1 /* $OpenBSD: ftp-proxy.c,v 1.19 2008/06/13 07:25:26 claudio Exp $ */
4 * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 #include <sys/cdefs.h>
20 __FBSDID("$FreeBSD$");
22 #include <sys/queue.h>
23 #include <sys/types.h>
25 #include <sys/resource.h>
26 #include <sys/socket.h>
29 #include <net/pfvar.h>
30 #include <netinet/in.h>
31 #include <arpa/inet.h>
50 #define CONNECT_TIMEOUT 30
53 #define MAX_LOGLINE 300
55 #define TCP_BACKLOG 10
57 #define CHROOT_DIR "/var/empty"
58 #define NOPRIV_USER "proxy"
60 /* pfctl standard NAT range. */
61 #define PF_NAT_PROXY_PORT_LOW 50001
62 #define PF_NAT_PROXY_PORT_HIGH 65535
65 #define LIST_END(a) NULL
69 #define getrtable(a) 0
72 #define sstosa(ss) ((struct sockaddr *)(ss))
74 enum { CMD_NONE = 0, CMD_PORT, CMD_EPRT, CMD_PASV, CMD_EPSV };
78 struct sockaddr_storage client_ss;
79 struct sockaddr_storage proxy_ss;
80 struct sockaddr_storage server_ss;
81 struct sockaddr_storage orig_server_ss;
82 struct bufferevent *client_bufev;
83 struct bufferevent *server_bufev;
93 LIST_ENTRY(session) entry;
96 LIST_HEAD(, session) sessions = LIST_HEAD_INITIALIZER(sessions);
98 void client_error(struct bufferevent *, short, void *);
99 int client_parse(struct session *s);
100 int client_parse_anon(struct session *s);
101 int client_parse_cmd(struct session *s);
102 void client_read(struct bufferevent *, void *);
103 int drop_privs(void);
104 void end_session(struct session *);
105 void exit_daemon(void);
106 int getline(char *, size_t *);
107 void handle_connection(const int, short, void *);
108 void handle_signal(int, short, void *);
109 struct session * init_session(void);
110 void logmsg(int, const char *, ...);
111 u_int16_t parse_port(int);
112 u_int16_t pick_proxy_port(void);
113 void proxy_reply(int, struct sockaddr *, u_int16_t);
114 void server_error(struct bufferevent *, short, void *);
115 int server_parse(struct session *s);
116 int allow_data_connection(struct session *s);
117 void server_read(struct bufferevent *, void *);
118 const char *sock_ntop(struct sockaddr *);
121 char linebuf[MAX_LINE + 1];
124 char ntop_buf[NTOP_BUFS][INET6_ADDRSTRLEN];
126 struct sockaddr_storage fixed_server_ss, fixed_proxy_ss;
127 const char *fixed_server, *fixed_server_port, *fixed_proxy, *listen_ip, *listen_port,
129 int anonymous_only, daemonize, id_count, ipv6_mode, loglevel, max_sessions,
130 rfc_mode, session_count, timeout, verbose;
131 extern char *__progname;
134 client_error(struct bufferevent *bufev __unused, short what, void *arg)
136 struct session *s = arg;
138 if (what & EVBUFFER_EOF)
139 logmsg(LOG_INFO, "#%d client close", s->id);
140 else if (what == (EVBUFFER_ERROR | EVBUFFER_READ))
141 logmsg(LOG_ERR, "#%d client reset connection", s->id);
142 else if (what & EVBUFFER_TIMEOUT)
143 logmsg(LOG_ERR, "#%d client timeout", s->id);
144 else if (what & EVBUFFER_WRITE)
145 logmsg(LOG_ERR, "#%d client write error: %d", s->id, what);
147 logmsg(LOG_ERR, "#%d abnormal client error: %d", s->id, what);
153 client_parse(struct session *s)
155 /* Reset any previous command. */
159 /* Commands we are looking for are at least 4 chars long. */
163 if (linebuf[0] == 'P' || linebuf[0] == 'p' ||
164 linebuf[0] == 'E' || linebuf[0] == 'e') {
165 if (!client_parse_cmd(s))
169 * Allow active mode connections immediately, instead of
170 * waiting for a positive reply from the server. Some
171 * rare servers/proxies try to probe or setup the data
172 * connection before an actual transfer request.
