libssh/examples/sample.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 <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>

#include <sys/select.h>
#include <sys/time.h>
#include <sys/statvfs.h>
#ifdef HAVE_PTY_H
#include <pty.h>
#endif
#include <sys/ioctl.h>
#include <signal.h>
#include <errno.h>
#include <libssh/callbacks.h>
#include <libssh/libssh.h>
#include <libssh/sftp.h>

#include <fcntl.h>

#define MAXCMD 10
char *host;
char *user;
int is_sftp;
char *cmds[MAXCMD];
struct termios terminal;

void do_sftp(ssh_session session);

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

  (void) verify;
  (void) userdata;

  if (echo) {
    while ((answer = fgets(buf, len, stdin)) == NULL);
    if ((ptr = strchr(buf, '\n'))) {
      ptr = '\0';
    }
  } else {
    answer = getpass(prompt);
  }

  if (answer == NULL) {
    return -1;
  }

  strncpy(buf, answer, len);

  return 0;
}

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

static void add_cmd(char *cmd){
    int n;
    for(n=0;cmds[n] && (n<MAXCMD);n++);
    if(n==MAXCMD)
        return;
    cmds[n]=strdup(cmd);
}

static void usage(){
    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",
    ssh_version(0));
    exit(0);
}

static int opts(int argc, char **argv){
    int i;
    if(strstr(argv[0],"sftp"))
        is_sftp=1;
//    for(i=0;i<argc;i++)
//        printf("%d : %s\n",i,argv[i]);
    /* insert your own arguments here */
    while((i=getopt(argc,argv,""))!=-1){
        switch(i){
            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);
}

ssh_channel chan;
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 = { 0, 0, 0, 0 };
    ioctl(1, TIOCGWINSZ, &win);
    channel_change_pty_size(chan,win.ws_col, win.ws_row);
//    printf("Changed pty size\n");
    setsignal();
}
static void select_loop(ssh_session session,ssh_channel channel){
    fd_set fds;
    struct timeval timeout;
    char buffer[10];
    ssh_buffer readbuf=buffer_new();
    ssh_channel channels[2];
    int lus;
    int eof=0;
    int maxfd;
    int ret;
    while(channel){
       /* when a signal is caught, ssh_select will return
         * with SSH_EINTR, which means it should be started
         * again. It lets you handle the signal the faster you
         * can, like in this window changed example. Of course, if
         * your signal handler doesn't call libssh at all, you're
         * free to handle signals directly in sighandler.
         */
        do{
            FD_ZERO(&fds);
            if(!eof)
                FD_SET(0,&fds);
            timeout.tv_sec=30;
            timeout.tv_usec=0;
            FD_SET(ssh_get_fd(session),&fds);
            maxfd=ssh_get_fd(session)+1;
            ret=select(maxfd,&fds,NULL,NULL,&timeout);
            if(ret==EINTR)
                continue;
            if(FD_ISSET(0,&fds)){
                lus=read(0,buffer,10);
                if(lus)
                    channel_write(channel,buffer,lus);
                else {
                    eof=1;
                    channel_send_eof(channel);
                }
            }
            if(FD_ISSET(ssh_get_fd(session),&fds)){
                ssh_set_fd_toread(session);
            }
            channels[0]=channel; // set the first channel we want to read from
            channels[1]=NULL;
            ret=channel_select(channels,NULL,NULL,NULL); // no specific timeout - just poll
            if(signal_delayed)
                sizechanged();
        } while (ret==EINTR || ret==SSH_EINTR);

