libssh/examples/ssh_client.c

/* client.c */
/*
Copyright 2003-2009 Aris Adamantiadis

This file is part of the SSH Library

You are free to copy this file, modify it in any way, consider it being public
domain. This does not apply to the rest of the library though, but it is
allowed to cut-and-paste working code from this file to any license of
program.
The goal is to show the API in action. It's not a reference on how terminal
clients must be made or how a client should react.
*/

#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/select.h>
#include <sys/time.h>

#ifdef HAVE_TERMIOS_H
#include <termios.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_PTY_H
#include <pty.h>
#endif

#include <sys/ioctl.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>

#include <libssh/callbacks.h>
#include <libssh/libssh.h>
#include <libssh/sftp.h>


#include "examples_common.h"
#define MAXCMD 10

static char *host;
static char *user;
static char *cmds[MAXCMD];
static struct termios terminal;

static char *pcap_file = NULL;

static char *proxycommand;

static int auth_callback(const char *prompt,
                         char *buf,
                         size_t len,
                         int echo,
                         int verify,
                         void *userdata)
{
    (void) verify;
    (void) userdata;

    return ssh_getpass(prompt, buf, len, echo, verify);
}

struct ssh_callbacks_struct cb = {
    .auth_function = auth_callback,
    .userdata = NULL,
};

static void add_cmd(char *cmd)
{
    int n;

    for (n = 0; (n < MAXCMD) && cmds[n] != NULL; n++);

    if (n == MAXCMD) {
        return;
    }

    cmds[n] = strdup(cmd);
}

static void usage(void)
{
    fprintf(stderr,
            "Usage : ssh [options] [login@]hostname\n"
            "sample client - libssh-%s\n"
            "Options :\n"
            "  -l user : log in as user\n"
            "  -p port : connect to port\n"
            "  -d : use DSS to verify host public key\n"
            "  -r : use RSA to verify host public key\n"
#ifdef WITH_PCAP
            "  -P file : create a pcap debugging file\n"
#endif
#ifndef _WIN32
            "  -T proxycommand : command to execute as a socket proxy\n"
#endif
            "\n",
            ssh_version(0));

    exit(0);
}

static int opts(int argc, char **argv)
{
    int i;

    while((i = getopt(argc,argv,"T:P:")) != -1) {
        switch(i){
        case 'P':
            pcap_file = optarg;
            break;
#ifndef _WIN32
        case 'T':
            proxycommand = optarg;
            break;
#endif
        default:
            fprintf(stderr, "Unknown option %c\n", optopt);
            usage();
        }
    }
    if (optind < argc) {
        host = argv[optind++];
    }

    while(optind < argc) {
        add_cmd(argv[optind++]);
    }

    if (host == NULL) {
        usage();
    }

    return 0;
}

#ifndef HAVE_CFMAKERAW
static void cfmakeraw(struct termios *termios_p)
{
    termios_p->c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON);
    termios_p->c_oflag &= ~OPOST;
    termios_p->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
    termios_p->c_cflag &= ~(CSIZE|PARENB);
    termios_p->c_cflag |= CS8;
}
#endif


static void do_cleanup(int i)
{
  /* unused variable */
  (void) i;

  tcsetattr(0, TCSANOW, &terminal);
}

static void do_exit(int i)
{
    /* unused variable */
    (void) i;

    do_cleanup(0);
    exit(0);
}

static ssh_channel chan;
static int signal_delayed = 0;

static void sigwindowchanged(int i)
{
    (void) i;
    signal_delayed = 1;
}

static void setsignal(void)
{
    signal(SIGWINCH, sigwindowchanged);
    signal_delayed = 0;
}

static void sizechanged(void)
{
    struct winsize win = {
        .ws_row = 0,
    };

    ioctl(1, TIOCGWINSZ, &win);
    ssh_channel_change_pty_size(chan,win.ws_col, win.ws_row);
    setsignal();
}

static void select_loop(ssh_session session,ssh_channel channel)
{
    ssh_connector connector_in, connector_out, connector_err;

    ssh_event event = ssh_event_new();

    /* stdin */
    connector_in = ssh_connector_new(session);
    ssh_connector_set_out_channel(connector_in, channel, SSH_CONNECTOR_STDOUT);
    ssh_connector_set_in_fd(connector_in, 0);
    ssh_event_add_connector(event, connector_in);

    /* stdout */
    connector_out = ssh_connector_new(session);
    ssh_connector_set_out_fd(connector_out, 1);
    ssh_connector_set_in_channel(connector_out, channel, SSH_CONNECTOR_STDOUT);
    ssh_event_add_connector(event, connector_out);

