+ 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));
+}
+
+// process outgoing (to tunnel) IP
+//
+static 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 b[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;
+ 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;
+ }
+
+ LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);
+
+ // Add on L2TP header
+ {
+ uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIP);
+ if (!p) return;
+ tunnelsend(b, len + (p-b), t); // send it...
+ }
+
+ // 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);
+
+ increment_counter(&sp->cout, &sp->cout_wrap, len); // byte count
+ sp->cout_delta += len;
+ sp->pout++;
+ udp_tx += len;
+
+ sess_local[s].cout += len; // To send to master..
+ sess_local[s].pout++;
+}
+
+// process outgoing (to tunnel) IPv6
+//
+static void processipv6out(uint8_t * buf, int len)
+{
+ sessionidt s;
+ sessiont *sp;
+ tunnelidt t;
+ in_addr_t ip;
+ struct in6_addr ip6;
+
+ uint8_t *data = buf; // Keep a copy of the originals.
+ int size = len;
+
+ uint8_t b[MAXETHER + 20];
+
+ CSTAT(processipv6out);
+
+ if (len < MIN_IP_SIZE)
+ {
+ LOG(1, 0, 0, "Short IPv6, %d bytes\n", len);
+ STAT(tunnel_tx_errors);
+ return;
+ }
+ if (len >= MAXETHER)
+ {
+ LOG(1, 0, 0, "Oversize IPv6 packet %d bytes\n", len);
+ STAT(tunnel_tx_errors);
+ return;
+ }
+
+ // Skip the tun header
+ buf += 4;
+ len -= 4;
+
+ // Got an IP header now
+ if (*(uint8_t *)(buf) >> 4 != 6)
+ {
+ LOG(1, 0, 0, "IP: Don't understand anything except IPv6\n");
+ return;
+ }
+
+ ip6 = *(struct in6_addr *)(buf+24);
+ s = sessionbyipv6(ip6);
+
+ if (s == 0)
+ {
+ ip = *(uint32_t *)(buf + 32);
+ s = sessionbyip(ip);
+ }
+
+ if (s == 0)
+ {
+ // 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.
+ {
+ // FIXME: Should send icmp6 host unreachable
+ }
+ return;
+ }
+ t = session[s].tunnel;
+ sp = &session[s];
+
+ // FIXME: add DoS prevention/filters?
+
+ 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;
+ }
+ else if (sp->walled_garden && !config->cluster_iam_master)
+ {
+ // We are walled-gardening this
+ master_garden_packet(s, data, size);
+ return;
+ }
+
+ LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);
+
+ // Add on L2TP header
+ {
+ uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIPV6);
+ if (!p) return;
+ tunnelsend(b, len + (p-b), t); // send it...
+ }
+
+ // 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);
+
+ increment_counter(&sp->cout, &sp->cout_wrap, len); // byte count
+ sp->cout_delta += len;
+ sp->pout++;
+ udp_tx += len;
+
+ sess_local[s].cout += len; // To send to master..
+ sess_local[s].pout++;
+}
+
+//
+// Helper routine for the TBF filters.
+// Used to send queued data in to the user!
+//
+static void send_ipout(sessionidt s, uint8_t *buf, int len)
+{
+ sessiont *sp;
+ tunnelidt t;
+ in_addr_t ip;
+
+ uint8_t b[MAXETHER + 20];
+
+ if (len < 0 || len > MAXETHER)
+ {
+ LOG(1, 0, 0, "Odd size IP packet: %d bytes\n", len);
+ return;
+ }
+
+ // Skip the tun header
+ buf += 4;
+ len -= 4;
+
+ ip = *(in_addr_t *)(buf + 16);
+
+ if (!session[s].ip)
+ return;
+
+ t = session[s].tunnel;
+ sp = &session[s];
+
+ LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);
projects / l2tpns.git / blobdiff