X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/0c678c5a03bcdc601ea50bb7d8e273101cc5e557..bde7904f922ed78582ef6289c3896978b51ce7cf:/l2tpns.c?ds=sidebyside diff --git a/l2tpns.c b/l2tpns.c index 9671a69..de1aecc 100644 --- a/l2tpns.c +++ b/l2tpns.c @@ -4,7 +4,7 @@ // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced // vim: sw=8 ts=8 -char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.132 2005-09-15 09:34:48 bodea Exp $"; +char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.133 2005-09-16 05:04:29 bodea Exp $"; #include #include @@ -75,6 +75,10 @@ static int syslog_log = 0; // are we logging to syslog static FILE *log_stream = 0; // file handle for direct logging (i.e. direct into file, not via syslog). uint32_t last_id = 0; // Unique ID for radius accounting +// calculated from config->l2tp_mtu +uint16_t MRU = 0; // PPP MRU +uint16_t MSS = 0; // TCP MSS + struct cli_session_actions *cli_session_actions = NULL; // Pending session changes requested by CLI struct cli_tunnel_actions *cli_tunnel_actions = NULL; // Pending tunnel changes required by CLI @@ -104,11 +108,11 @@ config_descriptt config_values[] = { CONFIG("log_file", log_filename, STRING), CONFIG("pid_file", pid_file, STRING), CONFIG("random_device", random_device, STRING), - CONFIG("l2tp_secret", l2tpsecret, STRING), + CONFIG("l2tp_secret", l2tp_secret, STRING), + CONFIG("l2tp_mtu", l2tp_mtu, INT), CONFIG("ppp_restart_time", ppp_restart_time, INT), CONFIG("ppp_max_configure", ppp_max_configure, INT), CONFIG("ppp_max_failure", ppp_max_failure, INT), - CONFIG("ppp_mru", ppp_mru, INT), CONFIG("primary_dns", default_dns1, IPv4), CONFIG("secondary_dns", default_dns2, IPv4), CONFIG("primary_radius", radiusserver[0], IPv4), @@ -979,6 +983,50 @@ int tun_write(uint8_t * data, int size) return write(tunfd, data, size); } +// adjust tcp mss to avoid fragmentation (called only for tcp packets with syn set) +void adjust_tcp_mss(sessionidt s, tunnelidt t, uint8_t *buf, int len, uint8_t *tcp) +{ + int d = (tcp[12] >> 4) * 4; + uint8_t *mss = 0; + uint8_t *data; + + if ((tcp[13] & 0x3f) & ~(TCP_FLAG_SYN|TCP_FLAG_ACK)) // only want SYN and SYN,ACK + return; + + if (tcp + d > buf + len) // short? + return; + + data = tcp + d; + tcp += 20; + + while (tcp < data) + { + if (*tcp == 2 && tcp[1] == 4) // mss option (2), length 4 + { + mss = tcp + 2; + if (mss + 2 > data) return; // short? + break; + } + + if (*tcp == 0) return; // end of options + if (*tcp == 1 || !tcp[1]) // no op (one byte), or no length (prevent loop) + tcp++; + else + tcp += tcp[1]; // skip over option + } + + if (!mss) return; // not found + if (ntohl(*(uint16_t *) mss) <= 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), *(uint16_t *)tcp, + fmtaddr(*(in_addr_t *)(buf + 16), 1), *(uint16_t *)(tcp + 2), + (tcp[13] & TCP_FLAG_ACK) ? ",ACK" : "", + ntohl(*(uint16_t *) mss), MSS); + + // FIXME +} + // process outgoing (to tunnel) IP // static void processipout(uint8_t *buf, int len) @@ -1086,6 +1134,14 @@ static void processipout(uint8_t *buf, int len) 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? @@ -2009,7 +2065,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr) uint16_t orig_len; // handle hidden AVPs - if (!*config->l2tpsecret) + if (!*config->l2tp_secret) { LOG(1, s, t, "Hidden AVP requested, but no L2TP secret.\n"); fatal = flags; @@ -2382,7 +2438,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr) if (amagic == 0) amagic = time_now; session[s].magic = amagic; // set magic number session[s].l2tp_flags = aflags; // set flags received - session[s].mru = config->ppp_mru; + session[s].mru = PPPMTU; // default controlnull(t); // ack // start LCP @@ -2390,6 +2446,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr) sess_local[s].lcp.conf_sent = 1; sess_local[s].lcp.nak_sent = 0; sess_local[s].lcp_authtype = config->radius_authprefer; + sess_local[s].ppp_mru = MRU; session[s].ppp.lcp = RequestSent; sendlcp(s, t); @@ -2535,8 +2592,6 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr) uint8_t buf[MAXETHER]; uint8_t *q; int mru = session[s].mru; - - if (!mru) mru = MAXMRU; if (mru > sizeof(buf)) mru = sizeof(buf); l += 6; @@ -3501,7 +3556,6 @@ static void initdata(int optdebug, char *optconfig) config->ppp_restart_time = 3; config->ppp_max_configure = 10; config->ppp_max_failure = 5; - config->ppp_mru = DEFAULT_MRU; strcpy(config->random_device, RANDOMDEVICE); log_stream = stderr; @@ -4171,7 +4225,7 @@ static void build_chap_response(uint8_t *challenge, uint8_t id, uint16_t challen MD5_CTX ctx; *challenge_response = NULL; - if (!*config->l2tpsecret) + if (!*config->l2tp_secret) { LOG(0, 0, 0, "LNS requested CHAP authentication, but no l2tp secret is defined\n"); return; @@ -4183,7 +4237,7 @@ static void build_chap_response(uint8_t *challenge, uint8_t id, uint16_t challen MD5_Init(&ctx); MD5_Update(&ctx, &id, 1); - MD5_Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret)); + MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret)); MD5_Update(&ctx, challenge, challenge_length); MD5_Final(*challenge_response, &ctx); @@ -4250,7 +4304,16 @@ static void update_config() setbuf(log_stream, NULL); } - if (config->ppp_mru < 0) config->ppp_mru = 0; +#define L2TP_HDRS (20+8+6+4) // L2TP data encaptulation: ip + udp + l2tp (data) + ppp (inc hdlc) +#define TCP_HDRS (20+20) // TCP encapsulation: ip + tcp + + if (config->l2tp_mtu <= 0) config->l2tp_mtu = PPPMTU; + else if (config->l2tp_mtu < MINMTU) config->l2tp_mtu = MINMTU; + else if (config->l2tp_mtu > MAXMTU) config->l2tp_mtu = MAXMTU; + + // reset MRU/MSS globals + MRU = config->l2tp_mtu - L2TP_HDRS; + MSS = MRU - TCP_HDRS; // Update radius config->numradiusservers = 0; @@ -5150,7 +5213,7 @@ static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vec // Compute initial pad MD5_Init(&ctx); MD5_Update(&ctx, (unsigned char *) &m, 2); - MD5_Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret)); + MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret)); MD5_Update(&ctx, vector, vec_len); MD5_Final(digest, &ctx); @@ -5163,7 +5226,7 @@ static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vec if (d >= sizeof(digest)) { MD5_Init(&ctx); - MD5_Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret)); + MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret)); MD5_Update(&ctx, last, sizeof(digest)); MD5_Final(digest, &ctx);