Hello All,
I am trying to use libssh2_channel_direct_tcpip_ex() for setting up the
channel.
I am able to get first request set correctly and getting right reply
from the http server which is running on different machine.
<<========================================>> channel
machine A <-----------------------------------------> machin B
(running apache) (access web)
apache on 8080 mapped @
8083
I am using select to handle multiple request, but its not helping.
below is my code.
rc = libssh2_init (0);
if (rc != 0) {
fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
return 1;
}
/* Connect to SSH server */
sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
sin.sin_family = AF_INET;
if (INADDR_NONE == (sin.sin_addr.s_addr = inet_addr(server_ip))) {
perror("inet_addr");
return -1;
}
sin.sin_port = htons(22);
if (connect(sock, (struct sockaddr*)(&sin),
sizeof(struct sockaddr_in)) != 0) {
fprintf(stderr, "failed to connect!\n");
return -1;
}
/* Create a session instance */
session = libssh2_session_init();
if(!session) {
fprintf(stderr, "Could not initialize SSH session!\n");
return -1;
}
/* ... start it up. This will trade welcome banners, exchange keys,
* * and setup crypto, compression, and MAC layers
* */
rc = libssh2_session_startup(session, sock);
if(rc) {
fprintf(stderr, "Error when starting up SSH session: %d\n", rc);
return -1;
}
/* At this point we havn't yet authenticated. The first thing to do
* * is check the hostkey's fingerprint against our known hosts
Your app
* * may have it hard coded, may go to a file, may present
it to the
* * user, that's your call
* */
fingerprint = libssh2_hostkey_hash(session,
LIBSSH2_HOSTKEY_HASH_SHA1);
fprintf(stderr, "Fingerprint: ");
for(i = 0; i < 20; i++)
fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
fprintf(stderr, "\n");
/* check what authentication methods are available */
userauthlist = libssh2_userauth_list(session, username,
strlen(username));
printf("Authentication methods: %s\n", userauthlist);
if (strstr(userauthlist, "password"))
auth |= AUTH_PASSWORD;
if (strstr(userauthlist, "publickey"))
auth |= AUTH_PUBLICKEY;
/* check for options */
if(argc > 8) {
if ((auth & AUTH_PASSWORD) && !strcasecmp(argv[8], "-p"))
auth = AUTH_PASSWORD;
if ((auth & AUTH_PUBLICKEY) && !strcasecmp(argv[8], "-k"))
auth = AUTH_PUBLICKEY;
}
if (auth & AUTH_PASSWORD) {
if (libssh2_userauth_password(session, username, password)) {
fprintf(stderr, "Authentication by password failed.\n");
goto shutdown;
}
} else if (auth & AUTH_PUBLICKEY) {
if (libssh2_userauth_publickey_fromfile(session, username,
keyfile1,
keyfile2, password)) {
printf("\tAuthentication by public key failed!\n");
goto shutdown;
}
printf("\tAuthentication by public key succeeded.\n");
} else {
printf("No supported authentication methods found!\n");
goto shutdown;
}
listensock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
sin.sin_family = AF_INET;
sin.sin_port = htons(local_listenport);
if (INADDR_NONE == (sin.sin_addr.s_addr =
inet_addr(local_listenip))) {
perror("inet_addr");
goto shutdown;
}
sockopt = 1;
setsockopt(listensock, SOL_SOCKET, SO_REUSEADDR, &sockopt,
sizeof(sockopt));
sinlen=sizeof(sin);
if (-1 == bind(listensock, (struct sockaddr *)&sin, sinlen)) {
perror("bind - 1 ");
goto shutdown;
}
if (-1 == listen(listensock, 2)) {
perror("listen");
goto shutdown;
}
printf("Waiting for TCP connection on %s:%d...\n",
inet_ntoa(sin.sin_addr), ntohs(sin.sin_port));
forwardsock = accept(listensock, (struct sockaddr *)&sin, &sinlen);
if (-1 == forwardsock) {
perror("accept");
goto shutdown;
}
shost = inet_ntoa(sin.sin_addr);
sport = ntohs(sin.sin_port);
printf("Forwarding connection from %s:%d here to remote %s:%d\n",
shost,
sport, remote_desthost, remote_destport);
channel = libssh2_channel_direct_tcpip_ex(session, remote_desthost,
remote_destport, shost, sport);
if (!channel) {
fprintf(stderr, "Could not open the direct-tcpip channel!\n"
"(Note that this can be a problem at the server!"
" Please review the server logs.)\n");
goto shutdown;
}
/* Must use non-blocking IO hereafter due to the current libssh2 API
*/
libssh2_session_set_blocking(session, 0);
while (1) {
FD_ZERO(&fds);
FD_SET(forwardsock, &fds);
tv.tv_sec = 0;
tv.tv_usec = 100000;
rc = select(forwardsock + 1, &fds, NULL, NULL, &tv);
if (-1 == rc) {
perror("select");
goto shutdown;
}
if (rc && FD_ISSET(forwardsock, &fds)) {
len = recv(forwardsock, buf, sizeof(buf), 0);
if (len < 0) {
perror("read");
goto shutdown;
} else if (0 == len) {
printf("The client at %s:%d disconnected!\n", shost,
sport);
goto shutdown;
}
wr = 0;
do {
i = libssh2_channel_write(channel, buf, len);
if (i < 0) {
fprintf(stderr, "libssh2_channel_write: %d\n", i);
goto shutdown;
}
wr += i;
} while(i > 0 && wr < len);
}
while (1) {
len = libssh2_channel_read(channel, buf, sizeof(buf));
if (LIBSSH2_ERROR_EAGAIN == len)
break;
else if (len < 0) {
fprintf(stderr, "libssh2_channel_read: %d", (int)len);
goto shutdown;
}
wr = 0;
while (wr < len) {
i = send(forwardsock, buf + wr, len - wr, 0);
if (i <= 0) {
perror("write");
goto shutdown;
}
wr += i;
}
if (libssh2_channel_eof(channel)) {
printf("The server at %s:%d disconnected!\n",
remote_desthost, remote_destport);
goto shutdown;
}
}
}
shutdown:
#ifdef WIN32
closesocket(forwardsock);
closesocket(listensock);
#else
close(forwardsock);
close(listensock);
#endif
if (channel)
libssh2_channel_free(channel);
libssh2_session_disconnect(session, "Client disconnecting
normally");
libssh2_session_free(session);
#ifdef WIN32
closesocket(sock);
#else
close(sock);
#endif
libssh2_exit();
Please let me know if something is wrong with this code.
Thanks,
Gaurav
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Received on 2012-02-03