crates/irtt-proto/src/close.rs

@@ -1,8 +1,8 @@
 use crate::{
     envelope::{self, FlagRule},
-    flags::{FLAG_CLOSE, FLAG_OPEN, FLAG_REPLY},
+    flags::{has, FLAG_CLOSE, FLAG_OPEN, FLAG_REPLY},
     layout::PacketLayout,
-    Result,
+    ProtoError, Result, TOKEN_SIZE,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -25,6 +25,35 @@ pub fn encode_close_request(request: &CloseRequest, hmac_key: Option<&[u8]>) ->
     envelope::finish(out, hmac_key)
 }
 
+pub fn decode_close_request(packet: &[u8], hmac_key: Option<&[u8]>) -> Result<CloseRequest> {
+    let envelope = envelope::decode(
+        packet,
+        hmac_key,
+        &[
+            FlagRule::Require(FLAG_CLOSE),
+            FlagRule::Reject(FLAG_OPEN),
+            FlagRule::Reject(FLAG_REPLY),
+        ],
+    )?;
+    let expected_len =
+        PacketLayout::close_request(has(envelope.flags, crate::FLAG_HMAC)).header_len();
+    if packet.len() != expected_len {
+        return Err(ProtoError::PacketLengthMismatch {
+            expected: expected_len,
+            actual: packet.len(),
+        });
+    }
+    envelope::verify(packet, hmac_key)?;
+
+    Ok(CloseRequest {
+        token: u64::from_le_bytes(
+            packet[envelope.body_offset..envelope.body_offset + TOKEN_SIZE]
+                .try_into()
+                .unwrap(),
+        ),
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/irtt-proto/src/lib.rs

@@ -31,13 +31,16 @@ pub mod open;
 pub mod params;
 pub mod varint;
 
-pub use close::{encode_close_request, CloseRequest};
+pub use close::{decode_close_request, encode_close_request, CloseRequest};
 pub use echo::{decode_echo_reply, encode_echo_request, EchoReply, EchoRequest, TimestampFields};
 pub use error::{ProtoError, Result};
 pub use flags::*;
 pub use hmac::{compute_hmac, compute_hmac_in_place, verify_hmac};
 pub use layout::{echo_header_len, echo_packet_len, PacketLayout};
-pub use open::{decode_open_reply, encode_open_request, OpenReply, OpenRequest};
+pub use open::{
+    decode_open_reply, decode_open_request, encode_open_reply, encode_open_request, OpenReply,
+    OpenRequest,
+};
 pub use params::{Clock, Params, ReceivedStats, ServerFill, StampAt, MAX_SERVER_FILL_BYTES};
 
 pub const MAGIC: [u8; 3] = [0x14, 0xA7, 0x5B];

crates/irtt-proto/src/open.rs

@@ -35,6 +35,37 @@ pub fn encode_open_request(request: &OpenRequest, hmac_key: Option<&[u8]>) -> Re
     envelope::finish(out, hmac_key)
 }
 
+pub fn decode_open_request(packet: &[u8], hmac_key: Option<&[u8]>) -> Result<OpenRequest> {
+    let envelope = envelope::decode(
+        packet,
+        hmac_key,
+        &[FlagRule::Require(FLAG_OPEN), FlagRule::Reject(FLAG_REPLY)],
+    )?;
+    envelope::verify(packet, hmac_key)?;
+
+    Ok(OpenRequest {
+        params: Params::decode(&packet[envelope.body_offset..])?,
+        close: has(envelope.flags, FLAG_CLOSE),
+    })
+}
+
+pub fn encode_open_reply(reply: &OpenReply, hmac_key: Option<&[u8]>) -> Result<Vec<u8>> {
+    let params = reply.params.encode();
+    let mut out = envelope::begin(
+        reply.flags,
+        hmac_key,
+        &[FlagRule::Require(FLAG_OPEN), FlagRule::Require(FLAG_REPLY)],
+        PacketLayout::open_reply(hmac_key.is_some()).header_len() + params.len(),
+    )?;
+    if reply.token == 0 && !has(reply.flags, FLAG_CLOSE) {
+        return Err(ProtoError::ZeroToken);
+    }
+
+    out.extend_from_slice(&reply.token.to_le_bytes());
+    out.extend_from_slice(&params);
+    envelope::finish(out, hmac_key)
+}
+
 pub fn decode_open_reply(packet: &[u8], hmac_key: Option<&[u8]>) -> Result<OpenReply> {
     let envelope = envelope::decode(
         packet,

