上一篇FTP客户端讲到如果制作一个简单的FTP客户端，功能实现了，但是后面我们发现了问题，就是FTP是使用明文进行操作的。对于普通情况来说就无所谓了。但有时候要安全的一点的话，就应该使用FTP的安全版本。有SFTP和FTPs，两者都是FTP的安全版本，但是两者的实现原理差别还是很大的，具体自己搜索了解。
0.环境安装
环境使用我的这一篇文章安装好libssh2库。
http://www.cnblogs.com/wunaozai/p/4528394.html
使用一个带有SFTP功能的FTP服务器。注意有些FTP服务器是不带SFTP功能的。这里我使用这个FreeSSHd作为SFTP服务器。
http://www.freesshd.com/?ctt=download
关于freesshd配置说两句，Server status标签 点击确定SSH server is running。SSH标签，确定配置完成。Authentication标签下Password authentication为Allowed，Public key authentication为Disabled，这样做的原因是我接下来要做的程序只支持密码登录，减少不必要的干扰，如果有需要，可以自己设定。Tunneling标签，所有选项选中，如果没有选中，本地如果网络复杂的话，可能会有问题。SFTP标签，选择一个作为FTP的根目录。Users标签，增加一个用户。基本设置就这些了。
1.示例讲解
我们先从libssh2中的示例程序进行讲解，libssh2源代码中的example文件夹中有几个常见的示例程序，我们此次先讲解上传文件和下载文件这两个基础功能。
下面这个是sftp_write_nonblock.c的源代码，已被折叠。
1 /*
2 * Sample showing how to do SFTP non-blocking write transfers.
3 *
4 * The sample code has default values for host name, user name, password
5 * and path to copy, but you can specify them on the command line like:
6 *
7 * "sftp 192.168.0.1 user password sftp_write_nonblock.c /tmp/sftp_write_nonblock.c"
8 */
9
10 #include "libssh2_config.h"
11 #include <libssh2.h>
12 #include <libssh2_sftp.h>
13
14 #ifdef HAVE_WINSOCK2_H
15 # include <winsock2.h>
16 #endif
17 #ifdef HAVE_SYS_SOCKET_H
18 # include <sys/socket.h>
19 #endif
20 #ifdef HAVE_NETINET_IN_H
21 # include <netinet/in.h>
22 #endif
23 #ifdef HAVE_SYS_SELECT_H
24 # include <sys/select.h>
25 #endif
26 # ifdef HAVE_UNISTD_H
27 #include <unistd.h>
28 #endif
29 #ifdef HAVE_ARPA_INET_H
30 # include <arpa/inet.h>
31 #endif
32 #ifdef HAVE_SYS_TIME_H
33 # include <sys/time.h>
34 #endif
35
36 #include <sys/types.h>
37 #include <fcntl.h>
38 #include <errno.h>
39 #include <stdio.h>
40 #include <ctype.h>
41 #include <time.h>
42
43 static int waitsocket(int socket_fd, LIBSSH2_SESSION *session)
44 {
45 struct timeval timeout;
46 int rc;
47 fd_set fd;
48 fd_set *writefd = NULL;
49 fd_set *readfd = NULL;
50 int dir;
51
52 timeout.tv_sec = 10;
53 timeout.tv_usec = 0;
54
55 FD_ZERO(&fd);
56
57 FD_SET(socket_fd, &fd);
58
59 /* now make sure we wait in the correct direction */
60 dir = libssh2_session_block_directions(session);
61
62 if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
63 readfd = &fd;
64
65 if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
66 writefd = &fd;
67
68 rc = select(socket_fd + 1, readfd, writefd, NULL, &timeout);
69
70 return rc;
71 }
72
73 int main(int argc, char *argv[])
74 {
75 unsigned long hostaddr;
76 int sock, i, auth_pw = 1;
77 struct sockaddr_in sin;
78 const char *fingerprint;
79 LIBSSH2_SESSION *session;
80 const char *username="username";
81 const char *password="password";
82 const char *loclfile="sftp_write_nonblock.c";
83 const char *sftppath="/tmp/sftp_write_nonblock.c";
84 int rc;
85 FILE *local;
86 LIBSSH2_SFTP *sftp_session;
87 LIBSSH2_SFTP_HANDLE *sftp_handle;
88 char mem[1024 * 100];
89 size_t nread;
90 char *ptr;
91 time_t start;
92 long total = 0;
93 int duration;
94
95 #ifdef WIN32
96 WSADATA wsadata;
97 int err;
98
99 err = WSAStartup(MAKEWORD(2,0), &wsadata);
100 if (err != 0) {
101 fprintf(stderr, "WSAStartup failed with error: %d\n", err);
102 return 1;
103 }
104 #endif
105
106 if (argc > 1) {
107 hostaddr = inet_addr(argv[1]);
108 } else {
109 hostaddr = htonl(0x7F000001);
110 }
111
112 if (argc > 2) {
113 username = argv[2];
114 }
115 if (argc > 3) {
116 password = argv[3];
117 }
118 if (argc > 4) {
119 loclfile = argv[4];
120 }
121 if (argc > 5) {
122 sftppath = argv[5];
123 }
124
125 rc = libssh2_init (0);
126 if (rc != 0) {
127 fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
128 return 1;
129 }
130
131 local = fopen(loclfile, "rb");
132 if (!local) {
133 fprintf(stderr, "Can‘t open local file %s\n", loclfile);
134 return -1;
135 }
136
137 /*
138 * The application code is responsible for creating the socket
139 * and establishing the connection
140 */
141 sock = socket(AF_INET, SOCK_STREAM, 0);
142
143 sin.sin_family = AF_INET;
