mirror of
https://github.com/libssh2/libssh2.git
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308 lines
8.0 KiB
C
308 lines
8.0 KiB
C
/* Copyright (C) The libssh2 project and its contributors.
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*
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* Sample showing how to use libssh2 to request agent forwarding
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* on the remote host. The command executed will run with agent forwarded
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* so you should be able to do things like clone out protected git
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* repos and such.
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*
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* The example uses agent authentication to ensure an agent to forward
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* is running.
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*
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* $ ./ssh2_agent_forwarding 127.0.0.1 user "uptime"
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "libssh2_setup.h"
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#include <libssh2.h>
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#ifdef HAVE_SYS_SOCKET_H
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#include <sys/socket.h>
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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#include <netinet/in.h>
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#endif
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#ifdef HAVE_ARPA_INET_H
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#include <arpa/inet.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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static const char *hostname = "127.0.0.1";
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static const char *commandline = "uptime";
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static const char *username;
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static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)
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{
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struct timeval timeout;
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int rc;
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fd_set fd;
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fd_set *writefd = NULL;
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fd_set *readfd = NULL;
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int dir;
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timeout.tv_sec = 10;
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timeout.tv_usec = 0;
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FD_ZERO(&fd);
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#if defined(__GNUC__) || defined(__clang__)
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wsign-conversion"
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#endif
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FD_SET(socket_fd, &fd);
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#if defined(__GNUC__) || defined(__clang__)
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#pragma GCC diagnostic pop
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#endif
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/* now make sure we wait in the correct direction */
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dir = libssh2_session_block_directions(session);
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if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
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readfd = &fd;
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if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
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writefd = &fd;
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rc = select((int)(socket_fd + 1), readfd, writefd, NULL, &timeout);
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return rc;
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}
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int main(int argc, char *argv[])
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{
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uint32_t hostaddr;
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libssh2_socket_t sock;
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struct sockaddr_in sin;
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int rc;
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LIBSSH2_SESSION *session = NULL;
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LIBSSH2_CHANNEL *channel;
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LIBSSH2_AGENT *agent = NULL;
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struct libssh2_agent_publickey *identity, *prev_identity = NULL;
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int exitcode;
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char *exitsignal = NULL;
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ssize_t bytecount = 0;
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#ifdef _WIN32
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WSADATA wsadata;
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rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
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if(rc) {
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fprintf(stderr, "WSAStartup failed with error: %d\n", rc);
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return 1;
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}
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#endif
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if(argc < 2) {
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fprintf(stderr, "At least IP and username arguments are required.\n");
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return 1;
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}
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/* must be ip address only */
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hostname = argv[1];
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username = argv[2];
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if(argc > 3) {
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commandline = argv[3];
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}
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rc = libssh2_init(0);
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if(rc) {
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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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hostaddr = inet_addr(hostname);
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/* Ultra basic "connect to port 22 on localhost". Your code is
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* responsible for creating the socket establishing the connection
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*/
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sock = socket(AF_INET, SOCK_STREAM, 0);
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if(sock == LIBSSH2_INVALID_SOCKET) {
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fprintf(stderr, "failed to create socket.\n");
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goto shutdown;
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}
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sin.sin_family = AF_INET;
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sin.sin_port = htons(22);
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sin.sin_addr.s_addr = hostaddr;
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if(connect(sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in))) {
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fprintf(stderr, "failed to connect.\n");
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goto shutdown;
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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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goto shutdown;
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}
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if(libssh2_session_handshake(session, sock) != 0) {
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fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
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goto shutdown;
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}
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/* Connect to the ssh-agent */
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agent = libssh2_agent_init(session);
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if(!agent) {
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fprintf(stderr, "Failure initializing ssh-agent support\n");
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rc = 1;
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goto shutdown;
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}
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if(libssh2_agent_connect(agent)) {
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fprintf(stderr, "Failure connecting to ssh-agent\n");
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rc = 1;
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goto shutdown;
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}
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if(libssh2_agent_list_identities(agent)) {
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fprintf(stderr, "Failure requesting identities to ssh-agent\n");
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rc = 1;
