mirror of https://gerrit.osmocom.org/libtelnet
add telnet-proxy
This commit is contained in:
Sean Middleditch
parent
7e517ecacb
commit
b9ab0b6b9a
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@ -0,0 +1,2 @@
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telnet-proxy: telnet-proxy.c libtelnet.c libtelnet.h
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$(CC) -o telnet-proxy -Wall telnet-proxy.c libtelnet.c
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@ -0,0 +1,228 @@
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <poll.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <ctype.h>
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#include <unistd.h>
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#include "libtelnet.h"
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static int server_sock;
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static int client_sock;
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static struct libtelnet_t server_telnet;
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static struct libtelnet_t client_telnet;
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static const char* get_name(int sock) {
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if (sock == server_sock)
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return "\e[31mSERVER";
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else
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return "\e[34mCLIENT";
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}
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static struct libtelnet_t *other_telnet(struct libtelnet_t *telnet) {
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if (telnet == &server_telnet)
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return &client_telnet;
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else
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return &server_telnet;
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}
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static void* other_socket(int sock) {
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if (sock == server_sock)
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return (void*)&client_sock;
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else
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return (void*)&server_sock;
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}
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static void print_buffer(unsigned char *buffer, unsigned int size) {
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unsigned int i;
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for (i = 0; i != size; ++i) {
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if (buffer[i] == ' ' || (isprint(buffer[i]) && !isspace(buffer[i])))
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printf("%c", (char)buffer[i]);
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else if (buffer[i] == '\n')
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printf("<%02X>\n", (int)buffer[i]);
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else
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printf("<%02X>", (int)buffer[i]);
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}
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}
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void libtelnet_input_cb(struct libtelnet_t *telnet, unsigned char *buffer,
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unsigned int size, void *user_data) {
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int sock = *(int*)user_data;
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printf("%s INPUT: ", get_name(sock));
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print_buffer(buffer, size);
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printf("\e[0m\n");
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libtelnet_send_data(other_telnet(telnet), buffer, size,
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other_socket(sock));
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}
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void libtelnet_output_cb(struct libtelnet_t *telnet, unsigned char *buffer,
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unsigned int size, void *user_data) {
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int sock = *(int*)user_data;
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/* DONT SPAM
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printf("%s OUTPUT: ", get_name(sock));
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print_buffer(buffer, size);
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printf("\e[0m\n");
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*/
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/* send data */
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send(sock, buffer, size, 0);
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}
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void libtelnet_command_cb(struct libtelnet_t *telnet, unsigned char cmd,
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void *user_data) {
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int sock = *(int*)user_data;
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printf("%s IAC %d\e[0m\n", get_name(sock), (int)cmd);
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libtelnet_send_command(other_telnet(telnet), cmd, other_socket(sock));
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}
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void libtelnet_negotiate_cb(struct libtelnet_t *telnet, unsigned char cmd,
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unsigned char opt, void *user_data) {
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int sock = *(int*)user_data;
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printf("%s IAC %d %d\e[0m\n", get_name(sock), (int)cmd, (int)opt);
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libtelnet_send_negotiate(other_telnet(telnet), cmd, opt,
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other_socket(sock));
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}
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void libtelnet_subrequest_cb(struct libtelnet_t *telnet, unsigned char type,
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unsigned char *buffer, unsigned int size, void *user_data) {
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int sock = *(int*)user_data;
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printf("%s SUBREQ %d: ", get_name(sock), (int)type);
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print_buffer(buffer, size);
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printf("\e[0m\n");
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libtelnet_send_subrequest(other_telnet(telnet), type, buffer, size,
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other_socket(sock));
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}
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void libtelnet_error_cb(struct libtelnet_t *telnet,
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enum libtelnet_error_t error, void *user_data) {
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int sock = *(int*)user_data;
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printf("%s ERROR: %d\e[0m\n", get_name(sock), (int)error);
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}
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int main(int argc, char **argv) {
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unsigned char buffer[512];
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int listen_sock;
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int rs;
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struct sockaddr_in addr;
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socklen_t addrlen;
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struct pollfd pfd[2];
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/* check usage */
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if (argc != 4) {
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fprintf(stderr, "Usage:\n ./telnet-proxy <remote ip> <remote port> <local port>\n");
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return 1;
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}
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/* create listening socket */
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if ((listen_sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
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fprintf(stderr, "socket() failed: %s\n", strerror(errno));
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return 1;
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}
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/* re-use addr */
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rs = 1;
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setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, &rs, sizeof(rs));
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/* bind */
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memset(&addr, 0, sizeof(addr));
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addr.sin_family = AF_INET;
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addr.sin_addr.s_addr = INADDR_ANY;
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addr.sin_port = htons(strtol(argv[3], 0, 10));
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if (bind(listen_sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
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fprintf(stderr, "bind() failed: %s\n", strerror(errno));
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return 1;
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}
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/* listen */
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if (listen(listen_sock, 5) == -1) {
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fprintf(stderr, "listen() failed: %s\n", strerror(errno));
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return 1;
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}
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/* wait for client connection */
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if ((client_sock = accept(listen_sock, (struct sockaddr *)&addr, &addrlen)) == -1) {
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fprintf(stderr, "accept() failed: %s\n", strerror(errno));
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return 1;
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}
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/* create server socket */
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if ((server_sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
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fprintf(stderr, "socket() failed: %s\n", strerror(errno));
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return 1;
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}
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/* bind */
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memset(&addr, 0, sizeof(addr));
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addr.sin_family = AF_INET;
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if (bind(server_sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
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fprintf(stderr, "bind() failed: %s\n", strerror(errno));
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return 1;
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}
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/* connect */
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memset(&addr, 0, sizeof(addr));
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if (inet_pton(AF_INET, argv[1], &addr.sin_addr) != 1) {
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fprintf(stderr, "inet_pton() failed: %s\n", strerror(errno));
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return 1;
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}
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addr.sin_family = AF_INET;
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addr.sin_port = htons(strtol(argv[2], 0, 10));
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if (connect(server_sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
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fprintf(stderr, "server() failed: %s\n", strerror(errno));
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return 1;
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}
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/* initialize telnet boxes */
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libtelnet_init(&server_telnet);
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libtelnet_init(&client_telnet);
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/* initialize poll descriptors */
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memset(pfd, 0, sizeof(pfd));
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pfd[0].fd = server_sock;
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pfd[0].events = POLLIN | POLLHUP;
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pfd[1].fd = client_sock;
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pfd[1].events = POLLIN | POLLHUP;
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/* loop while both connections are open */
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while (poll(pfd, 2, -1) != -1) {
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/* read from server */
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if (pfd[0].revents & POLLIN) {
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if ((rs = recv(pfd[0].fd, buffer, sizeof(buffer), 0)) > 0)
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libtelnet_push(&server_telnet, buffer, rs, (void*)&pfd[0].fd);
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}
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if (pfd[0].revents & POLLHUP)
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break;
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/* read from client */
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if (pfd[1].revents & POLLIN) {
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if ((rs = recv(pfd[1].fd, buffer, sizeof(buffer), 0)) > 0)
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libtelnet_push(&client_telnet, buffer, rs, (void*)&pfd[1].fd);
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}
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if (pfd[1].revents & POLLHUP)
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break;
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}
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/* clean up */
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libtelnet_free(&server_telnet);
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libtelnet_free(&client_telnet);
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close(server_sock);
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close(client_sock);
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close(listen_sock);
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return 0;
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}
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