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/* Copyright (C) 2022 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
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 3 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, see <https://www.gnu.org/licenses/>.
*/
#include "knot/server/proxyv2.h"
#include "contrib/proxyv2/proxyv2.h"
#include "knot/conf/conf.h"
int proxyv2_header_strip(knot_pkt_t **query,
const struct sockaddr_storage *remote,
struct sockaddr_storage *new_remote)
{
conf_t *pconf = conf();
if (!pconf->cache.srv_proxy_enabled) {
return KNOT_EDENIED;
}
uint8_t *pkt = (*query)->wire;
size_t pkt_len = (*query)->max_size;
int offset = proxyv2_header_offset(pkt, pkt_len);
if (offset <= 0) {
return KNOT_EMALF;
}
/*
* Check if the query was sent from an IP address authorized to send
* proxied DNS traffic.
*/
conf_val_t whitelist_val = conf_get(pconf, C_SRV, C_PROXY_ALLOWLIST);
if (!conf_addr_range_match(&whitelist_val, remote)) {
return KNOT_EDENIED;
}
/*
* Store the provided remote address.
*/
int ret = proxyv2_addr_store(pkt, pkt_len, new_remote);
if (ret != KNOT_EOK) {
return ret;
}
/*
* Re-parse the query message using the data in the
* packet following the PROXY v2 payload. And replace the original
* query with the decapsulated one.
*/
knot_pkt_t *q = knot_pkt_new(pkt + offset, pkt_len - offset, &(*query)->mm);
if (q == NULL) {
return KNOT_ENOMEM;
}
knot_pkt_free(*query);
*query = q;
return knot_pkt_parse(q, 0);
}
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