144 sin.sin_port = htons(22);
145 sin.sin_addr.s_addr = hostaddr;
146 if (connect(sock, (struct sockaddr*)(&sin),
147 sizeof(struct sockaddr_in)) != 0) {
148 fprintf(stderr, "failed to connect!\n");
149 return -1;
150 }
151
152 /* Create a session instance */
153 session = libssh2_session_init();
154 if (!session)
155 return -1;
156
157 /* Since we have set non-blocking, tell libssh2 we are non-blocking */
158 libssh2_session_set_blocking(session, 0);
159
160 /* ... start it up. This will trade welcome banners, exchange keys,
161 * and setup crypto, compression, and MAC layers
162 */
163 while ((rc = libssh2_session_handshake(session, sock))
164 == LIBSSH2_ERROR_EAGAIN);
165 if (rc) {
166 fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
167 return -1;
168 }
169
170 /* At this point we havn‘t yet authenticated. The first thing to do is
171 * check the hostkey‘s fingerprint against our known hosts Your app may
172 * have it hard coded, may go to a file, may present it to the user,
173 * that‘s your call
174 */
175 fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
176 fprintf(stderr, "Fingerprint: ");
177 for(i = 0; i < 20; i++) {
178 fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
179 }
180 fprintf(stderr, "\n");
181
182 if (auth_pw) {
183 /* We could authenticate via password */
184 while ((rc = libssh2_userauth_password(session, username, password)) ==
185 LIBSSH2_ERROR_EAGAIN);
186 if (rc) {
187 fprintf(stderr, "Authentication by password failed.\n");
188 goto shutdown;
189 }
190 } else {
191 /* Or by public key */
192 while ((rc = libssh2_userauth_publickey_fromfile(session, username,
193 "/home/username/.ssh/id_rsa.pub",
194 "/home/username/.ssh/id_rsa",
195 password)) ==
196 LIBSSH2_ERROR_EAGAIN);
197 if (rc) {
198 fprintf(stderr, "\tAuthentication by public key failed\n");
199 goto shutdown;
200 }
201 }
202
203 fprintf(stderr, "libssh2_sftp_init()!\n");
204 do {
205 sftp_session = libssh2_sftp_init(session);
206
207 if (!sftp_session &&
208 (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN)) {
209 fprintf(stderr, "Unable to init SFTP session\n");
210 goto shutdown;
211 }
212 } while (!sftp_session);
213
214 fprintf(stderr, "libssh2_sftp_open()!\n");
215 /* Request a file via SFTP */
216 do {
217 sftp_handle =
218 libssh2_sftp_open(sftp_session, sftppath,
219 LIBSSH2_FXF_WRITE|LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC,
220 LIBSSH2_SFTP_S_IRUSR|LIBSSH2_SFTP_S_IWUSR|
221 LIBSSH2_SFTP_S_IRGRP|LIBSSH2_SFTP_S_IROTH);
222
223 if (!sftp_handle &&
224 (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN)) {
225 fprintf(stderr, "Unable to open file with SFTP\n");
226 goto shutdown;
227 }
228 } while (!sftp_handle);
229
230 fprintf(stderr, "libssh2_sftp_open() is done, now send data!\n");
231
232 start = time(NULL);
233
234 do {
235 nread = fread(mem, 1, sizeof(mem), local);
236 if (nread <= 0) {
237 /* end of file */
238 break;
239 }
240 ptr = mem;
241
242 total += nread;
243
244 do {
245 /* write data in a loop until we block */
246 while ((rc = libssh2_sftp_write(sftp_handle, ptr, nread)) ==
247 LIBSSH2_ERROR_EAGAIN) {
248 waitsocket(sock, session);
249 }
250 if(rc < 0)
251 break;
252 ptr += rc;
253 nread -= rc;
254
255 } while (nread);
256 } while (rc > 0);
257
258 duration = (int)(time(NULL)-start);
259
260 fprintf(stderr, "%ld bytes in %d seconds makes %.1f bytes/sec\n",
261 total, duration, total/(double)duration);
262
263
264 fclose(local);
265 libssh2_sftp_close(sftp_handle);
266 libssh2_sftp_shutdown(sftp_session);
267
268 shutdown:
269
270 while (libssh2_session_disconnect(session, "Normal Shutdown, Thank you for playing")
271 == LIBSSH2_ERROR_EAGAIN);
272 libssh2_session_free(session);
273
274 #ifdef WIN32
275 closesocket(sock);
276 #else
277 close(sock);
278 #endif
279 fprintf(stderr, "all done\n");
280
281 libssh2_exit();
282
283 return 0;
284 }
下面这个是sftp_nonblock.c的源代码
1 /*
2 * Sample showing how to do SFTP non-blocking transfers.
