csn1: fix csnStreamDecoder(): skip bits unhandled by serialize()

This change fixes a bug that was reported by Keith Whyte and
confirmed in [1]. The problem is that a user-defined handler
in case of CSN_SERIALIZE may parse only a part of the given
bit-stream, leaving some bits unhandled. This is expected
because the sender (i.e. the MS) may use more recent RLC/MAC
message definitions containing new fields at the end.

Those bits that were left unhandled by serialize() shall not be
interpreted as continuation of the message, they shall be skipped.

Note that the encoded vector in the RLCMAC unit test still does
not match the original one. That's a known bug explained in [2].

[1] If5873355d52d7ddb06c2716154a88d34100f6ab5
[2] Ic46d6e56768f516203d27d8e7a5adb77afdf32b7

Change-Id: Id4cc042fed68fc54aca0355dcb986cab3f6b49ea
Related: OS#4338

1 files changed, 7 insertions, 0 deletions

diff --git a/src/csn1.c b/src/csn1.c
index 594e8ec0..21d3662e 100644
--- a/src/csn1.c
+++ b/src/csn1.c
@@ -571,6 +571,13 @@ csnStreamDecoder(csnStream_t* ar, const CSN_DESCR* pDescr, struct bitvec *vector
             remaining_bits_len = arT.remaining_bits_len;
             bit_offset         = arT.bit_offset;
           }
+
+          /* Skip bits not handled by serialize(), if any */
+          if (Status > 0) {
+            LOGPC(DCSN1, LOGL_NOTICE, "skipped = %d | ", Status);
+            *readIndex += Status;
+          }
+
           pDescr++;
         }
         else