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telnet.c
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telnet.c
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#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <complex.h>
#include <ctype.h>
#include <sys/time.h>
#include <unistd.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <pthread.h>
#include "sdr_ui.h"
void telnet_open(char *server);
int telnet_write(char *text);
void telnet_close();
static int telnet_sock = -1;
static pthread_t telnet_thread;
long get_address(char *host)
{
int i, dotcount=0;
char *p = host;
struct hostent *pent;
/* struct sockaddr_in addr; */ /* see the note on portabilit at the end of the routine */
/*try understanding if this is a valid ip address
we are skipping the values of the octets specified here.
for instance, this code will allow 952.0.320.567 through*/
while (*p)
{
for (i = 0; i < 3; i++, p++)
if (!isdigit(*p))
break;
if (*p != '.')
break;
p++;
dotcount++;
}
/* three dots with upto three digits in before, between and after ? */
if (dotcount == 3 && i > 0 && i <= 3)
return inet_addr(host);
/* try the system's own resolution mechanism for dns lookup:
required only for domain names.
inspite of what the rfc2543 :D Using SRV DNS Records recommends,
we are leaving it to the operating system to do the name caching.
this is an important implementational issue especially in the light
dynamic dns servers like dynip.com or dyndns.com where a dial
ip address is dynamically assigned a sub domain like farhan.dynip.com
although expensive, this is a must to allow OS to take
the decision to expire the DNS records as it deems fit.
*/
printf("Looking up %s\n", host);
pent = gethostbyname(host);
if (!pent){
printf("Failed to resolve %s\n", host);
return 0;
}
/* PORTABILITY-ISSUE: replacing a costly memcpy call with a hack, may not work on
some systems.
memcpy(&addr.sin_addr, (pent->h_addr), pent->h_length);
return addr.sin_addr.s_addr; */
return *((long *)(pent->h_addr));
}
/*
static int socket_ntp = -1;
#define NTP_PACKET_SIZE 48
void init_ntp_client(char *server){
struct sockaddr_storage serverStorage;
socklen_t addr_size;
struct sockaddr_in serverAddr;
char buff[200], host[100], port[7];
sprintf(buff, "Finding NTP server %s\n", server);
write_console(FONT_LOG, buff);
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(123);
serverAddr.sin_addr.s_addr = get_address(server);
socket_ntp = socket(AF_INET, SOCK_DGRAM, 0);
}
void query_ntp(char *server){
char packet[NTP_PACKET_SIZE];
packet[0] = 0b11100011; // LI, Version, Mode
packet[1] = 0; // Stratum, or type of clock
packet[2] = 6; // Polling Interval
packet[3] = 0xEC; // Peer Clock Precision
// 8 bytes of zero for Root Delay & Root Dispersion
packet[12] = 49;
packet[13] = 0x4E;
packet[14] = 49;
packet[15] = 52;
}
// returns the julian date of utc or -1
unsigned long poll_ntp(){
}
*/
void *telnet_thread_function(void *server){
struct sockaddr_storage serverStorage;
socklen_t addr_size;
struct sockaddr_in serverAddr;
char buff[200], host[100], port[7];
if (strlen(server) > sizeof(host) - 1)
return NULL;
int i;
char *p = server;
char *q = host;
for(i = 0; *p && *p != ':' && i < sizeof(host)-1; i++)
*q++ = *p++;
*q = 0;
q = port;
p++;
for(i = 0; *p && *p && i < sizeof(port)-1; i++)
*q++ = *p++;
*q = 0;
if(!strlen(host)){
write_console(FONT_TELNET, "Telnet : specify host and port\nex:'\topen dxc.g3lrs.org.uk:7300\n'");
return NULL;
}
if(!strlen(port)){
write_console(FONT_TELNET, "Telnet port is missing\n");
return NULL;
}
if (telnet_sock >= 0)
close(telnet_sock);
sprintf(buff, "Finding %s:%s\n", host, port);
write_console(FONT_TELNET, buff);
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(atoi(port));
serverAddr.sin_addr.s_addr = get_address(host);
sprintf(buff, "Opening %s:%s\n", host, port);
write_console(FONT_TELNET, buff);
telnet_sock = socket(AF_INET, SOCK_STREAM, 0);
if (connect(telnet_sock,
(struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0) {
printf("Telnet: failed to connect to %s\n", server);
write_console(FONT_TELNET, "Failed to open telnet, check hostname and port?\n");
close(telnet_sock);
telnet_sock = -1;
return NULL;
}
//send our callsign
char mycallsign[100];
get_field_value("#mycallsign", mycallsign);
telnet_write(mycallsign);
int e;
while((e = recv(telnet_sock, buff, sizeof(buff), 0)) >= 0){
if (e > 0){
buff[e] = 0;
//here we will try stripping too many spaces
char *p, *q, buff2[201]; // bigger than the original buff
int n_spaces = 0;
int tab_space = 3;
p = buff; q = buff2;
for (p = buff;*p;p++){
if (*p != ' '){
//add spaces for a shorter tab
if (n_spaces > tab_space){
int l = strlen(buff2);
int next_tab = (l/tab_space + 1)* tab_space;
for (int i = 0; i < next_tab - l; i++){
*q++ = ' ';
*q = 0;
}
}
*q++ = *p;
*q = 0;
n_spaces = 0;
}
else { // *p is a space
if (n_spaces < tab_space){
*q++ = *p;
*q = 0;
}
n_spaces++;
}
}
*q = 0;
// printf("compressed [%s] to [%s]\n", buff, buff2);
write_console(FONT_TELNET, buff2);
}
}
close(telnet_sock);
telnet_sock = -1;
}
int telnet_write(char *text){
if (telnet_sock < 0){
return -1;
}
char nl[] = "\n";
send (telnet_sock, text, strlen(text), 0);
send (telnet_sock, nl, strlen(nl), 0);
}
void telnet_close(){
puts("Telnet socket is closing");
close(telnet_sock);
telnet_sock = 0;
}
char telnet_server_name[100];
void telnet_open(char *server){
//close any existing telnet sessions
if (telnet_sock > 1){
close(telnet_sock);
telnet_sock = 0;
}
strcpy(telnet_server_name, server);
pthread_create( &telnet_thread, NULL, telnet_thread_function,
(void*)telnet_server_name);
}
/*
int main(int argc, char *argv[]){
telnet_open(argv[1]);
sleep(10);
telnet_write("vu2ese\n");
sleep(20);
telnet_close();
sleep(10);
}
*/