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Improve the ssh2 example program to run a command

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This performs better as an example since it shows more working code, and
in the simplest possible way. It also turns the program into an actually
useful tool out of the box, able to run an arbitrary command (with one
restriction) on a remote machine and return the response, without
needing to touch the source.

Closes #800
This commit is contained in:
Dan Fandrich
2023-02-20 16:29:10 -08:00
parent af1e591eee
commit 27ef3bbb25
1 changed files with 60 additions and 31 deletions
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91
example/ssh2.c
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@ -4,10 +4,11 @@
* 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:
*
* Usage: ssh2 hostip user password [-p|-i|-k]
* Usage: ssh2 hostip user password [[-p|-i|-k] [command]]
* -p authenticate using password
* -i authenticate using keyboard-interactive
* -k authenticate using public key (password argument decrypts keyfile)
* command executes on the remote machine
*/
#include "libssh2_config.h"
@ -82,11 +83,10 @@ int main(int argc, char *argv[])
#ifdef WIN32
WSADATA wsadata;
int err;
err = WSAStartup(MAKEWORD(2, 0), &wsadata);
if(err != 0) {
fprintf(stderr, "WSAStartup failed with error: %d\n", err);
rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
if(rc != 0) {
fprintf(stderr, "WSAStartup failed with error: %d\n", rc);
return 1;
}
#endif
@ -120,8 +120,8 @@ int main(int argc, char *argv[])
sin.sin_port = htons(22);
sin.sin_addr.s_addr = hostaddr;
fprintf(stderr, "Connecting to %s as user %s\n",
inet_ntoa(sin.sin_addr), username);
fprintf(stderr, "Connecting to %s:%d as user %s\n",
inet_ntoa(sin.sin_addr), ntohs(sin.sin_port), username);
if(connect(sock, (struct sockaddr*)(&sin),
sizeof(struct sockaddr_in)) != 0) {
@ -251,7 +251,7 @@ int main(int argc, char *argv[])
goto shutdown;
}
/* Request a shell */
/* Request a session channel on which to run a shell */
channel = libssh2_channel_open_session(session);
if(!channel) {
fprintf(stderr, "Unable to open a session\n");
@ -264,33 +264,62 @@ int main(int argc, char *argv[])
libssh2_channel_setenv(channel, "FOO", "bar");
/* Request a terminal with 'vanilla' terminal emulation
* See /etc/termcap for more options
* See /etc/termcap for more options. This is useful when opening
* an interactive shell.
*/
if(libssh2_channel_request_pty(channel, "vanilla")) {
fprintf(stderr, "Failed requesting pty\n");
goto skip_shell;
// if(libssh2_channel_request_pty(channel, "vanilla")) {
// fprintf(stderr, "Failed requesting pty\n");
// }
if(argc > 5) {
if(libssh2_channel_exec(channel, argv[5])) {
fprintf(stderr, "Unable to request command on channel\n");
goto shutdown;
}
/* Instead of just running a single command with libssh2_channel_exec,
* a shell can be opened on the channel instead, for interactive use.
* You usually want a pty allocated first in that case (see above). */
// if(libssh2_channel_shell(channel)) {
// fprintf(stderr, "Unable to request shell on allocated pty\n");
// goto shutdown;
// }
/* At this point the shell can be interacted with using
* libssh2_channel_read()
* libssh2_channel_read_stderr()
* libssh2_channel_write()
* libssh2_channel_write_stderr()
*
* Blocking mode may be (en|dis)abled with: libssh2_channel_set_blocking()
* If the server send EOF, libssh2_channel_eof() will return non-0
* To send EOF to the server use: libssh2_channel_send_eof()
* A channel can be closed with: libssh2_channel_close()
* A channel can be freed with: libssh2_channel_free()
*/
/* Read and display all the data received on stdout (ignoring stderr)
* until the channel closes. This will eventually block if the command
* produces too much data on stderr; the loop must be rewritten to use
* non-blocking mode and include interspersed calls to
* libssh2_channel_read_stderr() to avoid this. See ssh2_echo.c for
* an idea of how such a loop might look.
*/
while(!libssh2_channel_eof(channel)) {
char buf[1024];
ssize_t err = libssh2_channel_read(channel, buf, sizeof(buf));
if(err < 0)
fprintf(stderr, "Unable to read response: %zd\n", err);
else {
fwrite(buf, 1, err, stdout);
}
}
}
/* Open a SHELL on that pty */
if(libssh2_channel_shell(channel)) {
fprintf(stderr, "Unable to request shell on allocated pty\n");
goto shutdown;
}
rc = libssh2_channel_get_exit_status(channel);
/* At this point the shell can be interacted with using
* libssh2_channel_read()
* libssh2_channel_read_stderr()
* libssh2_channel_write()
* libssh2_channel_write_stderr()
*
* Blocking mode may be (en|dis)abled with: libssh2_channel_set_blocking()
* If the server send EOF, libssh2_channel_eof() will return non-0
* To send EOF to the server use: libssh2_channel_send_eof()
* A channel can be closed with: libssh2_channel_close()
* A channel can be freed with: libssh2_channel_free()
*/
if(libssh2_channel_close(channel))
fprintf(stderr, "Unable to close channel\n");
skip_shell:
if(channel) {
libssh2_channel_free(channel);
channel = NULL;
@ -317,5 +346,5 @@ int main(int argc, char *argv[])
libssh2_exit();
return 0;
return rc;
}