3 *
4 * The sample code has default values for host name, user name, password
5 * and path to copy, but you can specify them on the command line like:
6 *
7 * "sftp_nonblock 192.168.0.1 user password /tmp/secrets"
8 */
9
10 #include "libssh2_config.h"
11 #include <libssh2.h>
12 #include <libssh2_sftp.h>
13
14 #ifdef HAVE_WINSOCK2_H
15 # include <winsock2.h>
16 #endif
17 #ifdef HAVE_SYS_SOCKET_H
18 # include <sys/socket.h>
19 #endif
20 #ifdef HAVE_NETINET_IN_H
21 # include <netinet/in.h>
22 #endif
23 #ifdef HAVE_SYS_SELECT_H
24 # include <sys/select.h>
25 #endif
26 # ifdef HAVE_UNISTD_H
27 #include <unistd.h>
28 #endif
29 #ifdef HAVE_ARPA_INET_H
30 # include <arpa/inet.h>
31 #endif
32 #ifdef HAVE_SYS_TIME_H
33 # include <sys/time.h>
34 #endif
35
36 #include <sys/types.h>
37 #include <fcntl.h>
38 #include <errno.h>
39 #include <stdio.h>
40 #include <ctype.h>
41
42 /* diff in ms */
43 static long tvdiff(struct timeval newer, struct timeval older)
44 {
45 return (newer.tv_sec-older.tv_sec)*1000+
46 (newer.tv_usec-older.tv_usec)/1000;
47 }
48
49 static int waitsocket(int socket_fd, LIBSSH2_SESSION *session)
50 {
51 struct timeval timeout;
52 int rc;
53 fd_set fd;
54 fd_set *writefd = NULL;
55 fd_set *readfd = NULL;
56 int dir;
57
58 timeout.tv_sec = 10;
59 timeout.tv_usec = 0;
60
61 FD_ZERO(&fd);
62
63 FD_SET(socket_fd, &fd);
64
65 /* now make sure we wait in the correct direction */
66 dir = libssh2_session_block_directions(session);
67
68 if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
69 readfd = &fd;
70
71 if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
72 writefd = &fd;
73
74 rc = select(socket_fd + 1, readfd, writefd, NULL, &timeout);
75
76 return rc;
77 }
78
79 int main(int argc, char *argv[])
80 {
81 unsigned long hostaddr;
82 int sock, i, auth_pw = 1;
83 struct sockaddr_in sin;
84 const char *fingerprint;
85 LIBSSH2_SESSION *session;
86 const char *username="username";
87 const char *password="password";
88 const char *sftppath="/tmp/TEST";
89 struct timeval start;
90 struct timeval end;
91 int rc;
92 int total = 0;
93 long time_ms;
94 int spin = 0;
95 LIBSSH2_SFTP *sftp_session;
96 LIBSSH2_SFTP_HANDLE *sftp_handle;
97
98 #ifdef WIN32
99 WSADATA wsadata;
100 int err;
101
102 err = WSAStartup(MAKEWORD(2,0), &wsadata);
103 if (err != 0) {
104 fprintf(stderr, "WSAStartup failed with error: %d\n", err);
105 return 1;
106 }
107 #endif
108
109 if (argc > 1) {
110 hostaddr = inet_addr(argv[1]);
111 } else {
112 hostaddr = htonl(0x7F000001);
113 }
114
115 if (argc > 2) {
116 username = argv[2];
117 }
118 if (argc > 3) {
119 password = argv[3];
120 }
121 if (argc > 4) {
122 sftppath = argv[4];
123 }
124
125 rc = libssh2_init (0);
126 if (rc != 0) {
127 fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
128 return 1;
129 }
130
131 /*
132 * The application code is responsible for creating the socket
133 * and establishing the connection
134 */
135 sock = socket(AF_INET, SOCK_STREAM, 0);
136
137 sin.sin_family = AF_INET;
138 sin.sin_port = htons(22);
139 sin.sin_addr.s_addr = hostaddr;
140 if (connect(sock, (struct sockaddr*)(&sin),
141 sizeof(struct sockaddr_in)) != 0) {
142 fprintf(stderr, "failed to connect!\n");
143 return -1;
144 }
145
146 /* Create a session instance */
147 session = libssh2_session_init();
148 if (!session)
149 return -1;
150
