Fix #117: Allow incorrectly encoded alignment bits

If we receive incorrectly encoded alignment bits (not all 0), we simply log it as a warning but accept it. Signed-off-by: Abhijit Gadgil <gabhijit@iitbombay.org>
ystero-dev · May 7, 2024 · b5ee967 · b5ee967
1 parent 2d09588
commit b5ee967
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Showing 3 changed files with 24 additions and 2 deletions.
diff --git a/asn-compiler/src/parser/asn/structs/types/base.rs b/asn-compiler/src/parser/asn/structs/types/base.rs
@@ -3,6 +3,7 @@
 #[derive(Debug, Clone)]
 pub(crate) enum NamedValue {
     Number(String),
+    #[allow(dead_code)]
     ValueRef(String),
 }
 

diff --git a/codecs/src/per/mod.rs b/codecs/src/per/mod.rs
@@ -78,14 +78,24 @@ impl PerCodecData {
             .iter()
             .all(|b| b == false)
         {
-            Err(PerCodecError::new(
+            // Issue 117: Sometimes the sender doesn't send the bits correctly.
+            // Accept it but log.
+            log::warn!(
+                "{} Padding bits {} at Offset {} not all '0'",
+                remaining,
+                &self.bits[self.decode_offset..self.decode_offset + remaining],
+                self.decode_offset
+            );
+            self.decode_offset += remaining;
+            Ok(())
+            /* Err(PerCodecError::new(
                 PerCodecErrorCause::InvalidAlignment,
                 format!(
                     "{} Padding bits at Offset {} not all '0'.",
                     remaining, self.decode_offset,
                 )
                 .as_str(),
-            ))
+            )) */
         } else {
             self.decode_offset += remaining;
             Ok(())

diff --git a/examples/tests/13-ngap.rs b/examples/tests/13-ngap.rs
@@ -35,4 +35,15 @@ fn main() {
     let mut codec_data = PerCodecData::from_slice_aper(&response_data);
     let ngap_pdu = ngap::NGAP_PDU::aper_decode(&mut codec_data);
     eprintln!("ngap_pdu: {:?}", ngap_pdu);
+
+    let issue_117_data: [u8; 57] = [
+        0x00, 0x15, 0x00, 0x35, 0x00, 0x00, 0x04, 0x00, 0x1b, 0x00, 0x08, 0x00, 0x02, 0xf8, 0x39,
+        0x03, 0x80, 0x00, 0x04, 0x00, 0x52, 0x40, 0x09, 0x03, 0x00, 0x4e, 0x65, 0x72, 0x76, 0x69,
+        0x6f, 0x6e, 0x00, 0x66, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, 0xf8, 0x39,
+        0x00, 0x00, 0x10, 0x08, 0x00, 0x00, 0x01, 0x00, 0x15, 0x40, 0x01, 0x40,
+    ];
+
+    let mut codec_data = PerCodecData::from_slice_aper(&issue_117_data);
+    let ngap_pdu = ngap::NGAP_PDU::aper_decode(&mut codec_data).expect("Error decoding NGAP PDU");
+    eprintln!("Decoded NGAP PDU: {:#?}", ngap_pdu);
 }