+ int d = (tcp[12] >> 4) * 4;
+ uint8_t *mss = 0;
+ uint8_t *opts;
+ uint8_t *data;
+ uint16_t orig;
+ uint32_t sum;
+
+ if ((tcp[13] & 0x3f) & ~(TCP_FLAG_SYN|TCP_FLAG_ACK)) // only want SYN and SYN,ACK
+ return;
+
+ if (tcp + d > buf + len) // short?
+ return;
+
+ opts = tcp + 20;
+ data = tcp + d;
+
+ while (opts < data)
+ {
+ if (*opts == 2 && opts[1] == 4) // mss option (2), length 4
+ {
+ mss = opts + 2;
+ if (mss + 2 > data) return; // short?
+ break;
+ }
+
+ if (*opts == 0) return; // end of options
+ if (*opts == 1 || !opts[1]) // no op (one byte), or no length (prevent loop)
+ opts++;
+ else
+ opts += opts[1]; // skip over option
+ }
+
+ if (!mss) return; // not found
+ orig = ntohs(*(uint16_t *) mss);
+
+ if (orig <= MSS) return; // mss OK
+
+ LOG(5, s, t, "TCP: %s:%u -> %s:%u SYN%s: adjusted mss from %u to %u\n",
+ fmtaddr(*(in_addr_t *) (buf + 12), 0), ntohs(*(uint16_t *) tcp),
+ fmtaddr(*(in_addr_t *) (buf + 16), 1), ntohs(*(uint16_t *) (tcp + 2)),
+ (tcp[13] & TCP_FLAG_ACK) ? ",ACK" : "", orig, MSS);
+
+ // set mss
+ *(int16_t *) mss = htons(MSS);
+
+ // adjust checksum (see rfc1141)
+ sum = orig + (~MSS & 0xffff);
+ sum += ntohs(*(uint16_t *) (tcp + 16));
+ sum = (sum & 0xffff) + (sum >> 16);
+ *(uint16_t *) (tcp + 16) = htons(sum + (sum >> 16));
+}
+
+void processmpframe(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l, uint8_t extra)
+{
+ uint16_t proto;
+ if (extra) {
+ // Skip the four extra bytes
+ p += 4;
+ l -= 4;
+ }
+
+ if (*p & 1)
+ {
+ proto = *p++;
+ l--;
+ }
+ else
+ {
+ proto = ntohs(*(uint16_t *) p);
+ p += 2;
+ l -= 2;
+ }
+ if (proto == PPPIP)
+ {
+ if (session[s].die)
+ {
+ LOG(4, s, t, "MPPP: Session %d is closing. Don't process PPP packets\n", s);
+ return; // closing session, PPP not processed
+ }
+ session[s].last_packet = session[s].last_data = time_now;
+ processipin(s, t, p, l);
+ }
+ else if (proto == PPPIPV6 && config->ipv6_prefix.s6_addr[0])
+ {
+ if (session[s].die)
+ {
+ LOG(4, s, t, "MPPP: Session %d is closing. Don't process PPP packets\n", s);
+ return; // closing session, PPP not processed
+ }
+
+ session[s].last_packet = session[s].last_data = time_now;
+ processipv6in(s, t, p, l);
+ }
+ else if (proto == PPPIPCP)
+ {
+ session[s].last_packet = session[s].last_data = time_now;
+ processipcp(s, t, p, l);
+ }
+ else if (proto == PPPCCP)
+ {
+ session[s].last_packet = session[s].last_data = time_now;
+ processccp(s, t, p, l);
+ }
+ else
+ {
+ LOG(2, s, t, "MPPP: Unsupported MP protocol 0x%04X received\n",proto);
+ }
+}
+
+static void update_session_out_stat(sessionidt s, sessiont *sp, int len)
+{
+ increment_counter(&sp->cout, &sp->cout_wrap, len); // byte count
+ sp->cout_delta += len;
+ sp->pout++;
+ sp->last_data = time_now;
+
+ sess_local[s].cout += len; // To send to master..
+ sess_local[s].pout++;
+}
+
+// process outgoing (to tunnel) IP
+//
+// (i.e. this routine writes to data[-8]).
+void processipout(uint8_t *buf, int len)
+{
+ sessionidt s;
+ sessiont *sp;
+ tunnelidt t;
+ in_addr_t ip;
+
+ uint8_t *data = buf; // Keep a copy of the originals.
