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#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <signal.h>
#include "dns.h"
#include "log.h"
#define PRINT_ERRNO() {printf("%s:%i %i:%s\n", __FILE__, __LINE__, errno, strerror(errno));}
#define UDP_BUFFER_LEN 512
//main server socket
int sock_server;
int handle_connection ( int _socket,
struct sockaddr_in *sockaddr_client,
socklen_t sockaddr_client_len,
char* _buffer,
int _bufflen );
void signal_term ( );
void signal_term_child ( );
void signal_child ( );
int test_main( int argc,
char* argv[] )
{
printf("TEST MODE. NOT FUNCTIONAL\n");
char in[128];
char out[128];
strncpy ( in, "sub.domain.example.com\0", 127);
printf("%s\n", in);
int written = fqdn_to_qname (in,128,out,128);
if (written < 0) {
printf("invallid fqdn\n");
return 1;
}
for(int i = 0; i < written; i++)
printf(" %x ", out[i]);
written = qname_to_fqdn (out,128,in,128);
if (written < 0) {
printf("invalid qname\n");
return 1;
}
printf("%s\n", in);
printf("\n\n");
return 0;
}
int main( int argc,
char* argv[] )
{
int ret;
struct sockaddr_in sock_server_addr;
char recv_buffer[ UDP_BUFFER_LEN ];
signal ( SIGTERM, signal_term );
signal ( SIGINT, signal_term );
//Avoid zombie processes
signal (SIGCHLD, SIG_IGN);
log_init_stdout ( _LOG_DEBUG );
sock_server = socket ( AF_INET, SOCK_DGRAM, 0 );
if ( sock_server == -1 ) {
LOGPRINTF(_LOG_ERROR, "socket() failed");
return errno;
}
memset( &sock_server_addr, '\0', sizeof(struct sockaddr_in) );
sock_server_addr.sin_family = AF_INET;
sock_server_addr.sin_port = htons( 53 );
ret = inet_aton ( "0.0.0.0", & sock_server_addr.sin_addr );
if( ret == 0 ) { //Error on 0, no errno!
LOGPRINTF(_LOG_NOTE, "inet_aton(): Invalid bind IP\n" );
return 1;
}
ret = bind ( sock_server,
(struct sockaddr*) &sock_server_addr,
sizeof(struct sockaddr_in) );
if ( ret == -1 ) {
LOGPRINTF(_LOG_ERROR, "bind() failed");
return errno;
}
while( 1 )
{
struct sockaddr_in sock_client_addr;
socklen_t sock_client_addr_len;
pid_t pid;
sock_client_addr_len = sizeof ( struct sockaddr_in );
memset ( &sock_client_addr, '\0', sock_client_addr_len );
ret = recvfrom (sock_server,
recv_buffer,
UDP_BUFFER_LEN,
0,
(struct sockaddr*) &sock_client_addr,
&sock_client_addr_len );
if ( ret == -1 ) {
LOGPRINTF( _LOG_ERROR, "recvfrom()");
return errno;
}
LOGPRINTF(_LOG_DEBUG, "UDP Packet size %i", ret);
if ( (pid = handle_connection (sock_server,
&sock_client_addr,
sock_client_addr_len,
recv_buffer,
ret ) ) ) {
LOGPRINTF(_LOG_ERROR, "handle_connection() failed");
return errno;
}
else {
LOGPRINTF ( _LOG_DEBUG, "forked " );
}
}
close( sock_server );
return 0;
}
int handle_connection ( int _socket,
struct sockaddr_in *sockaddr_client,
socklen_t sockaddr_client_len,
char* _buffer,
int _bufflen )
{
pid_t pid = fork();
if ( pid > 0)
return 0;
else if ( pid < 0 )
return errno;
//Change signal handler. signal_term shuts down entire socket on TERM
signal ( SIGTERM, signal_term_child );
//echo request
sendto (_socket, _buffer, _bufflen, 0, (struct sockaddr*) sockaddr_client, sockaddr_client_len);
//Testing recieved question
//TODO remove
char out[128];
qname_to_fqdn((_buffer+12), _bufflen-12, out, 128);
printf("%s\n", out);
struct dns_message msg;
if (dns_parse_packet (_buffer, _bufflen, &msg) ) {
LOGPRINTF (_LOG_DEBUG, "Malformed packet recieved. parsing failed");
close ( _socket );
exit( 1 );
}
exit ( 0 );
}
void signal_term ( ) {
printf( "Recieved Signal. Terminating active connections and closing socket\n" );
//terminate all children >:)
kill ( 0, SIGTERM );
shutdown ( sock_server, SHUT_RDWR );
close ( sock_server );
printf( "done\n" );
exit( 0 );
}
void signal_term_child ( ) {
close ( sock_server );
printf ( "%i: Active connection terminated\n", getpid() );
exit( 0 );
}
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