commit - /dev/null
commit + b542d8003b0a24ba0e646257a8e9331cabc7ec9f
blob - /dev/null
blob + 13b0966257d91d948a4abb691e5acf181a043622 (mode 644)
--- /dev/null
+++ Makefile
+PROG = lstun
+LDADD = -levent
+WARNINGS = yes
+
+.ifdef DEBUG
+CFLAGS = -O0 -g
+.endif
+
+.include <bsd.prog.mk>
blob - /dev/null
blob + 63da816b52f1e0e2b2765536c07b204d292cc846 (mode 644)
--- /dev/null
+++ lstun.1
+.\" Copyright (c) 2021 Omar Polo <op@omarpolo.com>
+.\"
+.\" Permission to use, copy, modify, and distribute this software for any
+.\" purpose with or without fee is hereby granted, provided that the above
+.\" copyright notice and this permission notice appear in all copies.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+.Dd $Mdocdate: November 20 2021$
+.Dt LSTUN 1
+.Os
+.Sh NAME
+.Nm lstun
+.Nd lazy ssh tunnel
+.Sh SYNOPSIS
+.Nm
+.Bk -words
+.Fl B Ar port:host:hostport
+.Fl b Ar addr
+.Op Fl t Ar timeout
+.Ar destination
+.Ek
+.Sh DESCRIPTION
+.Nm
+binds the local
+.Ar addr
+and lazily spawns an
+.Xr ssh 1
+instance to forward the traffic to a remote end.
+After
+.Ar timeout
+seconds
+from the last client activity, the ssh tunnel is closed.
+.Pp
+The
+.Xr ssh 1
+tunnel is established by running
+.Bk
+.Pa /usr/bin/ssh
+.Fl L Ar port:host:hostport
+.Fl NTq
+.Ar destination .
+.Ek
+.Pp
+The arguments are as follows:
+.Bl -tag -width Ds
+.It Fl B Ar port:host:hostport
+Fed to
+.Xr ssh 1
+.Fl L
+flag.
+.It Fl b Ar addr
+Where to bind the local socket.
+A port number or the tuple host:port.
+.It Fl t Ar timeout
+Number of seconds after after the last client shutdown to kill the ssh
+process.
+Defaults to 120.
+.El
+.Sh AUTHORS
+.An -nosplit
+The
+.Nm
+utility was written by
+.An Omar Polo Aq Mt op@omarpolo.com .
blob - /dev/null
blob + bf3775c4b498876dfa73186e1daedaf40f129bcd (mode 644)
--- /dev/null
+++ lstun.c
+/*
+ * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+
+#include <err.h>
+#include <errno.h>
+#include <event.h>
+#include <limits.h>
+#include <netdb.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <stdint.h>
+
+#ifndef SSH_PATH
+#define SSH_PATH "/usr/bin/ssh"
+#endif
+
+#define MAXSOCK 4
+#define MAXCONN 16
+
+int rport; /* ssh port */
+const char *addr; /* our addr */
+const char *ssh_tunnel_flag;
+const char *ssh_dest;
+
+struct event sockev[MAXSOCK];
+int socks[MAXSOCK];
+int nsock;
+
+struct event sighupev;
+struct event sigintev;
+struct event sigtermev;
+struct event sigchldev;
+struct event siginfoev;
+
+struct timeval timeout;
+struct event timeoutev;
+
+pid_t ssh_pid = -1;
+
+int conn;
+
+struct conn {
+ int source;
+ struct bufferevent *sourcebev;
+ int to;
+ struct bufferevent *tobev;
+} conns[MAXCONN];
+
+static void
+terminate(int fd, short event, void *data)
+{
+ event_loopbreak();
+}
+
+static void
+chld(int fd, short event, void *data)
+{
+ int status;
+ pid_t pid;
+
+ if ((pid = waitpid(ssh_pid, &status, WNOHANG)) == -1)
+ err(1, "waitpid");
+}
+
+static void
+info(int fd, short event, void *data)
+{
+ warnx("connections: %d", conn);
+}
+
+static void
+spawn_ssh(void)
+{
+ warnx("spawning ssh...");
+
+ switch (ssh_pid = fork()) {
+ case -1:
+ err(1, "fork");
