Add a tcpip-forward example which demonstrates remote port forwarding
This commit is contained in:
Peter Stuge
parent
e95c7de453
commit
e394987911
1
example/.gitignore
vendored
1
example/.gitignore
vendored
@ -33,4 +33,5 @@ test-sftp_nonblock
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test-sftp_write
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test-sftp_write_nonblock
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test-ssh2_echo
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tcpip-forward
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x11
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@ -7,7 +7,7 @@ noinst_PROGRAMS = direct_tcpip ssh2 scp scp_nonblock scp_write \
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scp_write_nonblock sftp sftp_nonblock sftp_write sftp_write_nonblock \
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sftp_mkdir sftp_mkdir_nonblock sftp_RW_nonblock sftp_write_sliding \
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sftpdir sftpdir_nonblock ssh2_exec ssh2_agent ssh2_echo sftp_append \
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subsystem_netconf x11
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subsystem_netconf tcpip-forward x11
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AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/example
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LDADD = $(top_builddir)/src/libssh2.la
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292
example/tcpip-forward.c
Normal file
292
example/tcpip-forward.c
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@ -0,0 +1,292 @@
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#include "libssh2_config.h"
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#include <libssh2.h>
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#ifdef WIN32
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#include <windows.h>
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#include <winsock2.h>
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#include <ws2tcpip.h>
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#else
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <sys/time.h>
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#endif
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#include <fcntl.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/types.h>
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#ifdef HAVE_SYS_SELECT_H
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#include <sys/select.h>
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#endif
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#ifndef INADDR_NONE
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#define INADDR_NONE (in_addr_t)-1
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#endif
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const char *keyfile1 = "/home/username/.ssh/id_rsa.pub";
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const char *keyfile2 = "/home/username/.ssh/id_rsa";
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const char *username = "username";
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const char *password = "";
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const char *server_ip = "127.0.0.1";
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const char *remote_listenhost = "localhost"; /* resolved by the server */
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unsigned int remote_wantport = 2222;
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unsigned int remote_listenport;
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const char *local_destip = "127.0.0.1";
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unsigned int local_destport = 22;
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enum {
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AUTH_NONE = 0,
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AUTH_PASSWORD,
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AUTH_PUBLICKEY
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};
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int main(int argc, char *argv[])
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{
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int rc, sock = -1, forwardsock = -1, i, auth = AUTH_NONE;
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struct sockaddr_in sin;
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socklen_t sinlen = sizeof(sin);
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const char *fingerprint;
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char *userauthlist;
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LIBSSH2_SESSION *session;
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LIBSSH2_LISTENER *listener = NULL;
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LIBSSH2_CHANNEL *channel = NULL;
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const char *shost;
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unsigned int sport;
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fd_set fds;
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struct timeval tv;
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ssize_t len, wr;
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char buf[16384];
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#ifdef WIN32
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char sockopt;
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WSADATA wsadata;
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WSAStartup(MAKEWORD(2,0), &wsadata);
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#else
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int sockopt;
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#endif
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if (argc > 1)
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server_ip = argv[1];
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if (argc > 2)
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username = argv[2];
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if (argc > 3)
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password = argv[3];
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if (argc > 4)
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remote_listenhost = argv[4];
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if (argc > 5)
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remote_wantport = atoi(argv[5]);
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if (argc > 6)
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local_destip = argv[6];
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if (argc > 7)
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local_destport = atoi(argv[7]);
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rc = libssh2_init (0);
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if (rc != 0) {
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fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
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return 1;
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}
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/* Connect to SSH server */
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sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
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sin.sin_family = AF_INET;
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if (INADDR_NONE == (sin.sin_addr.s_addr = inet_addr(server_ip))) {
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perror("inet_addr");
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return -1;
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}
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sin.sin_port = htons(22);
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if (connect(sock, (struct sockaddr*)(&sin),
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sizeof(struct sockaddr_in)) != 0) {
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fprintf(stderr, "failed to connect!\n");
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return -1;
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}
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/* Create a session instance */
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session = libssh2_session_init();
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if(!session) {
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fprintf(stderr, "Could not initialize SSH session!\n");
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return -1;
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}
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/* ... start it up. This will trade welcome banners, exchange keys,
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* and setup crypto, compression, and MAC layers
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*/
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rc = libssh2_session_handshake(session, sock);
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if(rc) {
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fprintf(stderr, "Error when starting up SSH session: %d\n", rc);
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return -1;
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}
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/* At this point we havn't yet authenticated. The first thing to do
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* is check the hostkey's fingerprint against our known hosts Your app
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* may have it hard coded, may go to a file, may present it to the
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* user, that's your call
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*/
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fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
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fprintf(stderr, "Fingerprint: ");
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for(i = 0; i < 20; i++)
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fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
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fprintf(stderr, "\n");
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/* check what authentication methods are available */
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userauthlist = libssh2_userauth_list(session, username, strlen(username));
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printf("Authentication methods: %s\n", userauthlist);
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if (strstr(userauthlist, "password"))
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auth |= AUTH_PASSWORD;
