owntone-server/src/remote_pairing.c
ejurgensen 03513c56a8 [mdns] Simplify avahi implementation, e.g. drop record browser
- record browser and link level filtering doesn't seem required (I may regret this...)
- fix cast.c so it does not browse for ipv6 when disabled
2016-10-15 19:12:56 +02:00

995 lines
20 KiB
C

/*
* Copyright (C) 2010 Julien BLACHE <jb@jblache.org>
*
* iTunes - Remote pairing hash function published by Michael Paul Bailey
* <http://jinxidoru.blogspot.com/2009/06/itunes-remote-pairing-code.html>
* Simplified version using standard MD5 published by Jeff Sharkey
* <http://jsharkey.org/blog/2009/06/21/itunes-dacp-pairing-hash-is-broken/>
*
* Pairing process based on the work by
* - Michael Croes
* <http://blog.mycroes.nl/2008/08/pairing-itunes-remote-app-with-your-own.html>
* - Jeffrey Sharkey
* <http://dacp.jsharkey.org/>
*
* 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
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <stdint.h>
#include <inttypes.h>
#include <errno.h>
#include <pthread.h>
#if defined(HAVE_SYS_EVENTFD_H) && defined(HAVE_EVENTFD)
# define USE_EVENTFD
# include <sys/eventfd.h>
#endif
#include <event2/event.h>
#include <event2/buffer.h>
#include <event2/http.h>
#include <gcrypt.h>
#include "logger.h"
#include "conffile.h"
#include "mdns.h"
#include "misc.h"
#include "db.h"
#include "remote_pairing.h"
struct remote_info {
struct pairing_info pi;
char *paircode;
char *pin;
unsigned short v4_port;
unsigned short v6_port;
char *v4_address;
char *v6_address;
struct evhttp_connection *evcon;
struct remote_info *next;
};
/* Main event base, from main.c */
extern struct event_base *evbase_main;
#ifdef USE_EVENTFD
static int pairing_efd;
#else
static int pairing_pipe[2];
#endif
static struct event *pairingev;
static pthread_mutex_t remote_lck = PTHREAD_MUTEX_INITIALIZER;
static struct remote_info *remote_list;
/* iTunes - Remote pairing hash */
static char *
itunes_pairing_hash(char *paircode, char *pin)
{
char hash[33];
char ebuf[64];
uint8_t *hash_bytes;
size_t hashlen;
gcry_md_hd_t hd;
gpg_error_t gc_err;
int i;
if (strlen(paircode) != 16)
{
DPRINTF(E_LOG, L_REMOTE, "Paircode length != 16, cannot compute pairing hash\n");
return NULL;
}
if (strlen(pin) != 4)
{
DPRINTF(E_LOG, L_REMOTE, "Pin length != 4, cannot compute pairing hash\n");
return NULL;
}
gc_err = gcry_md_open(&hd, GCRY_MD_MD5, 0);
if (gc_err != GPG_ERR_NO_ERROR)
{
gpg_strerror_r(gc_err, ebuf, sizeof(ebuf));
DPRINTF(E_LOG, L_REMOTE, "Could not open MD5: %s\n", ebuf);
return NULL;
}
gcry_md_write(hd, paircode, 16);
/* Add pin code characters on 16 bits - remember Mac OS X is
* all UTF-16 (wchar_t).
