Ok(DnsRecord::CNAME { domain: domain, host: cname, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::MX => { - let priority = try!(buffer.read_u16()); + let priority = buffer.read_u16()?; let mut mx = String::new(); - try!(buffer.read_qname(&mut mx)); + buffer.read_qname(&mut mx)?; Ok(DnsRecord::MX { domain: domain, priority: priority, host: mx, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::UNKNOWN(_) => { - try!(buffer.step(data_len as usize)); + buffer.step(data_len as usize)?; Ok(DnsRecord::UNKNOWN { domain: domain, qtype: qtype_num, data_len: data_len, - ttl: ttl + ttl: ttl, }) } } } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result { - let start_pos = buffer.pos(); match *self { - DnsRecord::A { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::A.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(4)); + DnsRecord::A { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::A.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(4)?; let octets = addr.octets(); - try!(buffer.write_u8(octets[0])); - try!(buffer.write_u8(octets[1])); - try!(buffer.write_u8(octets[2])); - try!(buffer.write_u8(octets[3])); - }, - DnsRecord::NS { ref domain, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::NS.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.write_u8(octets[0])?; + buffer.write_u8(octets[1])?; + buffer.write_u8(octets[2])?; + buffer.write_u8(octets[3])?; + } + DnsRecord::NS { + ref domain, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::NS.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_qname(host)); + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::CNAME { ref domain, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::CNAME.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::CNAME { + ref domain, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::CNAME.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_qname(host)); + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::MX { ref domain, priority, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::MX.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::MX { + ref domain, + priority, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::MX.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_u16(priority)); - try!(buffer.write_qname(host)); + buffer.write_u16(priority)?; + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::AAAA { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::AAAA.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(16)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::AAAA { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::AAAA.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(16)?; for octet in &addr.segments() { - try!(buffer.write_u16(*octet)); + buffer.write_u16(*octet)?; } - }, + } DnsRecord::UNKNOWN { .. } => { println!("Skipping record: {:?}", self); } @@ -586,7 +618,6 @@ impl DnsRecord { Ok(buffer.pos() - start_pos) } - } #[derive(Clone, Debug)] @@ -595,7 +626,7 @@ pub struct DnsPacket { pub questions: Vec, pub answers: Vec, pub authorities: Vec, - pub resources: Vec + pub resources: Vec, } impl DnsPacket { @@ -605,85 +636,85 @@ impl DnsPacket { questions: Vec::new(), answers: Vec::new(), authorities: Vec::new(), - resources: Vec::new() + resources: Vec::new(), } } pub fn from_buffer(buffer: &mut BytePacketBuffer) -> Result { let mut result = DnsPacket::new(); - try!(result.header.read(buffer)); + result.header.read(buffer)?; for _ in 0..result.header.questions { - let mut question = DnsQuestion::new("".to_string(), - QueryType::UNKNOWN(0)); - try!(question.read(buffer)); + let mut question = DnsQuestion::new("".to_string(), QueryType::UNKNOWN(0)); + question.read(buffer)?; result.questions.push(question); } for _ in 0..result.header.answers { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.answers.push(rec); } for _ in 0..result.header.authoritative_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.authorities.push(rec); } for _ in 0..result.header.resource_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.resources.push(rec); } Ok(result) } - pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> - { + pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { self.header.questions = self.questions.len() as u16; self.header.answers = self.answers.len() as u16; self.header.authoritative_entries = self.authorities.len() as u16; self.header.resource_entries = self.resources.len() as u16; - try!(self.header.write(buffer)); + self.header.write(buffer)?; for question in &self.questions { - try!(question.write(buffer)); + question.write(buffer)?; } for rec in &self.answers { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.authorities { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.resources { - try!(rec.write(buffer)); + rec.write(buffer)?; } Ok(()) } } -fn main() { +fn main() -> Result<()> { let qname = "yahoo.com"; let qtype = QueryType::MX; let server = ("8.8.8.8", 53); - let socket = UdpSocket::bind(("0.0.0.0", 43210)).unwrap(); + let socket = UdpSocket::bind(("0.0.0.0", 43210))?; let mut packet = DnsPacket::new(); packet.header.id = 6666; packet.header.questions = 1; packet.header.recursion_desired = true; - packet.questions.push(DnsQuestion::new(qname.to_string(), qtype)); + packet + .questions + .push(DnsQuestion::new(qname.to_string(), qtype)); let mut req_buffer = BytePacketBuffer::new(); - packet.write(&mut req_buffer).unwrap(); - socket.send_to(&req_buffer.buf[0..req_buffer.pos], server).unwrap(); + packet.write(&mut req_buffer)?; + socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)?; let mut res_buffer = BytePacketBuffer::new(); - socket.recv_from(&mut res_buffer.buf).unwrap(); + socket.recv_from(&mut res_buffer.buf)?; - let res_packet = DnsPacket::from_buffer(&mut res_buffer).unwrap(); + let res_packet = DnsPacket::from_buffer(&mut res_buffer)?; println!("{:?}", res_packet.header); for q in res_packet.questions { @@ -698,4 +729,6 @@ fn main() { for rec in res_packet.resources { println!("{:?