+ case 0:
+ execl(SSH_PATH, "ssh", "-L", ssh_tunnel_flag,
+ "-NTq", ssh_dest, NULL);
+ err(1, "exec");
+ default:
+ sleep(5); /* XXX: wait for ssh to bind the port... */
+ }
+}
+
+static void
+killing_time(int fd, short event, void *data)
+{
+ if (ssh_pid == -1)
+ return;
+
+ warnx("killing time!");
+ kill(ssh_pid, SIGTERM);
+ ssh_pid = -1;
+}
+
+static void
+nopcb(struct bufferevent *bev, void *d)
+{
+ return;
+}
+
+static void
+sreadcb(struct bufferevent *bev, void *d)
+{
+ struct conn *c = d;
+
+ bufferevent_write_buffer(c->tobev, EVBUFFER_INPUT(bev));
+}
+
+static void
+treadcb(struct bufferevent *bev, void *d)
+{
+ struct conn *c = d;
+
+ bufferevent_write_buffer(c->sourcebev, EVBUFFER_INPUT(bev));
+}
+
+static void
+errcb(struct bufferevent *bev, short event, void *d)
+{
+ struct conn *c = d;
+
+ warnx("in errcb, closing connection");
+
+ bufferevent_free(c->sourcebev);
+ bufferevent_free(c->tobev);
+
+ close(c->source);
+ close(c->to);
+
+ c->source = -1;
+ c->to = -1;
+
+ if (--conn == 0) {
+ warnx("scheduling ssh termination (%lds)",
+ timeout.tv_sec);
+ evtimer_set(&timeoutev, killing_time, NULL);
+ evtimer_add(&timeoutev, &timeout);
+ }
+}
+
+static int
+connect_to_ssh(void)
+{
+ struct addrinfo hints, *res, *res0;
+ int r, saved_errno, sock;
+ char port[16];
+ const char *c, *cause;
+
+ if ((c = strchr(ssh_tunnel_flag, ':')) == NULL)
+ errx(1, "wrong flag format: %s", ssh_tunnel_flag);
+
+ if ((size_t)(c - ssh_tunnel_flag) >= sizeof(port)-1)
+ errx(1, "EPORTTOOLONG");
+
+ memset(port, 0, sizeof(port));
+ memcpy(port, ssh_tunnel_flag, c - ssh_tunnel_flag);
+
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_family = AF_UNSPEC;
+ hints.ai_socktype = SOCK_STREAM;
+
+ /* XXX: hardcoded */
+ r = getaddrinfo("localhost", port, &hints, &res0);
+ if (r != 0)
+ errx(1, "getaddrinfo(\"localhost\", \"%s\"): %s",
+ port, gai_strerror(r));
+
+ for (res = res0; res; res = res->ai_next) {
+ sock = socket(res->ai_family, res->ai_socktype,
+ res->ai_protocol);
+ if (sock == -1) {
+ cause = "socket";
+ continue;
+ }
+
+ if (connect(sock, res->ai_addr, res->ai_addrlen) == -1) {
+ cause = "connect";
+ saved_errno = errno;
+ close(sock);
+ errno = saved_errno;
+ sock = -1;
+ continue;
+ }
+
+ break;
+ }
+
+ if (sock == -1)
+ err(1, "%s", cause);
+
+ freeaddrinfo(res0);
+ return sock;
+}
+
+static void
+do_accept(int fd, short event, void *data)
+{
+ int s, sock, i;
+
+ warnx("handling connection");
+
+ if (evtimer_pending(&timeoutev, NULL))
+ evtimer_del(&timeoutev);
+
+ if ((s = accept(fd, NULL, 0)) == -1)
+ err(1, "accept");
+
+ if (conn == MAXCONN) {
+ /* oops */
+ close(s);
+ return;
+ }
+
+ conn++;
+
+ if (ssh_pid == -1)
+ spawn_ssh();
+
+ warnx("binding the socket to ssh");
+ sock = connect_to_ssh();
+
+ for (i = 0; i < MAXCONN; ++i) {
+ if (conns[i].source == -1) {
+ conns[i].source = s;
+ conns[i].to = sock;
+ conns[i].sourcebev = bufferevent_new(s,
+ sreadcb, nopcb, errcb, &conns[i]);
+ conns[i].tobev = bufferevent_new(sock,
+ treadcb, nopcb, errcb, &conns[i]);
+ if (conns[i].sourcebev == NULL ||
+ conns[i].tobev == NULL)
+ err(1, "bufferevent_new");
+ bufferevent_enable(conns[i].sourcebev,
