158 lines
4.2 KiB
C
158 lines
4.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netinet/tcp.h> /* TCP_NODELAY */
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#include <arpa/inet.h>
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#include <termios.h>
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#define DATA_BUFLEN 128
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#define DEV_PATH 32
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/* Structures used for communication parameters. */
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struct server_t {
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int socket; /* server socket */
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struct sockaddr_in address; /* server address information */
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unsigned int port; /* server port in host byte order, practical reference */
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};
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struct client_t {
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int socket; /* client socket */
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struct sockaddr_in address; /* client address information */
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char ip_string[INET_ADDRSTRLEN]; /* client IP address as a string */
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char data[DATA_BUFLEN]; /* buffer for data received from client */
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};
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struct tty_t {
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int fd; /* tty file descriptor */
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struct termios ttyset; /* tty termios settings */
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char path[DEV_PATH]; /* tty device path */
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char data[DATA_BUFLEN]; /* buffer for data received from tty */
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};
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/* Global variables used throughout the application. */
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struct server_t server; /* main server structure */
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struct client_t client; /* connected client structure */ //TODO working with only 1 client, this can be expanded into a list
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struct tty_t tty_dev; /* connected tty device */
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/* Functions handling server operation. */
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/**
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* Sets up the server on specific port, binds to a socket and listens for client connections.
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*
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* Returns:
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* - 0 on success,
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* - negative errno value set appropriately by error in setup process
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*/
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int server_setup(struct server_t *server, unsigned int port);
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/**
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* Closes the server socket.
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*
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* Returns:
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* 0 always, but internally tries closing again if it fails.
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*/
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int server_close(struct server_t *server);
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/**
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* Accepts incoming client connection.
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*
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* Returns:
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* - 0 on success,
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* - negative errno value set appropriately by error in setup process
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*/
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int server_accept(struct server_t *server, struct client_t *accepted_client);
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/**
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* Rejects incoming client connection.
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*
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* Returns:
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* 0 always, errors with rejected client are ignored
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*/
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int server_reject(struct server_t *server);
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/* Functions handling communication with clients. */
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/**
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* Closes client connection.
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*
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* Returns:
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* 0 always, but internally tries closing again if it fails.
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*/
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int client_close(struct client_t *client);
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/**
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* Reads data from client into client data buffer.
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*
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* Returns:
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* - number of read bytes on success,
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* - negative ENODATA value (-ENODATA) if client disconnected,
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* - negative errno value set appropriately by error in reading
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*/
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int client_read(struct client_t *client);
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/**
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* Sends data from a buffer to client.
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*
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* Returns:
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* - number of sent bytes on success,
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* - negative errno value set appropriately by error in sending
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*/
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int client_write(struct client_t *client, char *databuf, int datalen);
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/* Functions handling details related to telnet protocol. */
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/**
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* Tells client to go into "character" mode.
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*
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* Returns:
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* - 0 on success
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* - negative value if error occurred
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*/
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int telnet_set_character_mode(struct client_t *client);
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/**
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* Handles special characters in data buffer after receiving them from client.
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* Used to filter out handshake commands of telnet protocol.
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*
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* Returns:
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* 0 always
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*/
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int telnet_handle_client_read(char *databuf, int *datalen);
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/**
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* Handles special characters in data buffer before sending to client.
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* Used for echoing characters correctly to telnet client.
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*
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* Returns:
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* 0 always
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*/
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int telnet_handle_client_write(char *databuf, int *datalen);
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/* Functions handling communication with tty device. */
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/* Opens the tty device and configures it. */
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int tty_open(struct tty_t *tty_dev);
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/* Closes the tty device. */
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int tty_close(struct tty_t *tty_dev);
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/* Reconfigures the tty device. */
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int tty_reconfigure(struct tty_t *tty_dev, struct termios newttyset);
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/* Reads incoming data from tty device to tty data buffer. */
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int tty_read(struct tty_t *tty_dev);
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/* Sends data from a buffer to tty device. */
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int tty_write(struct tty_t *tty_dev, char *databuf, int datalen);
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/* Main tty thread function */
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void *tty_thread_func(void *arg);
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