151 /* Since we have set non-blocking, tell libssh2 we are non-blocking */
152 libssh2_session_set_blocking(session, 0);
153
154 gettimeofday(&start, NULL);
155
156 /* ... start it up. This will trade welcome banners, exchange keys,
157 * and setup crypto, compression, and MAC layers
158 */
159 while ((rc = libssh2_session_handshake(session, sock)) ==
160 LIBSSH2_ERROR_EAGAIN);
161 if (rc) {
162 fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
163 return -1;
164 }
165
166 /* At this point we havn‘t yet authenticated. The first thing to do
167 * is check the hostkey‘s fingerprint against our known hosts Your app
168 * may have it hard coded, may go to a file, may present it to the
169 * user, that‘s your call
170 */
171 fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
172 fprintf(stderr, "Fingerprint: ");
173 for(i = 0; i < 20; i++) {
174 fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
175 }
176 fprintf(stderr, "\n");
177
178 if (auth_pw) {
179 /* We could authenticate via password */
180 while ((rc = libssh2_userauth_password(session, username, password))
181 == LIBSSH2_ERROR_EAGAIN);
182 if (rc) {
183 fprintf(stderr, "Authentication by password failed.\n");
184 goto shutdown;
185 }
186 } else {
187 /* Or by public key */
188 while ((rc =
189 libssh2_userauth_publickey_fromfile(session, username,
190 "/home/username/"
191 ".ssh/id_rsa.pub",
192 "/home/username/"
193 ".ssh/id_rsa",
194 password)) ==
195 LIBSSH2_ERROR_EAGAIN);
196 if (rc) {
197 fprintf(stderr, "\tAuthentication by public key failed\n");
198 goto shutdown;
199 }
200 }
201 #if 0
202 libssh2_trace(session, LIBSSH2_TRACE_CONN);
203 #endif
204 fprintf(stderr, "libssh2_sftp_init()!\n");
205 do {
206 sftp_session = libssh2_sftp_init(session);
207
208 if(!sftp_session) {
209 if(libssh2_session_last_errno(session) ==
210 LIBSSH2_ERROR_EAGAIN) {
211 fprintf(stderr, "non-blocking init\n");
212 waitsocket(sock, session); /* now we wait */
213 }
214 else {
215 fprintf(stderr, "Unable to init SFTP session\n");
216 goto shutdown;
217 }
218 }
219 } while (!sftp_session);
220
221 fprintf(stderr, "libssh2_sftp_open()!\n");
222 /* Request a file via SFTP */
223 do {
224 sftp_handle = libssh2_sftp_open(sftp_session, sftppath,
225 LIBSSH2_FXF_READ, 0);
226
227 if (!sftp_handle) {
228 if (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN) {
229 fprintf(stderr, "Unable to open file with SFTP\n");
230 goto shutdown;
231 }
232 else {
233 fprintf(stderr, "non-blocking open\n");
234 waitsocket(sock, session); /* now we wait */
235 }
236 }
237 } while (!sftp_handle);
238
239 fprintf(stderr, "libssh2_sftp_open() is done, now receive data!\n");
240 do {
241 char mem[1024*24];
242
243 /* loop until we fail */
244 while ((rc = libssh2_sftp_read(sftp_handle, mem,
245 sizeof(mem))) == LIBSSH2_ERROR_EAGAIN) {
246 spin++;
247 waitsocket(sock, session); /* now we wait */
248 }
249 if (rc > 0) {
250 total += rc;
251 write(1, mem, rc);
252 } else {
253 break;
254 }
255 } while (1);
256
257 gettimeofday(&end, NULL);
258 time_ms = tvdiff(end, start);
259 fprintf(stderr, "Got %d bytes in %ld ms = %.1f bytes/sec spin: %d\n", total,
260 time_ms, total/(time_ms/1000.0), spin );
261
262 libssh2_sftp_close(sftp_handle);
263 libssh2_sftp_shutdown(sftp_session);
264
265 shutdown:
266
267 fprintf(stderr, "libssh2_session_disconnect\n");