+ EV_READ|EV_WRITE);
+ bufferevent_enable(conns[i].tobev,
+ EV_READ|EV_WRITE);
+ break;
+ }
+ }
+}
+
+static void __dead
+usage(void)
+{
+ fprintf(stderr, "usage: %s -B port:host:hostport -b addr [-t timeout]"
+ " destination\n", getprogname());
+ exit(1);
+}
+
+static void
+bind_socket(void)
+{
+ struct addrinfo hints, *res, *res0;
+ int r, saved_errno;
+ char host[64];
+ const char *c, *h, *port, *cause;
+
+ if ((c = strchr(addr, ':')) == NULL) {
+ h = NULL;
+ port = addr;
+ } else {
+ if ((size_t)(c - addr) >= sizeof(host) -1)
+ errx(1, "ENAMETOOLONG");
+ memset(host, 0, sizeof(host));
+ memcpy(host, c, c - addr);
+
+ h = host;
+ port = c+1;
+ }
+
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_family = AF_UNSPEC;
+ hints.ai_socktype = SOCK_STREAM;
+ hints.ai_flags = AI_PASSIVE;
+
+ r = getaddrinfo(h, port, &hints, &res0);
+ if (r != 0)
+ errx(1, "getaddrinfo(%s): %s",
+ addr, gai_strerror(r));
+
+ for (res = res0; res && nsock < MAXSOCK; res = res->ai_next) {
+ socks[nsock] = socket(res->ai_family, res->ai_socktype,
+ res->ai_protocol);
+ if (socks[nsock] == -1) {
+ cause = "socket";
+ continue;
+ }
+
+ if (bind(socks[nsock], res->ai_addr, res->ai_addrlen) == -1) {
+ cause = "bind";
+ saved_errno = errno;
+ close(socks[nsock]);
+ errno = saved_errno;
+ continue;
+ }
+
+ listen(socks[nsock], 5);
+
+ nsock++;
+ }
+ if (nsock == 0)
+ err(1, "%s", cause);
+
+ freeaddrinfo(res0);
+}
+
+int
+main(int argc, char **argv)
+{
+ pid_t pid;
+ int ch, tout, i, status;
+ const char *errstr;
+
+ while ((ch = getopt(argc, argv, "B:b:t:")) != -1) {
+ switch (ch) {
+ case 'B':
+ ssh_tunnel_flag = optarg;
+ break;
+ case 'b':
+ addr = optarg;
+ break;
+ case 't':
+ tout = strtonum(optarg, 1, INT_MAX, &errstr);
+ if (errstr != NULL)
+ errx(1, "timeout is %s: %s", errstr, optarg);
+ break;
+ default:
+ usage();
+ }
+ }
+ argc -= optind;
+ argv += optind;
+
+ if (argc != 1 || addr == NULL || ssh_tunnel_flag == NULL)
+ usage();
+
+ if (tout == 0)
+ tout = 120;
+
+ timeout.tv_sec = tout;
+ timeout.tv_usec = 0;
+
+ ssh_dest = argv[0];
+
+ for (i = 0; i < MAXCONN; ++i) {
+ conns[i].source = -1;
+ conns[i].to = -1;
+ }
+
+ bind_socket();
+
+ signal(SIGPIPE, SIG_IGN);
+
+ event_init();
+
+ /* initialize the timer */
+ evtimer_set(&timeoutev, killing_time, NULL);
+
+ signal_set(&sighupev, SIGHUP, terminate, NULL);
+ signal_set(&sigintev, SIGINT, terminate, NULL);
+ signal_set(&sigtermev, SIGTERM, terminate, NULL);
+ signal_set(&sigchldev, SIGCHLD, chld, NULL);
+ signal_set(&siginfoev, SIGINFO, info, NULL);
+
+ signal_add(&sighupev, NULL);
+ signal_add(&sigintev, NULL);
+ signal_add(&sigtermev, NULL);
+ signal_add(&sigchldev, NULL);
+ signal_add(&siginfoev, NULL);
+
+ for (i = 0; i < nsock; ++i) {
+ event_set(&sockev[i], socks[i], EV_READ|EV_PERSIST,
+ do_accept, NULL);
+ event_add(&sockev[i], NULL);
+ }
+
+ /*
+ * dns, inet: bind the socket and connect to the childs.
+ * proc, exec: execute ssh on demand.
+ */
+ if (pledge("stdio dns inet proc exec", NULL) == -1)
+ err(1, "pledge");
+
+ warnx("lift off!");
+ event_dispatch();
+
+ if (ssh_pid != -1)
+ kill(ssh_pid, SIGINT);
+
+ return 0;
+}