        // we already looked for input from stdin. Now, we are looking for input from the channel

        if(channel && channel_is_closed(channel)){
            ssh_log(session,SSH_LOG_RARE,"exit-status : %d\n",channel_get_exit_status(channel));

            channel_free(channel);
            channel=NULL;
            channels[0]=NULL;
        }
        if(channels[0]){
            while(channel && channel_is_open(channel) && channel_poll(channel,0)){
                lus=channel_read_buffer(channel,readbuf,0,0);
                if(lus==-1){
                    fprintf(stderr, "Error reading channel: %s\n",
                        ssh_get_error(session));
                    return;
                }
                if(lus==0){
                    ssh_log(session,SSH_LOG_RARE,"EOF received\n");
                    ssh_log(session,SSH_LOG_RARE,"exit-status : %d\n",channel_get_exit_status(channel));

                    channel_free(channel);
                    channel=channels[0]=NULL;
                } else
                    write(1,buffer_get(readbuf),lus);
            }
            while(channel && channel_is_open(channel) && channel_poll(channel,1)){ /* stderr */
                lus=channel_read_buffer(channel,readbuf,0,1);
                if(lus==-1){
                    fprintf(stderr, "Error reading channel: %s\n",
                        ssh_get_error(session));
                    return;
                }
                if(lus==0){
                    ssh_log(session,SSH_LOG_RARE,"EOF received\n");
                    ssh_log(session,SSH_LOG_RARE,"exit-status : %d\n",channel_get_exit_status(channel));
                    channel_free(channel);
                    channel=channels[0]=NULL;
                } else
                    write(2,buffer_get(readbuf),lus);
            }
        }
        if(channel && channel_is_closed(channel)){
            channel_free(channel);
            channel=NULL;
        }
    }
    buffer_free(readbuf);
}


static void shell(ssh_session session){
    ssh_channel channel;
    struct termios terminal_local;
    int interactive=isatty(0);
    channel = channel_new(session);
    if(interactive){
        tcgetattr(0,&terminal_local);
        memcpy(&terminal,&terminal_local,sizeof(struct termios));
    }
    if(channel_open_session(channel)){
        printf("error opening channel : %s\n",ssh_get_error(session));
        return;
    }
    chan=channel;
    if(interactive){
        channel_request_pty(channel);
        sizechanged();
    }
    if(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);
}

static void batch_shell(ssh_session session){
    ssh_channel channel;
    char buffer[1024];
    int i,s=0;
    for(i=0;i<MAXCMD && cmds[i];++i)
        s+=snprintf(buffer+s,sizeof(buffer)-s,"%s ",cmds[i]);
    channel=channel_new(session);
    channel_open_session(channel);
    if(channel_request_exec(channel,buffer)){
        printf("error executing \"%s\" : %s\n",buffer,ssh_get_error(session));
        return;
    }
    select_loop(session,channel);
}

#ifdef WITH_SFTP
/* it's just a proof of concept code for sftp, till i write a real documentation about it */
void do_sftp(ssh_session session){
    sftp_session sftp=sftp_new(session);
    sftp_dir dir;
    sftp_attributes file;
    sftp_statvfs_t sftpstatvfs;
    struct statvfs sysstatvfs;
    sftp_file fichier;
    sftp_file to;
    int len=1;
    unsigned int i;
    char data[8000]={0};
    char *lnk;

    unsigned int count;

    if(!sftp){
        fprintf(stderr, "sftp error initialising channel: %s\n",
            ssh_get_error(session));
        return;
    }
    if(sftp_init(sftp)){
        fprintf(stderr, "error initialising sftp: %s\n",
            ssh_get_error(session));
        return;
    }

    printf("Additional SFTP extensions provided by the server:\n");
    count = sftp_extensions_get_count(sftp);
    for (i = 0; i < count; i++) {
      printf("\t%s, version: %s\n",
          sftp_extensions_get_name(sftp, i),
          sftp_extensions_get_data(sftp, i));
    }

    /* test symlink and readlink */
    if (sftp_symlink(sftp, "/tmp/this_is_the_link",
          "/tmp/sftp_symlink_test") < 0) {
      fprintf(stderr, "Could not create link (%s)\n", ssh_get_error(session));
      return;
    }

    lnk = sftp_readlink(sftp, "/tmp/sftp_symlink_test");
    if (lnk == NULL) {
      fprintf(stderr, "Could not read link (%s)\n", ssh_get_error(session));
      return;
    }
    printf("readlink /tmp/sftp_symlink_test: %s\n", lnk);

    sftp_unlink(sftp, "/tmp/sftp_symlink_test");