*/
for (i = 0; i < 4; i++)
{
gcry_md_write(hd, pin + i, 1);
gcry_md_write(hd, "\0", 1);
}
hash_bytes = gcry_md_read(hd, GCRY_MD_MD5);
if (!hash_bytes)
{
DPRINTF(E_LOG, L_REMOTE, "Could not read MD5 hash\n");
return NULL;
}
hashlen = gcry_md_get_algo_dlen(GCRY_MD_MD5);
for (i = 0; i < hashlen; i++)
sprintf(hash + (2 * i), "%02X", hash_bytes[i]);
gcry_md_close(hd);
return strdup(hash);
}
/* Operations on the remote list must happen
* with the list lock held by the caller
*/
static struct remote_info *
add_remote(void)
{
struct remote_info *ri;
ri = (struct remote_info *)malloc(sizeof(struct remote_info));
if (!ri)
{
DPRINTF(E_WARN, L_REMOTE, "Out of memory for struct remote_info\n");
return NULL;
}
memset(ri, 0, sizeof(struct remote_info));
ri->next = remote_list;
remote_list = ri;
return ri;
}
static void
unlink_remote(struct remote_info *ri)
{
struct remote_info *p;
if (ri == remote_list)
remote_list = ri->next;
else
{
for (p = remote_list; p && (p->next != ri); p = p->next)
; /* EMPTY */
if (!p)
{
DPRINTF(E_LOG, L_REMOTE, "WARNING: struct remote_info not found in list; BUG!\n");
return;
}
p->next = ri->next;
}
}
static void
free_remote(struct remote_info *ri)
{
if (ri->paircode)
free(ri->paircode);
if (ri->pin)
free(ri->pin);
if (ri->v4_address)
free(ri->v4_address);
if (ri->v6_address)
free(ri->v6_address);
free_pi(&ri->pi, 1);
free(ri);
}
static void
remove_remote(struct remote_info *ri)
{
unlink_remote(ri);
free_remote(ri);
}
static void
remove_remote_address_byid(const char *id, int family)
{
struct remote_info *ri;
for (ri = remote_list; ri; ri = ri->next)
{
if (!ri->pi.remote_id)
continue;
if (strcmp(ri->pi.remote_id, id) == 0)
break;
}
if (!ri)
{
DPRINTF(E_WARN, L_REMOTE, "Remote %s not found in list\n", id);
return;
}
switch (family)
{
case AF_INET:
if (ri->v4_address)
{
free(ri->v4_address);
ri->v4_address = NULL;
}
break;
case AF_INET6:
if (ri->v6_address)
{
free(ri->v6_address);
ri->v6_address = NULL;
}
break;
}
if (!ri->v4_address && !ri->v6_address)
remove_remote(ri);
}
static int
add_remote_mdns_data(const char *id, int family, const char *address, int port, char *name, char *paircode)
{
struct remote_info *ri;
char *check_addr;
int ret;
for (ri = remote_list; ri; ri = ri->next)
{
if (!ri->pi.remote_id)
continue;
if (strcmp(ri->pi.remote_id, id) == 0)
break;
}
if (!ri)
{
DPRINTF(E_DBG, L_REMOTE, "Remote id %s not known, adding\n", id);
ri = add_remote();
if (!ri)
return -1;
ret = 0;
}
else
{
DPRINTF(E_DBG, L_REMOTE, "Remote id %s found\n", id);
free_pi(&ri->pi, 1);
switch (family)
{
case AF_INET:
if (ri->v4_address)
free(ri->v4_address);
break;
case AF_INET6:
if (ri->v6_address)
free(ri->v6_address);
break;
}
if (ri->paircode)
free(ri->paircode);
ret = 1;
}
ri->pi.remote_id = strdup(id);
switch (family)
{
case AF_INET:
ri->v4_address = strdup(address);
ri->v4_port = port;
check_addr = ri->v4_address;
break;
case AF_INET6:
ri->v6_address = strdup(address);
ri->v6_port = port;
check_addr = ri->v6_address;
break;
default:
DPRINTF(E_LOG, L_REMOTE, "Unknown address family %d\n", family);
check_addr = NULL;
break;
}
if (!ri->pi.remote_id || !check_addr)
{
DPRINTF(E_LOG, L_REMOTE, "Out of memory for remote pairing data\n");
remove_remote(ri);
return -1;
}
ri->pi.name = name;
ri->paircode = paircode;
return ret;
}
static int
add_remote_pin_data(char *devname, char *pin)
{
struct remote_info *ri;
for (ri = remote_list; ri; ri = ri->next)
{
if (strcmp(ri->pi.name, devname) == 0)
break;
}
if (!ri)
{
DPRINTF(E_LOG, L_REMOTE, "Remote '%s' not known from mDNS, ignoring\n", devname);
return -1;
}
DPRINTF(E_DBG, L_REMOTE, "Remote '%s' found\n", devname);
if (ri->pin)
free(ri->pin);
ri->pin = pin;
return 0;
}
static void
kickoff_pairing(void)
{
#ifdef USE_EVENTFD
int ret;
ret = eventfd_write(pairing_efd, 1);
if (ret < 0)