174 if (s->cmd == CMD_PORT || s->cmd == CMD_EPRT)
175 return (allow_data_connection(s));
178 if (anonymous_only && (linebuf[0] == 'U' || linebuf[0] == 'u'))
179 return (client_parse_anon(s));
185 client_parse_anon(struct session *s)
187 if (strcasecmp("USER ftp\r\n", linebuf) != 0 &&
188 strcasecmp("USER anonymous\r\n", linebuf) != 0) {
189 snprintf(linebuf, sizeof linebuf,
190 "500 Only anonymous FTP allowed\r\n");
191 logmsg(LOG_DEBUG, "#%d proxy: %s", s->id, linebuf);
193 /* Talk back to the client ourself. */
194 linelen = strlen(linebuf);
195 bufferevent_write(s->client_bufev, linebuf, linelen);
197 /* Clear buffer so it's not sent to the server. */
206 client_parse_cmd(struct session *s)
208 if (strncasecmp("PASV", linebuf, 4) == 0)
210 else if (strncasecmp("PORT ", linebuf, 5) == 0)
212 else if (strncasecmp("EPSV", linebuf, 4) == 0)
214 else if (strncasecmp("EPRT ", linebuf, 5) == 0)
219 if (ipv6_mode && (s->cmd == CMD_PASV || s->cmd == CMD_PORT)) {
220 logmsg(LOG_CRIT, "PASV and PORT not allowed with IPv6");
224 if (s->cmd == CMD_PORT || s->cmd == CMD_EPRT) {
225 s->port = parse_port(s->cmd);
226 if (s->port < MIN_PORT) {
227 logmsg(LOG_CRIT, "#%d bad port in '%s'", s->id,
231 s->proxy_port = pick_proxy_port();
232 proxy_reply(s->cmd, sstosa(&s->proxy_ss), s->proxy_port);
233 logmsg(LOG_DEBUG, "#%d proxy: %s", s->id, linebuf);
240 client_read(struct bufferevent *bufev, void *arg)
242 struct session *s = arg;
243 size_t buf_avail, clientread;
247 buf_avail = sizeof s->cbuf - s->cbuf_valid;
248 clientread = bufferevent_read(bufev, s->cbuf + s->cbuf_valid,
250 s->cbuf_valid += clientread;
252 while ((n = getline(s->cbuf, &s->cbuf_valid)) > 0) {
253 logmsg(LOG_DEBUG, "#%d client: %s", s->id, linebuf);
254 if (!client_parse(s)) {
258 bufferevent_write(s->server_bufev, linebuf, linelen);
262 logmsg(LOG_ERR, "#%d client command too long or not"
267 } while (clientread == buf_avail);
275 pw = getpwnam(NOPRIV_USER);
280 if (chroot(CHROOT_DIR) != 0 || chdir("/") != 0 ||
281 setgroups(1, &pw->pw_gid) != 0 ||
282 setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0 ||
283 setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0)
290 end_session(struct session *s)
294 logmsg(LOG_INFO, "#%d ending session", s->id);
296 /* Flush output buffers. */
297 if (s->client_bufev && s->client_fd != -1)
298 evbuffer_write(s->client_bufev->output, s->client_fd);
299 if (s->server_bufev && s->server_fd != -1)
300 evbuffer_write(s->server_bufev->output, s->server_fd);
302 if (s->client_fd != -1)
304 if (s->server_fd != -1)
308 bufferevent_free(s->client_bufev);
310 bufferevent_free(s->server_bufev);
312 /* Remove rulesets by commiting empty ones. */
314 if (prepare_commit(s->id) == -1)
316 else if (do_commit() == -1) {
321 logmsg(LOG_ERR, "#%d pf rule removal failed: %s", s->id,
324 LIST_REMOVE(s, entry);
332 struct session *s, *next;
334 for (s = LIST_FIRST(&sessions); s != LIST_END(&sessions); s = next) {
335 next = LIST_NEXT(s, entry);
346 getline(char *buf, size_t *valid)
350 if (*valid > MAX_LINE)
353 /* Copy to linebuf while searching for a newline. */
354 for (i = 0; i < *valid; i++) {
363 /* No newline found. */
372 linebuf[linelen] = '\0';
375 /* Move leftovers to the start. */
377 bcopy(buf + linelen, buf, *valid);
379 return ((int)linelen);
383 handle_connection(const int listen_fd, short event __unused, void *ev __unused)
385 struct sockaddr_storage tmp_ss;
386 struct sockaddr *client_sa, *server_sa, *fixed_server_sa;
387 struct sockaddr *client_to_proxy_sa, *proxy_to_server_sa;
390 int client_fd, fc, on;
393 * We _must_ accept the connection, otherwise libevent will keep
394 * coming back, and we will chew up all CPU.