    if (sftp_extension_supported(sftp, "statvfs@openssh.com", "2")) {
      sftpstatvfs = sftp_statvfs(sftp, "/tmp");
      if (sftpstatvfs == NULL) {
        fprintf(stderr, "statvfs failed (%s)\n", ssh_get_error(session));
        return;
      }

      printf("sftp statvfs:\n"
          "\tfile system block size: %llu\n"
          "\tfundamental fs block size: %llu\n"
          "\tnumber of blocks (unit f_frsize): %llu\n"
          "\tfree blocks in file system: %llu\n"
          "\tfree blocks for non-root: %llu\n"
          "\ttotal file inodes: %llu\n"
          "\tfree file inodes: %llu\n"
          "\tfree file inodes for to non-root: %llu\n"
          "\tfile system id: %llu\n"
          "\tbit mask of f_flag values: %llu\n"
          "\tmaximum filename length: %llu\n",
          (unsigned long long) sftpstatvfs->f_bsize,
          (unsigned long long) sftpstatvfs->f_frsize,
          (unsigned long long) sftpstatvfs->f_blocks,
          (unsigned long long) sftpstatvfs->f_bfree,
          (unsigned long long) sftpstatvfs->f_bavail,
          (unsigned long long) sftpstatvfs->f_files,
          (unsigned long long) sftpstatvfs->f_ffree,
          (unsigned long long) sftpstatvfs->f_favail,
          (unsigned long long) sftpstatvfs->f_fsid,
          (unsigned long long) sftpstatvfs->f_flag,
          (unsigned long long) sftpstatvfs->f_namemax);

      sftp_statvfs_free(sftpstatvfs);

      if (statvfs("/tmp", &sysstatvfs) < 0) {
        fprintf(stderr, "statvfs failed (%s)\n", strerror(errno));
        return;
      }

      printf("sys statvfs:\n"
          "\tfile system block size: %llu\n"
          "\tfundamental fs block size: %llu\n"
          "\tnumber of blocks (unit f_frsize): %llu\n"
          "\tfree blocks in file system: %llu\n"
          "\tfree blocks for non-root: %llu\n"
          "\ttotal file inodes: %llu\n"
          "\tfree file inodes: %llu\n"
          "\tfree file inodes for to non-root: %llu\n"
          "\tfile system id: %llu\n"
          "\tbit mask of f_flag values: %llu\n"
          "\tmaximum filename length: %llu\n",
          (unsigned long long) sysstatvfs.f_bsize,
          (unsigned long long) sysstatvfs.f_frsize,
          (unsigned long long) sysstatvfs.f_blocks,
          (unsigned long long) sysstatvfs.f_bfree,
          (unsigned long long) sysstatvfs.f_bavail,
          (unsigned long long) sysstatvfs.f_files,
          (unsigned long long) sysstatvfs.f_ffree,
          (unsigned long long) sysstatvfs.f_favail,
          (unsigned long long) sysstatvfs.f_fsid,
          (unsigned long long) sysstatvfs.f_flag,
          (unsigned long long) sysstatvfs.f_namemax);
    }

    /* the connection is made */
    /* opening a directory */
    dir=sftp_opendir(sftp,"./");
    if(!dir) {
        fprintf(stderr, "Directory not opened(%s)\n", ssh_get_error(session));
        return ;
    }
    /* reading the whole directory, file by file */
    while((file=sftp_readdir(sftp,dir))){
        fprintf(stderr, "%30s(%.8o) : %.5d.%.5d : %.10llu bytes\n",
            file->name,
            file->permissions,
            file->uid,
            file->gid,
            (long long unsigned int) file->size);
        sftp_attributes_free(file);
    }
    /* when file=NULL, an error has occured OR the directory listing is end of file */
    if(!sftp_dir_eof(dir)){
        fprintf(stderr, "Error: %s\n", ssh_get_error(session));
        return;
    }
    if(sftp_closedir(dir)){
        fprintf(stderr, "Error: %s\n", ssh_get_error(session));
        return;
    }
    /* this will open a file and copy it into your /home directory */
    /* the small buffer size was intended to stress the library. of course, you can use a buffer till 20kbytes without problem */