+ int size = len;
+
+ uint8_t fragbuf[MAXETHER + 20];
+
+ CSTAT(processipout);
+
+ if (len < MIN_IP_SIZE)
+ {
+ LOG(1, 0, 0, "Short IP, %d bytes\n", len);
+ STAT(tun_rx_errors);
+ return;
+ }
+ if (len >= MAXETHER)
+ {
+ LOG(1, 0, 0, "Oversize IP packet %d bytes\n", len);
+ STAT(tun_rx_errors);
+ return;
+ }
+
+ // Skip the tun header
+ buf += 4;
+ len -= 4;
+
+ // Got an IP header now
+ if (*(uint8_t *)(buf) >> 4 != 4)
+ {
+ LOG(1, 0, 0, "IP: Don't understand anything except IPv4\n");
+ return;
+ }
+
+ ip = *(uint32_t *)(buf + 16);
+ if (!(s = sessionbyip(ip)))
+ {
+ // Is this a packet for a session that doesn't exist?
+ static int rate = 0; // Number of ICMP packets we've sent this second.
+ static int last = 0; // Last time we reset the ICMP packet counter 'rate'.
+
+ if (last != time_now)
+ {
+ last = time_now;
+ rate = 0;
+ }
+
+ if (rate++ < config->icmp_rate) // Only send a max of icmp_rate per second.
+ {
+ LOG(4, 0, 0, "IP: Sending ICMP host unreachable to %s\n", fmtaddr(*(in_addr_t *)(buf + 12), 0));
+ host_unreachable(*(in_addr_t *)(buf + 12), *(uint16_t *)(buf + 4),
+ config->bind_address ? config->bind_address : my_address, buf, len);
+ }
+ return;
+ }
+
+ t = session[s].tunnel;
+ if (len > session[s].mru || (session[s].mrru && len > session[s].mrru))
+ {
+ LOG(3, s, t, "Packet size more than session MRU\n");
+ return;
+ }
+
+ sp = &session[s];
+
+ // DoS prevention: enforce a maximum number of packets per 0.1s for a session
+ if (config->max_packets > 0)
+ {
+ if (sess_local[s].last_packet_out == TIME)
+ {
+ int max = config->max_packets;
+
+ // All packets for throttled sessions are handled by the
+ // master, so further limit by using the throttle rate.
+ // A bit of a kludge, since throttle rate is in kbps,
+ // but should still be generous given our average DSL
+ // packet size is 200 bytes: a limit of 28kbps equates
+ // to around 180 packets per second.
+ if (!config->cluster_iam_master && sp->throttle_out && sp->throttle_out < max)
+ max = sp->throttle_out;
+
+ if (++sess_local[s].packets_out > max)
+ {
+ sess_local[s].packets_dropped++;
+ return;
+ }
+ }
+ else
+ {
+ if (sess_local[s].packets_dropped)
+ {
+ INC_STAT(tun_rx_dropped, sess_local[s].packets_dropped);
+ LOG(3, s, t, "Dropped %u/%u packets to %s for %suser %s\n",
+ sess_local[s].packets_dropped, sess_local[s].packets_out,
+ fmtaddr(ip, 0), sp->throttle_out ? "throttled " : "",
+ sp->user);
+ }
+
+ sess_local[s].last_packet_out = TIME;
+ sess_local[s].packets_out = 1;
+ sess_local[s].packets_dropped = 0;
+ }
+ }
+
+ // run access-list if any
+ if (session[s].filter_out && !ip_filter(buf, len, session[s].filter_out - 1))
+ return;
+
+ // adjust MSS on SYN and SYN,ACK packets with options
+ if ((ntohs(*(uint16_t *) (buf + 6)) & 0x1fff) == 0 && buf[9] == IPPROTO_TCP) // first tcp fragment
+ {
+ int ihl = (buf[0] & 0xf) * 4; // length of IP header
+ if (len >= ihl + 20 && (buf[ihl + 13] & TCP_FLAG_SYN) && ((buf[ihl + 12] >> 4) > 5))
+ adjust_tcp_mss(s, t, buf, len, buf + ihl);
+ }
+
+ if (sp->tbf_out)
+ {
+ // Are we throttling this session?
+ if (config->cluster_iam_master)
+ tbf_queue_packet(sp->tbf_out, data, size);
+ else
+ master_throttle_packet(sp->tbf_out, data, size);
+ return;
+ }
+
+ if (sp->walled_garden && !config->cluster_iam_master)
+ {
+ // We are walled-gardening this
+ master_garden_packet(s, data, size);
+ return;
+ }
+
+ if(session[s].bundle != 0 && bundle[session[s].bundle].num_of_links > 1)
+ {
+
+ if (!config->cluster_iam_master)
+ {
+ // The MPPP packets must be managed by the Master.
