diff options
Diffstat (limited to 'third_party/rust/dns-parser/src/header.rs')
| -rw-r--r-- | third_party/rust/dns-parser/src/header.rs | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/third_party/rust/dns-parser/src/header.rs b/third_party/rust/dns-parser/src/header.rs new file mode 100644 index 0000000000..01d18add99 --- /dev/null +++ b/third_party/rust/dns-parser/src/header.rs @@ -0,0 +1,203 @@ +use byteorder::{BigEndian, ByteOrder}; + +use {Error, ResponseCode, Opcode}; + +mod flag { + pub const QUERY: u16 = 0b1000_0000_0000_0000; + pub const OPCODE_MASK: u16 = 0b0111_1000_0000_0000; + pub const AUTHORITATIVE: u16 = 0b0000_0100_0000_0000; + pub const TRUNCATED: u16 = 0b0000_0010_0000_0000; + pub const RECURSION_DESIRED: u16 = 0b0000_0001_0000_0000; + pub const RECURSION_AVAILABLE: u16 = 0b0000_0000_1000_0000; + pub const AUTHENTICATED_DATA: u16 = 0b0000_0000_0010_0000; + pub const CHECKING_DISABLED: u16 = 0b0000_0000_0001_0000; + pub const RESERVED_MASK: u16 = 0b0000_0000_0100_0000; + pub const RESPONSE_CODE_MASK: u16 = 0b0000_0000_0000_1111; +} + +/// Represents parsed header of the packet +#[derive(Debug, PartialEq, Eq, Clone, Copy)] +#[allow(missing_docs)] // fields are from the spec I think +pub struct Header { + pub id: u16, + pub query: bool, + pub opcode: Opcode, + pub authoritative: bool, + pub truncated: bool, + pub recursion_desired: bool, + pub recursion_available: bool, + pub authenticated_data: bool, + pub checking_disabled: bool, + pub response_code: ResponseCode, + pub questions: u16, + pub answers: u16, + pub nameservers: u16, + pub additional: u16, +} + +impl Header { + /// Parse the header into a header structure + pub fn parse(data: &[u8]) -> Result<Header, Error> { + if data.len() < 12 { + return Err(Error::HeaderTooShort); + } + let flags = BigEndian::read_u16(&data[2..4]); + if flags & flag::RESERVED_MASK != 0 { + return Err(Error::ReservedBitsAreNonZero); + } + let header = Header { + id: BigEndian::read_u16(&data[..2]), + query: flags & flag::QUERY == 0, + opcode: ((flags & flag::OPCODE_MASK) + >> flag::OPCODE_MASK.trailing_zeros()).into(), + authoritative: flags & flag::AUTHORITATIVE != 0, + truncated: flags & flag::TRUNCATED != 0, + recursion_desired: flags & flag::RECURSION_DESIRED != 0, + recursion_available: flags & flag::RECURSION_AVAILABLE != 0, + authenticated_data: flags & flag::AUTHENTICATED_DATA != 0, + checking_disabled: flags & flag::CHECKING_DISABLED != 0, + response_code: From::from((flags&flag::RESPONSE_CODE_MASK) as u8), + questions: BigEndian::read_u16(&data[4..6]), + answers: BigEndian::read_u16(&data[6..8]), + nameservers: BigEndian::read_u16(&data[8..10]), + additional: BigEndian::read_u16(&data[10..12]), + }; + Ok(header) + } + /// Write a header to a buffer slice + /// + /// # Panics + /// + /// When buffer size is not exactly 12 bytes + pub fn write(&self, data: &mut [u8]) { + if data.len() != 12 { + panic!("Header size is exactly 12 bytes"); + } + let mut flags = 0u16; + flags |= Into::<u16>::into(self.opcode) + << flag::OPCODE_MASK.trailing_zeros(); + flags |= Into::<u8>::into(self.response_code) as u16; + if !self.query { flags |= flag::QUERY; } + if self.authoritative { flags |= flag::AUTHORITATIVE; } + if self.recursion_desired { flags |= flag::RECURSION_DESIRED; } + if self.recursion_available { flags |= flag::RECURSION_AVAILABLE; } + if self.truncated { flags |= flag::TRUNCATED; } + BigEndian::write_u16(&mut data[..2], self.id); + BigEndian::write_u16(&mut data[2..4], flags); + BigEndian::write_u16(&mut data[4..6], self.questions); + BigEndian::write_u16(&mut data[6..8], self.answers); + BigEndian::write_u16(&mut data[8..10], self.nameservers); + BigEndian::write_u16(&mut data[10..12], self.additional); + } + /// Set "truncated flag" in the raw data + // shouldn't this method be non-public? + pub fn set_truncated(data: &mut [u8]) { + let oldflags = BigEndian::read_u16(&data[2..4]); + BigEndian::write_u16(&mut data[2..4], oldflags & flag::TRUNCATED); + } + /// Returns a size of the header (always 12 bytes) + pub fn size() -> usize { 12 } +} + + +#[cfg(test)] +mod test { + + use {Header}; + use Opcode::*; + use ResponseCode::NoError; + + #[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 header = Header::parse(query).unwrap(); + assert_eq!(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, + }); + } + + #[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 header = Header::parse(response).unwrap(); + assert_eq!(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, + }); + } + + #[test] + fn parse_query_with_ad_set() { + let query = b"\x06%\x01\x20\x00\x01\x00\x00\x00\x00\x00\x00\ + \x07example\x03com\x00\x00\x01\x00\x01"; + let header = Header::parse(query).unwrap(); + assert_eq!(header, Header { + id: 1573, + query: true, + opcode: StandardQuery, + authoritative: false, + truncated: false, + recursion_desired: true, + recursion_available: false, + authenticated_data: true, + checking_disabled: false, + response_code: NoError, + questions: 1, + answers: 0, + nameservers: 0, + additional: 0, + }); + } + + #[test] + fn parse_query_with_cd_set() { + let query = b"\x06%\x01\x10\x00\x01\x00\x00\x00\x00\x00\x00\ + \x07example\x03com\x00\x00\x01\x00\x01"; + let header = Header::parse(query).unwrap(); + assert_eq!(header, Header { + id: 1573, + query: true, + opcode: StandardQuery, + authoritative: false, + truncated: false, + recursion_desired: true, + recursion_available: false, + authenticated_data: false, + checking_disabled: true, + response_code: NoError, + questions: 1, + answers: 0, + nameservers: 0, + additional: 0, + }); + } +} |