jeena/moxanix
1
0
Fork 0
Code Issues Pull requests Projects Packages Wiki Activity Actions

Extract telnet functions into a separate header

Browse source
This commit is contained in:
Igor Socec 2016-11-18 22:42:29 +01:00
parent f1372827c1
commit c59b2138f4
4 changed files with 110 additions and 108 deletions
Download patch file Download diff file Expand all files Collapse all files

4
moxerver.c
View file

@ -193,7 +193,9 @@ int main(int argc, char *argv[]) {
continue;
}
/* put client in "character" mode */
telnet_set_character_mode(&client);
char msg[TELNET_MSG_SIZE_CHARMODE];
telnet_message_set_character_mode(msg);
client_write(&client, msg, TELNET_MSG_SIZE_CHARMODE);
}
/* setup parameters for select() */

29
moxerver.h
View file

@ -12,6 +12,8 @@
#include <termios.h>
#include <time.h>
#include <telnet.h>
#define DATABUF_LEN 128
#define DEV_PATH 128
#define TIMESTAMP_FORMAT "%Y-%m-%dT%H:%M:%S" /* ISO 8601 */
@ -159,34 +161,7 @@ int client_wait_line(client_t *client);
int client_ask_username(client_t *client);
/* Functions handling details related to telnet protocol. */
/**
* Tells client to go into "character" mode.
*
* Returns:
* - 0 on success
* - negative value if error occurred
*/
int telnet_set_character_mode(client_t *client);
/**
* Handles special characters in data buffer after receiving them from client.
* Used to filter out handshake commands of telnet protocol.
*
* Returns:
* 0 always
*/
int telnet_handle_client_read(char *databuf, int *datalen);
/**
* Handles special characters in data buffer before sending to client.
* Used for echoing characters correctly to telnet client.
*
* Returns:
* 0 always
*/
int telnet_handle_client_write(char *databuf, int *datalen);
/* Functions handling communication with tty device. */

