X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/a54a4886e9dc530bb16e5eb0f6a8cfcb03824960..d674ec8153ca664525d38bab8c761cc34ecd79bd:/ppp.c

diff --git a/ppp.c b/ppp.c
index 4114bb4..3f5a9a5 100644
--- a/ppp.c
+++ b/ppp.c
@@ -1999,16 +1999,55 @@ 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)
+	{
+		uint8_t end_found = 0;
+		// look for end of previous frame
+		// start at M-1, going backward
+		for (end_index = (M_index + (MAXFRAGNUM-1)) & MAXFRAGNUM_MASK;
+		     end_index != this_fragmentation->start_index;
+		     end_index = (end_index + (MAXFRAGNUM-1)) & MAXFRAGNUM_MASK)
+		{
+			fragmentt *this_frag = &this_fragmentation->frag[end_index];
+			fragmentt *front_frag = &this_fragmentation->frag[(end_index+1)&MAXFRAGNUM_MASK];
+			// before a MP_BEGIN, we must be a MP_END
+			if (front_frag->length && (front_frag->flags & MP_BEGIN))
+			{
+				end_found = 1;
+				break;
+			}
+			// we are a MP_END
+			if (this_frag->length && (this_frag->flags & MP_END))
+			{
+				end_found = 1;
+				break;
+			}
+		}
+		// ok, we may not count it for found if end_index == this_fragmentation->start_index
+		// but it complicates things too much and it will be discarded on next round anyway
+
+		//clear length and flags of the discarded fragments
+		if (end_found)
+		{
+			begin_index = this_fragmentation->start_index;
+			while (begin_index != end_index)
+			{
+				this_fragmentation->fragment[begin_index].flags = 0;
+				this_fragmentation->fragment[begin_index].length = 0;
+				begin_index = (begin_index + 1) & MAXFRAGNUM_MASK;
+			}
+			this_fragmentation->fragment[begin_index].flags = 0;
+			this_fragmentation->fragment[begin_index].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);