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use std::i32;
use byteorder::{BigEndian, ByteOrder};
use {Header, Packet, Error, Question, Name, QueryType, QueryClass};
use {Type, Class, ResourceRecord, RData};
use rdata::opt::Record as Opt;
const OPT_RR_START: [u8; 3] = [0, 0, 41];
impl<'a> Packet<'a> {
/// Parse a full DNS Packet and return a structure that has all the
/// data borrowed from the passed buffer.
pub fn parse(data: &[u8]) -> Result<Packet, Error> {
let header = try!(Header::parse(data));
let mut offset = Header::size();
let mut questions = Vec::with_capacity(header.questions as usize);
for _ in 0..header.questions {
let name = try!(Name::scan(&data[offset..], data));
offset += name.byte_len();
if offset + 4 > data.len() {
return Err(Error::UnexpectedEOF);
}
let qtype = try!(QueryType::parse(
BigEndian::read_u16(&data[offset..offset+2])));
offset += 2;
let (prefer_unicast, qclass) = try!(parse_qclass_code(
BigEndian::read_u16(&data[offset..offset+2])));
offset += 2;
questions.push(Question {
qname: name,
qtype: qtype,
prefer_unicast: prefer_unicast,
qclass: qclass,
});
}
let mut answers = Vec::with_capacity(header.answers as usize);
for _ in 0..header.answers {
answers.push(try!(parse_record(data, &mut offset)));
}
let mut nameservers = Vec::with_capacity(header.nameservers as usize);
for _ in 0..header.nameservers {
nameservers.push(try!(parse_record(data, &mut offset)));
}
let mut additional = Vec::with_capacity(header.additional as usize);
let mut opt = None;
for _ in 0..header.additional {
if offset + 3 <= data.len() && data[offset..offset+3] == OPT_RR_START {
if opt.is_none() {
opt = Some(try!(parse_opt_record(data, &mut offset)));
} else {
return Err(Error::AdditionalOPT);
}
} else {
additional.push(try!(parse_record(data, &mut offset)));
}
}
Ok(Packet {
header: header,
questions: questions,
answers: answers,
nameservers: nameservers,
additional: additional,
opt: opt,
})
}
}
fn parse_qclass_code(value: u16) -> Result<(bool, QueryClass), Error> {
let prefer_unicast = value & 0x8000 == 0x8000;
let qclass_code = value & 0x7FFF;
let qclass = try!(QueryClass::parse(qclass_code));
Ok((prefer_unicast, qclass))
}
fn parse_class_code(value: u16) -> Result<(bool, Class), Error> {
let is_unique = value & 0x8000 == 0x8000;
let class_code = value & 0x7FFF;
let cls = try!(Class::parse(class_code));
Ok((is_unique, cls))
}
// Generic function to parse answer, nameservers, and additional records.
