diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/dns.c | 2 | ||||
| -rw-r--r-- | src/dns.h | 2 | ||||
| -rw-r--r-- | src/server.c | 143 | ||||
| -rw-r--r-- | src/server.h | 11 |
4 files changed, 91 insertions, 67 deletions
@@ -26,7 +26,7 @@ int dns_construct_header ( char* _buffer, int _bufflen, dns_header_t* _header ) *((uint16_t*)(_buffer + 8 )) = FLIP_BYTES(_header->authorative_count); *((uint16_t*)(_buffer + 10)) = FLIP_BYTES(_header->additional_count); - return 12; + return DNS_HEADER_LEN; } int dns_construct_answer ( @@ -71,6 +71,8 @@ enum dns_responsecode { REFUSED = 5 }; +#define DNS_HEADER_LEN 12 + #define FLIP_BYTES(u) (((0x00FF & u) << 8) | ((0xFF00 & u) >> 8)) /** diff --git a/src/server.c b/src/server.c index 8cd378a..7088dbe 100644 --- a/src/server.c +++ b/src/server.c @@ -7,7 +7,10 @@ void server_start ( server_config_t* _config ) { - char recv_buffer[ UDP_BUFFER_LEN ]; + fd_set sel_fds; + struct timeval sel_interval; + int sel_ret = 0; + database_t zone_db; signal ( SIGTERM, signal_term ); @@ -23,85 +26,107 @@ void server_start ( server_config_t* _config ) LOGPRINTF(_LOG_NOTE, "Done!"); while( 1 ) { - struct sockaddr_in sock_client_addr; - socklen_t sock_client_addr_len = sizeof( struct sockaddr_in ); - int recv_len = 0; - - memset ( &sock_client_addr, 0, sock_client_addr_len ); - - recv_len = recvfrom (sock_server, - recv_buffer, - UDP_BUFFER_LEN, - 0, - (struct sockaddr*) &sock_client_addr, - &sock_client_addr_len ); - if ( recv_len == -1 ) { - LOGPRINTF( _LOG_ERRNO, "recvfrom()"); - exit ( errno ); + FD_ZERO ( &sel_fds ); + FD_SET ( sock_server, &sel_fds ); + sel_interval.tv_sec = 0; + sel_interval.tv_usec = 10000; + + sel_ret = select( sock_server + 1, &sel_fds, NULL, NULL, &sel_interval ); + + if ( sel_ret < 0 ) { + LOGPRINTF( _LOG_ERRNO, "select()" ); + exit(1); + } else if ( sel_ret ) { + // A connection is available + DEBUG("Connection"); + server_handle_connection( sock_server, &zone_db ); } - - DEBUG("Packet size %i from %s:%i", recv_len, inet_ntoa(sock_client_addr.sin_addr), sock_client_addr.sin_port ); - - handle_connection ( sock_server, - &sock_client_addr, - sock_client_addr_len, - recv_buffer, - recv_len, - &zone_db ); } close( sock_server ); exit(0); } -int handle_connection ( int _socket, - struct sockaddr_in *sockaddr_client, - socklen_t sockaddr_client_len, - char* _buffer, - int _bufflen, - database_t* _zone_db ) { - dns_message_t msg; +void server_handle_connection ( int _socket, database_t* _zone_db ) { + char recv_buffer[ UDP_BUFFER_LEN ]; + int recv_len = 0; + + char answ_buffer[ UDP_BUFFER_LEN ]; + int answ_len = UDP_BUFFER_LEN; + int answ_cnt = DNS_HEADER_LEN; + // preload with header length, because it is written last. - if ( dns_parse_packet (_buffer, _bufflen, &msg) ) { + struct sockaddr_in sock_client_addr; + socklen_t sock_client_addr_len = sizeof( struct sockaddr_in ); + + dns_message_t dns_req; + dns_header_t answ_header; + + memset ( &sock_client_addr, 0, sock_client_addr_len ); + + recv_len = recvfrom ( _socket, recv_buffer, UDP_BUFFER_LEN, + 0, (struct sockaddr*) &sock_client_addr, + &sock_client_addr_len ); + + if ( recv_len == -1 ) { + LOGPRINTF( _LOG_ERRNO, "recvfrom()"); + exit ( 1 ); + } + + if ( dns_parse_packet( recv_buffer, recv_len, &dns_req ) ) { DEBUG("Malformed packet recieved. parsing failed"); - return 