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addressing review comments: minor refactor for optimization, and correction of rrc_rel size

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This commit is contained in:
Carlos Guerra
2026-06-03 13:19:18 +02:00
committed by Will Greenberg
parent c424902560
commit 76c2039556
2 changed files with 19 additions and 29 deletions
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lib/src/gsmtap/parser.rs
+17 -28
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@@ -177,37 +177,30 @@ fn log_to_gsmtap(value: LogBody) -> Result<Option<GsmtapMessage>, GsmtapParserEr
// Returns None if the log contains no MSG2 (no Timing Advance was received).
fn parse_rach_response(payload: &[u8]) -> Option<GsmtapMessage> {
// Outer header: version(u8) + num_subpackets(u8) + reserved(u16)
if payload.len() < 4 || payload[0] != 0x01 {
if *payload.get(0)? != 0x01 {
return None;
}
let num_subpackets = payload[1] as usize;
let num_subpackets = *payload.get(1)? as usize;
let mut offset = 4;
for _ in 0..num_subpackets {
// Subpacket header: id(u8) + version(u8) + size(u16 LE)
if offset + 4 > payload.len() {
break;
}
let sp_id = payload[offset];
let sp_version = payload[offset + 1];
let sp_size = u16::from_le_bytes([payload[offset + 2], payload[offset + 3]]) as usize;
let sp_hdr = payload.get(offset..offset + 4)?;
let sp_id = sp_hdr[0];
let sp_version = sp_hdr[1];
let sp_size = u16::from_le_bytes([sp_hdr[2], sp_hdr[3]]) as usize;
if sp_size < 4 {
break;
}
let sp_end = offset + sp_size;
if sp_end > payload.len() {
break;
return None;
}
let sp_body = payload.get(offset + 4..offset + sp_size)?;
if sp_id == 0x06 {
// RACH Attempt subpacket
if let Some(msg) = extract_rach_attempt_gsmtap(&payload[offset + 4..sp_end], sp_version)
{
if let Some(msg) = extract_rach_attempt_gsmtap(sp_body, sp_version) {
return Some(msg);
}
}
offset = sp_end;
offset += sp_size;
}
None
}
@@ -225,11 +218,9 @@ fn extract_rach_attempt_gsmtap(body: &[u8], version: u8) -> Option<GsmtapMessage
_ => return None,
};
if body.len() < hdr_size {
return None;
}
let msg_bitmask = body[bitmask_offset];
let rapid = body[rapid_offset] & 0x3F;
let hdr = body.get(..hdr_size)?;
let msg_bitmask = hdr[bitmask_offset];
let rapid = hdr[rapid_offset] & 0x3F;
let msg1_present = msg_bitmask & 0x01 != 0;
let msg2_present = msg_bitmask & 0x02 != 0;
@@ -238,12 +229,10 @@ fn extract_rach_attempt_gsmtap(body: &[u8], version: u8) -> Option<GsmtapMessage
}
// MSG2: backoff(u16) + result(u8) + tc_rnti(u16) + ta(u16) = 7 bytes
let msg2_offset = hdr_size + if msg1_present { msg1_size } else { 0 };
if body.len() < msg2_offset + 7 {
return None;
}
let tc_rnti = u16::from_le_bytes([body[msg2_offset + 3], body[msg2_offset + 4]]);
let ta_raw = u16::from_le_bytes([body[msg2_offset + 5], body[msg2_offset + 6]]);
let msg2_start = hdr_size + if msg1_present { msg1_size } else { 0 };
let msg2 = body.get(msg2_start..msg2_start + 7)?;
let tc_rnti = u16::from_le_bytes([msg2[3], msg2[4]]);
let ta_raw = u16::from_le_bytes([msg2[5], msg2[6]]);
// 0xFFFF is a Qualcomm sentinel meaning the RAR was received but TA was not valid
if ta_raw == 0xFFFF {
return None;