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/*
** Copyright (C) 2006 Olivier DEMBOUR
** $Id: rr.c,v 1.6.4.3 2010/01/20 16:09:07 collignon Exp $
**
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with This program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "list.h"
#include "dns.h"
#include "server.h"
#include "rr.h"
#include "requests.h"
#include "dns.h"
#include "debug.h"
#include <string.h>
static const t_rr_functions rr_function[] = {
{ TYPE_TXT, TYPE_TXT, &rr_add_reply_encode, 0, &rr_get_reply_length_encode},
{ TYPE_KEY, TYPE_KEY, &rr_add_reply_raw, 0, &rr_get_reply_length_raw},
// { TYPE_A, TYPE_CNAME, &rr_add_reply_cname, 0, &rr_get_reply_length_cname},
// { TYPE_NS, TYPE_NS, 0, 0, 0},
// {TYPE_SIG, TYPE_SIG, &rr_add_reply_raw, 0, &rr_get_reply_length_raw},
{0,0,0,0}
};
static void *rr_add_data(struct dns_hdr *, void *, uint16_t, char *, uint16_t);
/**
* @brief get functions pointer for decoding data
* @param[in] request type
* @retval functions pointer
**/
const t_rr_functions *get_rr_function_by_type(uint16_t type)
{
int i = 0;
while (rr_function[i].type
&& (rr_function[i].type != type))
i++;
return (rr_function[i].type ? &rr_function[i] : 0);
}
/**
* @brief add a answer in the DNS request
* @param[in] hdr DNS header
* @param[in] where memory to write
* @param[in] type type of request (TXT, KEY ...)
* @param[in] encoded_data data to put
* @param[in] what compress pointer to the subdomain or 0
* @retval rr header
**/
static void *rr_add_data(struct dns_hdr *hdr, void *where, uint16_t type, char *encoded_data, uint16_t what)
{
struct rr_hdr *rr;
PUT_16(&hdr->ancount, GET_16(&hdr->ancount)+1);
hdr->arcount = 0;
if (!what) /* std compression */
PUT_16(where, sizeof(struct dns_hdr) | COMPRESS_FLAG);
else
PUT_16(where, what | COMPRESS_FLAG);
rr = where + sizeof(uint16_t);
PUT_16(&rr->type, type);
PUT_16(&rr->klass, CLASS_IN);
PUT_32(&rr->ttl, 3);
if (encoded_data)
{
JUMP_RR_HDR(rr)[0] = 'A' + GET_16(&hdr->ancount)-1;
strcpy(JUMP_RR_HDR(rr)+1, encoded_data);
}
else /* fake IP adress */
{
PUT_16(&rr->rdlength,4);
strcpy(JUMP_RR_HDR(rr), "AAAA");
}
return (rr);
}
/**
* @brief add data as a CNAME no available
**/
void *rr_add_reply_cname(t_conf *conf, t_request *req, struct dns_hdr *hdr, void *where, char *encoded_data)
{
struct rr_hdr *rr;
int len;
char domain[MAX_EDNS_LEN];
char *my_domain;
/* TODO : should avoid the strcpy each time */
strncpy(domain, req->domain, sizeof(domain));
dns_encode(domain);
my_domain = strstr((char *) (hdr+1), domain);
rr = rr_add_data(hdr, where, req->reply_functions->reply_type , encoded_data, 0);
where = JUMP_RR_HDR(rr);
dns_encode(where);
len = strlen(where);
((char *)where)[len] = COMPRESS_FLAG_CHAR; /* add domain name */
((char *)where)[len+1] = (uint16_t) (my_domain - (char *)hdr);
PUT_16(&rr->rdlength,len + 2);
/* Add fake entry CNAME is at x.x.x.x */
rr = rr_add_data(hdr, where+len+2, TYPE_A, 0, JUMP_RR_HDR(rr) - (char *)hdr);
where = JUMP_RR_HDR(rr);
// PUT_16(&rr->type, TYPE_A);
len = strlen(where);
return (where + len);
}
/**
* @brief add data and dns_encode it
* @param[in] conf configuration
* @param[in] req request received
* @param[in] hdr DNS header
* @param[in] where memory address
* @param[in] encoded_data data encoded in base64
**/
void *rr_add_reply_encode(t_conf *conf, t_request *req, struct dns_hdr *hdr, void *where, char *encoded_data)
{
struct rr_hdr *rr;
int len;
rr = rr_add_data(hdr, where, req->reply_functions->reply_type, encoded_data, 0);
where = JUMP_RR_HDR(rr);
dns_encode(where);
len = strlen(where) + 1; /* len + byte 0 (label data) */
PUT_16(&rr->rdlength,len);
return (where + len);
}
/**
* @brief add data but don't dns_encode it
* @param[in] conf configuration
* @param[in] req request received
* @param[in] hdr DNS header
* @param[in] where memory address
* @param[in] encoded_data data encoded in base64
**/
void *rr_add_reply_raw(t_conf *conf, t_request *req, struct dns_hdr *hdr,
void *where, char *encoded_data)
{
struct rr_hdr *rr;
int len;
rr = rr_add_data(hdr, where, req->reply_functions->reply_type, encoded_data, 0);
where =JUMP_RR_HDR(rr);
len = strlen(where);
PUT_16(&rr->rdlength,len);
return (where + len);
}
int rr_get_reply_length_cname(struct dns_hdr *hdr, t_simple_list *client, int query_len)
{
/*
*/
return (0);
}
/**
* @brief check available length left before being encoded
* @param[in] client client
* @param[in] query_len query len
* @retval len available
**/
int rr_get_reply_length_encode(struct dns_hdr *hdr, t_simple_list *client, int query_len)
{
void *end_query;
int len;
int total_query_len;
if (!(end_query = jump_end_answer(hdr, query_len)))
return (0);
total_query_len = (int) (end_query - (void *)hdr);
len = (ENCODE_DATA_AVAILABLE(total_query_len,
strlen(JUMP_DNS_HDR(hdr)), MAX_DNS_LEN));
if ((len > 0) && (len > PACKET_LEN + 2))
/* IDX + EOL = 2 bytes */
len -= (PACKET_LEN + 2);
else
len = 0;
if (client && client->control.mtu_size)
len = MIN(DECODED_LEN(client->control.mtu_size), len);
DPRINTF(3, "%s return %d\n", __FUNCTION__, len);
return (len);
}
/**
* @brief check available length left for raw data
* @param[in] client client
* @param[in] query_len query len
* @retval len available
**/
int rr_get_reply_length_raw(struct dns_hdr *hdr, t_simple_list *client, int query_len)
{
char *end_query;
int len;
int total_query_len;
if (!(end_query = jump_end_answer(hdr, query_len)))
return (0);
total_query_len = (int) (end_query - (char *)hdr);
len = (RAW_DATA_AVAILABLE(total_query_len,
strlen(JUMP_DNS_HDR(hdr)), MAX_DNS_LEN));
if ((len > 0) && (len > PACKET_LEN + 2))
/* IDX + EOL = 2 bytes */
len -= (PACKET_LEN + 2);
else
len = 0;
/* max mtu ? */
if (client && client->control.mtu_size)
len = MIN(client->control.mtu_size, len);
DPRINTF(3, "%s return %d\n", __FUNCTION__, len);
return (len);
}
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