}", rec); } + + Ok(()) } diff --git a/samples/sample4.rs b/examples/sample4.rs similarity index 55% rename from samples/sample4.rs rename to examples/sample4.rs index d609c52..d85ba9c 100644 --- a/samples/sample4.rs +++ b/examples/sample4.rs @@ -1,18 +1,19 @@ -use std::io::{Result, Read}; -use std::io::{Error, ErrorKind}; -use std::net::{Ipv4Addr,Ipv6Addr}; use std::net::UdpSocket; +use std::net::{Ipv4Addr, Ipv6Addr}; + +type Error = Box; +type Result = std::result::Result; pub struct BytePacketBuffer { pub buf: [u8; 512], - pub pos: usize + pub pos: usize, } impl BytePacketBuffer { pub fn new() -> BytePacketBuffer { BytePacketBuffer { buf: [0; 512], - pos: 0 + pos: 0, } } @@ -34,7 +35,7 @@ impl BytePacketBuffer { fn read(&mut self) -> Result { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } let res = self.buf[self.pos]; self.pos += 1; @@ -44,61 +45,66 @@ impl BytePacketBuffer { fn get(&mut self, pos: usize) -> Result { if pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } Ok(self.buf[pos]) } fn get_range(&mut self, start: usize, len: usize) -> Result<&[u8]> { if start + len >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } - Ok(&self.buf[start..start+len as usize]) + Ok(&self.buf[start..start + len as usize]) } - fn read_u16(&mut self) -> Result - { - let res = ((try!(self.read()) as u16) << 8) | - (try!(self.read()) as u16); + fn read_u16(&mut self) -> Result { + let res = ((self.read()? as u16) << 8) | (self.read()? as u16); Ok(res) } - fn read_u32(&mut self) -> Result - { - let res = ((try!(self.read()) as u32) << 24) | - ((try!(self.read()) as u32) << 16) | - ((try!(self.read()) as u32) << 8) | - ((try!(self.read()) as u32) << 0); + fn read_u32(&mut self) -> Result { + let res = ((self.read()? as u32) << 24) + | ((self.read()? as u32) << 16) + | ((self.read()? as u32) << 8) + | ((self.read()? as u32) << 0); Ok(res) } - fn read_qname(&mut self, outstr: &mut String) -> Result<()> - { + fn read_qname(&mut self, outstr: &mut String) -> Result<()> { let mut pos = self.pos(); let mut jumped = false; let mut delim = ""; + let max_jumps = 5; + let mut jumps_performed = 0; loop { - let len = try!(self.get(pos)); + // Dns Packets are untrusted data, so we need to be paranoid. Someone + // can craft a packet with a cycle in the jump instructions. This guards + // against such packets. + if jumps_performed > max_jumps { + return Err(format!("Limit of {} jumps exceeded", max_jumps).into()); + } + + let len = self.get(pos)?; // A two byte sequence, where the two highest bits of the first byte is // set, represents a offset relative to the start of the buffer. We // handle this by jumping to the offset, setting a flag to indicate // that we shouldn't update the shared buffer position once done. if (len & 0xC0) == 0xC0 { - // When a jump is performed, we only modify the shared buffer // position once, and avoid making the change later on. if !jumped { - try!(self.seek(pos+2)); + self.seek(pos + 2)?; } - let b2 = try!(self.get(pos+1)) as u16; + let b2 = self.get(pos + 1)? as u16; let offset = (((len as u16) ^ 0xC0) << 8) | b2; pos = offset as usize; jumped = true; + jumps_performed += 1; continue; } @@ -111,7 +117,7 @@ impl BytePacketBuffer { outstr.push_str(delim); - let str_buffer = try!(self.get_range(pos, len as usize)); + let str_buffer = self.get_range(pos, len as usize)?; outstr.push_str(&String::from_utf8_lossy(str_buffer).to_lowercase()); delim = "."; @@ -120,7 +126,7 @@ impl BytePacketBuffer { } if !jumped { - try!(self.seek(pos)); + self.seek(pos)?; } Ok(()) @@ -128,7 +134,7 @@ impl BytePacketBuffer { fn write(&mut self, val: u8) -> Result<()> { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } self.buf[self.pos] = val; self.pos += 1; @@ -136,44 +142,43 @@ impl BytePacketBuffer { } fn write_u8(&mut self, val: u8) -> Result<()> { - try!(self.write(val)); + self.write(val)?; Ok(()) } fn write_u16(&mut self, val: u16) -> Result<()> { - try!(self.write((val >> 8) as u8)); - try!(self.write((val & 0xFF) as u8)); + self.write((val >> 8) as u8)?; + self.write((val & 0xFF) as u8)?; Ok(()) } fn write_u32(&mut self, val: u32) -> Result<()> { - try!(self.write(((val >> 24) & 0xFF) as u8)); - try!(self.write(((val >> 16) & 0xFF) as u8)); - try!(self.write(((val >> 8) & 0xFF) as u8)); - try!(self.write(((val >> 0) & 0xFF) as u8)); + self.write(((val >> 24) & 0xFF) as u8)?; + self.write(((val >> 16) & 0xFF) as u8)?; + self.write(((val >> 8) & 0xFF) as u8)?; + self.write(((val >> 0) & 0xFF) as u8)?; Ok(()) } fn write_qname(&mut self, qname: &str) -> Result<()> { - let split_str = qname.split('.').collect::>(); for label in split_str { let len = label.len(); if len > 0x34 { - return Err(Error::new(ErrorKind::InvalidInput, "Single label exceeds 63 characters of length")); + return Err("Single label exceeds 63 characters of length".into()); } - try!(self.write_u8(len as u8)); + self.write_u8(len as u8)?; for b in label.as_bytes() { - try!(self.write_u8(*b)); + self.write_u8(*b)?; } } - try!(self.write_u8(0)); + self.write_u8(0)?; Ok(()) } @@ -185,21 +190,21 @@ impl BytePacketBuffer { } fn set_u16(&mut self, pos: usize, val: u16) -> Result<()> { - try!(self.set(pos,(val >> 8) as u8)); - try!(self.set(pos+1,(val & 0xFF) as u8)); + self.set(pos, (val >> 8) as u8)?; + self.set(pos + 1, (val & 0xFF) as u8)?; Ok(()) } } -#[derive(Copy,Clone,Debug,PartialEq,Eq)] +#[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ResultCode { NOERROR = 0, FORMERR = 1, SERVFAIL = 2, NXDOMAIN = 3, NOTIMP = 4, - REFUSED = 5 + REFUSED = 5, } impl ResultCode { @@ -210,59 +215,61 @@ impl ResultCode { 3 => ResultCode::NXDOMAIN, 4 => ResultCode::NOTIMP, 5 => ResultCode::REFUSED, - 0 | _ => ResultCode::NOERROR + 0 | _ => ResultCode::NOERROR, } } } -#[derive(Clone,Debug)] +#[derive(Clone, Debug)] pub struct DnsHeader { pub id: u16, // 16 bits - pub recursion_desired: bool, // 1 bit - pub truncated_message: bool, // 1 bit + pub recursion_desired: bool, // 1 bit + pub truncated_message: bool, // 1 bit pub authoritative_answer: bool, // 1 bit - pub opcode: u8, // 4 bits - pub response: bool, // 1 bit + pub opcode: u8, // 4 bits + pub response: bool, // 1 bit - pub rescode: ResultCode, // 4 bits - pub checking_disabled: bool, // 1 bit - pub authed_data: bool, // 1 bit - pub z: bool, // 1 bit + pub rescode: ResultCode, // 4 bits + pub checking_disabled: bool, // 1 bit + pub authed_data: bool, // 1 bit + pub z: bool, // 1 bit pub recursion_available: bool, // 1 bit - pub questions: u16, // 16 bits - pub answers: u16, // 16 bits + pub questions: u16, // 16 bits + pub answers: u16, // 16 bits pub authoritative_entries: u16, // 16 bits - pub resource_entries: u16 // 16 bits + pub resource_entries: u16, // 16 bits } impl DnsHeader { pub fn new() -> DnsHeader { - DnsHeader { id: 0, + DnsHeader { + id: 0, - recursion_desired: false, - truncated_message: false, - authoritative_answer: false, - opcode: 0, - response: false, + recursion_desired: false, + truncated_message: false, + authoritative_answer: false, + opcode: 0, + response: false, - rescode: ResultCode::NOERROR, - checking_disabled: false, - authed_data: false, - z: false, - recursion_available: false, + rescode: ResultCode::NOERROR, + checking_disabled: false, + authed_data: false, + z: false, + recursion_available: false, - questions: 0, - answers: 0, - authoritative_entries: 0, - resource_entries: 0 } + questions: 0, + answers: 0, + authoritative_entries: 0, + resource_entries: 0, + } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - self.id = try!