int do_connect(int type)
{
int sock = 0;
if (type != SOCK_STREAM && type != SOCK_DGRAM)
return -1;
/* We need a socket that can be inherited by child processes in
ncat_exec_win.c, for --exec and --sh-exec. inheritable_socket is from
nbase. */
sock = inheritable_socket(targetss.storage.ss_family, type, 0);
if (srcaddr.storage.ss_family != AF_UNSPEC) {
size_t sa_len;
#ifdef HAVE_SOCKADDR_SA_LEN
sa_len = srcaddr.sockaddr.sa_len;
#else
sa_len = sizeof(srcaddr);
#endif
if (bind(sock, &srcaddr.sockaddr, sa_len) < 0) {
bye("bind to %s:%hu: %s.", inet_socktop(&srcaddr),
inet_port(&srcaddr), socket_strerror(socket_errno()));
}
}
if (sock != -1) {
if (connect(sock, &targetss.sockaddr, (int) targetsslen) != -1)
return sock;
else if (socket_errno() == EINPROGRESS || socket_errno() == EAGAIN)
return sock;
}
return -1;
}
/* Just like inet_socktop, but it puts IPv6 addresses in square brackets. */
static const char *sock_to_url(const union sockaddr_u *su)
{
static char buf[INET6_ADDRSTRLEN + 32];
const char *host_str;
unsigned short port;
host_str = inet_socktop(su);
port = inet_port(su);
if (su->storage.ss_family == AF_INET)
Snprintf(buf, sizeof(buf), "%s:%hu", host_str, port);
else if (su->storage.ss_family == AF_INET6)
Snprintf(buf, sizeof(buf), "[%s]:%hu]", host_str, port);
else
bye("Unknown address family in sock_to_url_host.");
return buf;
}
/* Return a listening socket after setting various characteristics on it.
Returns -1 on error. */
int do_listen(int type, int proto, const union sockaddr_u *srcaddr_u)
{
int sock = 0, option_on = 1;
size_t sa_len;
if (type != SOCK_STREAM && type != SOCK_DGRAM)
return -1;
/* We need a socket that can be inherited by child processes in
ncat_exec_win.c, for --exec and --sh-exec. inheritable_socket is from
nbase. */
sock = inheritable_socket(srcaddr_u->storage.ss_family, type, proto);
if (sock < 0)
return -1;
Setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &option_on, sizeof(int));
/* IPPROTO_IPV6 is defined in Visual C++ only when _WIN32_WINNT >= 0x501.
Nbase's nbase_winunix.h defines _WIN32_WINNT to a lower value for
compatibility with older versions of Windows. This code disables IPv6 sockets
that also receive IPv4 connections. This is the default on Windows anyway so
it doesn't make a difference.
http://support.microsoft.com/kb/950688
http://msdn.microsoft.com/en-us/library/bb513665
*/
#ifdef IPPROTO_IPV6
#ifdef IPV6_V6ONLY
if (srcaddr_u->storage.ss_family == AF_INET6) {
int set = 1;
/* Tell it to not try and bind to IPV4 */
if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &set, sizeof(set)) == -1)
die("Unable to set IPV6 socket to bind only to IPV6");
}
#endif
#endif
#ifdef HAVE_SYS_UN_H
if (srcaddr_u->storage.ss_family == AF_UNIX)
sa_len = SUN_LEN(&srcaddr_u->un);
else
#endif
#ifdef HAVE_SOCKADDR_SA_LEN
sa_len = srcaddr_u->sockaddr.sa_len;
#else
sa_len = sizeof(*srcaddr_u);
#endif
if (bind(sock, &srcaddr_u->sockaddr, sa_len) < 0) {
#ifdef HAVE_SYS_UN_H
if (srcaddr_u->storage.ss_family == AF_UNIX)
bye("bind to %s: %s.", srcaddr_u->un.sun_path,
socket_strerror(socket_errno()));
else
#endif
bye("bind to %s:%hu: %s.", inet_socktop(srcaddr_u),
inet_port(srcaddr_u), socket_strerror(socket_errno()));
}
if (type == SOCK_STREAM)
Listen(sock, BACKLOG);
if (o.verbose) {
#ifdef HAVE_SYS_UN_H
if (srcaddr_u->storage.ss_family == AF_UNIX)
loguser("Listening on %s\n", srcaddr_u->un.sun_path);
else
#endif
loguser("Listening on %s:%hu\n", inet_socktop(srcaddr_u), inet_port(srcaddr_u));
}
if (o.test)
logtest("LISTEN\n");
return sock;
}
int ncat_connect(void)
{
nsock_pool mypool;
int rc;
/* Unless explicitely asked not to do so, ncat uses the
* fallback nsock engine to maximize compatibility between
* operating systems and the different use cases.