+ master_forward_mppp_packet(s, data, size);
+ return;
+ }
+
+ // Add on L2TP header
+ sessionidt members[MAXBUNDLESES];
+ bundleidt bid = session[s].bundle;
+ bundlet *b = &bundle[bid];
+ uint32_t num_of_links, nb_opened;
+ int i;
+
+ num_of_links = b->num_of_links;
+ nb_opened = 0;
+ for (i = 0;i < num_of_links;i++)
+ {
+ s = b->members[i];
+ if (session[s].ppp.lcp == Opened)
+ {
+ members[nb_opened] = s;
+ nb_opened++;
+ }
+ }
+
+ if (nb_opened < 1)
+ {
+ LOG(3, s, t, "MPPP: PROCESSIPOUT ERROR, no session opened in bundle:%d\n", bid);
+ return;
+ }
+
+ num_of_links = nb_opened;
+ b->current_ses = (b->current_ses + 1) % num_of_links;
+ s = members[b->current_ses];
+ t = session[s].tunnel;
+ sp = &session[s];
+ LOG(4, s, t, "MPPP: (1)Session number becomes: %d\n", s);
+
+ if (num_of_links > 1)
+ {
+ if(len > MINFRAGLEN)
+ {
+ //for rotate traffic among the member links
+ uint32_t divisor = num_of_links;
+ if (divisor > 2)
+ divisor = divisor/2 + (divisor & 1);
+
+ // Partition the packet to "num_of_links" fragments
+ uint32_t fraglen = len / divisor;
+ uint32_t last_fraglen = fraglen + len % divisor;
+ uint32_t remain = len;
+
+ // send the first packet
+ uint8_t *p = makeppp(fragbuf, sizeof(fragbuf), buf, fraglen, s, t, PPPIP, 0, bid, MP_BEGIN);
+ if (!p) return;
+ tunnelsend(fragbuf, fraglen + (p-fragbuf), t); // send it...
+
+ // statistics
+ update_session_out_stat(s, sp, fraglen);
+
+ remain -= fraglen;
+ while (remain > last_fraglen)
+ {
+ b->current_ses = (b->current_ses + 1) % num_of_links;
+ s = members[b->current_ses];
+ t = session[s].tunnel;
+ sp = &session[s];
+ LOG(4, s, t, "MPPP: (2)Session number becomes: %d\n", s);
+ p = makeppp(fragbuf, sizeof(fragbuf), buf+(len - remain), fraglen, s, t, PPPIP, 0, bid, 0);
+ if (!p) return;
+ tunnelsend(fragbuf, fraglen + (p-fragbuf), t); // send it...
+ update_session_out_stat(s, sp, fraglen);
+ remain -= fraglen;
+ }
+ // send the last fragment
+ b->current_ses = (b->current_ses + 1) % num_of_links;
+ s = members[b->current_ses];
+ t = session[s].tunnel;
+ sp = &session[s];
+ LOG(4, s, t, "MPPP: (2)Session number becomes: %d\n", s);
+ p = makeppp(fragbuf, sizeof(fragbuf), buf+(len - remain), remain, s, t, PPPIP, 0, bid, MP_END);
+ if (!p) return;
+ tunnelsend(fragbuf, remain + (p-fragbuf), t); // send it...
+ update_session_out_stat(s, sp, remain);
+ if (remain != last_fraglen)
+ LOG(3, s, t, "PROCESSIPOUT ERROR REMAIN != LAST_FRAGLEN, %d != %d\n", remain, last_fraglen);
+ }
+ else
+ {
+ // Send it as one frame
+ uint8_t *p = makeppp(fragbuf, sizeof(fragbuf), buf, len, s, t, PPPIP, 0, bid, MP_BOTH_BITS);
+ if (!p) return;
+ tunnelsend(fragbuf, len + (p-fragbuf), t); // send it...
+ LOG(4, s, t, "MPPP: packet sent as one frame\n");
+ update_session_out_stat(s, sp, len);
+ }
+ }
+ else
+ {
+ // Send it as one frame (NO MPPP Frame)
+ uint8_t *p = makeppp(fragbuf, sizeof(fragbuf), buf, len, s, t, PPPIP, 0, 0, 0);
+ if (!p) return;
+ tunnelsend(fragbuf, len + (p-fragbuf), t); // send it...
+ update_session_out_stat(s, sp, len);
+ }
+ }
+ else
+ {
+ uint8_t *p = makeppp(fragbuf, sizeof(fragbuf), buf, len, s, t, PPPIP, 0, 0, 0);
+ if (!p) return;
+ tunnelsend(fragbuf, len + (p-fragbuf), t); // send it...
+ update_session_out_stat(s, sp, len);
+ }
+
+ // Snooping this session, send it to intercept box
+ if (sp->snoop_ip && sp->snoop_port)
+ snoop_send_packet(buf, len, sp->snoop_ip, sp->snoop_port);
+
+ udp_tx += len;
+}
+
+// process outgoing (to tunnel) IPv6
+//
+static void processipv6out(uint8_t * buf, int len)
+{
+ sessionidt s;
projects / l2tpns.git / blobdiff