libssh2/example/ssh2_exec.c at master · libssh2/libssh2 · GitHub

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/* Copyright (C) The libssh2 project and its contributors.

* Sample showing how to use libssh2 to execute a command remotely.

* The sample code has fixed values for hostname, username, password

* and command to run.

* $ ./ssh2_exec 127.0.0.1 user password "uptime"

* SPDX-License-Identifier: BSD-3-Clause

#include "libssh2_setup.h"

#include <libssh2.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#ifndef _WIN32

#include <sys/socket.h>

#include <unistd.h>

#endif

#ifdef HAVE_SYS_SELECT_H

#include <sys/select.h>

#endif

#ifdef HAVE_NETINET_IN_H

#include <netinet/in.h>

#endif

#ifdef HAVE_ARPA_INET_H

#include <arpa/inet.h>

#endif

#if !defined(_WIN32) || defined(__MINGW32__)

#include <sys/time.h> /* for timeval */

#endif

static const char *hostname = "127.0.0.1";

static const char *commandline = "uptime";

static const char *pubkey = "/home/username/.ssh/id_rsa.pub";

static const char *privkey = "/home/username/.ssh/id_rsa";

static const char *username = "user";

static const char *password = "password";

static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)

{

struct timeval timeout;

int rc;

fd_set fd;

fd_set *writefd = NULL;

fd_set *readfd = NULL;

int dir;

timeout.tv_sec = 10;

timeout.tv_usec = 0;

FD_ZERO(&fd);

#if defined(__GNUC__) || defined(__clang__)

#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Wsign-conversion"

#endif

FD_SET(socket_fd, &fd);

#if defined(__GNUC__) || defined(__clang__)

#pragma GCC diagnostic pop

#endif

/* now make sure we wait in the correct direction */

dir = libssh2_session_block_directions(session);

if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)

readfd = &fd;

if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)

writefd = &fd;

rc = select((int)(socket_fd + 1), readfd, writefd, NULL, &timeout);

return rc;

}

int main(int argc, char *argv[])

{

uint32_t hostaddr;

libssh2_socket_t sock;

struct sockaddr_in sin;

const char *fingerprint;

int rc;

LIBSSH2_SESSION *session = NULL;

LIBSSH2_CHANNEL *channel;

int exitcode = 0;

char *exitsignal = NULL;

ssize_t bytecount = 0;

size_t len;

LIBSSH2_KNOWNHOSTS *nh;

int type;

#ifdef _WIN32

WSADATA wsadata;

rc = WSAStartup(MAKEWORD(2, 0), &wsadata);

if(rc) {

fprintf(stderr, "WSAStartup failed with error: %d\n", rc);

return 1;

}

#endif

if(argc > 1)

hostname = argv[1]; /* must be ip address only */

if(argc > 2)

username = argv[2];

if(argc > 3)

password = argv[3];

if(argc > 4)

commandline = argv[4];

rc = libssh2_init(0);

if(rc) {

fprintf(stderr, "libssh2 initialization failed (%d)\n", rc);

return 1;

}

hostaddr = inet_addr(hostname);

/* 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);

if(sock == LIBSSH2_INVALID_SOCKET) {

fprintf(stderr, "failed to create socket.\n");

goto shutdown;

}

sin.sin_family = AF_INET;

sin.sin_port = htons(22);

sin.sin_addr.s_addr = hostaddr;

if(connect(sock, (struct sockaddr *)&sin, sizeof(struct sockaddr_in))) {

fprintf(stderr, "failed to connect.\n");

goto shutdown;

}

/* Create a session instance */

session = libssh2_session_init();

if(!session) {

fprintf(stderr, "Could not initialize SSH session.\n");

goto shutdown;

}

/* tell libssh2 we want it all done non-blocking */

libssh2_session_set_blocking(session, 0);

/* ... start it up. This trades welcome banners, exchange keys,

* and setup crypto, compression, and MAC layers

while((rc = libssh2_session_handshake(session, sock)) ==

LIBSSH2_ERROR_EAGAIN)

;

if(rc) {

fprintf(stderr, "Failure establishing SSH session: %d\n", rc);

goto shutdown;

}

nh = libssh2_knownhost_init(session);

if(!nh) {

exitcode = 2;

goto shutdown;