160
telnet.c
View file

@ -1,8 +1,5 @@
/*
* Handling details related to telnet protocol.
*/
#include "moxerver.h"
#include <telnet.h>
#include <moxerver.h>
/* structure for holding telnet option name and value */
typedef struct
@ -12,7 +9,8 @@ typedef struct
} telnet_option_t;
/* supported telnet option values */
telnet_option_t telnet_options[] = {
telnet_option_t telnet_options[] =
{
{"WILL", 251},
{"WONT", 252},
{"DO", 253},
@ -25,118 +23,118 @@ telnet_option_t telnet_options[] = {
/* this list must end with {NULL, 0} */
};
/* Returns telnet option name based on the value. */
static const char* telnet_option_name(int value) {
int i = 0;
while (telnet_options[i].name) {
if (telnet_options[i].value == value) return telnet_options[i].name;
i++;
/* Returns the name of a telnet option based on the value. */
static const char* telnet_option_name(int value)
{
int i;
for (i = 0; telnet_options[i].name != NULL; i++)
{
if (telnet_options[i].value == value)
{
return telnet_options[i].name;
}
}
/* default value */
return '\0';
}
/* Returns telnet option value based on the name. */
static char telnet_option_value(const char* name) {
int i = 0;
while (telnet_options[i].name) {
if (!strcmp(telnet_options[i].name, name)) return telnet_options[i].value;
i++;
/* Returns the value of a telnet option based on the name. */
static char telnet_option_value(const char* name)
{
int i;
for (i = 0; telnet_options[i].name != NULL; i++)
{
if (strcmp(telnet_options[i].name, name) == 0)
{
return telnet_options[i].value;
}
}
/* default value */
return 0;
}
/* Sends telnet option command. Returns 0 on success, -1 on failure. */
static int telnet_send_command(client_t *client, const char* option, const char* command) {
char data[3];
/* pack command */
data[0] = telnet_option_value("IAC");
data[1] = telnet_option_value(option);
data[2] = telnet_option_value(command);
/* send command */
if (client_write(client, data, 3) <= 0) {
fprintf(stderr, "[%s:%d] failed sending %s %s\n", __func__, __LINE__, option, command);
return -1;
}
fprintf(stderr, "[%s] sent %s %s\n", __func__, option, command);
return 0;
}
/* Handles received telnet option command. Always returns 0.*/
static int telnet_handle_command(char *databuf, int datalen) {
/* currently just print received commands because we set the client, we don't adapt to client commands */
if (databuf[0] == telnet_option_value("IAC")) {
/* Handles a received telnet option command. */
static void telnet_handle_command(char *databuf, int datalen)
{
/* just print received commands:
* we set the client, we don't adapt to client commands */
if (databuf[0] == telnet_option_value("IAC"))
{
fprintf(stderr, "[%s] received %s %s\n", __func__,
telnet_option_name(databuf[1]), telnet_option_name(databuf[2]));
telnet_option_name(databuf[1]),
telnet_option_name(databuf[2]));
}
return 0;
}
/* Tells client to go into "character" mode. */
int telnet_set_character_mode(client_t *client) {
int err = 0;
/* send predefined commands and add up their return vaules */
err += telnet_send_command(client, "WILL", "ECHO");
err += telnet_send_command(client, "WILL", "SGA");
err += telnet_send_command(client, "WONT", "LINEMODE"); /* this depends on telnet client */
void telnet_message_set_character_mode(char *databuf)
{
/* send a predefined set of commands proven to work */
databuf[0] = telnet_option_value("IAC");
databuf[1] = telnet_option_value("WILL");
databuf[2] = telnet_option_value("ECHO");
databuf[3] = telnet_option_value("IAC");
databuf[4] = telnet_option_value("WILL");
databuf[5] = telnet_option_value("SGA");
/* this one really depends on telnet client */
databuf[6] = telnet_option_value("IAC");
databuf[7] = telnet_option_value("WONT");
databuf[8] = telnet_option_value("LINEMODE");
//TODO Do we verify client response? What do we do if the response is not how we expected?
return err;
}
/* Handles special characters in data buffer after receiving them from client.
* Used to filter out handshake commands of telnet protocol. */
int telnet_handle_client_read(char *databuf, int *datalen) {
void telnet_handle_client_read(char *databuf, int *datalen)
{
int i;
char newdata[DATABUF_LEN];
int newlen = 0;
/* process data using a new buffer */
for (i = 0; i < *datalen; i++) {
for (i = 0; i < *datalen; i++)
{
/* handle and discard telnet commands */
if (databuf[i] == telnet_option_value("IAC")) {
if (databuf[i] == telnet_option_value("IAC"))
{
telnet_handle_command((databuf+i), 3);
i += 2;
}
/* let other data pass through */
else {
else
{
newdata[newlen++] = databuf[i];
}
}
/* overwrite data with new buffer */
for (i = 0; i < newlen; i++) databuf[i] = newdata[i];
/* overwrite the data with the new buffer */
for (i = 0; i < newlen; i++)
{
databuf[i] = newdata[i];
}
/* update data length */
*datalen = newlen;
return 0;
}
/* Handles special characters in data buffer before sending to client.
* Used for echoing characters correctly to telnet client. */
int telnet_handle_client_write(char *databuf, int *datalen) {
void telnet_handle_client_write(char *databuf, int *datalen)
{
int i;
char newdata[DATABUF_LEN];
char newdata[DATABUF_LEN]; // TODO: maybe use realloc, this is risky
int newlen = 0;
/* process data using a new buffer */
for (i = 0; i < *datalen; i++) {
for (i = 0; i < *datalen; i++)
{
/* pressed ENTER */
if (databuf[i] == 13) {
if (databuf[i] == 13)
{
fprintf(stderr, "[%s] handling ENTER\n", __func__);
newdata[newlen++] = '\r';
newdata[newlen++] = '\n';
}
/* pressed BACKSPACE */
if (databuf[i] == 127) {
if (databuf[i] == 127)
{
fprintf(stderr, "[%s] handling BACKSPACE\n", __func__);
newdata[newlen++] = 8;
newdata[newlen++] = ' ';
@ -146,9 +144,11 @@ int telnet_handle_client_write(char *databuf, int *datalen) {
newdata[newlen++] = databuf[i];
}
}
/* overwrite data with new buffer */
for (i = 0; i < newlen; i++) databuf[i] = newdata[i];
/* overwrite the data with the new buffer */
for (i = 0; i < newlen; i++)
{
databuf[i] = newdata[i];
}
/* update data length */
*datalen = newlen;
return 0;
}

25
telnet.h Normal file
View file

@ -0,0 +1,25 @@
/* Handles details related to telnet protocol. */
#define TELNET_MSG_SIZE_CHARMODE 9
/**
* Creates a telnet protocol message that tells client to go into "character"
* mode. The passed data buffer must be big enough to hold the message payload
* with the size defined by TELNET_MSG_SIZE_CHARMODE.
* Operates directly on the passed data buffer.
*/
void telnet_message_set_character_mode(char *databuf);
/**
* Handles special characters in the data buffer after receiving them from the
* client. Used to filter out the handshake commands of telnet protocol.
* Operates directly on the passed data buffer and modifies the payload length.
*/
void telnet_handle_client_read(char *databuf, int *datalen);
/**
* Handles special characters in the data buffer before sending them to the
* client. Used to correctly echo the characters to the telnet client.
* Operates directly on the passed data buffer and modifies the payload length.
*/
void telnet_handle_client_write(char *databuf, int *datalen);