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