lib: serialize MAC RACH attempts to GSMTAP

This also refactors the gsmtap code into a neater module, and adds MAC
UL & DL logs to our diag capture.

lib/src/gsmtap/parser.rs

@@ -1,8 +1,9 @@
 use crate::diag::Message;
 use crate::diag::diaglog::{LogBody, Nas4GMessageDirection, Timestamp};
+use crate::gsmtap::mac::mac_subpacket_to_gsmtap;
 use crate::gsmtap::{GsmtapHeader, GsmtapMessage, GsmtapType, LteNasSubtype, LteRrcSubtype};
 
-use log::debug;
+use log::{debug, warn};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -11,6 +12,8 @@ pub enum GsmtapParserError {
     InvalidLteRrcOtaExtHeaderVersion(u8),
     #[error("Invalid LteRrcOtaMessage header/PDU number combination: {0}/{1}")]
     InvalidLteRrcOtaHeaderPduNum(u8, u8),
+    #[error("Invalid LteMacRachResponse packet: {0}")]
+    InvalidLteMacRachResponse(String),
 }
 
 pub fn parse(msg: Message) -> Result<Option<(Timestamp, GsmtapMessage)>, GsmtapParserError> {
@@ -165,7 +168,18 @@ fn log_to_gsmtap(value: LogBody) -> Result<Option<GsmtapMessage>, GsmtapParserEr
                 payload: vec![],
             }))
         }
-        LogBody::LteMacRachResponse { payload } => Ok(parse_rach_response(&payload)),
+        LogBody::LteMacRachResponse { packet } => {
+            if packet.subpackets.len() > 1 {
+                warn!("expected 1 MAC subpacket for LogBody::LteMacRachResponse, but got {}! ignoring all but the first", packet.subpackets.len());
+            }
+            let Some(subpacket) = packet.subpackets.get(0) else {
+                return Err(GsmtapParserError::InvalidLteMacRachResponse(format!("no subpackets")));
+            };
+            mac_subpacket_to_gsmtap(&subpacket.body)
+                .map_err(|err| {
+                    GsmtapParserError::InvalidLteMacRachResponse(format!("unable to serialize GSMTAP payload: {err:?}"))
+                })
+        },
         _ => {
             debug!("gsmtap_sink: ignoring unhandled log type: {value:?}");
             Ok(None)