}

/* read all hosts from here */

libssh2_knownhost_readfile(nh, "known_hosts",

LIBSSH2_KNOWNHOST_FILE_OPENSSH);

/* store all known hosts to here */

libssh2_knownhost_writefile(nh, "dumpfile",

LIBSSH2_KNOWNHOST_FILE_OPENSSH);

fingerprint = libssh2_session_hostkey(session, &len, &type);

if(fingerprint) {

struct libssh2_knownhost *host;

int check = libssh2_knownhost_checkp(nh, hostname, 22,

fingerprint, len,

LIBSSH2_KNOWNHOST_TYPE_PLAIN |

LIBSSH2_KNOWNHOST_KEYENC_RAW,

&host);

fprintf(stderr, "Host check: %d, key: %s\n", check,

(check <= LIBSSH2_KNOWNHOST_CHECK_MISMATCH) ?

host->key : "<none>");

/*****

* At this point, we could verify that 'check' tells us the key is

* fine or bail out.

*****/

}

else {

libssh2_knownhost_free(nh);

exitcode = 3;

goto shutdown;

}

libssh2_knownhost_free(nh);

if(strlen(password)) {

/* We could authenticate via password */

while((rc = libssh2_userauth_password(session, username, password)) ==

LIBSSH2_ERROR_EAGAIN)

;

if(rc) {

fprintf(stderr, "Authentication by password failed.\n");

goto shutdown;

}

else {

/* Or by public key */

while((rc = libssh2_userauth_publickey_fromfile(session, username,

pubkey, privkey,

password)) ==

LIBSSH2_ERROR_EAGAIN)

;

if(rc) {

fprintf(stderr, "Authentication by public key failed.\n");

goto shutdown;

}

#if 0

libssh2_trace(session, ~0);

#endif

/* Exec non-blocking on the remote host */

do {

channel = libssh2_channel_open_session(session);

if(channel ||

libssh2_session_last_error(session, NULL, NULL, 0) !=

LIBSSH2_ERROR_EAGAIN)

break;

waitsocket(sock, session);

} while(1);

if(!channel) {

fprintf(stderr, "Error\n");

return 1;

}

while((rc = libssh2_channel_exec(channel, commandline)) ==

LIBSSH2_ERROR_EAGAIN)

waitsocket(sock, session);

if(rc) {

fprintf(stderr, "exec error\n");

return 1;

}

for(;;) {

ssize_t nread;

/* loop until we block */

do {

char buffer[0x4000];

nread = libssh2_channel_read(channel, buffer, sizeof(buffer));

if(nread > 0) {

ssize_t i;

bytecount += nread;

fprintf(stderr, "We read:\n");

for(i = 0; i < nread; ++i)

fputc(buffer[i], stderr);

fprintf(stderr, "\n");

}

else if(nread < 0 && nread != LIBSSH2_ERROR_EAGAIN)

/* no need to output this for the EAGAIN case */

fprintf(stderr, "libssh2_channel_read returned %ld\n",

(long)nread);

} while(nread > 0);

/* this is due to blocking that would occur otherwise so we loop on

this condition */

if(nread == LIBSSH2_ERROR_EAGAIN)

waitsocket(sock, session);

else

break;

}

exitcode = 127;

while((rc = libssh2_channel_close(channel)) == LIBSSH2_ERROR_EAGAIN)

waitsocket(sock, session);

if(rc == 0) {

exitcode = libssh2_channel_get_exit_status(channel);

libssh2_channel_get_exit_signal(channel, &exitsignal,

NULL, NULL, NULL, NULL, NULL);

}

if(exitsignal)

fprintf(stderr, "\nGot signal: %s\n",

exitsignal ? exitsignal : "none");

else

fprintf(stderr, "\nEXIT: %d bytecount: %ld\n",

exitcode, (long)bytecount);

libssh2_channel_free(channel);

shutdown:

if(session) {

libssh2_session_disconnect(session, "Normal Shutdown");

libssh2_session_free(session);

}

if(sock != LIBSSH2_INVALID_SOCKET) {

shutdown(sock, 2 /* SHUT_RDWR */);

LIBSSH2_SOCKET_CLOSE(sock);

}

fprintf(stderr, "all done\n");

libssh2_exit();

#ifdef _WIN32

WSACleanup();

#endif

return exitcode;

}

libssh2/example/ssh2_exec.c at master · libssh2/libssh2 · GitHub

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