X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/fbd2194031738e255e7b1297f2c7e612c1a6944e..4df24fd868177859ddd778f1f45bc825f6264cfb:/ppp.c diff --git a/ppp.c b/ppp.c index 7942e6e..518f6ec 100644 --- a/ppp.c +++ b/ppp.c @@ -1,6 +1,6 @@ // L2TPNS PPP Stuff -char const *cvs_id_ppp = "$Id: ppp.c,v 1.104 2009/12/08 14:49:28 bodea Exp $"; +//#define LAC #include #include @@ -14,6 +14,10 @@ char const *cvs_id_ppp = "$Id: ppp.c,v 1.104 2009/12/08 14:49:28 bodea Exp $"; #include "tbf.h" #include "cluster.h" +#ifdef LAC +#include "l2tplac.h" +#endif + extern tunnelt *tunnel; extern bundlet *bundle; extern fragmentationt *frag; @@ -23,6 +27,7 @@ extern int tunfd; extern char hostname[]; extern uint32_t eth_tx; extern time_t time_now; +extern uint64_t time_now_ms; extern configt *config; static int add_lcp_auth(uint8_t *b, int size, int authtype); @@ -101,6 +106,14 @@ void processpap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) LOG(3, s, t, "PAP login %s/%s\n", user, pass); } +#ifdef LAC + if (forwardtolns(s, user)) + { + LOG(3, s, t, "Forwarding login for %s to other LNS\n", user); + return; + } +#endif + if (session[s].ip || !(r = radiusnew(s))) { // respond now, either no RADIUS available or already authenticated @@ -252,6 +265,17 @@ void processchap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) packet.username = calloc(l + 1, 1); memcpy(packet.username, p, l); +#ifdef LAC + if (forwardtolns(s, packet.username)) + { + LOG(3, s, t, "Forwarding login for %s to other LNS\n", packet.username); + + free(packet.username); + free(packet.password); + return; + } +#endif + run_plugins(PLUGIN_PRE_AUTH, &packet); if (!packet.continue_auth) { @@ -821,6 +845,10 @@ void processlcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) break; + case Closing: + sessionshutdown(s, "LCP: ConfigReq in state Closing. This should not happen. Killing session.", CDN_ADMIN_DISC, TERM_LOST_SERVICE); + break; + default: LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp)); return; @@ -1536,7 +1564,7 @@ void processipv6cp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) uint8_t *o = p + 4; int length = l - 4; int gotip = 0; - uint8_t ident[8]; + uint32_t ident[2]; while (length > 2) { @@ -1548,12 +1576,12 @@ void processipv6cp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) gotip++; // seen address if (o[1] != 10) return; - *(uint32_t *) ident = htonl(session[s].ip); - *(uint32_t *) (ident + 4) = 0; + ident[0] = htonl(session[s].ip); + ident[1] = 0; if (memcmp(o + 2, ident, sizeof(ident))) { - q = ppp_conf_nak(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o, ident, sizeof(ident)); + q = ppp_conf_nak(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o, (uint8_t *)ident, sizeof(ident)); if (!q) return; } @@ -1807,189 +1835,383 @@ void processipin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) // process Multilink PPP packet received void processmpin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l) { - bundleidt b = session[s].bundle; + bundleidt b = session[s].bundle; bundlet * this_bundle = &bundle[b]; - uint32_t frag_offset, M_offset; - uint16_t frag_index, M_index; + uint32_t maskSeq, max_seq; + int frag_offset; + uint16_t frag_index, frag_index_next, frag_index_prev; 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 end_frame = (*p & MP_END); + uint32_t seq_num, seq_num_next, seq_num_prev; + uint32_t i; 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(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; - } + 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); - } + /* 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); + max_seq = this_bundle->max_seq; + maskSeq = 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; - } + /* + * Expand sequence number to 32 bits, making it as close + * as possible to this_fragmentation->M. + */ + seq_num |= this_fragmentation->M & ~maskSeq; + if ((int)(this_fragmentation->M - seq_num) > (int)(maskSeq >> 1)) + { + seq_num += maskSeq + 1; + } + else if ((int)(seq_num - this_fragmentation->M) > (int)(maskSeq >> 1)) + { + seq_num -= maskSeq + 1; /* should never happen */ + } + + // calculate this fragment's offset from the begin seq in the bundle + frag_offset = (int) (seq_num - this_fragmentation->start_seq); - // update M sess_local[s].last_seq = seq_num; + + // calculate the jitter average + uint32_t ljitter = time_now_ms - sess_local[s].prev_time; + if (ljitter > 0) + { + sess_local[s].jitteravg = (sess_local[s].jitteravg + ljitter)>>1; + sess_local[s].prev_time = time_now_ms; + } + + uint32_t Mmin; + if (seq_num < this_fragmentation->M) + { + Mmin = seq_num; this_fragmentation->M = seq_num; + } else { - uint32_t i, min = sess_local[(this_bundle->members[0])].last_seq;; + Mmin = 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; + uint32_t s_seq = sess_local[(this_bundle->members[i])].last_seq; + if (s_seq < Mmin) + Mmin = s_seq; } - this_fragmentation->M = min; + this_fragmentation->M = Mmin; } - 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); + // calculate M offset of the M seq in the bundle + int M_offset = (int) (Mmin - this_fragmentation->start_seq); + + if (M_offset >= MAXFRAGNUM) + { + // There have a long break of the link !!!!!!!! + // M_offset is bigger that the fragmentation buffer size + LOG(3, s, t, "MPPP: M_offset out of range, min:%d, begin_seq:%d, jitteravg:%d\n", Mmin, this_fragmentation->start_seq, sess_local[s].jitteravg); + + // Calculate the new start index, the previous frag are lost + begin_index = (M_offset + this_fragmentation->start_index) & MAXFRAGNUM_MASK; + + // Set new Start sequence + this_fragmentation->start_index = begin_index; + this_fragmentation->start_seq = Mmin; + M_offset = 0; + // recalculate the fragment offset from the new begin seq in the bundle + frag_offset = (int) (seq_num - Mmin); + } + + // discard this fragment if the packet comes before the start sequence + if (frag_offset < 0) + { + // this packet comes before the next + LOG(3, s, t, "MPPP: packet comes before the next, seq:%d, begin_seq:%d, size frag:%d\n", seq_num, this_fragmentation->start_seq, l); + return; + } + + // discard if frag_offset is bigger that the fragmentation buffer size + if (frag_offset >= MAXFRAGNUM) + { + // frag_offset is bigger that the fragmentation buffer size + LOG(3, s, t, "MPPP: Index out of range, seq:%d, begin_seq:%d, jitteravg:%d\n", seq_num, this_fragmentation->start_seq, sess_local[s].jitteravg); + return; + } - //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; + // insert the frame in it's place + fragmentt *this_frag = &this_fragmentation->fragment[frag_index]; + + if (this_frag->length > 0) + // This fragment is lost, It was around the buffer and it was never completed the packet. + LOG(3, this_frag->sid, this_frag->tid, "MPPP: (INSERT) seq_num:%d frag_index:%d flags:%d jitteravg:%d is LOST\n", + this_frag->seq, frag_index, this_frag->flags, this_frag->jitteravg); + + this_frag->length = l; + this_frag->sid = s; + this_frag->tid = t; + this_frag->flags = flags; + this_frag->seq = seq_num; + this_frag->jitteravg = sess_local[s].jitteravg; + memcpy(this_frag->data, p, l); + + LOG(4, s, t, "MPPP: seq_num:%d frag_index:%d INSERTED flags: %02X\n", seq_num, frag_index, flags); + + //next frag index + frag_index_next = (frag_index + 1) & MAXFRAGNUM_MASK; + //previous frag index + frag_index_prev = (frag_index - 1) & MAXFRAGNUM_MASK; + // next seq + seq_num_next = seq_num + 1; + // previous seq + seq_num_prev = seq_num - 1; + + // Clean the buffer and log the lost fragments + if ((frag_index_next != this_fragmentation->start_index) && this_fragmentation->fragment[frag_index_next].length) + { + // check if the next frag is a lost fragment + if (this_fragmentation->fragment[frag_index_next].seq != seq_num_next) + { + // This fragment is lost, It was around the