268 while (libssh2_session_disconnect(session,
269 "Normal Shutdown, Thank you") ==
270 LIBSSH2_ERROR_EAGAIN);
271 libssh2_session_free(session);
272
273 #ifdef WIN32
274 closesocket(sock);
275 #else
276 close(sock);
277 #endif
278 fprintf(stderr, "all done\n");
279
280 libssh2_exit();
281
282 return 0;
283 }
上面一个是发送文件到sftp服务器，下面是从sftp服务器获取文件。编译和运行结果如下图所示。
2.修改示例程序
软件提供的源代码是比较完整的，为了方便，对里面的功能进行修改。修改为符合本次使用的windows版本，仅支持密码访问。
sftp-write.c 用于把本地文件上传到sftp服务器中
1 #include "libssh2_config.h"
2 #include <libssh2.h>
3 #include <libssh2_sftp.h>
4 #include <winsock2.h>
5 #include <unistd.h>
6 #include <sys/time.h>
7 #include <sys/types.h>
8 #include <fcntl.h>
9 #include <errno.h>
10 #include <stdio.h>
11 #include <ctype.h>
12
13 #define PORT 22
14 #define HOST "127.0.0.1"
15 #define USER "user"
16 #define PWD "user"
17 #define FILENAME "wunaozai.txt"
18 #define LOCLFILE "wunaozai.txt"
19
20 long tvdiff(struct timeval newer, struct timeval older);
21 int waitsocket(int socket_fd, LIBSSH2_SESSION *session);
22
23 int main(int argc,char *argv[])
24 {
25 int sock, i;
26 struct sockaddr_in sin;
27 const char *fingerprint;
28 LIBSSH2_SESSION *session;
29 LIBSSH2_SFTP *sftp_session;
30 LIBSSH2_SFTP_HANDLE *sftp_handle;
31 int rc;
32 FILE *local;
33 char mem[1024 * 100];
34 size_t nread;
35 char *ptr;
36 time_t start;
37 long total = 0;
38 int duration;
39 int ret=-1; //用于表示返回结果
40 int err;
41
42 WSADATA wsadata;
43 err = WSAStartup(MAKEWORD(2,0), &wsadata);
44 if (err != 0) {
45 fprintf(stderr, "WSAStartup failed with error: %d\n", err);
46 return 1;
47 }
48
49 rc = libssh2_init (0);
50 if (rc != 0) {
51 fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
52 return 1;
53 }
54
55 local = fopen(LOCLFILE, "rb");
56 if (!local) {
57 fprintf(stderr, "Can‘t open local file %s\n", LOCLFILE);
58 return -1;
59 }
60
61 /*
62 * The application code is responsible for creating the socket
63 * and establishing the connection
64 */
65 sock = socket(AF_INET, SOCK_STREAM, 0);
66
67 sin.sin_family = AF_INET;
68 sin.sin_port = htons(PORT);
69 sin.sin_addr.S_un.S_addr = inet_addr(HOST);
70 if (connect(sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in)) != 0) {
71 fprintf(stderr, "failed to connect!\n");
72 return -1;
73 }
74
75 /* Create a session instance */
76 session = libssh2_session_init();
77 if (!session) return -1;
78
79 /* Since we have set non-blocking, tell libssh2 we are non-blocking */
80 libssh2_session_set_blocking(session, 0);
81
82 /* ... start it up. This will trade welcome banners, exchange keys,
83 * and setup crypto, compression, and MAC layers
84 */
85 while ((rc = libssh2_session_handshake(session, sock)) == LIBSSH2_ERROR_EAGAIN)
86 ;
87 if (rc) {
88 fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
89 return -1;
90 }
91
92 //到这里我们还没有权限访问，所以接下来要做的是检查hostkey‘s finger,然后知道我们验证方式
93 fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
94 fprintf(stderr, "Fingerprint: ");
95 for(i = 0; i < 20; i++) {
96 fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
97 }
98 fprintf(stderr, "\n");
99
100 //只能使用密码验证
101 while ((rc = libssh2_userauth_password(session, USER, PWD)) == LIBSSH2_ERROR_EAGAIN)
102 ;
103 if (rc) {
104 fprintf(stderr, "Authentication by password failed.\n");
105 goto shutdown;
106 }
107
108 //fprintf(stderr, "libssh2_sftp_init()!\n");
109 do {