*/
if (!o.nsock_engine)
nsock_set_default_engine("select");
/* Create an nsock pool */
if ((mypool = nsp_new(NULL)) == NULL)
bye("Failed to create nsock_pool.");
if (o.debug >= 6)
nsock_set_loglevel(mypool, NSOCK_LOG_DBG_ALL);
else if (o.debug >= 3)
nsock_set_loglevel(mypool, NSOCK_LOG_DBG);
else if (o.debug >= 1)
nsock_set_loglevel(mypool, NSOCK_LOG_INFO);
else
nsock_set_loglevel(mypool, NSOCK_LOG_ERROR);
/* Allow connections to broadcast addresses. */
nsp_setbroadcast(mypool, 1);
#ifdef HAVE_OPENSSL
set_ssl_ctx_options((SSL_CTX *) nsp_ssl_init(mypool));
#endif
if (httpconnect.storage.ss_family == AF_UNSPEC
&& socksconnect.storage.ss_family == AF_UNSPEC) {
/* A non-proxy connection. Create an iod for a new socket. */
cs.sock_nsi = nsi_new(mypool, NULL);
if (cs.sock_nsi == NULL)
bye("Failed to create nsock_iod.");
if (nsi_set_hostname(cs.sock_nsi, o.target) == -1)
bye("Failed to set hostname on iod.");
#if HAVE_SYS_UN_H
/* For DGRAM UNIX socket we have to use source socket */
if (o.af == AF_UNIX && o.udp)
{
if (srcaddr.storage.ss_family != AF_UNIX) {
char *tmp_name = NULL;
/* If no source socket was specified, we have to create temporary one. */
if ((tmp_name = tempnam(NULL, "ncat.")) == NULL)
bye("Failed to create name for temporary DGRAM source Unix domain socket (tempnam).");
srcaddr.un.sun_family = AF_UNIX;
strncpy(srcaddr.un.sun_path, tmp_name, sizeof(srcaddr.un.sun_path));
free (tmp_name);
}
nsi_set_localaddr(cs.sock_nsi, &srcaddr.storage, SUN_LEN((struct sockaddr_un *)&srcaddr.storage));
if (o.verbose)
loguser("[%s] used as source DGRAM Unix domain socket.\n", srcaddr.un.sun_path);
}
else
#endif
if (srcaddr.storage.ss_family != AF_UNSPEC)
nsi_set_localaddr(cs.sock_nsi, &srcaddr.storage, sizeof(srcaddr.storage));
if (o.numsrcrtes) {
unsigned char *ipopts = NULL;
size_t ipoptslen = 0;
if (o.af != AF_INET)
bye("Sorry, -g can only currently be used with IPv4.");
ipopts = buildsrcrte(targetss.in.sin_addr, o.srcrtes, o.numsrcrtes, o.srcrteptr, &ipoptslen);
nsi_set_ipoptions(cs.sock_nsi, ipopts, ipoptslen);
free(ipopts); /* Nsock has its own copy */
}
#if HAVE_SYS_UN_H
if (o.af == AF_UNIX) {
if (o.udp) {
nsock_connect_unixsock_datagram(mypool, cs.sock_nsi, connect_handler, NULL,
&targetss.sockaddr,
SUN_LEN((struct sockaddr_un *)&targetss.sockaddr));
} else {
nsock_connect_unixsock_stream(mypool, cs.sock_nsi, connect_handler, o.conntimeout,
NULL, &targetss.sockaddr,
SUN_LEN((struct sockaddr_un *)&targetss.sockaddr));
}
} else
#endif
if (o.udp) {
nsock_connect_udp(mypool, cs.sock_nsi, connect_handler,
NULL, &targetss.sockaddr, targetsslen,
inet_port(&targetss));
}
#ifdef HAVE_OPENSSL
else if (o.sctp && o.ssl) {