1; + // free? + return; } - if ( ! msg.question_count ) { + if ( ! dns_req.question_count ) { DEBUG("No questions in request."); - return 1; + goto end; } - if (msg.question_count > 0) { - char out[128]; - qname_to_fqdn( (char*) msg.question[0].qname, msg.question[0].qname_len, out, 128); - LOGPRINTF(_LOG_DEBUG, "Request for %s QTYPE %i", out, msg.question[0].qtype); - } + DEBUG("Valid data with %i question(s)", dns_req.question_count); - // Only handles first request - // TODO heavy refactoring. major POC vibe + memset ( &answ_header, 0, sizeof( dns_header_t ) ); - database_rdata_t rdata; - dns_question_t* quest = & msg.question[0]; + answ_header.id = dns_req.header.id; + answ_header.QR = 1; //Response + answ_header.AA = 1; + + // TODO test with artificially large rdata to exceed buffer + for (unsigned int i = 0; i < dns_req.question_count; i++) { + int cnt_inc = 0; + database_rdata_t db_rdata; + dns_question_t *quest = &dns_req.question[i]; + dns_answer_t dns_answ = {quest->qname, quest->qname_len, quest->qtype, quest->qclass, 0, 0, NULL }; - int db_ret = database_query( &rdata, _zone_db, quest->qname, quest->qname_len, quest->qtype, quest->qclass ); - if (db_ret) { - LOGPRINTF(_LOG_DEBUG, "DB Query exited with code %i", db_ret); - dns_destroy_struct ( &msg ); - return 1; - } - dns_header_t head = {msg.header.id,1,OP_QUERY,0,0,0,0,0,RCODE_NOERR,0,1,0,0}; - dns_answer_t answ = {quest->qname, quest->qname_len, RR_A, CL_IN, rdata.ttl, rdata.rdlen, rdata.rdata }; + if( database_query( &db_rdata, _zone_db, quest->qname, quest->qname_len, quest->qtype, quest->qclass ) ) { + answ_header.RCODE = RCODE_NAMEERR; + DEBUG("Could not answer question %i", i); + continue; + } + + dns_answ.rdlength = db_rdata.rdlen; + dns_answ.rdata = db_rdata.rdata; + dns_answ.ttl = db_rdata.ttl; + + cnt_inc += dns_construct_answer( &answ_buffer[answ_cnt], answ_len - answ_cnt, &dns_answ ); + + if (cnt_inc <= 0) { + LOGPRINTF(_LOG_ERROR, "dns_construct_answer() return <= 0"); + goto end; + } + + answ_cnt += cnt_inc; + answ_header.answer_count += 1; + } - char ret[512]; - int hlen = dns_construct_header ( ret, 512, &head ); - int alen = dns_construct_answer ( ret + hlen, 512-hlen, &answ ); - sendto( _socket, ret, hlen + alen, 0, (struct sockaddr*) sockaddr_client, sockaddr_client_len ); + dns_construct_header( answ_buffer, answ_len, &answ_header ); - dns_destroy_struct ( &msg ); + sendto( _socket, answ_buffer, answ_cnt, 0, (struct sockaddr*) &sock_client_addr, sock_client_addr_len ); - return 0; +end: + dns_destroy_struct ( &dns_req ); } int server_get_socket ( char* _bind_ip, uint16_t _bind_port ) { diff --git a/src/server.h b/src/server.h index 1751fae..d4ecf49 100644 --- a/src/server.h +++ b/src/server.h @@ -20,6 +20,8 @@ #include <signal.h> +#include <sys/select.h> + #include "dns.h" #include "log.h" #include "database.h" @@ -37,13 +39,8 @@ static int sock_server; void server_start ( server_config_t* _config ); -int server_get_socket ( char* _bind_ip, uint16_t _bind_port ); +void server_handle_connection ( int _socket, database_t* _zone_db ); -int handle_connection ( int _socket, - struct sockaddr_in *sockaddr_client, - socklen_t sockaddr_client_len, - char* _buffer, - int _bufflen, - database_t* _zone_db ); +int server_get_socket ( char* _bind_ip, uint16_t _bind_port ); void signal_term ( ); |