LibSSH2简单入门-exec、sftp
1、libssh2官方地址：libssh2
libssh2的官方文档和官方示例代码非常的棒，基本可以直接参考
官方文档：libssh2 docs
官方示例：libssh2 examples
2、推荐阅读两个示例，基本可以完成对libssh2的理解和使用了
2.1、ssh2_exec.c 通过libssh2在远端机器上执行指令，并获取指令的返回值
c
/* 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 host name, user name, 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>
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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);
FD_SET(socket_fd, &fd);
/* 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;
char *exitsignal = (char *)"none";
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 will trade 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) {
/* eeek, do cleanup here */
return 2;
}
/* 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 {
/* eeek, do cleanup here */
return 3;
}
libssh2_knownhost_free(nh);
if(strlen(password) != 0) {
/* 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");
exit(1);
}
while((rc = libssh2_channel_exec(channel, commandline)) == LIBSSH2_ERROR_EAGAIN) {
waitsocket(sock, session);
}
if(rc) {
fprintf(stderr, "exec error\n");
exit(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 != LIBSSH2_ERROR_EAGAIN)
/* no need to output this for the EAGAIN case */
fprintf(stderr, "libssh2_channel_read returned %d\n",
(int)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);
else
fprintf(stderr, "\nEXIT: %d bytecount: %d\n",
exitcode, (int)bytecount);
libssh2_channel_free(channel);
channel = NULL;
shutdown:
if(session) {
libssh2_session_disconnect(session, "Normal Shutdown");
libssh2_session_free(session);
}
if(sock != LIBSSH2_INVALID_SOCKET) {
shutdown(sock, 2);
#ifdef WIN32
closesocket(sock);
#else
close(sock);
#endif
}
fprintf(stderr, "all done\n");
libssh2_exit();
return 0;
}2.2、sftp_write_nonblock.c 使用libssh2进行sftp将本端文件传输到远端机器上的功能
c
/* Copyright (C) The libssh2 project and its contributors.
*
* Sample showing how to do SFTP non-blocking write transfers.
*
* The sample code has default values for host name, user name, password
* and path to copy, but you can specify them on the command line like:
*
* $ ./sftp_write_nonblock 192.168.0.1 user password thisfile /tmp/storehere
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "libssh2_setup.h"
#include <libssh2.h>
#include <libssh2_sftp.h>
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#include <stdio.h>
#include <time.h>
static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
static const char *privkey = "/home/username/.ssh/id_rsa";
static const char *username = "username";
static const char *password = "password";
static const char *loclfile = "sftp_write_nonblock.c";
static const char *sftppath = "/tmp/sftp_write_nonblock.c";
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);
FD_SET(socket_fd, &fd);
/* 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;
int i, auth_pw = 1;
struct sockaddr_in sin;
const char *fingerprint;
int rc;
LIBSSH2_SESSION *session = NULL;
LIBSSH2_SFTP *sftp_session;
LIBSSH2_SFTP_HANDLE *sftp_handle;
FILE *local;
char mem[1024 * 100];
size_t nread;
ssize_t nwritten;
char *ptr;
time_t start;
libssh2_struct_stat_size total = 0;
int duration;
#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) {
hostaddr = inet_addr(argv[1]);
}
else {
hostaddr = htonl(0x7F000001);
}
if(argc > 2) {
username = argv[2];
}
if(argc > 3) {
password = argv[3];
}
if(argc > 4) {
loclfile = argv[4];
}
if(argc > 5) {
sftppath = argv[5];
}
rc = libssh2_init(0);
if(rc) {
fprintf(stderr, "libssh2 initialization failed (%d)\n", rc);
return 1;
}
local = fopen(loclfile, "rb");
if(!local) {
fprintf(stderr, "Cannot open local file %s\n", loclfile);
return 1;
}
/*
* The application code is responsible for creating the socket
* and 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;
}
/* Since we have set non-blocking, tell libssh2 we are non-blocking */
libssh2_session_set_blocking(session, 0);
/* ... start it up. This will trade 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;
}
/* At this point we have not yet authenticated. The first thing to do
* is check the hostkey's fingerprint against our known hosts Your app
* may have it hard coded, may go to a file, may present it to the
* user, that's your call
*/
fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
fprintf(stderr, "Fingerprint: ");
for(i = 0; i < 20; i++) {
fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
}
fprintf(stderr, "\n");
if(auth_pw) {
/* 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;
}
}
fprintf(stderr, "libssh2_sftp_init().\n");
do {
sftp_session = libssh2_sftp_init(session);
if(!sftp_session &&
libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN) {
fprintf(stderr, "Unable to init SFTP session\n");
goto shutdown;
}
} while(!sftp_session);
fprintf(stderr, "libssh2_sftp_open().\n");
/* Request a file via SFTP */
do {
sftp_handle = libssh2_sftp_open(sftp_session, sftppath,
LIBSSH2_FXF_WRITE |
LIBSSH2_FXF_CREAT |
LIBSSH2_FXF_TRUNC,
LIBSSH2_SFTP_S_IRUSR |
LIBSSH2_SFTP_S_IWUSR |
LIBSSH2_SFTP_S_IRGRP |
LIBSSH2_SFTP_S_IROTH);
if(!sftp_handle &&
libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN) {
fprintf(stderr, "Unable to open file with SFTP: %ld\n",
libssh2_sftp_last_error(sftp_session));
goto shutdown;
}
} while(!sftp_handle);
fprintf(stderr, "libssh2_sftp_open() is done, now send data.\n");
start = time(NULL);
do {
nread = fread(mem, 1, sizeof(mem), local);
if(nread <= 0) {
/* end of file */
break;
}
ptr = mem;
total += nread;
do {
/* write data in a loop until we block */
while((nwritten = libssh2_sftp_write(sftp_handle, ptr, nread)) ==
LIBSSH2_ERROR_EAGAIN) {
waitsocket(sock, session);
}
if(nwritten < 0)
break;
ptr += nwritten;
nread -= nwritten;
} while(nread);
} while(nwritten > 0);
duration = (int)(time(NULL) - start);
fprintf(stderr, "%ld bytes in %d seconds makes %.1f bytes/sec\n",
(long)total, duration, (double)total / duration);
fclose(local);
libssh2_sftp_close(sftp_handle);
libssh2_sftp_shutdown(sftp_session);
shutdown:
if(session) {
while(libssh2_session_disconnect(session, "Normal Shutdown") ==
LIBSSH2_ERROR_EAGAIN);
libssh2_session_free(session);
}
if(sock != LIBSSH2_INVALID_SOCKET) {
shutdown(sock, 2);
#ifdef WIN32
closesocket(sock);
#else
close(sock);
#endif
}
fprintf(stderr, "all done\n");
libssh2_exit();
return 0;
}注：示例代码中的fingerprint可以不一定需要使用。