(buffer.read_u16()); + self.id = buffer.read_u16()?; - let flags = try!(buffer.read_u16()); + let flags = buffer.read_u16()?; let a = (flags >> 8) as u8; let b = (flags & 0xFF) as u8; self.recursion_desired = (a & (1 << 0)) > 0; @@ -277,47 +284,51 @@ impl DnsHeader { self.z = (b & (1 << 6)) > 0; self.recursion_available = (b & (1 << 7)) > 0; - self.questions = try!(buffer.read_u16()); - self.answers = try!(buffer.read_u16()); - self.authoritative_entries = try!(buffer.read_u16()); - self.resource_entries = try!(buffer.read_u16()); + self.questions = buffer.read_u16()?; + self.answers = buffer.read_u16()?; + self.authoritative_entries = buffer.read_u16()?; + self.resource_entries = buffer.read_u16()?; // Return the constant header size Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.write_u16(self.id)); + buffer.write_u16(self.id)?; - try!(buffer.write_u8( ((self.recursion_desired as u8)) | - ((self.truncated_message as u8) << 1) | - ((self.authoritative_answer as u8) << 2) | - (self.opcode << 3) | - ((self.response as u8) << 7) as u8) ); + buffer.write_u8( + (self.recursion_desired as u8) + | ((self.truncated_message as u8) << 1) + | ((self.authoritative_answer as u8) << 2) + | (self.opcode << 3) + | ((self.response as u8) << 7) as u8, + )?; - try!(buffer.write_u8( (self.rescode.clone() as u8) | - ((self.checking_disabled as u8) << 4) | - ((self.authed_data as u8) << 5) | - ((self.z as u8) << 6) | - ((self.recursion_available as u8) << 7) )); + buffer.write_u8( + (self.rescode.clone() as u8) + | ((self.checking_disabled as u8) << 4) + | ((self.authed_data as u8) << 5) + | ((self.z as u8) << 6) + | ((self.recursion_available as u8) << 7), + )?; - try!(buffer.write_u16(self.questions)); - try!(buffer.write_u16(self.answers)); - try!(buffer.write_u16(self.authoritative_entries)); - try!(buffer.write_u16(self.resource_entries)); + buffer.write_u16(self.questions)?; + buffer.write_u16(self.answers)?; + buffer.write_u16(self.authoritative_entries)?; + buffer.write_u16(self.resource_entries)?; Ok(()) } } -#[derive(PartialEq,Eq,Debug,Clone,Hash,Copy)] +#[derive(PartialEq, Eq, Debug, Clone, Hash, Copy)] pub enum QueryType { UNKNOWN(u16), - A, // 1 - NS, // 2 + A, // 1 + NS, // 2 CNAME, // 5 - MX, // 15 - AAAA, // 28 + MX, // 15 + AAAA, // 28 } impl QueryType { @@ -339,246 +350,267 @@ impl QueryType { 5 => QueryType::CNAME, 15 => QueryType::MX, 28 => QueryType::AAAA, - _ => QueryType::UNKNOWN(num) + _ => QueryType::UNKNOWN(num), } } } -#[derive(Debug,Clone,PartialEq,Eq)] +#[derive(Debug, Clone, PartialEq, Eq)] pub struct DnsQuestion { pub name: String, - pub qtype: QueryType + pub qtype: QueryType, } impl DnsQuestion { pub fn new(name: String, qtype: QueryType) -> DnsQuestion { DnsQuestion { name: name, - qtype: qtype + qtype: qtype, } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.read_qname(&mut self.name)); - self.qtype = QueryType::from_num(try!(buffer.read_u16())); // qtype - let _ = try!(buffer.read_u16()); // class + buffer.read_qname(&mut self.name)?; + self.qtype = QueryType::from_num(buffer.read_u16()?); // qtype + let _ = buffer.read_u16()?; // class Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - - try!(buffer.write_qname(&self.name)); + buffer.write_qname(&self.name)?; let typenum = self.qtype.to_num(); - try!(buffer.write_u16(typenum)); - try!(buffer.write_u16(1)); + buffer.write_u16(typenum)?; + buffer.write_u16(1)?; Ok(()) } - } -#[derive(Debug,Clone,PartialEq,Eq,Hash,PartialOrd,Ord)] +#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] #[allow(dead_code)] pub enum DnsRecord { UNKNOWN { domain: String, qtype: u16, data_len: u16, - ttl: u32 + ttl: u32, }, // 0 A { domain: String, addr: Ipv4Addr, - ttl: u32 + ttl: u32, }, // 1 NS { domain: String, host: String, - ttl: u32 + ttl: u32, }, // 2 CNAME { domain: String, host: String, - ttl: u32 + ttl: u32, }, // 5 MX { domain: String, priority: u16, host: String, - ttl: u32 + ttl: u32, }, // 15 AAAA { domain: String, addr: Ipv6Addr, - ttl: u32 + ttl: u32, }, // 28 } impl DnsRecord { - pub fn read(buffer: &mut BytePacketBuffer) -> Result { let mut domain = String::new(); - try!(buffer.read_qname(&mut domain)); + buffer.read_qname(&mut domain)?; - let qtype_num = try!(buffer.read_u16()); + let qtype_num = buffer.read_u16()?; let qtype = QueryType::from_num(qtype_num); - let _ = try!(buffer.read_u16()); - let ttl = try!(buffer.read_u32()); - let data_len = try!(buffer.read_u16()); + let _ = buffer.read_u16()?; + let ttl = buffer.read_u32()?; + let data_len = buffer.read_u16()?; match qtype { - QueryType::A => { - let raw_addr = try!(buffer.read_u32()); - let addr = Ipv4Addr::new(((raw_addr >> 24) & 0xFF) as u8, - ((raw_addr >> 16) & 0xFF) as u8, - ((raw_addr >> 8) & 0xFF) as u8, - ((raw_addr >> 0) & 0xFF) as u8); + QueryType::A => { + let raw_addr = buffer.read_u32()?; + let addr = Ipv4Addr::new( + ((raw_addr >> 24) & 0xFF) as u8, + ((raw_addr >> 16) & 0xFF) as u8, + ((raw_addr >> 8) & 0xFF) as u8, + ((raw_addr >> 0) & 0xFF) as u8, + ); Ok(DnsRecord::A { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::AAAA => { - let raw_addr1 = try!(buffer.read_u32()); - let raw_addr2 = try!(buffer.read_u32()); - let raw_addr3 = try!(buffer.read_u32()); - let raw_addr4 = try!