libssh2/example/ssh2.c

/*
 * Sample showing how to do SSH2 connect.
 *
 * The sample code has default values for host name, user name, password
 * and path to copy, but you can specify them on the command line like:
 *
 * Usage: ssh2 hostip user password [[-p|-i|-k] [command]]
 *  -p authenticate using password
 *  -i authenticate using keyboard-interactive
 *  -k authenticate using public key (password argument decrypts keyfile)
 *  command executes on the remote machine
 */

#ifdef WIN32
#ifndef _WINSOCK_DEPRECATED_NO_WARNINGS
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#endif
#endif

#include "libssh2_config.h"
#include <libssh2.h>
#include <libssh2_sftp.h>

#ifdef WIN32
# include <windows.h>
#endif
#ifdef HAVE_WINSOCK2_H
# include <winsock2.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
# include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
# ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
# ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif

#include <stdlib.h>
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>

#if defined(_MSC_VER) && _MSC_VER < 1900
#define snprintf _snprintf
#endif

const char *keyfile1 = ".ssh/id_rsa.pub";
const char *keyfile2 = ".ssh/id_rsa";
const char *username = "username";
const char *password = "password";


static void kbd_callback(const char *name, int name_len,
                         const char *instruction, int instruction_len,
                         int num_prompts,
                         const LIBSSH2_USERAUTH_KBDINT_PROMPT *prompts,
                         LIBSSH2_USERAUTH_KBDINT_RESPONSE *responses,
                         void **abstract)
{
    (void)name;
    (void)name_len;
    (void)instruction;
    (void)instruction_len;
    if(num_prompts == 1) {
        responses[0].text = strdup(password);
        responses[0].length = (unsigned int)strlen(password);
    }
    (void)prompts;
    (void)abstract;
} /* kbd_callback */


int main(int argc, char *argv[])
{
    uint32_t hostaddr;
    libssh2_socket_t sock;
    int rc, i, auth_pw = 0;
    struct sockaddr_in sin;
    const char *fingerprint;
    char *userauthlist;
    LIBSSH2_SESSION *session;
    LIBSSH2_CHANNEL *channel;

#ifdef WIN32
    WSADATA wsadata;

    rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
    if(rc != 0) {
        fprintf(stderr, "WSAStartup failed with error: %d\n", rc);
        return 1;
    }
#endif

    if(argc > 1) {
        hostaddr = inet_addr(argv[1]);
    }
    else {
        hostaddr = htonl(0x7F000001);
    }

    if(argc > 2) {
        username = argv[2];
    }
    if(argc > 3) {
        password = argv[3];
    }

    rc = libssh2_init(0);
    if(rc != 0) {
        fprintf(stderr, "libssh2 initialization failed (%d)\n", rc);
        return 1;
    }

    /* Ultra basic "connect to port 22 on localhost".  Your code is
     * responsible for creating the socket establishing the connection
     */
    sock = socket(AF_INET, SOCK_STREAM, 0);

    sin.sin_family = AF_INET;
    sin.sin_port = htons(22);
    sin.sin_addr.s_addr = hostaddr;

    fprintf(stderr, "Connecting to %s:%d as user %s\n",
            inet_ntoa(sin.sin_addr), ntohs(sin.sin_port), username);

    if(connect(sock, (struct sockaddr*)(&sin),
                sizeof(struct sockaddr_in)) != 0) {
        fprintf(stderr, "failed to connect!\n");
        return -1;
    }

    /* Create a session instance and start it up. This will trade welcome
     * banners, exchange keys, and setup crypto, compression, and MAC layers
     */
    session = libssh2_session_init();
    /* Enable all debugging when libssh2 was built with debugging enabled */
    libssh2_trace(session,
        LIBSSH2_TRACE_TRANS     |
        LIBSSH2_TRACE_KEX       |
        LIBSSH2_TRACE_AUTH      |
        LIBSSH2_TRACE_CONN      |
        LIBSSH2_TRACE_SCP       |
        LIBSSH2_TRACE_SFTP      |
        LIBSSH2_TRACE_ERROR     |
        LIBSSH2_TRACE_PUBLICKEY |
        LIBSSH2_TRACE_SOCKET
    );

    if(libssh2_session_handshake(session, sock)) {
        fprintf(stderr, "Failure establishing SSH session\n");
        return -1;
    }

    /* At this point we have not 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,
                                         (unsigned int)strlen(username));
    fprintf(stderr, "Authentication methods: %s\n", userauthlist);
    if(strstr(userauthlist, "password") != NULL) {
        auth_pw |= 1;
    }
    if(strstr(userauthlist, "keyboard-interactive") != NULL) {
        auth_pw |= 2;
    }
    if(strstr(userauthlist, "publickey") != NULL) {
        auth_pw |= 4;
    }

