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Implement serializing answers, authorities and additionals #5

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15 changes: 10 additions & 5 deletions src/dns.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -258,10 +258,15 @@ impl Message {
req.extend_from_slice(&(question.class as u16).to_be_bytes());
}

// TODO Implement answers, etc types.
assert!(self.answers.is_empty());
assert!(self.authoritys.is_empty());
assert!(self.additionals.is_empty());
for record in &self.answers {
record.write(&mut req)?
}
for record in &self.authoritys {
record.write(&mut req)?
}
for record in &self.additionals {
record.write(&mut req)?
}

if let Some(e) = &self.extension {
e.write(&mut req)?
Expand All @@ -279,7 +284,7 @@ impl Message {
/// any compressed pointers) in bytes.
///
// TODO Support compression.
fn write_qname(buf: &mut Vec<u8>, domain: &str) -> io::Result<()> {
pub(crate) fn write_qname(buf: &mut Vec<u8>, domain: &str) -> io::Result<()> {
// Decode this label into the original unicode.
// TODO Switch to using our own idna::Config. (but we can't use disallowed_by_std3_ascii_rules).
let domain = match idna::domain_to_ascii(domain) {
Expand Down
108 changes: 89 additions & 19 deletions src/resource.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,43 @@ pub type PTR = String;
pub struct TXT(pub Vec<Vec<u8>>);

impl Record {
pub(crate) fn write(&self, bfr: &mut Vec<u8>) -> io::Result<()> {
Message::write_qname(bfr, &self.name)?;
bfr.extend_from_slice(&(self.r#type() as u16).to_be_bytes());
bfr.extend_from_slice(&(self.class as u16).to_be_bytes());
bfr.extend_from_slice(&(self.ttl.as_secs() as u32).to_be_bytes());

// At this point we don't know the total length of this record
// Create a temporary buffer that's going to be added to the final
// buffer later

let mut record: Vec<u8> = Vec::new();

match &self.resource {
Resource::A(ip4) => record.extend_from_slice(&ip4.octets()),
Resource::AAAA(ip6) => record.extend_from_slice(&ip6.octets()),

Resource::NS(str) => Message::write_qname(&mut record, &str)?,
Resource::SOA(soa) => soa.write(&mut record)?,
Resource::CNAME(str) => Message::write_qname(&mut record, &str)?,
Resource::PTR(str) => Message::write_qname(&mut record, &str)?,
Resource::MX(mx) => mx.write(&mut record)?,
Resource::TXT(txt) => txt.write(&mut record),
Resource::SPF(spf) => spf.write(&mut record),
Resource::SRV(srv) => srv.write(&mut record)?,

Resource::OPT | Resource::ANY => {
bail!(InvalidData, "invalid record type '{}'", self.r#type());
}
};

// Merge the record buffer into the final one
bfr.extend_from_slice(&(record.len() as u16).to_be_bytes());
bfr.extend(record);

Ok(())
}

pub(crate) fn parse(
cur: &mut Cursor<&[u8]>,
name: String,
Expand Down Expand Up @@ -74,8 +111,8 @@ impl Record {
Type::CNAME => Resource::CNAME(record.read_qname()?),
Type::PTR => Resource::PTR(record.read_qname()?),
Type::MX => Resource::MX(MX::parse(&mut record)?),
Type::TXT => Resource::TXT(parse_txt(&mut record)?),
Type::SPF => Resource::SPF(parse_txt(&mut record)?),
Type::TXT => Resource::TXT(TXT::parse(&mut record)?),
Type::SPF => Resource::SPF(TXT::parse(&mut record)?),
Type::SRV => Resource::SRV(SRV::parse(&mut record)?),

// This should never appear in a answer record unless we have invalid data.
Expand Down Expand Up @@ -177,25 +214,34 @@ fn parse_aaaa(cur: &mut Cursor<&[u8]>, class: Class) -> io::Result<AAAA> {
}
}

fn parse_txt(cur: &mut Cursor<&[u8]>) -> io::Result<TXT> {
let mut txts = Vec::new();

loop {
// Keep reading until EOF is reached.
let len = match cur.read_u8() {
Ok(len) => len,
Err(e) => match e.kind() {
io::ErrorKind::UnexpectedEof => break,
_ => return Err(e),
},
};

let mut txt = vec![0; len.into()];
cur.read_exact(&mut txt)?;
txts.push(txt)
impl TXT {
pub(crate) fn parse(cur: &mut Cursor<&[u8]>) -> io::Result<TXT> {
let mut txts = Vec::new();

loop {
// Keep reading until EOF is reached.
let len = match cur.read_u8() {
Ok(len) => len,
Err(e) => match e.kind() {
io::ErrorKind::UnexpectedEof => break,
_ => return Err(e),
},
};

let mut txt = vec![0; len.into()];
cur.read_exact(&mut txt)?;
txts.push(txt)
}

Ok(TXT(txts))
}

Ok(TXT(txts))
pub(crate) fn write(&self, bfr: &mut Vec<u8>) {
for v in &self.0 {
bfr.extend_from_slice(&(v.len() as u8).to_be_bytes());
bfr.extend(v);
}
}
}

impl SOA {
Expand All @@ -221,6 +267,18 @@ impl SOA {
})
}

pub(crate) fn write(&self, bfr: &mut Vec<u8>) -> io::Result<()> {
Message::write_qname(bfr, &self.mname)?;
Message::write_qname(bfr, &Self::email_to_rname(&self.rname).unwrap())?;

bfr.extend_from_slice(&self.serial.to_be_bytes());
bfr.extend_from_slice(&(self.refresh.as_secs() as u32).to_be_bytes());
bfr.extend_from_slice(&(self.retry.as_secs() as u32).to_be_bytes());
bfr.extend_from_slice(&(self.expire.as_secs() as u32).to_be_bytes());
bfr.extend_from_slice(&(self.minimum.as_secs() as u32).to_be_bytes());
Ok(())
}

/// Converts rnames to email address, for example, "admin.example.com" is
/// converted to "[email protected]", per the rules in
/// https://datatracker.ietf.org/doc/html/rfc1035#section-8
Expand Down Expand Up @@ -275,6 +333,11 @@ impl MX {
exchange,
})
}

pub(crate) fn write(&self, bfr: &mut Vec<u8>) -> io::Result<()> {
bfr.extend_from_slice(&self.preference.to_be_bytes());
Message::write_qname(bfr, &self.exchange)
}
}

impl SRV {
Expand All @@ -292,6 +355,13 @@ impl SRV {
name,
})
}

pub(crate) fn write(&self, bfr: &mut Vec<u8>) -> io::Result<()> {
bfr.extend_from_slice(&self.priority.to_be_bytes());
bfr.extend_from_slice(&self.weight.to_be_bytes());
bfr.extend_from_slice(&self.port.to_be_bytes());
Message::write_qname(bfr, &self.name)
}
}

impl From<&str> for TXT {
Expand Down