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if (strstr(userauthlist, "publickey"))
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auth |= AUTH_PUBLICKEY;
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/* check for options */
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if(argc > 8) {
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if ((auth & AUTH_PASSWORD) && !strcasecmp(argv[8], "-p"))
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auth = AUTH_PASSWORD;
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if ((auth & AUTH_PUBLICKEY) && !strcasecmp(argv[8], "-k"))
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auth = AUTH_PUBLICKEY;
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}
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if (auth & AUTH_PASSWORD) {
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if (libssh2_userauth_password(session, username, password)) {
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fprintf(stderr, "Authentication by password failed.\n");
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goto shutdown;
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}
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} else if (auth & AUTH_PUBLICKEY) {
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if (libssh2_userauth_publickey_fromfile(session, username, keyfile1,
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keyfile2, password)) {
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printf("\tAuthentication by public key failed!\n");
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goto shutdown;
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}
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printf("\tAuthentication by public key succeeded.\n");
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} else {
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printf("No supported authentication methods found!\n");
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goto shutdown;
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}
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printf("Asking server to listen on remote %s:%d\n", remote_listenhost,
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remote_wantport);
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listener = libssh2_channel_forward_listen_ex(session, remote_listenhost,
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remote_wantport, &remote_listenport, 1);
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if (!listener) {
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fprintf(stderr, "Could not start the tcpip-forward listener!\n"
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"(Note that this can be a problem at the server!"
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" Please review the server logs.)\n");
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goto shutdown;
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}
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printf("Server is listening on %s:%d\n", remote_listenhost,
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remote_listenport);
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printf("Waiting for remote connection\n");
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channel = libssh2_channel_forward_accept(listener);
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if (!channel) {
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fprintf(stderr, "Could not accept connection!\n"
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"(Note that this can be a problem at the server!"
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" Please review the server logs.)\n");
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goto shutdown;
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}
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printf("Accepted remote connection. Connecting to local server %s:%d\n",
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local_destip, local_destport);
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forwardsock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
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sin.sin_family = AF_INET;
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sin.sin_port = htons(local_destport);
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if (INADDR_NONE == (sin.sin_addr.s_addr = inet_addr(local_destip))) {
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perror("inet_addr");
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goto shutdown;
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}
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if (-1 == connect(forwardsock, (struct sockaddr *)&sin, sinlen)) {
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perror("connect");
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goto shutdown;
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}
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printf("Forwarding connection from remote %s:%d to local %s:%d\n",
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remote_listenhost, remote_listenport, local_destip, local_destport);
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/* Must use non-blocking IO hereafter due to the current libssh2 API */
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libssh2_session_set_blocking(session, 0);
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while (1) {
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FD_ZERO(&fds);
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FD_SET(forwardsock, &fds);
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tv.tv_sec = 0;
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tv.tv_usec = 100000;
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rc = select(forwardsock + 1, &fds, NULL, NULL, &tv);
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if (-1 == rc) {
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perror("select");
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goto shutdown;
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}
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if (rc && FD_ISSET(forwardsock, &fds)) {
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len = recv(forwardsock, buf, sizeof(buf), 0);
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if (len < 0) {
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perror("read");
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goto shutdown;
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} else if (0 == len) {
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printf("The local server at %s:%d disconnected!\n",
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local_destip, local_destport);
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goto shutdown;
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}
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wr = 0;
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do {
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i = libssh2_channel_write(channel, buf, len);
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if (i < 0) {
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fprintf(stderr, "libssh2_channel_write: %d\n", i);
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goto shutdown;
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}
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wr += i;
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} while(i > 0 && wr < len);
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}
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while (1) {
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len = libssh2_channel_read(channel, buf, sizeof(buf));
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if (LIBSSH2_ERROR_EAGAIN == len)
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break;
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else if (len < 0) {
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fprintf(stderr, "libssh2_channel_read: %d", (int)len);
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goto shutdown;
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}
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wr = 0;
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while (wr < len) {
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i = send(forwardsock, buf + wr, len - wr, 0);
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if (i <= 0) {
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perror("write");
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goto shutdown;
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}
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wr += i;
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}
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if (libssh2_channel_eof(channel)) {
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printf("The remote client at %s:%d disconnected!\n",
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remote_listenhost, remote_listenport);
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goto shutdown;
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}
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}
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}
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shutdown:
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#ifdef WIN32
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closesocket(forwardsock);
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#else
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close(forwardsock);
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#endif
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if (channel)
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libssh2_channel_free(channel);
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if (listener)
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libssh2_channel_forward_cancel(listener);
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libssh2_session_disconnect(session, "Client disconnecting normally");
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libssh2_session_free(session);
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#ifdef WIN32
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closesocket(sock);
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#else
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close(sock);
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#endif
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libssh2_exit();
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return 0;
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}
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