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Clean up error handling in chapter 4 and 5

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This commit is contained in:
Emil Hernvall
2020-06-18 02:03:56 +02:00
parent f815075ae4
commit 45cbfa59f7
4 changed files with 215 additions and 282 deletions
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127
examples/sample5.rs
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@@ -832,84 +832,63 @@ fn recursive_lookup(qname: &str, qtype: QueryType) -> Result<DnsPacket> {
}
}
fn handle_query(socket: &UdpSocket) -> Result<()> {
let mut req_buffer = BytePacketBuffer::new();
let (_, src) = socket.recv_from(&mut req_buffer.buf)?;
let request = DnsPacket::from_buffer(&mut req_buffer)?;
let mut packet = DnsPacket::new();
packet.header.id = request.header.id;
packet.header.recursion_desired = true;
packet.header.recursion_available = true;
packet.header.response = true;
if request.questions.is_empty() {
packet.header.rescode = ResultCode::FORMERR;
} else {
let question = &request.questions[0];
println!("Received query: {:?}", question);
if let Ok(result) = recursive_lookup(&question.name, question.qtype) {
packet.questions.push(question.clone());
packet.header.rescode = result.header.rescode;
for rec in result.answers {
println!("Answer: {:?}", rec);
packet.answers.push(rec);
}
for rec in result.authorities {
println!("Authority: {:?}", rec);
packet.authorities.push(rec);
}
for rec in result.resources {
println!("Resource: {:?}", rec);
packet.resources.push(rec);
}
} else {
packet.header.rescode = ResultCode::SERVFAIL;
}
}
let mut res_buffer = BytePacketBuffer::new();
packet.write(&mut res_buffer)?;
let len = res_buffer.pos();
let data = res_buffer.get_range(0, len)?;
socket.send_to(data, src)?;
Ok(())
}
fn main() -> Result<()> {
let socket = UdpSocket::bind(("0.0.0.0", 2053))?;
loop {
let mut req_buffer = BytePacketBuffer::new();
let (_, src) = match socket.recv_from(&mut req_buffer.buf) {
Ok(x) => x,
Err(e) => {
println!("Failed to read from UDP socket: {:?}", e);
continue;
}
};
let request = match DnsPacket::from_buffer(&mut req_buffer) {
Ok(x) => x,
Err(e) => {
println!("Failed to parse UDP query packet: {:?}", e);
continue;
}
};
let mut packet = DnsPacket::new();
packet.header.id = request.header.id;
packet.header.recursion_desired = true;
packet.header.recursion_available = true;
packet.header.response = true;
if request.questions.is_empty() {
packet.header.rescode = ResultCode::FORMERR;
} else {
let question = &request.questions[0];
println!("Received query: {:?}", question);
if let Ok(result) = recursive_lookup(&question.name, question.qtype) {
packet.questions.push(question.clone());
packet.header.rescode = result.header.rescode;
for rec in result.answers {
println!("Answer: {:?}", rec);
packet.answers.push(rec);
}
for rec in result.authorities {
println!("Authority: {:?}", rec);
packet.authorities.push(rec);
}
for rec in result.resources {
println!("Resource: {:?}", rec);
packet.resources.push(rec);
}
} else {
packet.header.rescode = ResultCode::SERVFAIL;
}
match handle_query(&socket) {
Ok(_) => {},
Err(e) => eprintln!("An error occured: {}", e),
}
let mut res_buffer = BytePacketBuffer::new();
match packet.write(&mut res_buffer) {
Ok(_) => {}
Err(e) => {
println!("Failed to encode UDP response packet: {:?}", e);
continue;
}
};
let len = res_buffer.pos();
let data = match res_buffer.get_range(0, len) {
Ok(x) => x,
Err(e) => {
println!("Failed to retrieve response buffer: {:?}", e);
continue;
}
};
match socket.send_to(data, src) {
Ok(_) => {}
Err(e) => {
println!("Failed to send response buffer: {:?}", e);
continue;
}
};
}
}