fn parse_record<'a>(data: &'a [u8], offset: &mut usize) -> Result<ResourceRecord<'a>, Error> {
let name = try!(Name::scan(&data[*offset..], data));
*offset += name.byte_len();
if *offset + 10 > data.len() {
return Err(Error::UnexpectedEOF);
}
let typ = try!(Type::parse(
BigEndian::read_u16(&data[*offset..*offset+2])));
*offset += 2;
let class_code = BigEndian::read_u16(&data[*offset..*offset+2]);
let (multicast_unique, cls) = try!(parse_class_code(class_code));
*offset += 2;
let mut ttl = BigEndian::read_u32(&data[*offset..*offset+4]);
if ttl > i32::MAX as u32 {
ttl = 0;
}
*offset += 4;
let rdlen = BigEndian::read_u16(&data[*offset..*offset+2]) as usize;
*offset += 2;
if *offset + rdlen > data.len() {
return Err(Error::UnexpectedEOF);
}
let data = try!(RData::parse(typ,
&data[*offset..*offset+rdlen], data));
*offset += rdlen;
Ok(ResourceRecord {
name: name,
multicast_unique: multicast_unique,
cls: cls,
ttl: ttl,
data: data,
})
}
// Function to parse an RFC 6891 OPT Pseudo RR
fn parse_opt_record<'a>(data: &'a [u8], offset: &mut usize) -> Result<Opt<'a>, Error> {
if *offset + 11 > data.len() {
return Err(Error::UnexpectedEOF);
}
*offset += 1;
let typ = try!(Type::parse(
BigEndian::read_u16(&data[*offset..*offset+2])));
if typ != Type::OPT {
return Err(Error::InvalidType(typ as u16));
}
*offset += 2;
let udp = BigEndian::read_u16(&data[*offset..*offset+2]);
*offset += 2;
let extrcode = data[*offset];
*offset += 1;
let version = data[*offset];
*offset += 1;
let flags = BigEndian::read_u16(&data[*offset..*offset+2]);
*offset += 2;
let rdlen = BigEndian::read_u16(&data[*offset..*offset+2]) as usize;
*offset += 2;
if *offset + rdlen > data.len() {
return Err(Error::UnexpectedEOF);
}
let data = try!(RData::parse(typ,
&data[*offset..*offset+rdlen], data));
*offset += rdlen;
Ok(Opt {
udp: udp,
extrcode: extrcode,
version: version,
flags: flags,
data: data,
})
}
#[cfg(test)]
mod test {
use std::net::Ipv4Addr;
use {Packet, Header};
use Opcode::*;
use ResponseCode::NoError;
use QueryType as QT;
use QueryClass as QC;
use Class as C;
use RData;
#[test]
fn parse_example_query() {
let query = b"\x06%\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\
\x07example\x03com\x00\x00\x01\x00\x01";
let packet = Packet::parse(query).unwrap();
assert_eq!(packet.header, Header {
id: 1573,
query: true,
opcode: StandardQuery,
authoritative: false,
truncated: false,
recursion_desired: true,
recursion_available: false,
authenticated_data: false,
checking_disabled: false,
response_code: NoError,
questions: 1,
answers: 0,
nameservers: 0,
additional: 0,
});
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::A);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(&packet.questions[0].qname.to_string()[..], "example.com");
assert_eq!(packet.answers.len(), 0);
}
#[test]
fn parse_example_response() {
let response = b"\x06%\x81\x80\x00\x01\x00\x01\x00\x00\x00\x00\
\x07example\x03com\x00\x00\x01\x00\x01\
\xc0\x0c\x00\x01\x00\x01\x00\x00\x04\xf8\
\x00\x04]\xb8\xd8\"";
let packet = Packet::parse(response).unwrap();
assert_eq!(packet.header, Header {
id: 1573,
query: false,
opcode: StandardQuery,
authoritative: false,
truncated: false,
recursion_desired: true,
recursion_available: true,
authenticated_data: false,
checking_disabled: false,
response_code: NoError,
questions: 1,
answers: 1,
nameservers: 0,
additional: 0,
});
