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/*
* ldnsd. Light-weight DNS daemon
*
* Tiny dns server to show how a real one could be built.
*
* (c) NLnet Labs, 2005
* See the file LICENSE for the license
*/
#include "config.h"
#include <ldns/ldns.h>
#ifdef HAVE_SYS_SOCKET_H
# include <sys/socket.h>
#endif
#ifdef HAVE_ARPA_INET_H
# include <arpa/inet.h>
#endif
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#ifdef HAVE_NETINET_UDP_H
# include <netinet/udp.h>
#endif
#ifdef HAVE_NETINET_IGMP_H
# include <netinet/igmp.h>
#endif
#include <errno.h>
#define INBUF_SIZE 4096
static void usage(FILE *output)
{
fprintf(output, "Usage: ldnsd <address> <port> <zone> <zonefile>\n");
fprintf(output, "Listens on the specified port and answers queries for the given zone\n");
fprintf(output, "This is NOT a full-fledged authoritative nameserver!\n");
}
static int udp_bind(int sock, int port, const char *my_address)
{
struct sockaddr_in addr;
in_addr_t maddr = INADDR_ANY;
if (my_address) {
#ifdef AF_INET6
if (inet_pton(AF_INET6, my_address, &maddr) < 1) {
#else
if (0) {
#endif
if (inet_pton(AF_INET, my_address, &maddr) < 1) {
return -2;
}
}
}
#ifndef S_SPLINT_S
addr.sin_family = AF_INET;
#endif
addr.sin_port = (in_port_t) htons((uint16_t)port);
addr.sin_addr.s_addr = maddr;
return bind(sock, (struct sockaddr *)&addr, (socklen_t) sizeof(addr));
}
/* this will probably be moved to a better place in the library itself */
static ldns_rr_list *
get_rrset(const ldns_zone *zone, const ldns_rdf *owner_name, const ldns_rr_type qtype, const ldns_rr_class qclass)
{
uint16_t i;
ldns_rr_list *rrlist = ldns_rr_list_new();
ldns_rr *cur_rr;
if (!zone || !owner_name) {
fprintf(stderr, "Warning: get_rrset called with NULL zone or owner name\n");
return rrlist;
}
for (i = 0; i < ldns_zone_rr_count(zone); i++) {
cur_rr = ldns_rr_list_rr(ldns_zone_rrs(zone), i);
if (ldns_dname_compare(ldns_rr_owner(cur_rr), owner_name) == 0 &&
ldns_rr_get_class(cur_rr) == qclass &&
ldns_rr_get_type(cur_rr) == qtype
) {
ldns_rr_list_push_rr(rrlist, ldns_rr_clone(cur_rr));
}
}
printf("Found rrset of %u rrs\n", (unsigned int) ldns_rr_list_rr_count(rrlist));
return rrlist;
}
int
main(int argc, char **argv)
{
/* arguments */
int port;
const char *zone_file;
/* network */
int sock;
ssize_t nb;
struct sockaddr addr_me;
struct sockaddr addr_him;
socklen_t hislen = (socklen_t) sizeof(addr_him);
uint8_t inbuf[INBUF_SIZE];
uint8_t *outbuf;
/* dns */
ldns_status status;
ldns_pkt *query_pkt;
ldns_pkt *answer_pkt;
size_t answer_size;
ldns_rr *query_rr;
ldns_rr_list *answer_qr;
ldns_rr_list *answer_an;
ldns_rr_list *answer_ns;
ldns_rr_list *answer_ad;
ldns_rdf *origin = NULL;
/* zone */
ldns_zone *zone;
int line_nr;
FILE *zone_fp;
/* use this to listen on specified interfaces later? */
char *my_address = NULL;
if (argc < 5) {
usage(stderr);
exit(EXIT_FAILURE);
} else {
my_address = argv[1];
port = atoi(argv[2]);
if (port < 1) {
usage(stderr);
exit(EXIT_FAILURE);
}
if (ldns_str2rdf_dname(&origin, argv[3]) != LDNS_STATUS_OK) {