110 sftp_session = libssh2_sftp_init(session);
111 if (!sftp_session && (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN)) {
112 fprintf(stderr, "Unable to init SFTP session\n");
113 goto shutdown;
114 }
115 } while (!sftp_session);
116 //fprintf(stderr, "libssh2_sftp_open()!\n");
117
118
119 //请求一个文件，通过ssh2方式
120 do {
121 sftp_handle =
122 libssh2_sftp_open(sftp_session, FILENAME, LIBSSH2_FXF_WRITE|LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC,
123 LIBSSH2_SFTP_S_IRUSR|LIBSSH2_SFTP_S_IWUSR|
124 LIBSSH2_SFTP_S_IRGRP|LIBSSH2_SFTP_S_IROTH);
125
126 if (!sftp_handle && (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN)) {
127 fprintf(stderr, "Unable to open file with SFTP\n"); //可能是没有写入权限，或者没有对应的目录
128 goto shutdown;
129 }
130 } while (!sftp_handle);
131
132 fprintf(stderr, "libssh2_sftp_open() is done, now send data!\n");
133
134 start = time(NULL);
135
136 do {
137 nread = fread(mem, 1, sizeof(mem), local);
138 if (nread <= 0) { //文件结束
139 break;
140 }
141 ptr = mem;
142 total += nread;
143 do {
144 //持续写入文件
145 while ((rc = libssh2_sftp_write(sftp_handle, ptr, nread)) == LIBSSH2_ERROR_EAGAIN) {
146 waitsocket(sock, session);
147 }
148 if(rc < 0)
149 break;
150 ptr += rc;
151 nread -= rc;
152 } while (nread);
153 } while (rc > 0);
154
155 duration = (int)(time(NULL)-start);
156
157 fprintf(stderr, "%ldK bytes in %d seconds makes %.1fK bytes/sec\n", total/1024, duration+1, total/((double)duration+1)/1024);
158
159
160 fclose(local);
161 libssh2_sftp_close(sftp_handle);
162 libssh2_sftp_shutdown(sftp_session);
163
164 ret = 0; //如果执行到这一步，那么表示成功上传文件到服务器
165 shutdown:
166
167 while (libssh2_session_disconnect(session, "Normal Shutdown, Thank you for playing") == LIBSSH2_ERROR_EAGAIN)
168 ;
169 libssh2_session_free(session);
170 closesocket(sock);
171 fprintf(stderr, "all done\n");
172 libssh2_exit();
173
174 return ret;
175 }
176
177 int waitsocket(int socket_fd, LIBSSH2_SESSION *session)
178 {
179 struct timeval timeout;
180 int rc;
181 fd_set fd;
182 fd_set *writefd = NULL;
183 fd_set *readfd = NULL;
184 int dir;
185
186 timeout.tv_sec = 10;
187 timeout.tv_usec = 0;
188
189 FD_ZERO(&fd);
190
191 FD_SET(socket_fd, &fd);
192
193 /* now make sure we wait in the correct direction */
194 dir = libssh2_session_block_directions(session);
195
196 if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
197 readfd = &fd;
198
199 if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
200 writefd = &fd;
201
202 rc = select(socket_fd + 1, readfd, writefd, NULL, &timeout);
203 return rc;
204 }
205 /* diff in ms */
206 long tvdiff(struct timeval newer, struct timeval older)
207 {
208 return (newer.tv_sec-older.tv_sec)*1000+ (newer.tv_usec-older.tv_usec)/1000;
209 }
sftp-read.c 用于把服务器上的文件下载到本地中
1 #include "libssh2_config.h"
2 #include <libssh2.h>
3 #include <libssh2_sftp.h>
4 #include <winsock2.h>
5 #include <unistd.h>
6 #include <sys/time.h>
7 #include <sys/types.h>
8 #include <fcntl.h>
9 #include <errno.h>
10 #include <stdio.h>
11 #include <ctype.h>
12
13 #define PORT 22
14 #define HOST "127.0.0.1"
15 #define USER "user"
16 #define PWD "user"
17 #define FILENAME "wunaozai.txt"
18 #define LOCLFILE "wunaozai.txt"
19
20 long tvdiff(struct timeval newer, struct timeval older);
21 int waitsocket(int socket_fd, LIBSSH2_SESSION *session);
22
23
24 int main(int argc, char *argv[])