(buffer.read_u32()); - let addr = Ipv6Addr::new(((raw_addr1 >> 16) & 0xFFFF) as u16, - ((raw_addr1 >> 0) & 0xFFFF) as u16, - ((raw_addr2 >> 16) & 0xFFFF) as u16, - ((raw_addr2 >> 0) & 0xFFFF) as u16, - ((raw_addr3 >> 16) & 0xFFFF) as u16, - ((raw_addr3 >> 0) & 0xFFFF) as u16, - ((raw_addr4 >> 16) & 0xFFFF) as u16, - ((raw_addr4 >> 0) & 0xFFFF) as u16); + let raw_addr1 = buffer.read_u32()?; + let raw_addr2 = buffer.read_u32()?; + let raw_addr3 = buffer.read_u32()?; + let raw_addr4 = buffer.read_u32()?; + let addr = Ipv6Addr::new( + ((raw_addr1 >> 16) & 0xFFFF) as u16, + ((raw_addr1 >> 0) & 0xFFFF) as u16, + ((raw_addr2 >> 16) & 0xFFFF) as u16, + ((raw_addr2 >> 0) & 0xFFFF) as u16, + ((raw_addr3 >> 16) & 0xFFFF) as u16, + ((raw_addr3 >> 0) & 0xFFFF) as u16, + ((raw_addr4 >> 16) & 0xFFFF) as u16, + ((raw_addr4 >> 0) & 0xFFFF) as u16, + ); Ok(DnsRecord::AAAA { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::NS => { let mut ns = String::new(); - try!(buffer.read_qname(&mut ns)); + buffer.read_qname(&mut ns)?; Ok(DnsRecord::NS { domain: domain, host: ns, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::CNAME => { let mut cname = String::new(); - try!(buffer.read_qname(&mut cname)); + buffer.read_qname(&mut cname)?; Ok(DnsRecord::CNAME { domain: domain, host: cname, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::MX => { - let priority = try!(buffer.read_u16()); + let priority = buffer.read_u16()?; let mut mx = String::new(); - try!(buffer.read_qname(&mut mx)); + buffer.read_qname(&mut mx)?; Ok(DnsRecord::MX { domain: domain, priority: priority, host: mx, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::UNKNOWN(_) => { - try!(buffer.step(data_len as usize)); + buffer.step(data_len as usize)?; Ok(DnsRecord::UNKNOWN { domain: domain, qtype: qtype_num, data_len: data_len, - ttl: ttl + ttl: ttl, }) } } } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result { - let start_pos = buffer.pos(); match *self { - DnsRecord::A { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::A.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(4)); + DnsRecord::A { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::A.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(4)?; let octets = addr.octets(); - try!(buffer.write_u8(octets[0])); - try!(buffer.write_u8(octets[1])); - try!(buffer.write_u8(octets[2])); - try!(buffer.write_u8(octets[3])); - }, - DnsRecord::NS { ref domain, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::NS.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.write_u8(octets[0])?; + buffer.write_u8(octets[1])?; + buffer.write_u8(octets[2])?; + buffer.write_u8(octets[3])?; + } + DnsRecord::NS { + ref domain, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::NS.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_qname(host)); + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::CNAME { ref domain, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::CNAME.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::CNAME { + ref domain, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::CNAME.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_qname(host)); + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::MX { ref domain, priority, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::MX.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::MX { + ref domain, + priority, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::MX.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_u16(priority)); - try!(buffer.write_qname(host)); + buffer.write_u16(priority)?; + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::AAAA { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::AAAA.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(16)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::AAAA { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::AAAA.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(16)?; for octet in &addr.segments() { - try!(buffer.write_u16(*octet)); + buffer.write_u16(*octet)?; } - }, + } DnsRecord::UNKNOWN { .. } => { println!("Skipping record: {:?}", self); } @@ -586,7 +618,6 @@ impl DnsRecord { Ok(buffer.pos() - start_pos) } - } #[derive(Clone, Debug)] @@ -595,7 +626,7 @@ pub struct DnsPacket { pub questions: Vec, pub answers: Vec, pub authorities: Vec, - pub resources: Vec + pub resources: Vec, } impl DnsPacket { @@ -605,57 +636,55 @@ impl DnsPacket { questions: Vec::new(), answers: Vec::new(), authorities: Vec::new(), - resources: Vec::new() + resources: Vec::new(), } } pub fn from_buffer(buffer: &mut BytePacketBuffer) -> Result { let mut result = DnsPacket::new(); - try!(result.header.read(buffer)); + result.header.read(buffer)?; for _ in 0..result.header.questions { - let mut question = DnsQuestion::new("".to_string(), - QueryType::UNKNOWN(0)); - try!(question.read(buffer)); + let mut question = DnsQuestion::new("".to_string(), QueryType::UNKNOWN(0)); + question.read(buffer)?; result.questions.push(question); } for _ in 0..result.header.answers { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.answers.push(rec); } for _ in 0..result.header.authoritative_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.authorities.push(rec); } for _ in 0..result.header.resource_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.resources.push(rec); } Ok(result) } - pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> - { + pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { self.header.questions = self.questions.len() as u16; self.header.answers = self.answers.len() as u16; self.header.authoritative_entries = self.authorities.len() as u16; self.header.resource_entries = self.resources.len() as u16; - try!(self.header.write(buffer)); + self.header.write(buffer)?; for question in &self.questions { - try!(question.write(buffer)); + question.write(buffer)?; } for rec in &self.answers { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.authorities { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.resources { - try!(rec.write(buffer)); + rec.write(buffer)?; } Ok(()) @@ -663,29 +692,31 @@ impl DnsPacket { } fn lookup(qname: &str, qtype: QueryType, server: (&str, u16)) -> Result { - let socket = try!