396 client_sa = sstosa(&tmp_ss);
397 len = sizeof(struct sockaddr_storage);
398 if ((client_fd = accept(listen_fd, client_sa, &len)) < 0) {
399 logmsg(LOG_CRIT, "accept failed: %s", strerror(errno));
403 /* Refuse connection if the maximum is reached. */
404 if (session_count >= max_sessions) {
405 logmsg(LOG_ERR, "client limit (%d) reached, refusing "
406 "connection from %s", max_sessions, sock_ntop(client_sa));
411 /* Allocate session and copy back the info from the accept(). */
414 logmsg(LOG_CRIT, "init_session failed");
418 s->client_fd = client_fd;
419 memcpy(sstosa(&s->client_ss), client_sa, client_sa->sa_len);
421 /* Cast it once, and be done with it. */
422 client_sa = sstosa(&s->client_ss);
423 server_sa = sstosa(&s->server_ss);
424 client_to_proxy_sa = sstosa(&tmp_ss);
425 proxy_to_server_sa = sstosa(&s->proxy_ss);
426 fixed_server_sa = sstosa(&fixed_server_ss);
428 /* Log id/client early to ease debugging. */
429 logmsg(LOG_DEBUG, "#%d accepted connection from %s", s->id,
430 sock_ntop(client_sa));
433 * Find out the real server and port that the client wanted.
435 len = sizeof(struct sockaddr_storage);
436 if ((getsockname(s->client_fd, client_to_proxy_sa, &len)) < 0) {
437 logmsg(LOG_CRIT, "#%d getsockname failed: %s", s->id,
441 if (server_lookup(client_sa, client_to_proxy_sa, server_sa) != 0) {
442 logmsg(LOG_CRIT, "#%d server lookup failed (no rdr?)", s->id);
446 memcpy(sstosa(&s->orig_server_ss), server_sa,
448 memcpy(server_sa, fixed_server_sa, fixed_server_sa->sa_len);
451 /* XXX: check we are not connecting to ourself. */
454 * Setup socket and connect to server.
456 if ((s->server_fd = socket(server_sa->sa_family, SOCK_STREAM,
458 logmsg(LOG_CRIT, "#%d server socket failed: %s", s->id,
462 if (fixed_proxy && bind(s->server_fd, sstosa(&fixed_proxy_ss),
463 fixed_proxy_ss.ss_len) != 0) {
464 logmsg(LOG_CRIT, "#%d cannot bind fixed proxy address: %s",
465 s->id, strerror(errno));
469 /* Use non-blocking connect(), see CONNECT_TIMEOUT below. */
470 if ((fc = fcntl(s->server_fd, F_GETFL)) == -1 ||
471 fcntl(s->server_fd, F_SETFL, fc | O_NONBLOCK) == -1) {
472 logmsg(LOG_CRIT, "#%d cannot mark socket non-blocking: %s",
473 s->id, strerror(errno));
476 if (connect(s->server_fd, server_sa, server_sa->sa_len) < 0 &&
477 errno != EINPROGRESS) {
478 logmsg(LOG_CRIT, "#%d proxy cannot connect to server %s: %s",
479 s->id, sock_ntop(server_sa), strerror(errno));
483 len = sizeof(struct sockaddr_storage);
484 if ((getsockname(s->server_fd, proxy_to_server_sa, &len)) < 0) {
485 logmsg(LOG_CRIT, "#%d getsockname failed: %s", s->id,
490 logmsg(LOG_INFO, "#%d FTP session %d/%d started: client %s to server "
491 "%s via proxy %s ", s->id, session_count, max_sessions,
492 sock_ntop(client_sa), sock_ntop(server_sa),
493 sock_ntop(proxy_to_server_sa));
495 /* Keepalive is nice, but don't care if it fails. */
497 setsockopt(s->client_fd, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
499 setsockopt(s->server_fd, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
503 * Setup buffered events.