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::A);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(&packet.questions[0].qname.to_string()[..], "example.com");
assert_eq!(packet.answers.len(), 1);
assert_eq!(&packet.answers[0].name.to_string()[..], "example.com");
assert_eq!(packet.answers[0].multicast_unique, false);
assert_eq!(packet.answers[0].cls, C::IN);
assert_eq!(packet.answers[0].ttl, 1272);
match packet.answers[0].data {
RData::A(addr) => {
assert_eq!(addr.0, Ipv4Addr::new(93, 184, 216, 34));
}
ref x => panic!("Wrong rdata {:?}", x),
}
}
#[test]
fn parse_response_with_multicast_unique() {
let response = b"\x06%\x81\x80\x00\x01\x00\x01\x00\x00\x00\x00\
\x07example\x03com\x00\x00\x01\x00\x01\
\xc0\x0c\x00\x01\x80\x01\x00\x00\x04\xf8\
\x00\x04]\xb8\xd8\"";
let packet = Packet::parse(response).unwrap();
assert_eq!(packet.answers.len(), 1);
assert_eq!(packet.answers[0].multicast_unique, true);
assert_eq!(packet.answers[0].cls, C::IN);
}
#[test]
fn parse_additional_record_response() {
let response = b"\x4a\xf0\x81\x80\x00\x01\x00\x01\x00\x01\x00\x01\
\x03www\x05skype\x03com\x00\x00\x01\x00\x01\
\xc0\x0c\x00\x05\x00\x01\x00\x00\x0e\x10\
\x00\x1c\x07\x6c\x69\x76\x65\x63\x6d\x73\x0e\x74\
\x72\x61\x66\x66\x69\x63\x6d\x61\x6e\x61\x67\x65\
\x72\x03\x6e\x65\x74\x00\
\xc0\x42\x00\x02\x00\x01\x00\x01\xd5\xd3\x00\x11\
\x01\x67\x0c\x67\x74\x6c\x64\x2d\x73\x65\x72\x76\x65\x72\x73\
\xc0\x42\
\x01\x61\xc0\x55\x00\x01\x00\x01\x00\x00\xa3\x1c\
\x00\x04\xc0\x05\x06\x1e";
let packet = Packet::parse(response).unwrap();
assert_eq!(packet.header, Header {
id: 19184,
query: false,
opcode: StandardQuery,
authoritative: false,
truncated: false,
recursion_desired: true,
recursion_available: true,
authenticated_data: false,
checking_disabled: false,
response_code: NoError,
questions: 1,
answers: 1,
nameservers: 1,
additional: 1,
});
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::A);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(&packet.questions[0].qname.to_string()[..], "www.skype.com");
assert_eq!(packet.answers.len(), 1);
assert_eq!(&packet.answers[0].name.to_string()[..], "www.skype.com");
assert_eq!(packet.answers[0].cls, C::IN);
assert_eq!(packet.answers[0].ttl, 3600);
match packet.answers[0].data {
RData::CNAME(cname) => {
assert_eq!(&cname.0.to_string()[..], "livecms.trafficmanager.net");
}
ref x => panic!("Wrong rdata {:?}", x),
}
assert_eq!(packet.nameservers.len(), 1);
assert_eq!(&packet.nameservers[0].name.to_string()[..], "net");
assert_eq!(packet.nameservers[0].cls, C::IN);
assert_eq!(packet.nameservers[0].ttl, 120275);
match packet.nameservers[0].data {
RData::NS(ns) => {
assert_eq!(&ns.0.to_string()[..], "g.gtld-servers.net");
}
ref x => panic!("Wrong rdata {:?}", x),
}
assert_eq!(packet.additional.len(), 1);
assert_eq!(&packet.additional[0].name.to_string()[..], "a.gtld-servers.net");
assert_eq!(packet.additional[0].cls, C::IN);
assert_eq!(packet.additional[0].ttl, 41756);
match packet.additional[0].data {
RData::A(addr) => {
assert_eq!(addr.0, Ipv4Addr::new(192, 5, 6, 30));
}
ref x => panic!("Wrong rdata {:?}", x),
}
}
#[test]
fn parse_multiple_answers() {
let response = b"\x9d\xe9\x81\x80\x00\x01\x00\x06\x00\x00\x00\x00\
\x06google\x03com\x00\x00\x01\x00\x01\xc0\x0c\
\x00\x01\x00\x01\x00\x00\x00\xef\x00\x04@\xe9\
\xa4d\xc0\x0c\x00\x01\x00\x01\x00\x00\x00\xef\
\x00\x04@\xe9\xa4\x8b\xc0\x0c\x00\x01\x00\x01\
\x00\x00\x00\xef\x00\x04@\xe9\xa4q\xc0\x0c\x00\