(UdpSocket::bind(("0.0.0.0", 43210))); + let socket = UdpSocket::bind(("0.0.0.0", 43210))?; let mut packet = DnsPacket::new(); packet.header.id = 6666; packet.header.questions = 1; packet.header.recursion_desired = true; - packet.questions.push(DnsQuestion::new(qname.to_string(), qtype)); + packet + .questions + .push(DnsQuestion::new(qname.to_string(), qtype)); let mut req_buffer = BytePacketBuffer::new(); - packet.write(&mut req_buffer).unwrap(); - try!(socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)); + packet.write(&mut req_buffer)?; + socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)?; let mut res_buffer = BytePacketBuffer::new(); - socket.recv_from(&mut res_buffer.buf).unwrap(); + socket.recv_from(&mut res_buffer.buf)?; DnsPacket::from_buffer(&mut res_buffer) } -fn main() { +fn main() -> Result<()> { let server = ("8.8.8.8", 53); - let socket = UdpSocket::bind(("0.0.0.0", 2053)).unwrap(); + let socket = UdpSocket::bind(("0.0.0.0", 2053))?; loop { let mut req_buffer = BytePacketBuffer::new(); @@ -713,8 +744,7 @@ fn main() { if request.questions.is_empty() { packet.header.rescode = ResultCode::FORMERR; - } - else { + } else { let question = &request.questions[0]; println!("Received query: {:?}", question); @@ -741,7 +771,7 @@ fn main() { let mut res_buffer = BytePacketBuffer::new(); match packet.write(&mut res_buffer) { - Ok(_) => {}, + Ok(_) => {} Err(e) => { println!("Failed to encode UDP response packet: {:?}", e); continue; @@ -758,7 +788,7 @@ fn main() { }; match socket.send_to(data, src) { - Ok(_) => {}, + Ok(_) => {} Err(e) => { println!("Failed to send response buffer: {:?}", e); continue; diff --git a/samples/sample5.rs b/examples/sample5.rs similarity index 58% rename from samples/sample5.rs rename to examples/sample5.rs index a53f0f1..191fdd6 100644 --- a/samples/sample5.rs +++ b/examples/sample5.rs @@ -1,18 +1,19 @@ -use std::io::{Result, Read}; -use std::io::{Error, ErrorKind}; -use std::net::{Ipv4Addr,Ipv6Addr}; use std::net::UdpSocket; +use std::net::{Ipv4Addr, Ipv6Addr}; + +type Error = Box; +type Result = std::result::Result; pub struct BytePacketBuffer { pub buf: [u8; 512], - pub pos: usize + pub pos: usize, } impl BytePacketBuffer { pub fn new() -> BytePacketBuffer { BytePacketBuffer { buf: [0; 512], - pos: 0 + pos: 0, } } @@ -34,7 +35,7 @@ impl BytePacketBuffer { fn read(&mut self) -> Result { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } let res = self.buf[self.pos]; self.pos += 1; @@ -44,61 +45,66 @@ impl BytePacketBuffer { fn get(&mut self, pos: usize) -> Result { if pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } Ok(self.buf[pos]) } fn get_range(&mut self, start: usize, len: usize) -> Result<&[u8]> { if start + len >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } - Ok(&self.buf[start..start+len as usize]) + Ok(&self.buf[start..start + len as usize]) } - fn read_u16(&mut self) -> Result - { - let res = ((try!(self.read()) as u16) << 8) | - (try!(self.read()) as u16); + fn read_u16(&mut self) -> Result { + let res = ((self.read()? as u16) << 8) | (self.read()? as u16); Ok(res) } - fn read_u32(&mut self) -> Result - { - let res = ((try!(self.read()) as u32) << 24) | - ((try!(self.read()) as u32) << 16) | - ((try!(self.read()) as u32) << 8) | - ((try!(self.read()) as u32) << 0); + fn read_u32(&mut self) -> Result { + let res = ((self.read()? as u32) << 24) + | ((self.read()? as u32) << 16) + | ((self.read()? as u32) << 8) + | ((self.read()? as u32) << 0); Ok(res) } - fn read_qname(&mut self, outstr: &mut String) -> Result<()> - { + fn read_qname(&mut self, outstr: &mut String) -> Result<()> { let mut pos = self.pos(); let mut jumped = false; let mut delim = ""; + let max_jumps = 5; + let mut jumps_performed = 0; loop { - let len = try!(self.get(pos)); + // Dns Packets are untrusted data, so we need to be paranoid. Someone + // can craft a packet with a cycle in the jump instructions. This guards + // against such packets. + if jumps_performed > max_jumps { + return Err(format!("Limit of {} jumps exceeded", max_jumps).into()); + } + + let len = self.get(pos)?; // A two byte sequence, where the two highest bits of the first byte is // set, represents a offset relative to the start of the buffer. We // handle this by jumping to the offset, setting a flag to indicate // that we shouldn't update the shared buffer position once done. if (len & 0xC0) == 0xC0 { - // When a jump is performed, we only modify the shared buffer // position once, and avoid making the change later on. if !jumped { - try!(self.seek(pos+2)); + self.seek(pos + 2)?; } - let b2 = try!(self.get(pos+1)) as u16; + let b2 = self.get(pos + 1)? as u16; let offset = (((len as u16) ^ 0xC0) << 8) | b2; pos = offset as usize; jumped = true; + jumps_performed += 1; continue; } @@ -111,7 +117,7 @@ impl BytePacketBuffer { outstr.push_str(delim); - let str_buffer = try!(self.get_range(pos, len as usize)); + let str_buffer = self.get_range(pos, len as usize)?; outstr.push_str(&String::from_utf8_lossy(str_buffer).to_lowercase()); delim = "."; @@ -120,7 +126,7 @@ impl BytePacketBuffer { } if !jumped { - try!(self.seek(pos)); + self.seek(pos)?; } Ok(()) @@ -128,7 +134,7 @@ impl BytePacketBuffer { fn write(&mut self, val: u8) -> Result<()> { if self.pos >= 512 { - return Err(Error::new(ErrorKind::InvalidInput, "End of buffer")); + return Err("End of buffer".into()); } self.buf[self.pos] = val; self.pos += 1; @@ -136,44 +142,43 @@ impl BytePacketBuffer { } fn write_u8(&mut self, val: u8) -> Result<()> { - try!(self.write(val)); + self.write(val)?; Ok(()) } fn write_u16(&mut self, val: u16) -> Result<()> { - try!(self.write((val >> 8) as u8)); - try!(self.write((val & 0xFF) as u8)); + self.write((val >> 8) as u8)?; + self.write((val & 0xFF) as u8)?; Ok(()) } fn write_u32(&mut self, val: u32) -> Result<()> { - try!(self.write(((val >> 24) & 0xFF) as u8)); - try!(self.write(((val >> 16) & 0xFF) as u8)); - try!(self.write(((val >> 8) & 0xFF) as u8)); - try!(self.write(((val >> 0) & 0xFF) as u8)); + self.write(((val >> 24) & 0xFF) as u8)?; + self.write(((val >> 16) & 0xFF) as u8)?; + self.write(((val >> 8) & 0xFF) as u8)?; + self.write(((val >> 0) & 0xFF) as u8)?; Ok(()) } fn write_qname(&mut self, qname: &str) -> Result<()> { - let split_str = qname.split('.').collect::>(); for label in split_str { let len = label.len(); if len > 0x34 { - return Err(Error::new(ErrorKind::InvalidInput, "Single label exceeds 63 characters of length")); + return Err("Single label exceeds 63 characters of length".into()); } - try!