505 s->client_bufev = bufferevent_new(s->client_fd, &client_read, NULL,
507 if (s->client_bufev == NULL) {
508 logmsg(LOG_CRIT, "#%d bufferevent_new client failed", s->id);
511 bufferevent_settimeout(s->client_bufev, timeout, 0);
512 bufferevent_enable(s->client_bufev, EV_READ | EV_TIMEOUT);
514 s->server_bufev = bufferevent_new(s->server_fd, &server_read, NULL,
516 if (s->server_bufev == NULL) {
517 logmsg(LOG_CRIT, "#%d bufferevent_new server failed", s->id);
520 bufferevent_settimeout(s->server_bufev, CONNECT_TIMEOUT, 0);
521 bufferevent_enable(s->server_bufev, EV_READ | EV_TIMEOUT);
530 handle_signal(int sig, short event __unused, void *arg __unused)
533 * Signal handler rules don't apply, libevent decouples for us.
536 logmsg(LOG_ERR, "exiting on signal %d", sig);
547 s = calloc(1, sizeof(struct session));
558 s->client_bufev = NULL;
559 s->server_bufev = NULL;
563 LIST_INSERT_HEAD(&sessions, s, entry);
570 logmsg(int pri, const char *message, ...)
577 va_start(ap, message);
580 /* syslog does its own vissing. */
581 vsyslog(pri, message, ap);
583 char buf[MAX_LOGLINE];
584 char visbuf[2 * MAX_LOGLINE];
586 /* We don't care about truncation. */
587 vsnprintf(buf, sizeof buf, message, ap);
589 strvis(visbuf, buf, VIS_CSTYLE | VIS_NL);
591 strnvis(visbuf, buf, sizeof visbuf, VIS_CSTYLE | VIS_NL);
593 fprintf(stderr, "%s\n", visbuf);
600 main(int argc, char *argv[])
603 struct addrinfo hints, *res;
604 struct event ev, ev_sighup, ev_sigint, ev_sigterm;
605 int ch, error, listenfd, on;
613 fixed_server_port = "21";
616 listen_port = "8021";
617 loglevel = LOG_NOTICE;
625 /* Other initialization. */
629 while ((ch = getopt(argc, argv, "6Aa:b:D:dm:P:p:q:R:rT:t:v")) != -1) {
638 fixed_proxy = optarg;
644 loglevel = strtonum(optarg, LOG_EMERG, LOG_DEBUG,
647 errx(1, "loglevel %s", errstr);
653 max_sessions = strtonum(optarg, 1, 500, &errstr);
655 errx(1, "max sessions %s", errstr);
658 fixed_server_port = optarg;
661 listen_port = optarg;
664 if (strlen(optarg) >= PF_QNAME_SIZE)
665 errx(1, "queuename too long");
669 fixed_server = optarg;
675 if (strlen(optarg) >= PF_TAG_NAME_SIZE)
676 errx(1, "tagname too long");
680 timeout = strtonum(optarg, 0, 86400, &errstr);
682 errx(1, "timeout %s", errstr);
694 if (listen_ip == NULL)
695 listen_ip = ipv6_mode ? "::1" : "127.0.0.1";
697 /* Check for root to save the user from cryptic failure messages. */
699 errx(1, "needs to start as root");
701 /* Raise max. open files limit to satisfy max. sessions. */
702 rlp.rlim_cur = rlp.rlim_max = (2 * max_sessions) + 10;
703 if (setrlimit(RLIMIT_NOFILE, &rlp) == -1)
707 memset(&hints, 0, sizeof hints);
708 hints.ai_flags = AI_NUMERICHOST;
709 hints.ai_family = ipv6_mode ? AF_INET6 : AF_INET;
710 hints.ai_socktype = SOCK_STREAM;
711 error = getaddrinfo(fixed_proxy, NULL, &hints, &res);
