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force client into character mode

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This commit is contained in:
socec 2014-03-08 18:26:04 +01:00
parent b1b990d861
commit 9c6269218e
5 changed files with 200 additions and 16 deletions
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2
build.sh
View file

@ -7,6 +7,6 @@
name="moxerver"
include_dir="."
src_list="$name.c server.c client.c tty.c"
src_list="$name.c server.c client.c tty.c telnet.c"
gcc $src_list -o $name -I $include_dir

43
client.c
View file

@ -23,26 +23,49 @@ int client_read(struct client_t *client) {
fprintf(stderr, "[%s:%d] error %d: %s\n", __func__, __LINE__, errno, strerror(errno));
return -errno;
}
/* null-terminate received data */
client->data[len] = '\0';
//TODO how does a client disconnect? For now let's wait for QUIT command...
if (!strncmp(client->data, "QUIT", 4)) {
client_close(client);
//TODO let's print received bytes during development phase...
{
int i;
for(i = 0; i < len; i++) {
fprintf(stderr, "client %s <- %u '%c'\n",
client->ip_string,
(unsigned char) client->data[i],
(unsigned char) client->data[i]);
}
}
//TODO let's print the data during development phase...
fprintf(stderr, "client %s says: %s", client->ip_string, client->data);
/* handle special telnet characters coming from client */
telnet_handle_client_read(client->data, &len);
return 0;
return len;
}
/* Sends data from a buffer to client. */
int client_write(struct client_t *client, char *databuf, int datalen) {
int len;
/* handle special telnet characters to display them correctly on client */
telnet_handle_client_write(databuf, &datalen);
//TODO let's print received bytes during development phase...
{
int i;
for(i = 0; i < len; i++) {
fprintf(stderr, "client %s -> %u '%c'\n",
client->ip_string,
(unsigned char) databuf[i],
(unsigned char) databuf[i]);
}
}
/* send data to client */
if (send(client->socket, databuf, datalen, 0) == -1) {
len = send(client->socket, databuf, datalen, 0);
if (len == -1) {
fprintf(stderr, "[%s:%d] error %d: %s\n", __func__, __LINE__, errno, strerror(errno));
return -errno;
}
return 0;
return len;
}

15
moxerver.c
View file

@ -2,12 +2,12 @@
#include <unistd.h> /* getopt() */
#define SERVER_WAIT_TIMEOUT 5 /* seconds for select() timeout in server loop */
#define SERVER_WAIT_TIMEOUT 10 /* seconds for select() timeout in server loop */
#define PORT_MIN 4001 /* minimum TCP port number */
#define PORT_MAX 4008 /* maximum TCP port number */
/* Prints help message. */
void usage() {
static void usage() {
//TODO maybe some styling should be done
fprintf(stderr, "Usage: moxerver -p tcp_port -t tty_path [-h]\n");
fprintf(stderr, "- tcp_port range [%d .. %d]\n\n", PORT_MIN, PORT_MAX);
@ -82,7 +82,7 @@ int main(int argc, char *argv[]) {
//TODO this is a good place to create and start the TTY thread, use "tty_path" when opening device
/* loop with timeouts waiting for client connection */
/* loop with timeouts waiting for client connection and data*/
while (1) {
/* setup parameters for select() */
@ -114,6 +114,8 @@ int main(int argc, char *argv[]) {
fprintf(stderr, "problem accepting client\n");
continue;
}
/* put client in "character" mode */
telnet_set_character_mode(&client);
}
/* reject connection request if a client is already connected */
else {
@ -124,12 +126,15 @@ int main(int argc, char *argv[]) {
if ( (client.socket != -1) && FD_ISSET(client.socket, &read_fds) ) {
/* read client data */
ret = client_read(&client);
if ( ret != 0) {
if ( ret < 0) {
/* print error but continue waiting for new data */
fprintf(stderr, "problem reading client\n");
continue;
}
//TODO we should send this data to TTY device
/* echo back to client */
client_write(&client, client.data, ret);
//TODO we should send this data to TTY device here
}
}
if (ret == 0) {