(self.write_u8(len as u8)); + self.write_u8(len as u8)?; for b in label.as_bytes() { - try!(self.write_u8(*b)); + self.write_u8(*b)?; } } - try!(self.write_u8(0)); + self.write_u8(0)?; Ok(()) } @@ -185,21 +190,21 @@ impl BytePacketBuffer { } fn set_u16(&mut self, pos: usize, val: u16) -> Result<()> { - try!(self.set(pos,(val >> 8) as u8)); - try!(self.set(pos+1,(val & 0xFF) as u8)); + self.set(pos, (val >> 8) as u8)?; + self.set(pos + 1, (val & 0xFF) as u8)?; Ok(()) } } -#[derive(Copy,Clone,Debug,PartialEq,Eq)] +#[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ResultCode { NOERROR = 0, FORMERR = 1, SERVFAIL = 2, NXDOMAIN = 3, NOTIMP = 4, - REFUSED = 5 + REFUSED = 5, } impl ResultCode { @@ -210,59 +215,61 @@ impl ResultCode { 3 => ResultCode::NXDOMAIN, 4 => ResultCode::NOTIMP, 5 => ResultCode::REFUSED, - 0 | _ => ResultCode::NOERROR + 0 | _ => ResultCode::NOERROR, } } } -#[derive(Clone,Debug)] +#[derive(Clone, Debug)] pub struct DnsHeader { pub id: u16, // 16 bits - pub recursion_desired: bool, // 1 bit - pub truncated_message: bool, // 1 bit + pub recursion_desired: bool, // 1 bit + pub truncated_message: bool, // 1 bit pub authoritative_answer: bool, // 1 bit - pub opcode: u8, // 4 bits - pub response: bool, // 1 bit + pub opcode: u8, // 4 bits + pub response: bool, // 1 bit - pub rescode: ResultCode, // 4 bits - pub checking_disabled: bool, // 1 bit - pub authed_data: bool, // 1 bit - pub z: bool, // 1 bit + pub rescode: ResultCode, // 4 bits + pub checking_disabled: bool, // 1 bit + pub authed_data: bool, // 1 bit + pub z: bool, // 1 bit pub recursion_available: bool, // 1 bit - pub questions: u16, // 16 bits - pub answers: u16, // 16 bits + pub questions: u16, // 16 bits + pub answers: u16, // 16 bits pub authoritative_entries: u16, // 16 bits - pub resource_entries: u16 // 16 bits + pub resource_entries: u16, // 16 bits } impl DnsHeader { pub fn new() -> DnsHeader { - DnsHeader { id: 0, + DnsHeader { + id: 0, - recursion_desired: false, - truncated_message: false, - authoritative_answer: false, - opcode: 0, - response: false, + recursion_desired: false, + truncated_message: false, + authoritative_answer: false, + opcode: 0, + response: false, - rescode: ResultCode::NOERROR, - checking_disabled: false, - authed_data: false, - z: false, - recursion_available: false, + rescode: ResultCode::NOERROR, + checking_disabled: false, + authed_data: false, + z: false, + recursion_available: false, - questions: 0, - answers: 0, - authoritative_entries: 0, - resource_entries: 0 } + questions: 0, + answers: 0, + authoritative_entries: 0, + resource_entries: 0, + } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - self.id = try!(buffer.read_u16()); + self.id = buffer.read_u16()?; - let flags = try!(buffer.read_u16()); + let flags = buffer.read_u16()?; let a = (flags >> 8) as u8; let b = (flags & 0xFF) as u8; self.recursion_desired = (a & (1 << 0)) > 0; @@ -277,47 +284,51 @@ impl DnsHeader { self.z = (b & (1 << 6)) > 0; self.recursion_available = (b & (1 << 7)) > 0; - self.questions = try!(buffer.read_u16()); - self.answers = try!(buffer.read_u16()); - self.authoritative_entries = try!(buffer.read_u16()); - self.resource_entries = try!(buffer.read_u16()); + self.questions = buffer.read_u16()?; + self.answers = buffer.read_u16()?; + self.authoritative_entries = buffer.read_u16()?; + self.resource_entries = buffer.read_u16()?; // Return the constant header size Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.write_u16(self.id)); + buffer.write_u16(self.id)?; - try!(buffer.write_u8( ((self.recursion_desired as u8)) | - ((self.truncated_message as u8) << 1) | - ((self.authoritative_answer as u8) << 2) | - (self.opcode << 3) | - ((self.response as u8) << 7) as u8) ); + buffer.write_u8( + (self.recursion_desired as u8) + | ((self.truncated_message as u8) << 1) + | ((self.authoritative_answer as u8) << 2) + | (self.opcode << 3) + | ((self.response as u8) << 7) as u8, + )?; - try!(buffer.write_u8( (self.rescode.clone() as u8) | - ((self.checking_disabled as u8) << 4) | - ((self.authed_data as u8) << 5) | - ((self.z as u8) << 6) | - ((self.recursion_available as u8) << 7) )); + buffer.write_u8( + (self.rescode.clone() as u8) + | ((self.checking_disabled as u8) << 4) + | ((self.authed_data as u8) << 5) + | ((self.z as u8) << 6) + | ((self.recursion_available as u8) << 7), + )?; - try!(buffer.write_u16(self.questions)); - try!(buffer.write_u16(self.answers)); - try!(buffer.write_u16(self.authoritative_entries)); - try!(buffer.write_u16(self.resource_entries)); + buffer.write_u16(self.questions)?; + buffer.write_u16(self.answers)?; + buffer.write_u16(self.authoritative_entries)?; + buffer.write_u16(self.resource_entries)?; Ok(()) } } -#[derive(PartialEq,Eq,Debug,Clone,Hash,Copy)] +#[derive(PartialEq, Eq, Debug, Clone, Hash, Copy)] pub enum QueryType { UNKNOWN(u16), - A, // 1 - NS, // 2 + A, // 1 + NS, // 2 CNAME, // 5 - MX, // 15 - AAAA, // 28 + MX, // 15 + AAAA, // 28 } impl QueryType { @@ -339,246 +350,267 @@ impl QueryType { 5 => QueryType::CNAME, 15 => QueryType::MX, 28 => QueryType::AAAA, - _ => QueryType::UNKNOWN(num) + _ => QueryType::UNKNOWN(num), } } } -#[derive(Debug,Clone,PartialEq,Eq)] +#[derive(Debug, Clone, PartialEq, Eq)] pub struct DnsQuestion { pub name: String, - pub qtype: QueryType + pub qtype: QueryType, } impl DnsQuestion { pub fn new(name: String, qtype: QueryType) -> DnsQuestion { DnsQuestion { name: name, - qtype: qtype + qtype: qtype, } } pub fn read(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { - try!(buffer.read_qname(&mut self.name)); - self.qtype = QueryType::from_num(try!(buffer.read_u16())); // qtype - let _ = try!(buffer.read_u16()); // class + buffer.read_qname(&mut self.name)?; + self.qtype = QueryType::from_num(buffer.read_u16()?); // qtype + let _ = buffer.read_u16()?; // class Ok(()) } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result<()> { - - try!(buffer.write_qname(&self.name)); + buffer.write_qname(&self.name)?; let typenum = self.qtype.to_num(); - try!(buffer.write_u16(typenum)); - try!