crates/irtt-proto/tests/directional_codecs.rs

@@ -0,0 +1,135 @@
+use irtt_proto::{
+    decode_close_request, decode_open_reply, decode_open_request, encode_close_request,
+    encode_open_reply, encode_open_request, CloseRequest, OpenReply, OpenRequest, Params,
+    ProtoError, FLAG_CLOSE, FLAG_HMAC, FLAG_OPEN, FLAG_REPLY, MAGIC,
+};
+
+const KEY: &[u8] = b"testkey";
+const TOKEN: u64 = 0x7896_b6ab_8771_5213;
+
+#[test]
+fn authenticated_open_reply_encoder_sets_hmac_from_key() {
+    let reply = OpenReply {
+        flags: FLAG_OPEN | FLAG_REPLY,
+        token: TOKEN,
+        params: Params {
+            protocol_version: 1,
+            ..Params::default()
+        },
+    };
+    let packet = encode_open_reply(&reply, Some(KEY)).unwrap();
+
+    assert_eq!(packet[3], FLAG_OPEN | FLAG_REPLY | FLAG_HMAC);
+    assert_eq!(
+        decode_open_reply(&packet, Some(KEY)),
+        Ok(OpenReply {
+            flags: FLAG_OPEN | FLAG_REPLY | FLAG_HMAC,
+            ..reply
+        })
+    );
+}
+
+#[test]
+fn rejected_open_reply_round_trips_and_zero_token_requires_close() {
+    let rejected = OpenReply {
+        flags: FLAG_OPEN | FLAG_REPLY | FLAG_CLOSE,
+        token: 0,
+        params: Params {
+            protocol_version: 1,
+            ..Params::default()
+        },
+    };
+    let packet = encode_open_reply(&rejected, None).unwrap();
+    assert_eq!(decode_open_reply(&packet, None), Ok(rejected.clone()));
+
+    assert_eq!(
+        encode_open_reply(
+            &OpenReply {
+                flags: FLAG_OPEN | FLAG_REPLY,
+                ..rejected
+            },
+            None,
+        ),
+        Err(ProtoError::ZeroToken)
+    );
+}
+
+#[test]
+fn open_and_close_codecs_enforce_directional_flags() {
+    let params = Params::default();
+    let open_reply_packet = encode_open_reply(
+        &OpenReply {
+            flags: FLAG_OPEN | FLAG_REPLY,
+            token: TOKEN,
+            params: params.clone(),
+        },
+        None,
+    )
+    .unwrap();
+    assert_eq!(
+        decode_open_request(&open_reply_packet, None),
+        Err(ProtoError::UnexpectedFlag(FLAG_REPLY))
+    );
+    assert_eq!(
+        encode_open_reply(
+            &OpenReply {
+                flags: FLAG_REPLY,
+                token: TOKEN,
+                params: params.clone(),
+            },
+            None,
+        ),
+        Err(ProtoError::MissingFlag(FLAG_OPEN))
+    );
+
+    let no_test_packet = encode_open_request(
+        &OpenRequest {
+            params,
+            close: true,
+        },
+        None,
+    )
+    .unwrap();
+    assert_eq!(
+        decode_close_request(&no_test_packet, None),
+        Err(ProtoError::UnexpectedFlag(FLAG_OPEN))
+    );
+}
+
+#[test]
+fn open_and_close_malformed_bodies_and_exact_lengths_are_rejected() {
+    let mut malformed_open_request = MAGIC.to_vec();
+    malformed_open_request.push(FLAG_OPEN);
+    malformed_open_request.extend_from_slice(&[1, 0x80]);
+    assert_eq!(
+        decode_open_request(&malformed_open_request, None),
+        Err(ProtoError::TruncatedVarint)
+    );
+
+    let mut malformed_open_reply = MAGIC.to_vec();
+    malformed_open_reply.push(FLAG_OPEN | FLAG_REPLY);
+    malformed_open_reply.extend_from_slice(&TOKEN.to_le_bytes());
+    malformed_open_reply.extend_from_slice(&[1, 0x80]);
+    assert_eq!(
+        decode_open_reply(&malformed_open_reply, None),
+        Err(ProtoError::TruncatedVarint)
+    );
+
+    let close_packet = encode_close_request(&CloseRequest { token: TOKEN }, None).unwrap();
+    assert_eq!(
+        decode_close_request(&close_packet[..11], None),
+        Err(ProtoError::PacketLengthMismatch {
+            expected: 12,
+            actual: 11,
+        })
+    );
+    let mut long_close_packet = close_packet;
+    long_close_packet.push(0);
+    assert_eq!(
+        decode_close_request(&long_close_packet, None),
+        Err(ProtoError::PacketLengthMismatch {
+            expected: 12,
+            actual: 13,
+        })
+    );
+}