    /* if we got an 4. argument we set this option if supported */
    if(argc > 4) {
        if((auth_pw & 1) && !strcmp(argv[4], "-p")) {
            auth_pw = 1;
        }
        if((auth_pw & 2) && !strcmp(argv[4], "-i")) {
            auth_pw = 2;
        }
        if((auth_pw & 4) && !strcmp(argv[4], "-k")) {
            auth_pw = 4;
        }
    }

    if(auth_pw & 1) {
        /* We could authenticate via password */
        if(libssh2_userauth_password(session, username, password)) {
            fprintf(stderr, "\tAuthentication by password failed!\n");
            goto shutdown;
        }
        else {
            fprintf(stderr, "\tAuthentication by password succeeded.\n");
        }
    }
    else if(auth_pw & 2) {
        /* Or via keyboard-interactive */
        if(libssh2_userauth_keyboard_interactive(session, username,
                                                 &kbd_callback) ) {
            fprintf(stderr,
                    "\tAuthentication by keyboard-interactive failed!\n");
            goto shutdown;
        }
        else {
            fprintf(stderr,
                    "\tAuthentication by keyboard-interactive succeeded.\n");
        }
    }
    else if(auth_pw & 4) {
        /* Or by public key */
        size_t fn1sz, fn2sz;
        char *fn1, *fn2;
        char const *h = getenv("HOME");
        if(!h || !*h)
            h = ".";
        fn1sz = strlen(h) + strlen(keyfile1) + 2;
        fn2sz = strlen(h) + strlen(keyfile2) + 2;
        fn1 = malloc(fn1sz);
        fn2 = malloc(fn2sz);
        if(!fn1 || !fn2) {
            free(fn2);
            free(fn1);
            fprintf(stderr, "out of memory\n");
            goto shutdown;
        }
        /* Using asprintf() here would be much cleaner, but less portable */
        snprintf(fn1, fn1sz, "%s/%s", h, keyfile1);
        snprintf(fn2, fn2sz, "%s/%s", h, keyfile2);

        if(libssh2_userauth_publickey_fromfile(session, username, fn1,
                                               fn2, password)) {
            fprintf(stderr, "\tAuthentication by public key failed!\n");
            free(fn2);
            free(fn1);
            goto shutdown;
        }
        else {
            fprintf(stderr, "\tAuthentication by public key succeeded.\n");
        }
        free(fn2);
        free(fn1);
    }
    else {
        fprintf(stderr, "No supported authentication methods found!\n");
        goto shutdown;
    }

    /* Request a session channel on which to run a shell */
    channel = libssh2_channel_open_session(session);
    if(!channel) {
        fprintf(stderr, "Unable to open a session\n");
        goto shutdown;
    }

    /* Some environment variables may be set,
     * It's up to the server which ones it'll allow though
     */
    libssh2_channel_setenv(channel, "FOO", "bar");

    /* Request a terminal with 'vanilla' terminal emulation
     * See /etc/termcap for more options. This is useful when opening
     * an interactive shell.
     */
    #if 0
    if(libssh2_channel_request_pty(channel, "vanilla")) {
        fprintf(stderr, "Failed requesting pty\n");
    }
    #endif

    if(argc > 5) {
        if(libssh2_channel_exec(channel, argv[5])) {
            fprintf(stderr, "Unable to request command on channel\n");
            goto shutdown;
        }
        /* Instead of just running a single command with libssh2_channel_exec,
         * a shell can be opened on the channel instead, for interactive use.
         * You usually want a pty allocated first in that case (see above). */
          #if 0
          if(libssh2_channel_shell(channel)) {
              fprintf(stderr, "Unable to request shell on allocated pty\n");
              goto shutdown;
          }
          #endif

/* At this point the shell can be interacted with using
 * libssh2_channel_read()
 * libssh2_channel_read_stderr()
 * libssh2_channel_write()
 * libssh2_channel_write_stderr()
 *
 * Blocking mode may be (en|dis)abled with: libssh2_channel_set_blocking()
 * If the server send EOF, libssh2_channel_eof() will return non-0
 * To send EOF to the server use: libssh2_channel_send_eof()
 * A channel can be closed with: libssh2_channel_close()
 * A channel can be freed with: libssh2_channel_free()
 */

        /* Read and display all the data received on stdout (ignoring stderr)
         * until the channel closes. This will eventually block if the command
         * produces too much data on stderr; the loop must be rewritten to use
         * non-blocking mode and include interspersed calls to
         * libssh2_channel_read_stderr() to avoid this. See ssh2_echo.c for
         * an idea of how such a loop might look.
         */
        while(!libssh2_channel_eof(channel)) {
            char buf[1024];
            ssize_t err = libssh2_channel_read(channel, buf, sizeof(buf));
            if(err < 0)
                fprintf(stderr, "Unable to read response: %d\n", (int)err);
            else {
                fwrite(buf, 1, err, stdout);
            }
        }
    }

    rc = libssh2_channel_get_exit_status(channel);

    if(libssh2_channel_close(channel))
        fprintf(stderr, "Unable to close channel\n");

    if(channel) {
        libssh2_channel_free(channel);
        channel = NULL;
    }

    /* Other channel types are supported via:
     * libssh2_scp_send()
     * libssh2_scp_recv2()
     * libssh2_channel_direct_tcpip()
     */

  shutdown:

    libssh2_session_disconnect(session,
                               "Normal Shutdown, Thank you for playing");
    libssh2_session_free(session);

#ifdef WIN32
    closesocket(sock);
#else
    close(sock);
#endif
    fprintf(stderr, "all done!\n");

    libssh2_exit();

    return rc;
}