Hello again!
I've finished my small simple ssh client. The source code is attached.
Of course it's not perfect and printing command two times, but it still
simple and working.
Do you want me to send it in another format like patch for example?
Or, I suppose, the part of it can be added into current examples replacing
words:
"At this point the shell can be interacted with using *
libssh2_channel_read() ..."
I will be happy to see your comments and fix anything accordingly.
Another question, what is the best way to send signals to remote side?
Thank you!
//Ivan
2012/1/16 Peter Stuge <pe...@stuge.se>
> Ivan Tretyakov wrote:
> > I'll think about it, but at the moment it's not clear to me how do I
> > implement a simple ssh client.
>
> Maybe doing that is not so simple.
>
>
> > how to interact with a remote shell when I use libssh2_channel_shell
> > and want to execute commands remotely.
>
> So you need to study how to do full duplex communication in C.
>
>
> > In my mind it's a good to have such example at web-site example section.
>
> Feel free to send a perfect patch with such an example. I don't think
> anyone would be against adding it to the repo!
>
> There is already at least one example demonstrating the same concept
> however; look at examples/direct-tcpip.c
>
>
> //Peter
> _______________________________________________
> libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
>
--
С уважением,
Третьяков И.В.
/*
============================================================================
Name : SmallSimpleSSH.c
Author : Ivan Tretyakov
Version : 0.1
Copyright : GPLv3
Description : Libssh2 ssh client example
============================================================================
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <libssh2.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <poll.h>
#include <fcntl.h>
#define EXIT_COMMAND "exit\n"
/* Main function */
int main(int argc, char *argv[]) {
const char *username;
const char *password;
const char *hostaddr;
int rc;
int sock;
int written;
struct sockaddr_in sin;
LIBSSH2_SESSION *session;
LIBSSH2_CHANNEL *channel;
char commandbuf[BUFSIZ];
char inputbuf[BUFSIZ];
const char numfds = 2;
struct pollfd pfds[numfds];
/* Get IP and authorization data */
if (argv[1] != NULL && argv[2] != NULL && argv[3] != NULL) {
hostaddr = argv[1];
username = argv[2];
password = argv[3];
} else {
fprintf(stderr, "Usage: %s <target ip> <username> <password>\n",
argv[0]);
return (EXIT_FAILURE);
}
/* Libss2 init block */
rc = libssh2_init(0);
if (rc) {
fprintf(stderr, "Error: libssh_init()\n");
return (EXIT_FAILURE);
}
/* Creating socket */
sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock == -1) {
perror("socket");
return (EXIT_FAILURE);
}
/* Connect this socket to remote side */
sin.sin_family = AF_INET;
sin.sin_port = htons(22);
sin.sin_addr.s_addr = inet_addr(hostaddr);
if (connect(sock, (struct sockaddr*)(&sin),
sizeof(struct sockaddr_in)) != 0) {
fprintf(stderr, "Failed to connect\n");
return (EXIT_FAILURE);
}
/* Set socket non-blocking */
rc = fcntl(sock, F_SETFL, O_NONBLOCK);
if (rc == -1) {
perror("fcntl");
return (EXIT_FAILURE);
}
/* Set stdin non-blocking */
rc = fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);
if (rc == -1) {
perror("fcntl");
return (EXIT_FAILURE);
}
/* Create a session instance and start it up. This will trade welcome
* banners, exchange keys, and setup crypto, compression, and MAC layers */
session = libssh2_session_init();
if (!session) {
fprintf(stderr, "SSH init failed\n");
return (EXIT_FAILURE);
}
/* Handshake for session */
rc = libssh2_session_handshake(session, sock);
if (rc) {
fprintf(stderr, "SSH handshake failed\n");
return (EXIT_FAILURE);
}
/* Lets authenticate */
rc = libssh2_userauth_password(session, username, password);
if (rc) {
printf("Authentication by password failed\n");
return (EXIT_FAILURE);
} else {
printf("Authentication by password succeeded\n");
}
/* Request a shell */
channel = libssh2_channel_open_session(session);
if (!channel) {
fprintf(stderr, "Unable to open a session\n");
return (EXIT_FAILURE);
}
/* Request a terminal with 'vt100' terminal emulation */
rc = libssh2_channel_request_pty(channel, "vt100");
if (rc) {
fprintf(stderr, "Failed requesting pty\n");
return (EXIT_FAILURE);
}
/* Open a SHELL on that pty */
rc = libssh2_channel_shell(channel);
if (rc) {
fprintf(stderr, "Unable to request shell on allocated pty\n");
return (EXIT_FAILURE);
}
/* Set libssh2 to non-blocking mode */
libssh2_channel_set_blocking(channel, 0);
/* Prepare to use poll */
memset(pfds, 0, sizeof(struct pollfd) * numfds);
/* Main loop starts here.
* In it you will be requested to input a command
* command will be executed at remote side
* an you will get output from it */
do {
/* Declare that we neet to wait while
* socket or stdin not ready for reading */
pfds[0].fd = sock;
pfds[0].events = POLLIN;
pfds[0].revents = 0;
pfds[1].fd = STDIN_FILENO;
pfds[1].events = POLLIN;
pfds[1].revents = 0;
/* Polling on socket and stdin while we are
* not ready to read from it */
rc = poll(pfds, numfds, -1);
if (-1 == rc) {
perror("poll");
break;
}
if (pfds[0].revents & POLLIN) {
/* Read output from remote side */
do {
rc = libssh2_channel_read(channel, inputbuf, BUFSIZ);
printf("%s", inputbuf);
fflush(stdout);
memset(inputbuf, 0, BUFSIZ);
} while (LIBSSH2_ERROR_EAGAIN != rc && rc > 0);
}
if (rc < 0 && LIBSSH2_ERROR_EAGAIN != rc) {
fprintf(stderr, "libssh2_channel_read error code %d\n", rc);
return (EXIT_FAILURE);
}
if (pfds[1].revents & POLLIN) {
/* Request for command input */
fgets(commandbuf, BUFSIZ - 2, stdin);
if (strcmp(commandbuf, EXIT_COMMAND) == 0)
break;
/* Adjust command format */
commandbuf[strlen(commandbuf) - 1] = '\r';
commandbuf[strlen(commandbuf)] = '\n';
commandbuf[strlen(commandbuf) + 1] = '\0';
/* Write command to stdin of remote shell */
written = 0;
do {
rc = libssh2_channel_write(channel, commandbuf, strlen(commandbuf));
written += rc;
} while (LIBSSH2_ERROR_EAGAIN != rc
&& rc > 0
&& written != strlen(commandbuf));
memset(commandbuf, 0, BUFSIZ);
}
if (rc < 0 && LIBSSH2_ERROR_EAGAIN != rc) {
fprintf(stderr, "libssh2_channel_write error code %d\n", rc);
return (EXIT_FAILURE);
}
} while (1);
/* Main loop ends here */
/* De-init and pre-exit actions */
if (channel) {
libssh2_channel_free(channel);
channel = NULL;
}
/* Finish actions below */
rc = libssh2_session_disconnect(session, "Normal Shutdown");
if (rc) {
fprintf(stderr, "Session disconnect error\n");
return (EXIT_FAILURE);
} else
printf("Session finished successful\n");
libssh2_session_free(session);
close(sock);
libssh2_exit();
return (EXIT_SUCCESS);
}
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