From d674ec8153ca664525d38bab8c761cc34ecd79bd Mon Sep 17 00:00:00 2001 From: Benjamin Cama Date: Thu, 26 Jan 2012 02:38:49 +0100 Subject: [PATCH] MPPP: Fix discarding frames (a bit complicated) --- ppp.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 49 insertions(+), 10 deletions(-) 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); -- 2.20.1