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goto shutdown;
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}
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for(;;) {
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rc = libssh2_agent_get_identity(agent, &identity, prev_identity);
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if(rc == 1)
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break;
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if(rc < 0) {
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fprintf(stderr,
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"Failure obtaining identity from ssh-agent support\n");
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rc = 1;
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goto shutdown;
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}
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if(libssh2_agent_userauth(agent, username, identity)) {
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fprintf(stderr, "Authentication with username %s and "
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"public key %s failed.\n",
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username, identity->comment);
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}
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else {
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fprintf(stderr, "Authentication with username %s and "
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"public key %s succeeded.\n",
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username, identity->comment);
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break;
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}
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prev_identity = identity;
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}
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if(rc) {
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fprintf(stderr, "Could not continue authentication\n");
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goto shutdown;
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}
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#if 0
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libssh2_trace(session, ~0);
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#endif
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/* Set session to non-blocking */
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libssh2_session_set_blocking(session, 0);
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/* Exec non-blocking on the remote host */
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do {
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channel = libssh2_channel_open_session(session);
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if(channel ||
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libssh2_session_last_error(session, NULL, NULL, 0) !=
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LIBSSH2_ERROR_EAGAIN)
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break;
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waitsocket(sock, session);
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} while(1);
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if(!channel) {
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fprintf(stderr, "Error\n");
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return 1;
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}
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while((rc = libssh2_channel_request_auth_agent(channel)) ==
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LIBSSH2_ERROR_EAGAIN) {
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waitsocket(sock, session);
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}
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if(rc) {
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fprintf(stderr, "Error, could not request auth agent, "
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"error code %d.\n", rc);
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return 1;
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}
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else {
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fprintf(stdout, "Agent forwarding request succeeded.\n");
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}
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while((rc = libssh2_channel_exec(channel, commandline)) ==
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LIBSSH2_ERROR_EAGAIN) {
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waitsocket(sock, session);
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}
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if(rc) {
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fprintf(stderr, "Error\n");
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return 1;
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}
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for(;;) {
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ssize_t nread;
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/* loop until we block */
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do {
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char buffer[0x4000];
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nread = libssh2_channel_read(channel, buffer, sizeof(buffer) );
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if(nread > 0) {
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ssize_t i;
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bytecount += nread;
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fprintf(stderr, "We read:\n");
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for(i = 0; i < nread; ++i)
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fputc(buffer[i], stderr);
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fprintf(stderr, "\n");
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}
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else {
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if(nread != LIBSSH2_ERROR_EAGAIN)
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/* no need to output this for the EAGAIN case */
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fprintf(stderr, "libssh2_channel_read returned %ld\n",
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(long)nread);
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}
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} while(nread > 0);
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/* this is due to blocking that would occur otherwise so we loop on
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this condition */
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if(nread == LIBSSH2_ERROR_EAGAIN) {
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waitsocket(sock, session);
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}
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else
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break;
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}
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exitcode = 127;
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while((rc = libssh2_channel_close(channel)) == LIBSSH2_ERROR_EAGAIN) {
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waitsocket(sock, session);
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}
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if(rc == 0) {
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exitcode = libssh2_channel_get_exit_status(channel);
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libssh2_channel_get_exit_signal(channel, &exitsignal,
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NULL, NULL, NULL, NULL, NULL);
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}
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if(exitsignal) {
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fprintf(stderr, "\nGot signal: %s\n",
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exitsignal ? exitsignal : "none");
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}
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else {
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fprintf(stderr, "\nEXIT: %d bytecount: %ld\n",
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exitcode, (long)bytecount);
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}
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libssh2_channel_free(channel);
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channel = NULL;
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shutdown:
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if(session) {
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libssh2_session_disconnect(session, "Normal Shutdown");
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libssh2_session_free(session);
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}
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if(sock != LIBSSH2_INVALID_SOCKET) {
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shutdown(sock, 2);
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LIBSSH2_SOCKET_CLOSE(sock);
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}
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fprintf(stderr, "all done\n");
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libssh2_exit();
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#ifdef _WIN32
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WSACleanup();
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#endif
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return 0;
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}
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