25 {
26 int sock, i;
27 struct sockaddr_in sin;
28 const char *fingerprint;
29 LIBSSH2_SESSION *session;
30 LIBSSH2_SFTP *sftp_session;
31 LIBSSH2_SFTP_HANDLE *sftp_handle;
32 struct timeval start;
33 struct timeval end;
34 int total = 0;
35 long time_ms;
36 int spin = 0;
37 int ret=0;
38 int rc=1;
39 FILE * fp;
40
41 WSADATA wsadata;
42 ret = WSAStartup(MAKEWORD(2,0), &wsadata);
43 if (ret != 0) {
44 fprintf(stderr, "WSAStartup failed with error: %d\n", ret);
45 return 1;
46 }
47
48 ret = libssh2_init (0);
49 if (ret != 0) {
50 fprintf (stderr, "libssh2 initialization failed (%d)\n", ret);
51 return 1;
52 }
53
54 sock = socket(AF_INET, SOCK_STREAM, 0);
55 sin.sin_family = AF_INET;
56 sin.sin_port = htons(PORT); //SFTP默认端口为22端口
57 sin.sin_addr.S_un.S_addr = inet_addr(HOST);
58 if (connect(sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in)) != 0) {
59 fprintf(stderr, "failed to connect!\n");
60 return -1;
61 }
62
63 session = libssh2_session_init(); //创建一个session
64 if (!session) return -1;
65
66 libssh2_session_set_blocking(session, 0); //设置为非阻塞方式
67
68 while ((ret = libssh2_session_handshake(session, sock)) == LIBSSH2_ERROR_EAGAIN) //创建一个SSH session
69 ;
70
71 if (ret) {
72 fprintf(stderr, "Failure establishing SSH session: %d\n", ret);
73 return -1;
74 }
75 //到这里我们还没有权限访问，所以接下来要做的是检查hostkey‘s finger
76 fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
77 fprintf(stderr, "Fingerprint: ");
78 for(i = 0; i < 20; i++) {
79 fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
80 }
81 fprintf(stderr, "\n");
82
83 //只是用密码进行验证
84 while ((ret = libssh2_userauth_password(session, USER, PWD)) == LIBSSH2_ERROR_EAGAIN)
85 ;
86 if (ret) {
87 fprintf(stderr, "Authentication by password failed.\n");
88 goto shutdown2;
89 }
90
91 fprintf(stderr, "libssh2_sftp_init()!\n");
92 do {
93 sftp_session = libssh2_sftp_init(session);
94 if(!sftp_session) {
95 if(libssh2_session_last_errno(session) == LIBSSH2_ERROR_EAGAIN) {
96 fprintf(stderr, "non-blocking init\n");
97 waitsocket(sock, session); /* now we wait */
98 }
99 else {
100 fprintf(stderr, "Unable to init SFTP session\n");
101 goto shutdown2;
102 }
103 }
104 } while (!sftp_session);
105
106 fprintf(stderr, "libssh2_sftp_open()!\n");
107
108 //请求一个文件，通过ssh方式
109 do {
110 sftp_handle = libssh2_sftp_open(sftp_session, FILENAME, LIBSSH2_FXF_READ, 0);
111
112 if (!sftp_handle) {
113 if (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN) {
114 fprintf(stderr, "Unable to open file with SFTP\n");
115 goto shutdown2;
116 }
117 else {
118 fprintf(stderr, "non-blocking open\n");
119 waitsocket(sock, session); /* now we wait */
120 }
121 }
122 } while (!sftp_handle);
123
124 gettimeofday(&start,NULL);
125 //打开文件进行保存
126 fp = fopen(LOCLFILE,"wb");
127 if(fp==NULL)
128 {
129 fprintf(stderr,"Can‘t open local file %s\n",LOCLFILE);
130 return -1;
131 }
132 fprintf(stderr, "libssh2_sftp_open() is done, now receive data!\n");
133 do {
134 char mem[1024*24];
135
136 /* loop until we fail */
137 while ((ret = libssh2_sftp_read(sftp_handle, mem, sizeof(mem))) == LIBSSH2_ERROR_EAGAIN) {
138 spin++;
139 waitsocket(sock, session); /* now we wait */
140 }
141 if (ret > 0) {
142 total += ret;
143 //write(1, mem, ret);
144 fwrite(mem,1,ret,fp); //写入到文件中
145 } else {
146 break;
147 }
148 } while (1);
149 fclose(fp);
