基於libssh庫實現SSH的Linux客戶端程序

代碼如下：

#include <string.h>  
#include <sys/ioctl.h>  
#include <netinet/in.h>  
#include <arpa/inet.h>  
#include <unistd.h>  
#include <sys/types.h>  
#include <libgen.h>  
#include <fcntl.h>  
#include <errno.h>  
#include <stdio.h>  
#include <ctype.h>  
#include <stdlib.h>  
#include <termios.h>     
#include <libssh2.h>  
  
#define COPYRIGHT "SSH2 v1.0\nCopyright (C) 2014 \n\n"  
   
struct termios _saved_tio;  
int tio_saved = 0;  
   
static int _raw_mode(void)  
{  
    int rc;  
    struct termios tio;  
  
    rc = tcgetattr(fileno(stdin), &tio);  
    if (rc != -1) {  
        _saved_tio = tio;  
        tio_saved = 1;  
        cfmakeraw(&tio);  
        rc = tcsetattr(fileno(stdin), TCSADRAIN, &tio);  
    }  
  
    return rc;  
}  
   
static int _normal_mode(void)  
{  
    if (tio_saved)  
        return tcsetattr(fileno(stdin), TCSADRAIN, &_saved_tio);  
  
    return 0;  
}  
   
int main (int argc, char *argv[])  
{  
    int sock = 0;  
    unsigned long hostaddr = 0;  
    short port = 22;  
    char *username = NULL;  
    char *password = NULL;  
    struct sockaddr_in sin;  
    LIBSSH2_SESSION *session;  
    LIBSSH2_CHANNEL *channel;  
    int nfds = 1;  
    char buf;  
    LIBSSH2_POLLFD *fds = NULL;  
   
    /* Struct winsize for term size */   
    struct winsize w_size;  
    struct winsize w_size_bck;  
  
    /* For select on stdin */   
    fd_set set;  
    struct timeval timeval_out;  
    timeval_out.tv_sec = 0;  
    timeval_out.tv_usec = 10;  
  
    printf(COPYRIGHT);  
  
    if (argc > 4) {  
        hostaddr = inet_addr(argv[1]);  
        port = htons(atoi(argv[2]));  
        username = argv[3];  
        password = argv[4];  
    }  
    else {  
        fprintf(stderr, "Usage: %s ip port user password\n", basename(argv[0]));  
        return -1;  
    }  
  
    if (libssh2_init (0) != 0) {  
        fprintf (stderr, "libssh2 initialization failed\n");  
        return -1;  
    }  
  
    sock = socket (AF_INET, SOCK_STREAM, 0);  
    sin.sin_family = AF_INET;  
    sin.sin_port = port;  
    sin.sin_addr.s_addr = hostaddr;  
    if (connect(sock, (struct sockaddr *) &sin, sizeof(struct sockaddr_in)) != 0) {  
        fprintf (stderr, "Failed to established connection!\n");  
        return -1;  
    }  
  
    /* Open a session */   
    session = libssh2_session_init();  
    if (libssh2_session_startup (session, sock) != 0) {  
        fprintf(stderr, "Failed Start the SSH session\n");  
        return -1;  
    }  
      
    /* Authenticate via password */   
    if (libssh2_userauth_password(session, username, password) != 0) {  
        fprintf(stderr, "Failed to authenticate\n");  
        close(sock);  
        goto ERROR;  
    }  
      
    /* Open a channel */   
    channel = libssh2_channel_open_session(session);  
      
    if ( channel == NULL ) {  
        fprintf(stderr, "Failed to open a new channel\n");  
        close(sock);  
        goto ERROR;  
    }  
      
    /* Request a PTY */   
    if (libssh2_channel_request_pty( channel, "xterm") != 0) {  
        fprintf(stderr, "Failed to request a pty\n");  
        close(sock);  
        goto ERROR;  
    }  
      
    /* Request a shell */   
    if (libssh2_channel_shell(channel) != 0) {  
        fprintf(stderr, "Failed to open a shell\n");  
        close(sock);  
        goto ERROR;  
    }  
      
    if (_raw_mode() != 0) {  
        fprintf(stderr, "Failed to entered in raw mode\n");  
        close(sock);  
        goto ERROR;  
    }  
      
    while (1) {  
        FD_ZERO(&set);  
        FD_SET(fileno(stdin),&set);  
      
        ioctl(fileno(stdin), TIOCGWINSZ, &w_size);  
        if ((w_size.ws_row != w_size_bck.ws_row) ||  
            (w_size.ws_col != w_size_bck.ws_col)) {  
            w_size_bck = w_size;  
            libssh2_channel_request_pty_size(channel, w_size.ws_col, w_size.ws_row);  
        }  
      
        if ((fds = malloc (sizeof (LIBSSH2_POLLFD))) == NULL)  
            break;  
      
        fds[0].type = LIBSSH2_POLLFD_CHANNEL;  
        fds[0].fd.channel = channel;  
        fds[0].events = LIBSSH2_POLLFD_POLLIN;  
        fds[0].revents = LIBSSH2_POLLFD_POLLIN;  
      
        if (libssh2_poll(fds, nfds, 0) >0) {  
            libssh2_channel_read(channel, &buf, 1);  
            fprintf(stdout, "%c", buf);  
            fflush(stdout);  
        }  
      
        if (select(fileno(stdin)+1,&set,NULL,NULL,&timeval_out) > 0)  
            if (read(fileno(stdin), &buf, 1) > 0)  
                libssh2_channel_write(channel, &buf, 1);  
      
        free (fds);  
      
        if (libssh2_channel_eof(channel) == 1)  
         break;  
    }  
      
    if (channel) {  
        libssh2_channel_free (channel);  
        channel = NULL;  
    }  
      
    _normal_mode();  
      
    libssh2_exit();  
  
    return 0;  
ERROR:  
    libssh2_session_disconnect(session, "Session Shutdown, Thank you for playing");  
    libssh2_session_free(session);  
    return -1;  
}