crates/irtt-proto/tests/vectors.rs

@@ -1,7 +1,7 @@
 use irtt_proto::{
-    decode_echo_reply, decode_open_reply, encode_close_request, encode_echo_request,
-    encode_open_request, verify_hmac, Clock, CloseRequest, EchoRequest, OpenRequest, Params,
-    ReceivedStats, StampAt,
+    decode_close_request, decode_echo_reply, decode_open_reply, decode_open_request,
+    encode_close_request, encode_echo_request, encode_open_reply, encode_open_request, verify_hmac,
+    Clock, CloseRequest, EchoRequest, OpenRequest, Params, ReceivedStats, StampAt,
 };
 
 fn hex(input: &str) -> Vec<u8> {
@@ -50,6 +50,13 @@ fn vector_1_open_request_no_hmac() {
     )
     .unwrap();
     assert_eq!(packet, expected);
+    assert_eq!(
+        decode_open_request(&expected, None),
+        Ok(OpenRequest {
+            params: default_params_3s(),
+            close: false,
+        })
+    );
 }
 
 #[test]
@@ -59,6 +66,7 @@ fn vector_2_open_reply_no_hmac() {
     let reply = decode_open_reply(&packet, None).unwrap();
     assert_eq!(reply.token, 0x7896_b6ab_8771_5213);
     assert_eq!(reply.params, default_params_3s());
+    assert_eq!(encode_open_reply(&reply, None).unwrap(), packet);
 }
 
 #[test]
@@ -103,6 +111,12 @@ fn vector_5_close_request_no_hmac() {
     )
     .unwrap();
     assert_eq!(packet, expected);
+    assert_eq!(
+        decode_close_request(&expected, None),
+        Ok(CloseRequest {
+            token: 0x7896_b6ab_8771_5213,
+        })
+    );
 }
 
 #[test]
@@ -120,6 +134,13 @@ fn vector_6_hmac_open_request() {
     .unwrap();
     assert_eq!(packet, expected);
     verify_hmac(b"testkey", &packet, 4).unwrap();
+    assert_eq!(
+        decode_open_request(&expected, Some(b"testkey")),
+        Ok(OpenRequest {
+            params: hmac_params_2s(),
+            close: false,
+        })
+    );
 }
 
 #[test]
@@ -154,6 +175,12 @@ fn vector_8_hmac_close_request() {
     )
     .unwrap();
     assert_eq!(packet, expected);
+    assert_eq!(
+        decode_close_request(&expected, Some(b"testkey")),
+        Ok(CloseRequest {
+            token: 0x4387_e9eb_5d3f_ca59,
+        })
+    );
 }
 
 #[test]
@@ -169,6 +196,13 @@ fn vector_9_no_test_open_close_request() {
     )
     .unwrap();
     assert_eq!(packet, expected);
+    assert_eq!(
+        decode_open_request(&expected, None),
+        Ok(OpenRequest {
+            params: default_params_60s(),
+            close: true,
+        })
+    );
 }
 
 #[test]
@@ -179,6 +213,7 @@ fn vector_10_no_test_open_close_reply() {
     let reply = decode_open_reply(&packet, None).unwrap();
     assert_eq!(reply.token, 0);
     assert_eq!(reply.params, default_params_60s());
+    assert_eq!(encode_open_reply(&reply, None).unwrap(), packet);
 }
 
 #[test]