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telnet-server.c
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telnet-server.c
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#include "lib/common.h"
static int count;
static void sig_int(int signo) {
printf("\nreceived %d datagrams\n", count);
exit(0);
}
char *run_cmd(char *cmd) {
char *data = malloc(16384);
bzero(data, sizeof(data));
FILE *fdp;
const int max_buffer = 256;
char buffer[max_buffer];
fdp = popen(cmd, "r");
char *data_index = data;
if (fdp) {
while (!feof(fdp)) {
if (fgets(buffer, max_buffer, fdp) != NULL) {
int len = strlen(buffer);
memcpy(data_index, buffer, len);
data_index += len;
}
}
pclose(fdp);
}
return data;
}
int main(int argc, char **argv) {
int listenfd;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
server_addr.sin_port = htons(SERV_PORT);
int on = 1;
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
int rt1 = bind(listenfd, (struct sockaddr *) &server_addr, sizeof(server_addr));
if (rt1 < 0) {
error(1, errno, "bind failed ");
}
int rt2 = listen(listenfd, LISTENQ);
if (rt2 < 0) {
error(1, errno, "listen failed ");
}
signal(SIGPIPE, SIG_IGN);
int connfd;
struct sockaddr_in client_addr;
socklen_t client_len = sizeof(client_addr);
char buf[256];
count = 0;
while (1) {
if ((connfd = accept(listenfd, (struct sockaddr *) &client_addr, &client_len)) < 0) {
error(1, errno, "bind failed ");
}
while (1) {
bzero(buf, sizeof(buf));
int n = read(connfd, buf, sizeof(buf));
if (n < 0) {
error(1, errno, "error read message");
} else if (n == 0) {
printf("client closed \n");
close(connfd);
break;
}
count++;
buf[n] = 0;
if (strncmp(buf, "ls", n) == 0) {
char *result = run_cmd("ls");
if (send(connfd, result, strlen(result), 0) < 0){
return 1;
}
free(result);
} else if (strncmp(buf, "pwd", n) == 0) {
char buf[256];
char *result = getcwd(buf, 256);
if (send(connfd, result, strlen(result), 0) < 0)
return 1;
} else if (strncmp(buf, "cd ", 3) == 0) {
char target[256];
bzero(target, sizeof(target));
memcpy(target, buf + 3, strlen(buf) - 3);
if (chdir(target) == -1) {
printf("change dir failed, %s\n", target);
}
} else {
char *error = "error: unknown input type";
if (send(connfd, error, strlen(error), 0) < 0)
return 1;
}
}
}
exit(0);
}