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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 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
/* 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。
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