X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/a54a4886e9dc530bb16e5eb0f6a8cfcb03824960..2d1fefdb103465c572f87a5bcea3d5281ae124b9:/ppp.c

diff --git a/ppp.c b/ppp.c
index 4114bb4..afbffd8 100644
--- a/ppp.c
+++ b/ppp.c
@@ -1999,16 +1999,57 @@ void processmpin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 				break;
 		}
 	}
-	//discard fragments received before the recently assembled frame
-	begin_index = this_fragmentation->start_index;
-	this_fragmentation->start_index = (end_index + 1) & MAXFRAGNUM_MASK;
-	this_fragmentation->start_seq = (this_fragmentation->fragment[end_index].seq + 1) & (this_bundle->max_seq-1);
-	//clear length and flags of the discarded fragments
-	while (begin_index != this_fragmentation->start_index)
-	{
-		this_fragmentation->fragment[begin_index].flags = 0;
-		this_fragmentation->fragment[begin_index].length = 0;
-		begin_index = (begin_index + 1) & MAXFRAGNUM_MASK;
+
+discard_lost_frames:
+	//discard fragments numbererd below M and part of an unassembled frame,
+	//but not the one from the frame beginning just before M
+
+	// if we have something to discard
+	if (M_index != this_fragmentation->start_index)
+	{
+		// look for end of previous frame
+		// start at M-1, going backward
+		uint16_t index = M_index;
+		uint8_t end_or_hole_found = 0;
+
+		while (index != this_fragmentation->start_index)
+		{
+			fragmentt *this_frag;
+
+			if (!end_or_hole_found)
+			{
+				fragmentt *front_frag = &this_fragmentation->frag[index];
+
+				// before a MP_BEGIN, there must be a MP_END
+				if (front_frag->length && (front_frag->flags & MP_BEGIN))
+				{
+					end_or_hole_found = 1;
+					end_index = index;
+				}
+			}
+
+			index = (index + (MAXFRAGNUM-1)) & MAXFRAGNUM_MASK;
+			this_frag = &this_fragmentation->frag[index];
+
+			if (!end_or_hole_found)
+			{
+				// we are a hole or a MP_END
+				if (!this_frag->length || (this_frag->flags & MP_END))
+				{
+					end_or_hole_found = 1;
+					end_index = index;
+				}
+			}
+
+			if (end_or_hole_found)
+			{
+				this_frag->flags = 0;
+				this_frag->length = 0;
+			}
+		}
+
+		this_fragmentation->start_index = (end_index + 1) & MAXFRAGNUM_MASK;
+		this_fragmentation->start_seq = (this_fragmentation->fragment[end_index].seq + 1) & (this_bundle->max_seq-1);
 	}
 
 	LOG(4, s, t, "MPPP after assembling: M index is =%d, start index is = %d, start seq=%d\n",M_index, this_fragmentation->start_index, this_fragmentation->start_seq);