pub fn parse_initial(packet: &[u8]) -> Result<InitialHeader<'_>, Error>Expand description
Parse a QUIC Long Header Initial packet from a raw datagram.
Only the header fields are extracted; no decryption is performed. The
returned InitialHeader borrows directly from packet.
ยงErrors
Returns an error when the packet is too short, is not a long-header Initial packet, or contains a connection ID length exceeding 20 bytes.
Examples found in repository?
examples/parse_header.rs (line 14)
9fn main() {
10 // A minimal QUIC v1 Initial packet (truncated payload).
11 // In practice this would come from a UDP socket.
12 let packet: Vec<u8> = build_sample_initial();
13
14 match quic_parser::parse_initial(&packet) {
15 Ok(header) => {
16 println!("QUIC Initial packet parsed successfully");
17 println!(" version: {:#010x}", header.version);
18 println!(" dcid: {}", hex(header.dcid));
19 println!(" scid: {}", hex(header.scid));
20 println!(" token length: {}", header.token.len());
21 println!(" payload size: {} bytes", header.payload.len());
22 }
23 Err(e) => {
24 eprintln!("parse error: {e}");
25 }
26 }
27
28 // Peek at the DCID without a full parse.
29 if let Some(dcid) = quic_parser::peek_long_header_dcid(&packet) {
30 println!(" peeked dcid: {}", hex(dcid));
31 }
32}More examples
examples/decrypt_initial.rs (line 15)
11fn main() {
12 // RFC 9001 Appendix A.2 client Initial packet (complete, 1200 bytes).
13 let packet = rfc9001_client_initial();
14
15 let header = match quic_parser::parse_initial(&packet) {
16 Ok(h) => h,
17 Err(e) => {
18 eprintln!("header parse error: {e}");
19 return;
20 }
21 };
22
23 println!("Parsed header:");
24 println!(" version: {:#010x}", header.version);
25 println!(" dcid: {}", hex(header.dcid));
26 println!(" scid: {}", hex(header.scid));
27 println!(" payload: {} bytes", header.payload.len());
28
29 let decrypted = match quic_parser::decrypt_initial(&header) {
30 Ok(d) => d,
31 Err(e) => {
32 eprintln!("decryption error: {e}");
33 return;
34 }
35 };
36
37 println!("Decrypted {} bytes of frame data", decrypted.len());
38
39 let frames = match quic_parser::parse_crypto_frames(&decrypted) {
40 Ok(f) => f,
41 Err(e) => {
42 eprintln!("frame parse error: {e}");
43 return;
44 }
45 };
46
47 println!("Found {} CRYPTO frame(s)", frames.len());
48 for (i, f) in frames.iter().enumerate() {
49 println!(" frame {i}: offset={}, len={}", f.offset, f.data.len());
50 }
51
52 let stream = quic_parser::reassemble_crypto_stream(&frames);
53 println!("Reassembled crypto stream: {} bytes", stream.len());
54
55 if stream.len() >= 6 {
56 let msg_type = stream[0];
57 let length = u32::from_be_bytes([0, stream[1], stream[2], stream[3]]);
58 let tls_version = u16::from_be_bytes([stream[4], stream[5]]);
59 println!("TLS handshake: type={msg_type:#04x} length={length} version={tls_version:#06x}");
60 }
61}