buffer and it was never completed the packet. + LOG(3, this_fragmentation->fragment[frag_index_next].sid, this_fragmentation->fragment[frag_index_next].tid, + "MPPP: (NEXT) seq_num:%d frag_index:%d flags:%d jitteravg:%d is LOST\n", + this_fragmentation->fragment[frag_index_next].seq, frag_index_next, + this_fragmentation->fragment[frag_index_next].flags, this_fragmentation->fragment[frag_index_next].jitteravg); + // this frag is lost + this_fragmentation->fragment[frag_index_next].length = 0; + this_fragmentation->fragment[frag_index_next].flags = 0; + + if (begin_frame && (!end_frame)) return; // assembling frame failed + } } - else + + // Clean the buffer and log the lost fragments + if ((frag_index != this_fragmentation->start_index) && this_fragmentation->fragment[frag_index_prev].length) { - // 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) + // check if the next frag is a lost fragment + if (this_fragmentation->fragment[frag_index_prev].seq != seq_num_prev) { - if (this_fragmentation->fragment[begin_index].flags & MP_BEGIN) - break; - begin_index = (begin_index ? (begin_index -1) : (MAXFRAGNUM -1)); + // This fragment is lost, It was around the buffer and it was never completed the packet. + LOG(3, this_fragmentation->fragment[frag_index_prev].sid, this_fragmentation->fragment[frag_index_prev].tid, + "MPPP: (PREV) seq_num:%d frag_index:%d flags:%d jitteravg:%d is LOST\n", + this_fragmentation->fragment[frag_index_prev].seq, frag_index_prev, + this_fragmentation->fragment[frag_index_prev].flags, this_fragmentation->fragment[frag_index_prev].jitteravg); + + this_fragmentation->fragment[frag_index_prev].length = 0; + this_fragmentation->fragment[frag_index_prev].flags = 0; + + if (end_frame && (!begin_frame)) return; // assembling frame failed } + } - // 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) +find_frame: + begin_index = this_fragmentation->start_index; + uint32_t b_seq = this_fragmentation->start_seq; + // Try to find a Begin sequence from the start_seq sequence to M sequence + while (b_seq < Mmin) + { + if (this_fragmentation->fragment[begin_index].length) { - if (this_fragmentation->fragment[end_index].flags & MP_END) - break; - end_index = (end_index +1) & MAXFRAGNUM_MASK; + if (b_seq == this_fragmentation->fragment[begin_index].seq) + { + if (this_fragmentation->fragment[begin_index].flags & MP_BEGIN) + { + int isfoundE = 0; + // Adjust the new start sequence and start index + this_fragmentation->start_index = begin_index; + this_fragmentation->start_seq = b_seq; + // Begin Sequence found, now try to found the End Sequence to complete the frame + end_index = begin_index; + while (b_seq < Mmin) + { + if (this_fragmentation->fragment[end_index].length) + { + if (b_seq == this_fragmentation->fragment[end_index].seq) + { + if (this_fragmentation->fragment[end_index].flags & MP_END) + { + // The End sequence was found and the frame is complete + isfoundE = 1; + break; + } + } + else + { + // This fragment is lost, it was never completed the packet. + LOG(3, this_fragmentation->fragment[end_index].sid, this_fragmentation->fragment[end_index].tid, + "MPPP: (FIND END) seq_num:%d frag_index:%d flags:%d jitteravg:%d is LOST\n", + this_fragmentation->fragment[end_index].seq, begin_index, + this_fragmentation->fragment[end_index].flags, this_fragmentation->fragment[end_index].jitteravg); + // this frag is lost + this_fragmentation->fragment[end_index].length = 0; + this_fragmentation->fragment[end_index].flags = 0; + // This frame is not complete find the next Begin + break; + } + } + else + { + // This frame is not complete find the next Begin if exist + break; + } + end_index = (end_index +1) & MAXFRAGNUM_MASK; + b_seq++; + } + + if (isfoundE) + // The End sequence was found and the frame is complete + break; + else + // find the next Begin + begin_index = end_index; + } + } + else + { + // This fragment is lost, it was never