nsock_connect_ssl(mypool, cs.sock_nsi, connect_handler,
o.conntimeout, NULL,
&targetss.sockaddr, targetsslen,
IPPROTO_SCTP, inet_port(&targetss),
NULL);
}
#endif
else if (o.sctp) {
nsock_connect_sctp(mypool, cs.sock_nsi, connect_handler,
o.conntimeout, NULL,
&targetss.sockaddr, targetsslen,
inet_port(&targetss));
}
#ifdef HAVE_OPENSSL
else if (o.ssl) {
nsock_connect_ssl(mypool, cs.sock_nsi, connect_handler,
o.conntimeout, NULL,
&targetss.sockaddr, targetsslen,
IPPROTO_TCP, inet_port(&targetss),
NULL);
}
#endif
else {
nsock_connect_tcp(mypool, cs.sock_nsi, connect_handler,
o.conntimeout, NULL,
&targetss.sockaddr, targetsslen,
inet_port(&targetss));
}
} else {
/* A proxy connection. */
static int connect_socket;
int len;
char *line;
size_t n;
if (httpconnect.storage.ss_family != AF_UNSPEC) {
connect_socket = do_proxy_http();
if (connect_socket == -1)
return 1;
} else if (socksconnect.storage.ss_family != AF_UNSPEC) {
struct socket_buffer stateful_buf;
struct socks4_data socks4msg;
char socksbuf[8];
connect_socket = do_connect(SOCK_STREAM);
if (connect_socket == -1) {
loguser("Proxy connection failed: %s.\n", socket_strerror(socket_errno()));
return 1;
}
socket_buffer_init(&stateful_buf, connect_socket);
if (o.verbose) {
loguser("Connected to proxy %s:%hu\n", inet_socktop(&targetss),
inet_port(&targetss));
}
/* Fill the socks4_data struct */
zmem(&socks4msg, sizeof(socks4msg));
socks4msg.version = SOCKS4_VERSION;
socks4msg.type = SOCKS_CONNECT;
socks4msg.port = socksconnect.in.sin_port;
socks4msg.address = socksconnect.in.sin_addr.s_addr;
if (o.proxy_auth)
Strncpy(socks4msg.username, (char *) o.proxy_auth, sizeof(socks4msg.username));
len = 8 + strlen(socks4msg.username) + 1;
if (send(connect_socket, (char *) &socks4msg, len, 0) < 0) {
loguser("Error sending proxy request: %s.\n", socket_strerror(socket_errno()));
return 1;
}
/* The size of the socks4 response is 8 bytes. So read exactly
8 bytes from the buffer */
if (socket_buffer_readcount(&stateful_buf, socksbuf, 8) < 0) {
loguser("Error: short reponse from proxy.\n");
return 1;
}
if (socksbuf[1] != 90) {
loguser("Proxy connection failed.\n");
return 1;
}
/* Clear out whatever is left in the socket buffer which may be
already sent by proxy server along with http response headers. */
line = socket_buffer_remainder(&stateful_buf, &n);
/* Write the leftover data to stdout. */
Write(STDOUT_FILENO, line, n);
}
/* Once the proxy negotiation is done, Nsock takes control of the
socket. */
cs.sock_nsi = nsi_new2(mypool, connect_socket, NULL);
/* Create IOD for nsp->stdin */
if ((cs.stdin_nsi = nsi_new2(mypool, 0, NULL)) == NULL)
bye("Failed to create stdin nsiod.");
post_connect(mypool, cs.sock_nsi);
}
/* connect */