713 errx(1, "getaddrinfo fixed proxy address failed: %s",
714 gai_strerror(error));
715 memcpy(&fixed_proxy_ss, res->ai_addr, res->ai_addrlen);
716 logmsg(LOG_INFO, "using %s to connect to servers",
717 sock_ntop(sstosa(&fixed_proxy_ss)));
722 memset(&hints, 0, sizeof hints);
723 hints.ai_family = ipv6_mode ? AF_INET6 : AF_INET;
724 hints.ai_socktype = SOCK_STREAM;
725 error = getaddrinfo(fixed_server, fixed_server_port, &hints,
728 errx(1, "getaddrinfo fixed server address failed: %s",
729 gai_strerror(error));
730 memcpy(&fixed_server_ss, res->ai_addr, res->ai_addrlen);
731 logmsg(LOG_INFO, "using fixed server %s",
732 sock_ntop(sstosa(&fixed_server_ss)));
736 /* Setup listener. */
737 memset(&hints, 0, sizeof hints);
738 hints.ai_flags = AI_NUMERICHOST | AI_PASSIVE;
739 hints.ai_family = ipv6_mode ? AF_INET6 : AF_INET;
740 hints.ai_socktype = SOCK_STREAM;
741 error = getaddrinfo(listen_ip, listen_port, &hints, &res);
743 errx(1, "getaddrinfo listen address failed: %s",
744 gai_strerror(error));
745 if ((listenfd = socket(res->ai_family, SOCK_STREAM, IPPROTO_TCP)) == -1)
746 errx(1, "socket failed");
748 if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, (void *)&on,
750 err(1, "setsockopt failed");
751 if (bind(listenfd, (struct sockaddr *)res->ai_addr,
752 (socklen_t)res->ai_addrlen) != 0)
753 err(1, "bind failed");
754 if (listen(listenfd, TCP_BACKLOG) != 0)
755 err(1, "listen failed");
759 init_filter(qname, tagname, verbose);
762 if (daemon(0, 0) == -1)
763 err(1, "cannot daemonize");
764 openlog(__progname, LOG_PID | LOG_NDELAY, LOG_DAEMON);
767 /* Use logmsg for output from here on. */
770 logmsg(LOG_ERR, "cannot drop privileges: %s", strerror(errno));
776 /* Setup signal handler. */
777 signal(SIGPIPE, SIG_IGN);
778 signal_set(&ev_sighup, SIGHUP, handle_signal, NULL);
779 signal_set(&ev_sigint, SIGINT, handle_signal, NULL);
780 signal_set(&ev_sigterm, SIGTERM, handle_signal, NULL);
781 signal_add(&ev_sighup, NULL);
782 signal_add(&ev_sigint, NULL);
783 signal_add(&ev_sigterm, NULL);
785 event_set(&ev, listenfd, EV_READ | EV_PERSIST, handle_connection, &ev);
786 event_add(&ev, NULL);
788 logmsg(LOG_NOTICE, "listening on %s port %s", listen_ip, listen_port);
793 logmsg(LOG_ERR, "event_dispatch error: %s", strerror(errno));
803 unsigned int port, v[6];
807 /* Find the last space or left-parenthesis. */
808 for (p = linebuf + linelen; p > linebuf; p--)
809 if (*p == ' ' || *p == '(')
816 n = sscanf(p, " %u,%u,%u,%u,%u,%u", &v[0], &v[1], &v[2],
817 &v[3], &v[4], &v[5]);
818 if (n == 6 && v[0] < 256 && v[1] < 256 && v[2] < 256 &&
819 v[3] < 256 && v[4] < 256 && v[5] < 256)
820 return ((v[4] << 8) | v[5]);
823 n = sscanf(p, "(%u,%u,%u,%u,%u,%u)", &v[0], &v[1], &v[2],
824 &v[3], &v[4], &v[5]);
825 if (n == 6 && v[0] < 256 && v[1] < 256 && v[2] < 256 &&
826 v[3] < 256 && v[4] < 256 && v[5] < 256)