\x01\x00\x01\x00\x00\x00\xef\x00\x04@\xe9\xa4f\
\xc0\x0c\x00\x01\x00\x01\x00\x00\x00\xef\x00\x04@\
\xe9\xa4e\xc0\x0c\x00\x01\x00\x01\x00\x00\x00\xef\
\x00\x04@\xe9\xa4\x8a";
let packet = Packet::parse(response).unwrap();
assert_eq!(packet.header, Header {
id: 40425,
query: false,
opcode: StandardQuery,
authoritative: false,
truncated: false,
recursion_desired: true,
recursion_available: true,
authenticated_data: false,
checking_disabled: false,
response_code: NoError,
questions: 1,
answers: 6,
nameservers: 0,
additional: 0,
});
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::A);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(&packet.questions[0].qname.to_string()[..], "google.com");
assert_eq!(packet.answers.len(), 6);
let ips = vec![
Ipv4Addr::new(64, 233, 164, 100),
Ipv4Addr::new(64, 233, 164, 139),
Ipv4Addr::new(64, 233, 164, 113),
Ipv4Addr::new(64, 233, 164, 102),
Ipv4Addr::new(64, 233, 164, 101),
Ipv4Addr::new(64, 233, 164, 138),
];
for i in 0..6 {
assert_eq!(&packet.answers[i].name.to_string()[..], "google.com");
assert_eq!(packet.answers[i].cls, C::IN);
assert_eq!(packet.answers[i].ttl, 239);
match packet.answers[i].data {
RData::A(addr) => {
assert_eq!(addr.0, ips[i]);
}
ref x => panic!("Wrong rdata {:?}", x),
}
}
}
#[test]
fn parse_srv_query() {
let query = b"[\xd9\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\
\x0c_xmpp-server\x04_tcp\x05gmail\x03com\x00\x00!\x00\x01";
let packet = Packet::parse(query).unwrap();
assert_eq!(packet.header, Header {
id: 23513,
query: true,
opcode: StandardQuery,
authoritative: false,
truncated: false,
recursion_desired: true,
recursion_available: false,
authenticated_data: false,
checking_disabled: false,
response_code: NoError,
questions: 1,
answers: 0,
nameservers: 0,
additional: 0,
});
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::SRV);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(packet.questions[0].prefer_unicast, false);
assert_eq!(&packet.questions[0].qname.to_string()[..],
"_xmpp-server._tcp.gmail.com");
assert_eq!(packet.answers.len(), 0);
}
#[test]
fn parse_multicast_prefer_unicast_query() {
let query = b"\x06%\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\
\x07example\x03com\x00\x00\x01\x80\x01";
let packet = Packet::parse(query).unwrap();
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::A);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(packet.questions[0].prefer_unicast, true);
}
#[test]
fn parse_example_query_edns() {
let query = b"\x95\xce\x01\x00\x00\x01\x00\x00\x00\x00\x00\x01\
\x06google\x03com\x00\x00\x01\x00\
\x01\x00\x00\x29\x10\x00\x00\x00\x00\x00\x00\x00";
let packet = Packet::parse(query).unwrap();
assert_eq!(packet.header, Header {
id: 38350,
query: true,
opcode: StandardQuery,
authoritative: false,
truncated: false,
recursion_desired: true,
recursion_available: false,
authenticated_data: false,
checking_disabled: false,
response_code: NoError,
questions: 1,
answers: 0,
nameservers: 0,
additional: 1,
});
assert_eq!(packet.questions.len(), 1);
assert_eq!(packet.questions[0].qtype, QT::A);
assert_eq!(packet.questions[0].qclass, QC::IN);
assert_eq!(&packet.questions[0].qname.to_string()[..], "google.com");
assert_eq!(packet.answers.len(), 0);
match packet.opt {
Some(opt) => {
assert_eq!(opt.udp, 4096);
assert_eq!(opt.extrcode, 0);
assert_eq!(opt.version, 0);
assert_eq!(opt.flags, 0);
},
None => panic!("Missing OPT RR")
}
}
}