rc = nsock_loop(mypool, -1);
if (o.verbose) {
struct timeval end_time;
double time;
gettimeofday(&end_time, NULL);
time = TIMEVAL_MSEC_SUBTRACT(end_time, start_time) / 1000.0;
loguser("%lu bytes sent, %lu bytes received in %.2f seconds.\n",
nsi_get_write_count(cs.sock_nsi),
nsi_get_read_count(cs.sock_nsi), time);
}
#if HAVE_SYS_UN_H
if (o.af == AF_UNIX && o.udp) {
if (o.verbose)
loguser("Deleting source DGRAM Unix domain socket. [%s]\n", srcaddr.un.sun_path);
unlink(srcaddr.un.sun_path);
}
#endif
nsp_delete(mypool);
return rc == NSOCK_LOOP_ERROR ? 1 : 0;
}
/* Accept a connection on a listening socket. Allow or deny the connection.
Fork a command if o.cmdexec is set. Otherwise, add the new socket to the
watch set. */
static void handle_connection(int socket_accept)
{
union sockaddr_u remoteaddr;
socklen_t ss_len;
struct fdinfo s = { 0 };
int conn_count;
zmem(&s, sizeof(s));
zmem(&remoteaddr, sizeof(remoteaddr.storage));
ss_len = sizeof(remoteaddr.storage);
errno = 0;
s.fd = accept(socket_accept, &remoteaddr.sockaddr, &ss_len);
if (s.fd < 0) {
if (o.debug)
logdebug("Error in accept: %s\n", strerror(errno));
close(s.fd);
return;
}
if (o.verbose) {
#if HAVE_SYS_UN_H
if (remoteaddr.sockaddr.sa_family == AF_UNIX)
loguser("Connection from a client on Unix domain socket.\n");
else
#endif
if (o.chat)
loguser("Connection from %s on file descriptor %d.\n", inet_socktop(&remoteaddr), s.fd);
else
loguser("Connection from %s.\n", inet_socktop(&remoteaddr));
}
if (!o.keepopen && !o.broker) {
int i;
for (i = 0; i < num_listenaddrs; i++) {
Close(listen_socket[i]);
FD_CLR(listen_socket[i], &master_readfds);
rm_fd(&client_fdlist, listen_socket[i]);
}
}
if (o.verbose) {
#if HAVE_SYS_UN_H
if (remoteaddr.sockaddr.sa_family == AF_UNIX)
loguser("Connection from %s.\n", remoteaddr.un.sun_path);
else
#endif
loguser("Connection from %s:%hu.\n", inet_socktop(&remoteaddr), inet_port(&remoteaddr));
}
/* Check conditions that might cause us to deny the connection. */
conn_count = get_conn_count();
if (conn_count >= o.conn_limit) {
if (o.verbose)
loguser("New connection denied: connection limit reached (%d)\n", conn_count);
Close(s.fd);
return;
}
if (!allow_access(&remoteaddr)) {
if (o.verbose)
loguser("New connection denied: not allowed\n");
Close(s.fd);
return;
}
s.remoteaddr = remoteaddr;
conn_inc++;
unblock_socket(s.fd);
#ifdef HAVE_OPENSSL
if (o.ssl) {
/* Add the socket to the necessary descriptor lists. */
FD_SET(s.fd, &sslpending_fds);
FD_SET(s.fd, &master_readfds);
FD_SET(s.fd, &master_writefds);
/* Add it to our list of fds too for maintaining maxfd. */
if (add_fdinfo(&client_fdlist, &s) < 0)
bye("add_fdinfo() failed.");
} else
#endif
post_handle_connection(s);
}