completed the packet. + LOG(3, this_fragmentation->fragment[begin_index].sid, this_fragmentation->fragment[begin_index].tid, + "MPPP: (FIND BEGIN) seq_num:%d frag_index:%d flags:%d jitteravg:%d is LOST\n", + this_fragmentation->fragment[begin_index].seq, begin_index, + this_fragmentation->fragment[begin_index].flags, this_fragmentation->fragment[begin_index].jitteravg); + // this frag is lost + this_fragmentation->fragment[begin_index].length = 0; + this_fragmentation->fragment[begin_index].flags = 0; + } } + begin_index = (begin_index +1) & MAXFRAGNUM_MASK; + b_seq++; + } - // return if a lost fragment is found - if (!(this_fragmentation->fragment[end_index].length)) +assembling_frame: + // try to assemble the frame that has the received fragment as a member + // get the beginning of this frame + begin_index = end_index = this_fragmentation->start_index; + if (this_fragmentation->fragment[begin_index].length) + { + if (!(this_fragmentation->fragment[begin_index].flags & MP_BEGIN)) + { + // should occur only after an "M_Offset out of range" + // The start sequence must be a begin sequence + this_fragmentation->start_index = (begin_index +1) & MAXFRAGNUM_MASK; + this_fragmentation->start_seq++; return; // assembling frame failed + } + } + else + 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; + // get the end of his frame + while (this_fragmentation->fragment[end_index].length) + { + if (this_fragmentation->fragment[end_index].flags & MP_END) + break; - 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) + end_index = (end_index +1) & MAXFRAGNUM_MASK; + + if (end_index == this_fragmentation->start_index) + return; // assembling frame failed + } + + // 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 + + 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) { - this_fragmentation->fragment[i].length = 0; // Indicates that this fragment has been consumed - this_fragmentation->fragment[i].flags = 0; - if (i == end_index) - break; + 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; } } - //discard fragments received before the recently assembled frame - begin_index = this_fragmentation->start_index; + + // 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; + } + + // Set the new start_index and start_seq 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; - } + this_fragmentation->start_seq = this_fragmentation->fragment[end_index].seq + 1; + LOG(4, s, t, "MPPP after assembling: start index is = %d, start seq=%d\n", this_fragmentation->start_index, this_fragmentation->start_seq); + + begin_index = this_fragmentation->start_index; + if ((this_fragmentation->fragment[begin_index].length) && + (this_fragmentation->fragment[begin_index].seq != this_fragmentation->start_seq)) + { + LOG(3, this_fragmentation->fragment[begin_index].sid, this_fragmentation->fragment[begin_index].tid, + "MPPP: (START) seq_num:%d frag_index:%d flags:%d jitteravg:%d is LOST\n", + this_fragmentation->fragment[begin_index].seq, begin_index, + this_fragmentation->fragment[begin_index].flags, this_fragmentation->fragment[begin_index].jitteravg); + this_fragmentation->fragment[begin_index].length = 0; + this_fragmentation->fragment[begin_index].flags = 0; + } + + if (this_fragmentation->start_seq <= Mmin) + // It's possible to find other complete frame or lost frame. + goto find_frame; + else if ((this_fragmentation->fragment[begin_index].length) && + (this_fragmentation->fragment[begin_index].flags & MP_BEGIN)) + // may be that the next frame is completed + goto assembling_frame; - 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; } @@ -2371,7 +2593,7 @@ uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, sessionidt s, tunnelid if ((b - start) + l > size) { - LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%d)\n", size, (b - start) + l); + LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%td)\n", size, (b - start) + l); return NULL; }