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/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
*
* All Rights Reserved
*
* 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, see <http://www.gnu.org/licenses/>.
*/
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <errno.h>
#include <osmocom/core/select.h>
#include <osmocom/gsm/gsm_utils.h>
#include <osmocom/hlr/logging.h>
#include <osmocom/mslookup/mdns.h>
#include <osmocom/mslookup/mdns_sock.h>
#include <osmocom/mslookup/mslookup_client.h>
#include <osmocom/mslookup/mslookup_client_mdns.h>
struct osmo_mdns_method_state {
/* Parameters passed by _add_method_dns() */
struct osmo_sockaddr_str bind_addr;
const char *domain_suffix;
struct osmo_mdns_sock *mc;
struct osmo_mslookup_client *client;
struct llist_head requests;
uint16_t next_packet_id;
};
struct osmo_mdns_method_request {
struct llist_head entry;
uint32_t request_handle;
struct osmo_mslookup_query query;
uint16_t packet_id;
};
static int request_handle_by_query(uint32_t *request_handle, struct osmo_mdns_method_state *state,
struct osmo_mslookup_query *query, uint16_t packet_id)
{
struct osmo_mdns_method_request *request;
llist_for_each_entry(request, &state->requests, entry) {
if (strcmp(request->query.service, query->service) != 0)
continue;
if (osmo_mslookup_id_cmp(&request->query.id, &query->id) != 0)
continue;
/* Match! */
*request_handle = request->request_handle;
return 0;
}
return -1;
}
static int mdns_method_recv(struct osmo_fd *osmo_fd, unsigned int what)
{
struct osmo_mdns_method_state *state = osmo_fd->data;
struct osmo_mslookup_result result;
struct osmo_mslookup_query query;
uint16_t packet_id;
int n;
uint8_t buffer[1024];
uint32_t request_handle = 0;
void *ctx = state;
n = read(osmo_fd->fd, buffer, sizeof(buffer));
if (n < 0) {
LOGP(DMSLOOKUP, LOGL_ERROR, "failed to read from socket\n");
return n;
}
if (osmo_mdns_result_decode(ctx, buffer, n, &packet_id, &query, &result, state->domain_suffix) < 0)
return -EINVAL;
if (request_handle_by_query(&request_handle, state, &query, packet_id) != 0)
return -EINVAL;
osmo_mslookup_client_rx_result(state->client, request_handle, &result);
return n;
}
static void mdns_method_request(struct osmo_mslookup_client_method *method, const struct osmo_mslookup_query *query,
uint32_t request_handle)
{
char buf[256];
struct osmo_mdns_method_state *state = method->priv;
struct msgb *msg;
struct osmo_mdns_method_request *r = talloc_zero(method->client, struct osmo_mdns_method_request);
*r = (struct osmo_mdns_method_request){
.request_handle = request_handle,
.query = *query,
.packet_id = state->next_packet_id,
};
llist_add(&r->entry, &state->requests);
state->next_packet_id++;
msg = osmo_mdns_query_encode(method->client, r->packet_id, query, state->domain_suffix);
if (!msg) {
LOGP(DMSLOOKUP, LOGL_ERROR, "Cannot encode request: %s\n",
osmo_mslookup_result_name_b(buf, sizeof(buf), query, NULL));
}
/* Send over the wire */
LOGP(DMSLOOKUP, LOGL_DEBUG, "sending mDNS query: %s.%s\n", query->service,
osmo_mslookup_id_name_b(buf, sizeof(buf), &query->id));
if (osmo_mdns_sock_send(state->mc, msg) == -1)
LOGP(DMSLOOKUP, LOGL_ERROR, "sending mDNS query failed\n");
}
static void mdns_method_request_cleanup(struct osmo_mslookup_client_method *method, uint32_t request_handle)
{
struct osmo_mdns_method_state *state = method->priv;
/* Tear down any state associated with this handle. */
struct osmo_mdns_method_request *r;
llist_for_each_entry(r, &state->requests, entry) {
if (r->request_handle != request_handle)
continue;
llist_del(&r->entry);
talloc_free(r);
return;
}
}
static void mdns_method_destruct(struct osmo_mslookup_client_method *method)
{
struct osmo_mdns_method_state *state = method->priv;
struct osmo_mdns_method_request *e, *n;
if (!state)
return;
/* Drop all DNS lookup request state. Triggering a timeout event and cleanup for mslookup client users will
* happen in the mslookup_client.c, we will simply stop responding from this lookup method. */
llist_for_each_entry_safe(e, n, &state->requests, entry) {
llist_del(&e->entry);
}
osmo_mdns_sock_cleanup(state->mc);
}
/*! Initialize the mDNS lookup method.
* \param[in] client the client to attach the method to.
* \param[in] ip IPv4 or IPv6 address string.
* \param[in] port The port to bind to.
* \param[in] initial_packet_id Used in the first mslookup query, then increased by one in each following query. All
* servers answer to each query with the same packet ID. Set to -1 to use a random
* initial ID (recommended unless you need deterministic output). This ID is for visually
* distinguishing the packets in packet sniffers, the mslookup client uses not just the
* ID, but all query parameters (service type, ID, ID type), to determine if a reply is
* relevant.
* \param[in] domain_suffix is appended to each domain in the queries to avoid colliding with the top-level domains
* administrated by IANA. Example: "mdns.osmocom.org" */
struct osmo_mslookup_client_method *osmo_mslookup_client_add_mdns(struct osmo_mslookup_client *client, const char *ip,
uint16_t port, int initial_packet_id,
const char *domain_suffix)
{
struct osmo_mdns_method_state *state;
struct osmo_mslookup_client_method *m;
m = talloc_zero(client, struct osmo_mslookup_client_method);
OSMO_ASSERT(m);
state = talloc_zero(m, struct osmo_mdns_method_state);
OSMO_ASSERT(state);
INIT_LLIST_HEAD(&state->requests);
if (osmo_sockaddr_str_from_str(&state->bind_addr, ip, port)) {
LOGP(DMSLOOKUP, LOGL_ERROR, "mslookup mDNS: invalid address/port: %s %u\n",
ip, port);
goto error_cleanup;
}
if (initial_packet_id == -1) {
if (osmo_get_rand_id((uint8_t *)&state->next_packet_id, 2) < 0) {
LOGP(DMSLOOKUP, LOGL_ERROR, "mslookup mDNS: failed to generate random initial packet ID\n");
goto error_cleanup;
}
} else
state->next_packet_id = initial_packet_id;
state->client = client;
state->domain_suffix = domain_suffix;
state->mc = osmo_mdns_sock_init(state, ip, port, mdns_method_recv, state, 0);
if (!state->mc)
goto error_cleanup;
*m = (struct osmo_mslookup_client_method){
.name = "mDNS",
.priv = state,
.request = mdns_method_request,
.request_cleanup = mdns_method_request_cleanup,
.destruct = mdns_method_destruct,
};
osmo_mslookup_client_method_add(client, m);
return m;
error_cleanup:
talloc_free(m);
return NULL;
}
const struct osmo_sockaddr_str *osmo_mslookup_client_method_mdns_get_bind_addr(struct osmo_mslookup_client_method *dns_method)
{
struct osmo_mdns_method_state *state;
if (!dns_method || !dns_method->priv)
return NULL;
state = dns_method->priv;
return &state->bind_addr;
}
const char *osmo_mslookup_client_method_mdns_get_domain_suffix(struct osmo_mslookup_client_method *dns_method)
{
struct osmo_mdns_method_state *state;
if (!dns_method || !dns_method->priv)
return NULL;
state = dns_method->priv;
return state->domain_suffix;
}
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