(buffer.write_u16(1)); + buffer.write_u16(typenum)?; + buffer.write_u16(1)?; Ok(()) } - } -#[derive(Debug,Clone,PartialEq,Eq,Hash,PartialOrd,Ord)] +#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] #[allow(dead_code)] pub enum DnsRecord { UNKNOWN { domain: String, qtype: u16, data_len: u16, - ttl: u32 + ttl: u32, }, // 0 A { domain: String, addr: Ipv4Addr, - ttl: u32 + ttl: u32, }, // 1 NS { domain: String, host: String, - ttl: u32 + ttl: u32, }, // 2 CNAME { domain: String, host: String, - ttl: u32 + ttl: u32, }, // 5 MX { domain: String, priority: u16, host: String, - ttl: u32 + ttl: u32, }, // 15 AAAA { domain: String, addr: Ipv6Addr, - ttl: u32 + ttl: u32, }, // 28 } impl DnsRecord { - pub fn read(buffer: &mut BytePacketBuffer) -> Result { let mut domain = String::new(); - try!(buffer.read_qname(&mut domain)); + buffer.read_qname(&mut domain)?; - let qtype_num = try!(buffer.read_u16()); + let qtype_num = buffer.read_u16()?; let qtype = QueryType::from_num(qtype_num); - let _ = try!(buffer.read_u16()); - let ttl = try!(buffer.read_u32()); - let data_len = try!(buffer.read_u16()); + let _ = buffer.read_u16()?; + let ttl = buffer.read_u32()?; + let data_len = buffer.read_u16()?; match qtype { - QueryType::A => { - let raw_addr = try!(buffer.read_u32()); - let addr = Ipv4Addr::new(((raw_addr >> 24) & 0xFF) as u8, - ((raw_addr >> 16) & 0xFF) as u8, - ((raw_addr >> 8) & 0xFF) as u8, - ((raw_addr >> 0) & 0xFF) as u8); + QueryType::A => { + let raw_addr = buffer.read_u32()?; + let addr = Ipv4Addr::new( + ((raw_addr >> 24) & 0xFF) as u8, + ((raw_addr >> 16) & 0xFF) as u8, + ((raw_addr >> 8) & 0xFF) as u8, + ((raw_addr >> 0) & 0xFF) as u8, + ); Ok(DnsRecord::A { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::AAAA => { - let raw_addr1 = try!(buffer.read_u32()); - let raw_addr2 = try!(buffer.read_u32()); - let raw_addr3 = try!(buffer.read_u32()); - let raw_addr4 = try!(buffer.read_u32()); - let addr = Ipv6Addr::new(((raw_addr1 >> 16) & 0xFFFF) as u16, - ((raw_addr1 >> 0) & 0xFFFF) as u16, - ((raw_addr2 >> 16) & 0xFFFF) as u16, - ((raw_addr2 >> 0) & 0xFFFF) as u16, - ((raw_addr3 >> 16) & 0xFFFF) as u16, - ((raw_addr3 >> 0) & 0xFFFF) as u16, - ((raw_addr4 >> 16) & 0xFFFF) as u16, - ((raw_addr4 >> 0) & 0xFFFF) as u16); + let raw_addr1 = buffer.read_u32()?; + let raw_addr2 = buffer.read_u32()?; + let raw_addr3 = buffer.read_u32()?; + let raw_addr4 = buffer.read_u32()?; + let addr = Ipv6Addr::new( + ((raw_addr1 >> 16) & 0xFFFF) as u16, + ((raw_addr1 >> 0) & 0xFFFF) as u16, + ((raw_addr2 >> 16) & 0xFFFF) as u16, + ((raw_addr2 >> 0) & 0xFFFF) as u16, + ((raw_addr3 >> 16) & 0xFFFF) as u16, + ((raw_addr3 >> 0) & 0xFFFF) as u16, + ((raw_addr4 >> 16) & 0xFFFF) as u16, + ((raw_addr4 >> 0) & 0xFFFF) as u16, + ); Ok(DnsRecord::AAAA { domain: domain, addr: addr, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::NS => { let mut ns = String::new(); - try!(buffer.read_qname(&mut ns)); + buffer.read_qname(&mut ns)?; Ok(DnsRecord::NS { domain: domain, host: ns, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::CNAME => { let mut cname = String::new(); - try!(buffer.read_qname(&mut cname)); + buffer.read_qname(&mut cname)?; Ok(DnsRecord::CNAME { domain: domain, host: cname, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::MX => { - let priority = try!(buffer.read_u16()); + let priority = buffer.read_u16()?; let mut mx = String::new(); - try!(buffer.read_qname(&mut mx)); + buffer.read_qname(&mut mx)?; Ok(DnsRecord::MX { domain: domain, priority: priority, host: mx, - ttl: ttl + ttl: ttl, }) - }, + } QueryType::UNKNOWN(_) => { - try!(buffer.step(data_len as usize)); + buffer.step(data_len as usize)?; Ok(DnsRecord::UNKNOWN { domain: domain, qtype: qtype_num, data_len: data_len, - ttl: ttl + ttl: ttl, }) } } } pub fn write(&self, buffer: &mut BytePacketBuffer) -> Result { - let start_pos = buffer.pos(); match *self { - DnsRecord::A { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::A.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(4)); + DnsRecord::A { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::A.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(4)?; let octets = addr.octets(); - try!(buffer.write_u8(octets[0])); - try!(buffer.write_u8(octets[1])); - try!(buffer.write_u8(octets[2])); - try!(buffer.write_u8(octets[3])); - }, - DnsRecord::NS { ref domain, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::NS.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.write_u8(octets[0])?; + buffer.write_u8(octets[1])?; + buffer.write_u8(octets[2])?; + buffer.write_u8(octets[3])?; + } + DnsRecord::NS { + ref domain, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::NS.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_qname(host)); + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::CNAME { ref domain, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::CNAME.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::CNAME { + ref domain, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::CNAME.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_qname(host)); + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::MX { ref domain, priority, ref host, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::MX.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::MX { + ref domain, + priority, + ref host, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::MX.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; let pos = buffer.pos(); - try!(buffer.write_u16(0)); + buffer.write_u16(0)?; - try!(buffer.write_u16(priority)); - try!(buffer.write_qname(host)); + buffer.write_u16(priority)?; + buffer.write_qname(host)?; let size = buffer.pos() - (pos + 2); - try!(buffer.set_u16(pos, size as u16)); - }, - DnsRecord::AAAA { ref domain, ref addr, ttl } => { - try!(buffer.write_qname(domain)); - try!(buffer.write_u16(QueryType::AAAA.to_num())); - try!(buffer.write_u16(1)); - try!(buffer.write_u32(ttl)); - try!(buffer.write_u16(16)); + buffer.set_u16(pos, size as u16)?; + } + DnsRecord::AAAA { + ref domain, + ref addr, + ttl, + } => { + buffer.write_qname(domain)?; + buffer.write_u16(QueryType::AAAA.to_num())?; + buffer.write_u16(1)?; + buffer.write_u32(ttl)?; + buffer.write_u16(16)?; for octet in &addr.segments() { - try!(buffer.write_u16(*octet)); + buffer.write_u16(*octet)?; } - }, + } DnsRecord::UNKNOWN { .. } => { println!("Skipping record: {:?