150 gettimeofday(&end,NULL);
151 time_ms = tvdiff(end, start);
152 //打印传输速率
153 fprintf(stderr, "Got %.4lf Mbytes in %.2lf sec = %.4lf Kbytes/sec spin: %d\n", total/1024.0/1024.0,
154 time_ms/1000.0, total/((time_ms+1)/1000.0)/1024/1024, spin );
155
156 libssh2_sftp_close(sftp_handle);
157 libssh2_sftp_shutdown(sftp_session);
158
159 rc = 0;//执行到改行代码表示已经正常下载文件
160
161 shutdown2:
162
163 fprintf(stderr, "libssh2_session_disconnect\n");
164 while (libssh2_session_disconnect(session, "Normal Shutdown, Thank you") == LIBSSH2_ERROR_EAGAIN)
165 ;
166 libssh2_session_free(session);
167 closesocket(sock);
168 fprintf(stderr, "all done\n");
169 libssh2_exit();
170
171 return rc;
172 }
173
174 long tvdiff(struct timeval newer, struct timeval older)
175 {
176 return (newer.tv_sec-older.tv_sec)*1000+(newer.tv_usec-older.tv_usec)/1000;
177 }
178
179 int waitsocket(int socket_fd, LIBSSH2_SESSION *session)
180 {
181 struct timeval timeout;
182 int ret;
183 fd_set fd;
184 fd_set *writefd = NULL;
185 fd_set *readfd = NULL;
186 int dir;
187 timeout.tv_sec = 10;
188 timeout.tv_usec = 0;
189 FD_ZERO(&fd);
190 FD_SET(socket_fd, &fd);
191 /* now make sure we wait in the correct direction */
192 dir = libssh2_session_block_directions(session);
193 if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
194 readfd = &fd;
195 if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
196 writefd = &fd;
197 ret = select(socket_fd + 1, readfd, writefd, NULL, &timeout);
198 return ret;
199 }
至于用到的libssh2_config.h这个文件，没有的话可以在代码中注释掉.
下面这个是freesshd产生的日志中一部分
1 05-28-2015 14:18:05 HOST localhost SSH connection attempt. 2 05-28-2015 14:18:05 HOST localhost SSH user successfully logged on using password. 3 05-28-2015 14:18:06 SFTP service granted to user user. 4 05-28-2015 14:18:06 HOST localhost user is uploading wunaozai.txt (E:\wunaozai.txt) 5 05-28-2015 14:18:06 HOST localhost SSH user disconnected. 6 05-28-2015 14:18:23 HOST localhost SSH connection attempt. 7 05-28-2015 14:18:23 HOST localhost SSH user successfully logged on using password. 8 05-28-2015 14:18:23 SFTP service granted to user user. 9 05-28-2015 14:18:23 HOST localhost user is uploading wunaozai.txt (E:\wunaozai.txt) 10 05-28-2015 14:18:23 HOST localhost SSH user disconnected. 11 05-28-2015 14:18:49 HOST localhost SSH connection attempt. 12 05-28-2015 14:18:49 HOST localhost SSH user successfully logged on using password. 13 05-28-2015 14:18:49 SFTP service granted to user user. 14 05-28-2015 14:18:49 HOST localhost user is uploading wunaozai.txt (E:\wunaozai.txt) 15 05-28-2015 14:18:49 HOST localhost SSH user disconnected. 16 05-28-2015 14:18:55 HOST localhost SSH connection attempt. 17 05-28-2015 14:18:56 HOST localhost SSH user successfully logged on using password. 18 05-28-2015 14:18:56 SFTP service granted to user user. 19 05-28-2015 14:18:56 HOST localhost user is downloading wunaozai.txt (E:\wunaozai.txt) 20 05-28-2015 14:18:56 HOST localhost SSH user disconnected.
有了上面这两个主要的功能，SFTP的客户端就基本功能实现了，至于mkdir和dir功能就参考里面的示例程序，基本都可以看懂。
3.使用putty连接freesshd
了解过SFTP原理之后，就知道，SFTP其实跟FTP没有多大的关系，其实就是一个使用SSH协议，然后进行会话，会话过程保存为文件，嗯，大概就是这个样子了。所以我们可以使用普通的ssh软件进行登录，拿到该SFTP服务器站点的SHELL。然后可以各种操作，看起来很危险的样子，所以不管用什么SFTP服务器在配置用户的时候要注意的。 putty工具里面还有个PSFTP.exe这个工具可以连接到SFTP服务器，没事的也可以玩玩看。
本文地址: http://www.cnblogs.com/wunaozai/p/4534302.html
时间： 2024-11-05 17:33:07