827 return ((v[4] << 8) | v[5]);
830 n = sscanf(p, "(|||%u|)", &port);
831 if (n == 1 && port < 65536)
835 n = sscanf(p, " |1|%u.%u.%u.%u|%u|", &v[0], &v[1], &v[2],
837 if (n == 5 && v[0] < 256 && v[1] < 256 && v[2] < 256 &&
838 v[3] < 256 && port < 65536)
840 n = sscanf(p, " |2|%*[a-fA-F0-9:]|%u|", &port);
841 if (n == 1 && port < 65536)
852 pick_proxy_port(void)
854 /* Random should be good enough for avoiding port collisions. */
855 return (IPPORT_HIFIRSTAUTO +
856 arc4random_uniform(IPPORT_HILASTAUTO - IPPORT_HIFIRSTAUTO));
860 proxy_reply(int cmd, struct sockaddr *sa, u_int16_t port)
867 r = snprintf(linebuf, sizeof linebuf,
868 "PORT %s,%u,%u\r\n", sock_ntop(sa), port / 256,
872 r = snprintf(linebuf, sizeof linebuf,
873 "227 Entering Passive Mode (%s,%u,%u)\r\n", sock_ntop(sa),
874 port / 256, port % 256);
877 if (sa->sa_family == AF_INET)
878 r = snprintf(linebuf, sizeof linebuf,
879 "EPRT |1|%s|%u|\r\n", sock_ntop(sa), port);
880 else if (sa->sa_family == AF_INET6)
881 r = snprintf(linebuf, sizeof linebuf,
882 "EPRT |2|%s|%u|\r\n", sock_ntop(sa), port);
885 r = snprintf(linebuf, sizeof linebuf,
886 "229 Entering Extended Passive Mode (|||%u|)\r\n", port);
890 if (r < 0 || ((u_int)r) >= sizeof linebuf) {
891 logmsg(LOG_ERR, "proxy_reply failed: %d", r);
898 if (cmd == CMD_PORT || cmd == CMD_PASV) {
899 /* Replace dots in IP address with commas. */
900 for (i = 0; i < linelen; i++)
901 if (linebuf[i] == '.')
907 server_error(struct bufferevent *bufev __unused, short what, void *arg)
909 struct session *s = arg;
911 if (what & EVBUFFER_EOF)
912 logmsg(LOG_INFO, "#%d server close", s->id);
913 else if (what == (EVBUFFER_ERROR | EVBUFFER_READ))
914 logmsg(LOG_ERR, "#%d server refused connection", s->id);
915 else if (what & EVBUFFER_WRITE)
916 logmsg(LOG_ERR, "#%d server write error: %d", s->id, what);
917 else if (what & EVBUFFER_TIMEOUT)
918 logmsg(LOG_NOTICE, "#%d server timeout", s->id);
920 logmsg(LOG_ERR, "#%d abnormal server error: %d", s->id, what);
926 server_parse(struct session *s)
928 if (s->cmd == CMD_NONE || linelen < 4 || linebuf[0] != '2')
931 if ((s->cmd == CMD_PASV && strncmp("227 ", linebuf, 4) == 0) ||
932 (s->cmd == CMD_EPSV && strncmp("229 ", linebuf, 4) == 0))
933 return (allow_data_connection(s));
943 allow_data_connection(struct session *s)
945 struct sockaddr *client_sa, *orig_sa, *proxy_sa, *server_sa;
949 * The pf rules below do quite some NAT rewriting, to keep up
950 * appearances. Points to keep in mind:
951 * 1) The client must think it's talking to the real server,
952 * for both control and data connections. Transparently.
953 * 2) The server must think that the proxy is the client.
954 * 3) Source and destination ports are rewritten to minimize
955 * port collisions, to aid security (some systems pick weak
956 * ports) or to satisfy RFC requirements (source port 20).