    /* stderr */
    connector_err = ssh_connector_new(session);
    ssh_connector_set_out_fd(connector_err, 2);
    ssh_connector_set_in_channel(connector_err, channel, SSH_CONNECTOR_STDERR);
    ssh_event_add_connector(event, connector_err);

    while (ssh_channel_is_open(channel)) {
        if (signal_delayed) {
            sizechanged();
        }
        ssh_event_dopoll(event, 60000);
    }
    ssh_event_remove_connector(event, connector_in);
    ssh_event_remove_connector(event, connector_out);
    ssh_event_remove_connector(event, connector_err);

    ssh_connector_free(connector_in);
    ssh_connector_free(connector_out);
    ssh_connector_free(connector_err);

    ssh_event_free(event);
    ssh_channel_free(channel);
}

static void shell(ssh_session session)
{
    ssh_channel channel;
    struct termios terminal_local;
    int interactive=isatty(0);
    channel = ssh_channel_new(session);

    if (interactive) {
        tcgetattr(0, &terminal_local);
        memcpy(&terminal, &terminal_local, sizeof(struct termios));
    }

    if (ssh_channel_open_session(channel)) {
        printf("Error opening channel : %s\n", ssh_get_error(session));
        return;
    }
    chan = channel;
    if (interactive) {
        ssh_channel_request_pty(channel);
        sizechanged();
    }

    if (ssh_channel_request_shell(channel)) {
        printf("Requesting shell : %s\n", ssh_get_error(session));
        return;
    }

    if (interactive) {
        cfmakeraw(&terminal_local);
        tcsetattr(0, TCSANOW, &terminal_local);
        setsignal();
    }
    signal(SIGTERM, do_cleanup);
    select_loop(session, channel);
    if (interactive) {
        do_cleanup(0);
    }
}

static void batch_shell(ssh_session session)
{
    ssh_channel channel;
    char buffer[1024];
    size_t i;
    int s = 0;

    for (i = 0; i < MAXCMD && cmds[i]; ++i) {
        s += snprintf(buffer + s, sizeof(buffer) - s, "%s ", cmds[i]);
        free(cmds[i]);
        cmds[i] = NULL;
    }

    channel = ssh_channel_new(session);
    ssh_channel_open_session(channel);
    if (ssh_channel_request_exec(channel, buffer)) {
        printf("Error executing '%s' : %s\n", buffer, ssh_get_error(session));
        return;
    }
    select_loop(session, channel);
}

static int client(ssh_session session)
{
    int auth = 0;
    char *banner;
    int state;

    if (user) {
        if (ssh_options_set(session, SSH_OPTIONS_USER, user) < 0) {
            return -1;
        }
    }
    if (ssh_options_set(session, SSH_OPTIONS_HOST ,host) < 0) {
        return -1;
    }
    if (proxycommand != NULL) {
        if (ssh_options_set(session, SSH_OPTIONS_PROXYCOMMAND, proxycommand)) {
            return -1;
        }
    }
    ssh_options_parse_config(session, NULL);

    if (ssh_connect(session)) {
        fprintf(stderr, "Connection failed : %s\n", ssh_get_error(session));
        return -1;
    }

    state = verify_knownhost(session);
    if (state != 0) {
        return -1;
    }

    ssh_userauth_none(session, NULL);
    banner = ssh_get_issue_banner(session);
    if (banner) {
        printf("%s\n", banner);
        free(banner);
    }
    auth = authenticate_console(session);
    if (auth != SSH_AUTH_SUCCESS) {
        return -1;
    }
    if (cmds[0] == NULL) {
        shell(session);
    } else {
        batch_shell(session);
    }

    return 0;
}

static ssh_pcap_file pcap;
static void set_pcap(ssh_session session)
{
    if (pcap_file == NULL) {
        return;
    }

    pcap = ssh_pcap_file_new();
    if (pcap == NULL) {
        return;
    }

    if (ssh_pcap_file_open(pcap, pcap_file) == SSH_ERROR) {
        printf("Error opening pcap file\n");
        ssh_pcap_file_free(pcap);
        pcap = NULL;
        return;
    }
    ssh_set_pcap_file(session, pcap);
}

static void cleanup_pcap(void)
{
    if (pcap != NULL) {
        ssh_pcap_file_free(pcap);
    }
    pcap = NULL;
}

int main(int argc, char **argv)
{
    ssh_session session;

    session = ssh_new();

    ssh_callbacks_init(&cb);
    ssh_set_callbacks(session,&cb);

    if (ssh_options_getopt(session, &argc, argv)) {
        fprintf(stderr,
                "Error parsing command line: %s\n",
                ssh_get_error(session));
        usage();
    }
    opts(argc, argv);
    signal(SIGTERM, do_exit);

    set_pcap(session);
    client(session);

    ssh_disconnect(session);
    ssh_free(session);
    cleanup_pcap();

    ssh_finalize();

    return 0;
}