    fichier=sftp_open(sftp,"/usr/bin/ssh",O_RDONLY, 0);
    if(!fichier){
        fprintf(stderr, "Error opening /usr/bin/ssh: %s\n",
            ssh_get_error(session));
        return;
    }
    /* open a file for writing... */
    to=sftp_open(sftp,"ssh-copy",O_WRONLY | O_CREAT, 0700);
    if(!to){
        fprintf(stderr, "Error opening ssh-copy for writing: %s\n",
            ssh_get_error(session));
        return;
    }
    while((len=sftp_read(fichier,data,4096)) > 0){
        if(sftp_write(to,data,len)!=len){
            fprintf(stderr, "Error writing %d bytes: %s\n",
                len, ssh_get_error(session));
            return;
        }
    }
    printf("finished\n");
    if(len<0)
        fprintf(stderr, "Error reading file: %s\n", ssh_get_error(session));
    sftp_close(fichier);
    sftp_close(to);
    printf("fichiers ferm\n");
    to=sftp_open(sftp,"/tmp/grosfichier",O_WRONLY|O_CREAT, 0644);
    for(i=0;i<1000;++i){
        len=sftp_write(to,data,8000);
        printf("wrote %d bytes\n",len);
        if(len != 8000){
            printf("chunk %d : %d (%s)\n",i,len,ssh_get_error(session));
        }
    }
    sftp_close(to);

    /* close the sftp session */
    sftp_free(sftp);
    printf("sftp session terminated\n");
}
#endif

static int auth_kbdint(ssh_session session){
    int err=ssh_userauth_kbdint(session,NULL,NULL);
    const char *name, *instruction, *prompt;
    char *ptr;
    char buffer[128];
    int i,n;
    char echo;
    while (err==SSH_AUTH_INFO){
        name=ssh_userauth_kbdint_getname(session);
        instruction=ssh_userauth_kbdint_getinstruction(session);
        n=ssh_userauth_kbdint_getnprompts(session);
        if(strlen(name)>0)
            printf("%s\n",name);
        if(strlen(instruction)>0)
            printf("%s\n",instruction);
        for(i=0;i<n;++i){
            prompt=ssh_userauth_kbdint_getprompt(session,i,&echo);
            if(echo){
                printf("%s",prompt);
                fgets(buffer,sizeof(buffer),stdin);
                buffer[sizeof(buffer)-1]=0;
                if((ptr=strchr(buffer,'\n')))
                    *ptr=0;
                if (ssh_userauth_kbdint_setanswer(session,i,buffer) < 0) {
                  return SSH_AUTH_ERROR;
                }
                memset(buffer,0,strlen(buffer));
            } else {
                ptr=getpass(prompt);
                if (ssh_userauth_kbdint_setanswer(session,i,ptr) < 0) {
                  return SSH_AUTH_ERROR;
                }
            }
        }
        err=ssh_userauth_kbdint(session,NULL,NULL);
    }
    return err;
}

int main(int argc, char **argv){
    ssh_session session;
    int auth=0;
    char *password;
    char *banner;
    char *hexa;
    int state;
    char buf[10];
    unsigned char *hash = NULL;
    int hlen;
    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);

    if (user) {
      if (ssh_options_set(session, SSH_OPTIONS_USER, user) < 0) {
        ssh_disconnect(session);
        return 1;
      }
    }

    if (ssh_options_set(session, SSH_OPTIONS_HOST ,host) < 0) {
      ssh_disconnect(session);
      return 1;
    }

    ssh_options_parse_config(session, NULL);

    if(ssh_connect(session)){
        fprintf(stderr,"Connection failed : %s\n",ssh_get_error(session));
        ssh_disconnect(session);
	    ssh_finalize();
        return 1;
    }
    state=ssh_is_server_known(session);

