construct/authd/dns.c

/* authd/dns.h - header for authd DNS functions
 * Copyright (c) 2016 William Pitcock <nenolod@dereferenced.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice is present in all copies.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "authd.h"
#include "dns.h"

static void
submit_dns_answer(void *userdata, struct DNSReply *reply)
{
	struct dns_request *req = userdata;
	char response[64] = "*";
	char status = 'E';

	if (reply == NULL)
	{
		rb_helper_write(authd_helper, "E %s E %c *\n", req->reqid, req->type);
		goto cleanup;
	}

	switch (req->type)
	{
	case '4':
		if (GET_SS_FAMILY(&reply->addr) == AF_INET)
		{
			status = 'O';
			rb_inet_ntop_sock((struct sockaddr *) &reply->addr, response, sizeof(response));
		}
		break;
#ifdef RB_IPV6
	case '6':
		if (GET_SS_FAMILY(&reply->addr) == AF_INET6)
		{
			char tmpres[63];
			rb_inet_ntop_sock((struct sockaddr *) &reply->addr, tmpres, sizeof(tmpres));

			if (*tmpres == ':')
			{
				rb_strlcpy(response, "0", sizeof(response));
				rb_strlcat(response, tmpres, sizeof(response));
			}
			else
				rb_strlcpy(response, tmpres, sizeof(response));

			status = 'O';
		}
		break;
#endif
	case 'R':
		{
			struct sockaddr_in *ip, *ip_fwd;
			ip = (struct sockaddr_in *) &req->addr;
			ip_fwd = (struct sockaddr_in *) &reply->addr;

			if(ip->sin_addr.s_addr == ip_fwd->sin_addr.s_addr && strlen(reply->h_name) < 63)
			{
				rb_strlcpy(response, reply->h_name, sizeof(response));
				status = 'O';
			}
		}
		break;
#ifdef RB_IPV6
	case 'S':
		{
			struct sockaddr_in6 *ip, *ip_fwd;
			ip = (struct sockaddr_in6 *) &req->addr;
			ip_fwd = (struct sockaddr_in6 *) &reply->addr;

			if(memcmp(&ip->sin6_addr, &ip_fwd->sin6_addr, sizeof(struct in6_addr)) == 0 && strlen(reply->h_name) < 63)
			{
				rb_strlcpy(response, reply->h_name, sizeof(response));
				status = 'O';
			}
		}
		break;
#endif
	default:
		exit(7);
	}

	rb_helper_write(authd_helper, "E %s %c %c %s\n", req->reqid, status, req->type, response);
cleanup:
	rb_free(req);
}

void
resolve_dns(int parc, char *parv[])
{
	struct dns_request *req;
	char *requestid = parv[1];
	char *qtype = parv[2];
	char *rec = parv[3];
	int type;

	req = rb_malloc(sizeof(*req));
	rb_strlcpy(req->reqid, requestid, sizeof(req->reqid));
	req->type = *qtype;

	switch (req->type)
	{
	case '4':
		type = T_A;
		break;
	case '6':
		type = T_AAAA;
		break;
	case 'R':
	case 'S':
		if(!rb_inet_pton_sock(rec, (struct sockaddr *) &req->addr))
			exit(6);
		type = T_PTR;
		break;
	}

	req->query.ptr = req;
	req->query.callback = submit_dns_answer;

	if (type != T_PTR)
		gethost_byname_type(rec, &req->query, type);
	else
		gethost_byaddr(&req->addr, &req->query);
}