fprintf(stderr, "Bad origin, not a correct domain name\n");
usage(stderr);
exit(EXIT_FAILURE);
}
zone_file = argv[4];
}
printf("Reading zone file %s\n", zone_file);
zone_fp = fopen(zone_file, "r");
if (!zone_fp) {
fprintf(stderr, "Unable to open %s: %s\n", zone_file, strerror(errno));
exit(EXIT_FAILURE);
}
line_nr = 0;
status = ldns_zone_new_frm_fp_l(&zone, zone_fp, origin, 0, LDNS_RR_CLASS_IN, &line_nr);
if (status != LDNS_STATUS_OK) {
printf("Zone reader failed, aborting\n");
exit(EXIT_FAILURE);
} else {
printf("Read %u resource records in zone file\n", (unsigned int) ldns_zone_rr_count(zone));
}
fclose(zone_fp);
printf("Listening on port %d\n", port);
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
fprintf(stderr, "%s: socket(): %s\n", argv[0], strerror(errno));
exit(1);
}
memset(&addr_me, 0, sizeof(addr_me));
/* bind: try all ports in that range */
if (udp_bind(sock, port, my_address)) {
fprintf(stderr, "%s: cannot bind(): %s\n", argv[0], strerror(errno));
exit(errno);
}
/* Done. Now receive */
while (1) {
nb = recvfrom(sock, (void*)inbuf, INBUF_SIZE, 0,
&addr_him, &hislen);
if (nb < 1) {
fprintf(stderr, "%s: recvfrom(): %s\n",
argv[0], strerror(errno));
exit(1);
}
/*
show(inbuf, nb, nn, hp, sp, ip, bp);
*/
printf("Got query of %u bytes\n", (unsigned int) nb);
status = ldns_wire2pkt(&query_pkt, inbuf, (size_t) nb);
if (status != LDNS_STATUS_OK) {
printf("Got bad packet: %s\n", ldns_get_errorstr_by_id(status));
} else {
ldns_pkt_print(stdout, query_pkt);
}
query_rr = ldns_rr_list_rr(ldns_pkt_question(query_pkt), 0);
printf("QUERY RR: \n");
ldns_rr_print(stdout, query_rr);
answer_qr = ldns_rr_list_new();
ldns_rr_list_push_rr(answer_qr, ldns_rr_clone(query_rr));
answer_an = get_rrset(zone, ldns_rr_owner(query_rr), ldns_rr_get_type(query_rr), ldns_rr_get_class(query_rr));
answer_pkt = ldns_pkt_new();
answer_ns = ldns_rr_list_new();
answer_ad = ldns_rr_list_new();
ldns_pkt_set_qr(answer_pkt, 1);
ldns_pkt_set_aa(answer_pkt, 1);
ldns_pkt_set_id(answer_pkt, ldns_pkt_id(query_pkt));
ldns_pkt_push_rr_list(answer_pkt, LDNS_SECTION_QUESTION, answer_qr);
ldns_pkt_push_rr_list(answer_pkt, LDNS_SECTION_ANSWER, answer_an);
ldns_pkt_push_rr_list(answer_pkt, LDNS_SECTION_AUTHORITY, answer_ns);
ldns_pkt_push_rr_list(answer_pkt, LDNS_SECTION_ADDITIONAL, answer_ad);
status = ldns_pkt2wire(&outbuf, answer_pkt, &answer_size);
printf("Answer packet size: %u bytes.\n", (unsigned int) answer_size);
if (status != LDNS_STATUS_OK) {
printf("Error creating answer: %s\n", ldns_get_errorstr_by_id(status));
} else {
nb = sendto(sock, (void*)outbuf, answer_size, 0,
&addr_him, hislen);
}
ldns_pkt_free(query_pkt);
ldns_pkt_free(answer_pkt);
LDNS_FREE(outbuf);
ldns_rr_list_free(answer_qr);
ldns_rr_list_free(answer_an);
ldns_rr_list_free(answer_ns);
ldns_rr_list_free(answer_ad);
}
/* No cleanup because of the infinite loop
*
* ldns_rdf_deep_free(origin);
* ldns_zone_deep_free(zone);
* return 0;
*/
}
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