mongoose/examples/captive_dns_server/captive_dns_server.c
Deomid Ryabkov 083d398631 Only copy questions when creating reply
In particular, there may be additional records which should not be copied

PUBLISHED_FROM=6b348868cb62d7b3fc4df0e935ffd5a31a314a08
2016-04-19 12:27:48 +01:00

92 lines
2.3 KiB
C

/*
* Copyright (c) 2014 Cesanta Software Limited
* All rights reserved
*/
/*
* Try it out with:
* $ dig -t A www.google.com -4 @localhost -p 5533
*/
#include "../../mongoose.h"
#include <stdio.h>
static int s_exit_flag = 0;
static in_addr_t s_our_ip_addr;
static const char *s_listening_addr = "udp://:5533";
static void ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
struct mg_dns_message *msg;
struct mg_dns_resource_record *rr;
struct mg_dns_reply reply;
int i;
switch (ev) {
case MG_DNS_MESSAGE: {
struct mbuf reply_buf;
mbuf_init(&reply_buf, 512);
msg = (struct mg_dns_message *) ev_data;
reply = mg_dns_create_reply(&reply_buf, msg);
for (i = 0; i < msg->num_questions; i++) {
char rname[256];
rr = &msg->questions[i];
mg_dns_uncompress_name(msg, &rr->name, rname, sizeof(rname) - 1);
LOG(LL_INFO, ("Q type %d name %s", rr->rtype, rname));
if (rr->rtype == MG_DNS_A_RECORD) {
mg_dns_reply_record(&reply, rr, NULL, rr->rtype, 10, &s_our_ip_addr,
4);
}
}
/*
* We don't set the error flag even if there were no answers
* matching the MG_DNS_A_RECORD query type.
* This indicates that we have (synthetic) answers for MG_DNS_A_RECORD.
* See http://goo.gl/QWvufr for a distinction between NXDOMAIN and NODATA.
*/
mg_dns_send_reply(nc, &reply);
nc->flags |= MG_F_SEND_AND_CLOSE;
mbuf_free(&reply_buf);
break;
}
}
}
int main(int argc, char *argv[]) {
struct mg_mgr mgr;
struct mg_connection *nc;
int i;
mg_mgr_init(&mgr, NULL);
s_our_ip_addr = inet_addr("127.0.0.1");
cs_log_set_level(LL_INFO);
/* Parse command line arguments */
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-D") == 0) {
mgr.hexdump_file = argv[++i];
} else if (strcmp(argv[i], "-l") == 0 && i + 1 < argc) {
s_listening_addr = argv[++i];
} else {
s_our_ip_addr = inet_addr(argv[i]);
}
}
fprintf(stderr, "Listening on '%s'\n", s_listening_addr);
if ((nc = mg_bind(&mgr, s_listening_addr, ev_handler)) == NULL) {
fprintf(stderr, "cannot bind to socket\n");
exit(1);
}
mg_set_protocol_dns(nc);
while (s_exit_flag == 0) {
mg_mgr_poll(&mgr, 1000);
}
mg_mgr_free(&mgr);
return 0;
}