11
moxerver.h
View file

@ -51,6 +51,14 @@ int client_read(struct client_t *client);
int client_write(struct client_t *client, char *databuf, int datalen);
/* Tells client to go into "character" mode. */
int telnet_set_character_mode(struct client_t *client);
/* Handles special characters in data buffer after receiving them from client. */
int telnet_handle_client_read(char *databuf, int *datalen);
/* Handles special characters in data buffer before sending to client. */
int telnet_handle_client_write(char *databuf, int *datalen);
/* Opens the tty device and configures it. */
int tty_open(struct tty_t *tty_dev, char* path);
/* Closes the tty device. */
@ -61,3 +69,6 @@ int tty_reconfigure(struct tty_t *tty_dev, struct termios newttyset);
int tty_read(struct tty_t *tty_dev);
/* Sends data from a buffer to tty device. */
int tty_write(struct tty_t *tty_dev, char *databuf, int datalen);

145
telnet.c Normal file
View file

@ -0,0 +1,145 @@
#include "moxerver.h"
/* structure for holding telnet option name and value */
struct telnet_option_t {
const char *name;
char value;
};
/* supported telnet option values */
struct telnet_option_t telnet_options[] = {
{"WILL", 251},
{"WONT", 252},
{"DO", 253},
{"DONT", 254},
{"IAC", 255},
{"ECHO", 1},
{"SGA", 3},
{"LINEMODE", 34},
{"SLE", 45}
};
#define TELNET_OPTIONS_COUNT 9 /* keep this up with the number of supported options */
/* Returns telnet option name based on the value. */
static const char* telnet_option_name(int value) {
int i;
for (i = 0; i < TELNET_OPTIONS_COUNT; i ++)
if (telnet_options[i].value == value)
return telnet_options[i].name;
return '\0';
}
/* Returns telnet option value based on the name. */
static char telnet_option_value(const char* name) {
int i;
for (i = 0; i < TELNET_OPTIONS_COUNT; i ++)
if (!strcmp(telnet_options[i].name, name))
return telnet_options[i].value;
return 0;
}
/* Sends telnet option command. */
int telnet_send_command(struct 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. */
int telnet_handle_command(char *databuf, int datalen) {
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]));
}
return 0;
}
/* Tells client to go into "character" mode. */
int telnet_set_character_mode(struct 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 */
//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. */
int telnet_handle_client_read(char *databuf, int *datalen) {
int i;
char newdata[DATA_BUFLEN];
int newlen = 0;
/* process data using a new buffer */
for (i = 0; i < *datalen; i++) {
/* handle and discard telnet commands */
if (databuf[i] == telnet_option_value("IAC")) {
telnet_handle_command((databuf+i), 3);
i += 2;
}
/* let other data pass through */
else {
newdata[newlen++] = databuf[i];
}
}
/* overwrite data with new buffer */
for (i = 0; i < newlen; i++) databuf[i] = newdata[i];
*datalen = newlen;
return 0;
}
/* Handles special characters in data buffer before sending to client. */
int telnet_handle_client_write(char *databuf, int *datalen) {
int i;
char newdata[DATA_BUFLEN];
int newlen = 0;
/* process data using a new buffer */
for (i = 0; i < *datalen; i++) {
/* pressed ENTER */
if (databuf[i] == 13) {
fprintf(stderr, "[%s]: handling ENTER\n", __func__);
newdata[newlen++] = '\r';
newdata[newlen++] = '\n';
}
/* pressed BACKSPACE */
if (databuf[i] == 127) {
fprintf(stderr, "[%s]: handling BACKSPACE\n", __func__);
newdata[newlen++] = 8;
newdata[newlen++] = ' ';
newdata[newlen++] = 8;
}
else {
newdata[newlen++] = databuf[i];
}
}
/* overwrite data with new buffer */
for (i = 0; i < newlen; i++) databuf[i] = newdata[i];
*datalen = newlen;
return 0;
}