+// process Multilink PPP packet received
+void processmpin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
+{
+ bundleidt b = session[s].bundle;
+ bundlet * this_bundle = &bundle[b];
+ uint32_t frag_offset, M_offset;
+ uint16_t frag_index, M_index;
+ fragmentationt *this_fragmentation = &frag[b];
+ uint8_t begin_frame = (*p & MP_BEGIN);
+ uint8_t end_frame = (*p & MP_END);
+ uint32_t seq_num;
+ uint8_t flags = *p;
+ uint16_t begin_index, end_index;
+
+ // Perform length checking
+ if(l > MAXFRAGLEN)
+ {
+ LOG(2, s, t, "MPPP: discarding fragment larger than MAXFRAGLEN\n");
+ return;
+ }
+
+ if(!b)
+ {
+ LOG(2, s, t, "MPPP: Invalid bundle id: 0\n");
+ return;
+ }
+ // FIXME !! session[s].mssf means that the receiver wants to receive frames in mssf not means the receiver will send frames in mssf
+ /* if(session[s].mssf)
+ {
+ // Get 12 bit for seq number
+ seq_num = ntohs((*(uint16_t *) p) & 0xFF0F);
+ p += 2;
+ l -= 2;
+ // After this point the pointer should be advanced 2 bytes
+ LOG(3, s, t, "MPPP: 12 bits, sequence number: %d\n",seq_num);
+ }
+ else */
+ {
+ // Get 24 bit for seq number
+ seq_num = ntohl((*(uint32_t *) p) & 0xFFFFFF00);
+ p += 4;
+ l -= 4;
+ // After this point the pointer should be advanced 4 bytes
+ LOG(4, s, t, "MPPP: 24 bits sequence number:%d\n",seq_num);
+ }
+
+ // calculate this fragment's offset from the begin seq in the bundle
+ frag_offset = (seq_num + this_bundle->max_seq - this_fragmentation->start_seq) & (this_bundle->max_seq-1);
+
+ // discard this fragment if frag_offset is bigger that the fragmentation buffer size
+ if (frag_offset >= MAXFRAGNUM)
+ {
+ LOG(3, s, t, "MPPP: Index out of range, received more than MAXFRAGNUM fragment (lost frag) seq:%d, begin_seq:%d, bundle:%d, max:%d\n",seq_num, this_fragmentation->start_seq, b, this_bundle->max_seq);
+ return;
+ }
+
+ // update M
+ sess_local[s].last_seq = seq_num;
+ if (seq_num < this_fragmentation->M)
+ this_fragmentation->M = seq_num;
+ else
+ {
+ uint32_t i, min = sess_local[(this_bundle->members[0])].last_seq;;
+ for (i = 1; i < this_bundle->num_of_links; i++)
+ {
+ uint32_t s_seq = sess_local[(this_bundle->members[i])].last_seq;
+ if (s_seq < min)
+ min = s_seq;
+ }
+ this_fragmentation->M = min;
+ }
+
+ LOG(4, s, t, "MPPP: Setting M to %d\n", this_fragmentation->M);
+ //calculate M's offset from the begin seq in the bundle
+ M_offset = (this_fragmentation->M + this_bundle->max_seq - this_fragmentation->start_seq) & (this_bundle->max_seq-1);
+
+ //caculate M's index in the fragment array
+ M_index = (M_offset + this_fragmentation->start_index) & MAXFRAGNUM_MASK;
+
+ //caculate received fragment's index in the fragment array
+ frag_index = (frag_offset + this_fragmentation->start_index) & MAXFRAGNUM_MASK;
+
+ //frame with a single fragment
+ if (begin_frame && end_frame)
+ {
+ // process and reset fragmentation
+ LOG(4, s, t, "MPPP: Both bits are set (Begin and End).\n");
+ this_fragmentation->fragment[frag_index].length = l;
+ this_fragmentation->fragment[frag_index].sid = s;
+ this_fragmentation->fragment[frag_index].flags = flags;
+ this_fragmentation->fragment[frag_index].seq = seq_num;
+ this_fragmentation->re_frame_begin_index = frag_index;
+ this_fragmentation->re_frame_end_index = frag_index;
+ processmpframe(s, t, p, l, 0);
+ this_fragmentation->fragment[frag_index].length = 0;
+ this_fragmentation->fragment[frag_index].flags = 0;
+ end_index = frag_index;
+ }
+ else
+ {
+ // insert the frame in it's place
+ fragmentt *this_frag = &this_fragmentation->fragment[frag_index];
+ this_frag->length = l;
+ this_frag->sid = s;
+ this_frag->flags = flags;
+ this_frag->seq = seq_num;
+ memcpy(this_frag->data, p, l);
+
+ // try to assemble the frame that has the received fragment as a member
+ // get the beginning of this frame
+ begin_index = end_index = frag_index;
+ while (this_fragmentation->fragment[begin_index].length)
+ {
+ if (this_fragmentation->fragment[begin_index].flags & MP_BEGIN)
+ break;
+ begin_index = (begin_index ? (begin_index -1) : (MAXFRAGNUM -1));
+ }
+
+ // return if a lost fragment is found
+ if (!(this_fragmentation->fragment[begin_index].length))
+ return; // assembling frame failed
+ // get the end of his frame
+ while (this_fragmentation->fragment[end_index].length)
+ {
+ if (this_fragmentation->fragment[end_index].flags & MP_END)
+ break;
+ end_index = (end_index +1) & MAXFRAGNUM_MASK;
+ }
+
+ // return if a lost fragment is found
+ if (!(this_fragmentation->fragment[end_index].length))
+ return; // assembling frame failed
+
+ // assemble the packet
+ //assemble frame, process it, reset fragmentation
+ uint16_t cur_len = 4; // This is set to 4 to leave 4 bytes for function processipin
+ uint32_t i;
+
+ LOG(4, s, t, "MPPP: processing fragments from %d to %d\n", begin_index, end_index);
+ // Push to the receive buffer
+
+ for (i = begin_index;; i = (i + 1) & MAXFRAGNUM_MASK)
+ {
+ this_frag = &this_fragmentation->fragment[i];
+ if(cur_len + this_frag->length > MAXETHER)
+ {
+ LOG(2, s, t, "MPPP: discarding reassembled frames larger than MAXETHER\n");
+ break;
+ }
+ memcpy(this_fragmentation->reassembled_frame+cur_len, this_frag->data, this_frag->length);
+ LOG(5, s, t, "MPPP: processing frame at %d, with len %d\n", i, this_frag->length);
+ cur_len += this_frag->length;
+ if (i == end_index)
+ {
+ this_fragmentation->re_frame_len = cur_len;
+ this_fragmentation->re_frame_begin_index = begin_index;
+ this_fragmentation->re_frame_end_index = end_index;
+ // Process the resassembled frame
+ LOG(5, s, t, "MPPP: Process the reassembled frame, len=%d\n",cur_len);
+ processmpframe(s, t, this_fragmentation->reassembled_frame, this_fragmentation->re_frame_len, 1);
+ break;
+ }
+ }
+ // Set reassembled frame length to zero after processing it
+ this_fragmentation->re_frame_len = 0;
+ for (i = begin_index;; i = (i + 1) & MAXFRAGNUM_MASK)
+ {
+ this_fragmentation->fragment[i].length = 0; // Indicates that this fragment has been consumed
+ this_fragmentation->fragment[i].flags = 0;
+ if (i == end_index)
+ 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;
+ }
+
+ 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);
+ return;
+}
+
projects / l2tpns.git / blobdiff