959 /* Cast this once, to make code below it more readable. */
960 client_sa = sstosa(&s->client_ss);
961 server_sa = sstosa(&s->server_ss);
962 proxy_sa = sstosa(&s->proxy_ss);
964 /* Fixed server: data connections must appear to come
965 from / go to the original server, not the fixed one. */
966 orig_sa = sstosa(&s->orig_server_ss);
968 /* Server not fixed: orig_server == server. */
969 orig_sa = sstosa(&s->server_ss);
972 if (s->cmd == CMD_PASV || s->cmd == CMD_EPSV) {
973 s->port = parse_port(s->cmd);
974 if (s->port < MIN_PORT) {
975 logmsg(LOG_CRIT, "#%d bad port in '%s'", s->id,
979 s->proxy_port = pick_proxy_port();
980 logmsg(LOG_INFO, "#%d passive: client to server port %d"
981 " via port %d", s->id, s->port, s->proxy_port);
983 if (prepare_commit(s->id) == -1)
987 proxy_reply(s->cmd, orig_sa, s->proxy_port);
988 logmsg(LOG_DEBUG, "#%d proxy: %s", s->id, linebuf);
990 /* rdr from $client to $orig_server port $proxy_port -> $server
992 if (add_rdr(s->id, client_sa, orig_sa, s->proxy_port,
993 server_sa, s->port) == -1)
996 /* nat from $client to $server port $port -> $proxy */
997 if (add_nat(s->id, client_sa, server_sa, s->port, proxy_sa,
998 PF_NAT_PROXY_PORT_LOW, PF_NAT_PROXY_PORT_HIGH) == -1)
1001 /* pass in from $client to $server port $port */
1002 if (add_filter(s->id, PF_IN, client_sa, server_sa,
1006 /* pass out from $proxy to $server port $port */
1007 if (add_filter(s->id, PF_OUT, proxy_sa, server_sa,
1013 if (s->cmd == CMD_PORT || s->cmd == CMD_EPRT) {
1014 logmsg(LOG_INFO, "#%d active: server to client port %d"
1015 " via port %d", s->id, s->port, s->proxy_port);
1017 if (prepare_commit(s->id) == -1)
1021 /* rdr from $server to $proxy port $proxy_port -> $client port
1023 if (add_rdr(s->id, server_sa, proxy_sa, s->proxy_port,
1024 client_sa, s->port) == -1)
1027 /* nat from $server to $client port $port -> $orig_server port
1029 if (rfc_mode && s->cmd == CMD_PORT) {
1030 /* Rewrite sourceport to RFC mandated 20. */
1031 if (add_nat(s->id, server_sa, client_sa, s->port,
1032 orig_sa, 20, 20) == -1)
1035 /* Let pf pick a source port from the standard range. */
1036 if (add_nat(s->id, server_sa, client_sa, s->port,
1037 orig_sa, PF_NAT_PROXY_PORT_LOW,
1038 PF_NAT_PROXY_PORT_HIGH) == -1)
1042 /* pass in from $server to $client port $port */
1043 if (add_filter(s->id, PF_IN, server_sa, client_sa, s->port) ==
1047 /* pass out from $orig_server to $client port $port */
1048 if (add_filter(s->id, PF_OUT, orig_sa, client_sa, s->port) ==
1053 /* Commit rules if they were prepared. */
1054 if (prepared && (do_commit() == -1)) {
1057 /* One more try if busy. */
1059 if (do_commit() == -1)
1069 logmsg(LOG_CRIT, "#%d pf operation failed: %s", s->id, strerror(errno));
1076 server_read(struct bufferevent *bufev, void *arg)
1078 struct session *s = arg;
1079 size_t buf_avail, srvread;
1082 bufferevent_settimeout(bufev, timeout, 0);
1085 buf_avail = sizeof s->sbuf - s->sbuf_valid;
1086 srvread = bufferevent_read(bufev, s->sbuf + s->sbuf_valid,
1088 s->sbuf_valid += srvread;
1090 while ((n = getline(s->sbuf, &s->sbuf_valid)) > 0) {
1091 logmsg(LOG_DEBUG, "#%d server: %s", s->id, linebuf);
1092 if (!server_parse(s)) {
1096 bufferevent_write(s->client_bufev, linebuf, linelen);
1100 logmsg(LOG_ERR, "#%d server reply too long or not"
1105 } while (srvread == buf_avail);
1109 sock_ntop(struct sockaddr *sa)
1113 /* Cycle to next buffer. */
1114 n = (n + 1) % NTOP_BUFS;
1115 ntop_buf[n][0] = '\0';
1117 if (sa->sa_family == AF_INET) {
1118 struct sockaddr_in *sin = (struct sockaddr_in *)sa;
1120 return (inet_ntop(AF_INET, &sin->sin_addr, ntop_buf[n],
1121 sizeof ntop_buf[0]));
1124 if (sa->sa_family == AF_INET6) {
1125 struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;
1127 return (inet_ntop(AF_INET6, &sin6->sin6_addr, ntop_buf[n],
1128 sizeof ntop_buf[0]));
1137 fprintf(stderr, "usage: %s [-6Adrv] [-a address] [-b address]"
1138 " [-D level] [-m maxsessions]\n [-P port]"
1139 " [-p port] [-q queue] [-R address] [-T tag]\n"
1140 " [-t timeout]\n", __progname);