libssh-example/simple-server/main.c

#include "config.h"

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

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

#include "priv_key.h"

#define BUF_SIZE 2049

#define USER "odroid"
#define PASSWORD "odroid"

static int authenticated=0;
static int tries = 0;
static int error = 0;
static ssh_channel chan=NULL;

static int auth_none(ssh_session session,
                     const char *user,
                     void *userdata)
{
    char buf[100];
    ssh_string banner = NULL;

    (void)userdata; /* unused */

    ssh_set_auth_methods(session,
                         SSH_AUTH_METHOD_PASSWORD);

    sprintf(buf, "hello [%s]!\n", user);
    banner = ssh_string_from_char(buf);
    if (banner != NULL) {
        ssh_send_issue_banner(session, banner);
    }
    ssh_string_free(banner);

    return SSH_AUTH_DENIED;
}

static int auth_password(ssh_session session, const char *user,
        const char *password, void *userdata){
    (void)userdata;
    ssh_string banner = NULL;
    printf("Authenticating user %s pwd %s\n",user, password);
    if(strcmp(user,USER) == 0 && strcmp(password, PASSWORD) == 0){
        authenticated = 1;
        printf("Authenticated\n");
        banner = ssh_string_from_char("Authenticated\n");
        ssh_send_issue_banner(session, banner);
        ssh_string_free(banner);
        return SSH_AUTH_SUCCESS;
    }
    if (tries >= 3){
        printf("Too many authentication tries\n");
        ssh_disconnect(session);
        error = 1;
        return SSH_AUTH_DENIED;
    }
    tries++;
    return SSH_AUTH_DENIED;
}

static int pty_request(ssh_session session, ssh_channel channel, const char *term,
        int x,int y, int px, int py, void *userdata){
    (void) session;
    (void) channel;
    (void) userdata;
    printf("Allocated terminal\n");
    printf("trem: %s, x: %d, y: %d, px: %d, py %d\n", term, x, y, px, py);
    return 0;
}

static int shell_request(ssh_session session, ssh_channel channel, void *userdata){
    (void)session;
    (void)channel;
    (void)userdata;
    printf("Allocated shell\n");
    return 0;
}
struct ssh_channel_callbacks_struct channel_cb = {
    .channel_pty_request_function = pty_request,
    .channel_shell_request_function = shell_request
};

static ssh_channel new_session_channel(ssh_session session, void *userdata){
    (void) session;
    (void) userdata;
    if(chan != NULL)
        return NULL;
    printf("Allocated session channel\n");
    chan = ssh_channel_new(session);
    ssh_callbacks_init(&channel_cb);
    ssh_set_channel_callbacks(chan, &channel_cb);
    return chan;
}

int main(int argc, char **argv)
{
    ssh_session session = NULL;
    ssh_bind sshbind = NULL;
    ssh_event mainloop = NULL;
    struct ssh_server_callbacks_struct cb = {
        .userdata = NULL,
        .auth_none_function = auth_none,
        .auth_password_function = auth_password,
        .channel_open_request_session_function = new_session_channel
    };

    char buf[BUF_SIZE];
    int i;
    int r;

    sshbind=ssh_bind_new();
    session=ssh_new();
    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT_STR, "11422");
    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDADDR, "0.0.0.0");
    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_IMPORT_KEY_STR, HOST_KEY);

    (void) argc;
    (void) argv;

    if(ssh_bind_listen(sshbind)<0){
        printf("Error listening to socket: %s\n",ssh_get_error(sshbind));
        return 1;
    }
    r=ssh_bind_accept(sshbind,session);
    if(r==SSH_ERROR){
        printf("error accepting a connection : %s\n",ssh_get_error(sshbind));
        return 1;
    }
    ssh_callbacks_init(&cb);
    ssh_set_server_callbacks(session, &cb);

    if (ssh_handle_key_exchange(session)) {
        printf("ssh_handle_key_exchange: %s\n", ssh_get_error(session));
        return 1;
    }
    ssh_set_auth_methods(session,SSH_AUTH_METHOD_PASSWORD);
    mainloop = ssh_event_new();
    ssh_event_add_session(mainloop, session);

    while (!(authenticated && chan != NULL)){
        if(error)
            break;
        r = ssh_event_dopoll(mainloop, -1);
        if (r == SSH_ERROR){
            printf("Error : %s\n",ssh_get_error(session));
            ssh_disconnect(session);
            return 1;
        }
    }
    if(error){
        printf("Error, exiting loop\n");
    } else
        printf("Authenticated and got a channel\n");
    do{
        i=ssh_channel_read(chan, buf, sizeof(buf) - 1, 0);
        if(i>0) {
            if (ssh_channel_write(chan, buf, i) == SSH_ERROR) {
                printf("error writing to channel\n");
                return 1;
            }

            buf[i] = '\0';
            printf("%s", buf);
            fflush(stdout);

            if (buf[0] == '\x0d') {
                if (ssh_channel_write(chan, "\n", 1) == SSH_ERROR) {
                    printf("error writing to channel\n");
                    return 1;
                }

                printf("\n");
            }
        }
    } while (i>0);
    ssh_disconnect(session);
    ssh_bind_free(sshbind);
    ssh_finalize();
    return 0;
}