}", self); } @@ -586,7 +618,6 @@ impl DnsRecord { Ok(buffer.pos() - start_pos) } - } #[derive(Clone, Debug)] @@ -595,7 +626,7 @@ pub struct DnsPacket { pub questions: Vec, pub answers: Vec, pub authorities: Vec, - pub resources: Vec + pub resources: Vec, } impl DnsPacket { @@ -605,57 +636,55 @@ impl DnsPacket { questions: Vec::new(), answers: Vec::new(), authorities: Vec::new(), - resources: Vec::new() + resources: Vec::new(), } } pub fn from_buffer(buffer: &mut BytePacketBuffer) -> Result { let mut result = DnsPacket::new(); - try!(result.header.read(buffer)); + result.header.read(buffer)?; for _ in 0..result.header.questions { - let mut question = DnsQuestion::new("".to_string(), - QueryType::UNKNOWN(0)); - try!(question.read(buffer)); + let mut question = DnsQuestion::new("".to_string(), QueryType::UNKNOWN(0)); + question.read(buffer)?; result.questions.push(question); } for _ in 0..result.header.answers { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.answers.push(rec); } for _ in 0..result.header.authoritative_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.authorities.push(rec); } for _ in 0..result.header.resource_entries { - let rec = try!(DnsRecord::read(buffer)); + let rec = DnsRecord::read(buffer)?; result.resources.push(rec); } Ok(result) } - pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> - { + pub fn write(&mut self, buffer: &mut BytePacketBuffer) -> Result<()> { self.header.questions = self.questions.len() as u16; self.header.answers = self.answers.len() as u16; self.header.authoritative_entries = self.authorities.len() as u16; self.header.resource_entries = self.resources.len() as u16; - try!(self.header.write(buffer)); + self.header.write(buffer)?; for question in &self.questions { - try!(question.write(buffer)); + question.write(buffer)?; } for rec in &self.answers { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.authorities { - try!(rec.write(buffer)); + rec.write(buffer)?; } for rec in &self.resources { - try!(rec.write(buffer)); + rec.write(buffer)?; } Ok(()) @@ -664,7 +693,7 @@ impl DnsPacket { pub fn get_random_a(&self) -> Option { if !self.answers.is_empty() { let a_record = &self.answers[0]; - if let DnsRecord::A{ ref addr, .. } = *a_record { + if let DnsRecord::A { ref addr, .. } = *a_record { return Some(addr.to_string()); } } @@ -673,16 +702,25 @@ impl DnsPacket { } pub fn get_resolved_ns(&self, qname: &str) -> Option { - let mut new_authorities = Vec::new(); for auth in &self.authorities { - if let DnsRecord::NS { ref domain, ref host, .. } = *auth { + if let DnsRecord::NS { + ref domain, + ref host, + .. + } = *auth + { if !qname.ends_with(domain) { continue; } for rsrc in &self.resources { - if let DnsRecord::A{ ref domain, ref addr, ttl } = *rsrc { + if let DnsRecord::A { + ref domain, + ref addr, + ttl, + } = *rsrc + { if domain != host { continue; } @@ -690,7 +728,7 @@ impl DnsPacket { let rec = DnsRecord::A { domain: host.clone(), addr: *addr, - ttl: ttl + ttl: ttl, }; new_authorities.push(rec); @@ -709,10 +747,14 @@ impl DnsPacket { } pub fn get_unresolved_ns(&self, qname: &str) -> Option { - let mut new_authorities = Vec::new(); for auth in &self.authorities { - if let DnsRecord::NS { ref domain, ref host, .. } = *auth { + if let DnsRecord::NS { + ref domain, + ref host, + .. + } = *auth + { if !qname.ends_with(domain) { continue; } @@ -727,31 +769,31 @@ impl DnsPacket { None } - } fn lookup(qname: &str, qtype: QueryType, server: (&str, u16)) -> Result { - let socket = try!(UdpSocket::bind(("0.0.0.0", 43210))); + let socket = UdpSocket::bind(("0.0.0.0", 43210))?; let mut packet = DnsPacket::new(); packet.header.id = 6666; packet.header.questions = 1; packet.header.recursion_desired = true; - packet.questions.push(DnsQuestion::new(qname.to_string(), qtype)); + packet + .questions + .push(DnsQuestion::new(qname.to_string(), qtype)); let mut req_buffer = BytePacketBuffer::new(); - packet.write(&mut req_buffer).unwrap(); - try!(socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)); + packet.write(&mut req_buffer)?; + socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)?; let mut res_buffer = BytePacketBuffer::new(); - socket.recv_from(&mut res_buffer.buf).unwrap(); + socket.recv_from(&mut res_buffer.buf)?; DnsPacket::from_buffer(&mut res_buffer) } fn recursive_lookup(qname: &str, qtype: QueryType) -> Result { - let mut ns = "198.41.0.4".to_string(); // Start querying name servers @@ -761,12 +803,10 @@ fn recursive_lookup(qname: &str, qtype: QueryType) -> Result { let ns_copy = ns.clone(); let server = (ns_copy.as_str(), 53); - let response = try!(lookup(qname, qtype.clone(), server)); + let response = lookup(qname, qtype.clone(), server)?; // If we've got an actual answer, we're done! - if !response.answers.is_empty() && - response.header.rescode == ResultCode::NOERROR { - + if !response.answers.is_empty() && response.header.rescode == ResultCode::NOERROR { return Ok(response.clone()); } @@ -786,23 +826,23 @@ fn recursive_lookup(qname: &str, qtype: QueryType) -> Result { // If not, we'll have to resolve the ip of a NS record let new_ns_name = match response.get_unresolved_ns(qname) { Some(x) => x, - None => return Ok(response.clone()) + None => return Ok(response.clone()), }; // Recursively resolve the NS - let recursive_response = try!(recursive_lookup(&new_ns_name, QueryType::A)); + let recursive_response = recursive_lookup(&new_ns_name, QueryType::A)?; // Pick a random IP and restart if let Some(new_ns) = recursive_response.get_random_a() { ns = new_ns.clone(); } else { - return Ok(response.clone()) + return Ok(response.clone()); } } } -fn main() { - let socket = UdpSocket::bind(("0.0.0.0", 2053)).unwrap(); +fn main() -> Result<()> { + let socket = UdpSocket::bind(("0.0.0.0", 2053))?; loop { let mut req_buffer = BytePacketBuffer::new(); @@ -830,8 +870,7 @@ fn main() { if request.questions.is_empty() { packet.header.rescode = ResultCode::FORMERR; - } - else { + } else { let question = &request.questions[0]; println!("Received query: {:?}", question); @@ -858,7 +897,7 @@ fn main() { let mut res_buffer = BytePacketBuffer::new(); match packet.write(&mut res_buffer) { - Ok(_) => {}, + Ok(_) => {} Err(e) => { println!("Failed to encode UDP response packet: {:?}", e); continue; @@ -875,7 +914,7 @@ fn main() { }; match socket.send_to(data, src) { - Ok(_) => {}, + Ok(_) => {} Err(e) => { println!("Failed to send response buffer: {:?}", e); continue;