    hlen = ssh_get_pubkey_hash(session, &hash);
    if (hlen < 0) {
      ssh_disconnect(session);
      ssh_finalize();
      return 1;
    }
    switch(state){
        case SSH_SERVER_KNOWN_OK:
            break; /* ok */
        case SSH_SERVER_KNOWN_CHANGED:
            fprintf(stderr,"Host key for server changed : server's one is now :\n");
            ssh_print_hexa("Public key hash",hash, hlen);
            free(hash);
            fprintf(stderr,"For security reason, connection will be stopped\n");
            ssh_disconnect(session);
	        ssh_finalize();
            exit(-1);
        case SSH_SERVER_FOUND_OTHER:
            fprintf(stderr,"The host key for this server was not found but an other type of key exists.\n");
            fprintf(stderr,"An attacker might change the default server key to confuse your client"
                "into thinking the key does not exist\n"
                "We advise you to rerun the client with -d or -r for more safety.\n");
            ssh_disconnect(session);
		    ssh_finalize();
            exit(-1);
        case SSH_SERVER_FILE_NOT_FOUND:
            fprintf(stderr,"Could not find known host file. If you accept the host key here,\n");
            fprintf(stderr,"the file will be automatically created.\n");
            /* fallback to SSH_SERVER_NOT_KNOWN behavior */
        case SSH_SERVER_NOT_KNOWN:
            hexa = ssh_get_hexa(hash, hlen);
            fprintf(stderr,"The server is unknown. Do you trust the host key ?\n");
            fprintf(stderr, "Public key hash: %s\n", hexa);
            free(hexa);
            fgets(buf,sizeof(buf),stdin);
            if(strncasecmp(buf,"yes",3)!=0){
                ssh_disconnect(session);
                exit(-1);
            }
            fprintf(stderr,"This new key will be written on disk for further usage. do you agree ?\n");
            fgets(buf,sizeof(buf),stdin);
            if(strncasecmp(buf,"yes",3)==0){
                if (ssh_write_knownhost(session) < 0) {
                  free(hash);
                  fprintf(stderr, "error %s\n", strerror(errno));
                  exit(-1);
                }
            }

            break;
        case SSH_SERVER_ERROR:
            free(hash);
            fprintf(stderr,"%s",ssh_get_error(session));
            ssh_disconnect(session);
    	    ssh_finalize();
            exit(-1);
    }
    free(hash);

    ssh_userauth_none(session, NULL);

    auth = ssh_auth_list(session);
    printf("supported auth methods: ");
    if (auth & SSH_AUTH_METHOD_PUBLICKEY) {
      printf("publickey");
    }
    if (auth & SSH_AUTH_METHOD_INTERACTIVE) {
      printf(", keyboard-interactive");
    }
    printf("\n");

    /* no ? you should :) */
    auth=ssh_userauth_autopubkey(session, NULL);
    if(auth==SSH_AUTH_ERROR){
        fprintf(stderr,"Authenticating with pubkey: %s\n",ssh_get_error(session));
	    ssh_finalize();
        return -1;
    }
    banner=ssh_get_issue_banner(session);
    if(banner){
        printf("%s\n",banner);
        free(banner);
    }
    if(auth!=SSH_AUTH_SUCCESS){
        auth=auth_kbdint(session);
        if(auth==SSH_AUTH_ERROR){
            fprintf(stderr,"authenticating with keyb-interactive: %s\n",
                    ssh_get_error(session));
	        ssh_finalize();
            return -1;
        }
    }
    if(auth!=SSH_AUTH_SUCCESS){
        password=getpass("Password: ");
        if(ssh_userauth_password(session,NULL,password) != SSH_AUTH_SUCCESS){
            fprintf(stderr,"Authentication failed: %s\n",ssh_get_error(session));
            ssh_disconnect(session);
	        ssh_finalize();
            return -1;
        }
        memset(password,0,strlen(password));
    }
    ssh_log(session, SSH_LOG_FUNCTIONS, "Authentication success");
    if(strstr(argv[0],"sftp")){
        is_sftp=1;
        ssh_log(session, SSH_LOG_FUNCTIONS, "Doing sftp instead");
    }
    if(!is_sftp){
        if(!cmds[0])
            shell(session);
        else
            batch_shell(session);
    }
#ifdef WITH_SFTP
    else
        do_sftp(session);
#endif
    if(!is_sftp && !cmds[0])
        do_cleanup(0);
    ssh_disconnect(session);
    ssh_free(session);
    ssh_finalize();

    return 0;
}