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
/* 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 WIN32WSADATA wsadata;rc = WSAStartup(MAKEWORD(2, 0), &wsadata);if(rc) {fprintf(stderr, "WSAStartup failed with error: %d\n", rc);return 1;}
#endifif(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 0libssh2_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 onthis condition */ if(nread == LIBSSH2_ERROR_EAGAIN) {waitsocket(sock, session);}elsebreak;}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);elsefprintf(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 WIN32closesocket(sock);
#elseclose(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
/* 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 WIN32WSADATA wsadata;rc = WSAStartup(MAKEWORD(2, 0), &wsadata);if(rc) {fprintf(stderr, "WSAStartup failed with error: %d\n", rc);return 1;}
#endifif(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 WIN32closesocket(sock);
#elseclose(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。