DPRINTF(E_LOG, L_REMOTE, "Could not send pairing event: %s\n", strerror(errno));
#else
int dummy = 42;
int ret;
ret = write(pairing_pipe[1], &dummy, sizeof(dummy));
if (ret != sizeof(dummy))
DPRINTF(E_LOG, L_REMOTE, "Could not write to pairing fd: %s\n", strerror(errno));
#endif
}
/* Thread: main (pairing) */
static void
pairing_request_cb(struct evhttp_request *req, void *arg)
{
struct remote_info *ri;
struct evbuffer *input_buffer;
uint8_t *response;
char guid[17];
int buflen;
int response_code;
int len;
int i;
int ret;
ri = (struct remote_info *)arg;
if (!req)
{
DPRINTF(E_LOG, L_REMOTE, "Empty pairing request callback\n");
goto cleanup;
}
response_code = evhttp_request_get_response_code(req);
if (response_code != HTTP_OK)
{
DPRINTF(E_LOG, L_REMOTE, "Pairing failed with Remote %s/%s, HTTP response code %d\n", ri->pi.remote_id, ri->pi.name, response_code);
goto cleanup;
}
input_buffer = evhttp_request_get_input_buffer(req);
buflen = evbuffer_get_length(input_buffer);
if (buflen < 8)
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s/%s: pairing response too short\n", ri->pi.remote_id, ri->pi.name);
goto cleanup;
}
response = evbuffer_pullup(input_buffer, -1);
if ((response[0] != 'c') || (response[1] != 'm') || (response[2] != 'p') || (response[3] != 'a'))
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s/%s: unknown pairing response, expected cmpa\n", ri->pi.remote_id, ri->pi.name);
goto cleanup;
}
len = (response[4] << 24) | (response[5] << 16) | (response[6] << 8) | (response[7]);
if (buflen < 8 + len)
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s/%s: pairing response truncated (got %d expected %d)\n",
ri->pi.remote_id, ri->pi.name, buflen, len + 8);
goto cleanup;
}
response += 8;
for (; len > 0; len--, response++)
{
if ((response[0] != 'c') || (response[1] != 'm') || (response[2] != 'p') || (response[3] != 'g'))
continue;
else
{
len -= 8;
response += 8;
break;
}
}
if (len < 8)
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s/%s: cmpg truncated in pairing response\n", ri->pi.remote_id, ri->pi.name);
goto cleanup;
}
for (i = 0; i < 8; i++)
sprintf(guid + (2 * i), "%02X", response[i]);
ri->pi.guid = strdup(guid);
DPRINTF(E_LOG, L_REMOTE, "Pairing succeeded with Remote '%s' (id %s), GUID: %s\n", ri->pi.name, ri->pi.remote_id, guid);
ret = db_pairing_add(&ri->pi);
if (ret < 0)
{
DPRINTF(E_LOG, L_REMOTE, "Failed to register pairing!\n");
goto cleanup;
}
cleanup:
evhttp_connection_free(ri->evcon);
free_remote(ri);
}
/* Thread: main (pairing) */
static int
send_pairing_request(struct remote_info *ri, char *req_uri, int family)
{
struct evhttp_connection *evcon;
struct evhttp_request *req;
char *address;
unsigned short port;
int ret;
switch (family)
{
case AF_INET:
if (!ri->v4_address)
return -1;
address = ri->v4_address;
port = ri->v4_port;
break;
case AF_INET6:
if (!ri->v6_address)
return -1;
address = ri->v6_address;
port = ri->v6_port;
break;
default:
return -1;
}
evcon = evhttp_connection_base_new(evbase_main, NULL, address, port);
if (!evcon)
{
DPRINTF(E_LOG, L_REMOTE, "Could not create connection for pairing with %s\n", ri->pi.name);
return -1;
}
req = evhttp_request_new(pairing_request_cb, ri);
if (!req)
{
DPRINTF(E_WARN, L_REMOTE, "Could not create HTTP request for pairing\n");
goto request_fail;
}
ret = evhttp_make_request(evcon, req, EVHTTP_REQ_GET, req_uri);
if (ret < 0)
{
DPRINTF(E_WARN, L_REMOTE, "Could not make pairing request\n");
goto request_fail;
}
DPRINTF(E_DBG, L_REMOTE, "Pairing requested to %s\n", req_uri);
ri->evcon = evcon;
return 0;
request_fail:
evhttp_connection_free(evcon);
return -1;
}
/* Thread: main (pairing) */
static void
do_pairing(struct remote_info *ri)
{
char req_uri[128];
char *pairing_hash;
int ret;
pairing_hash = itunes_pairing_hash(ri->paircode, ri->pin);
if (!pairing_hash)
{
DPRINTF(E_LOG, L_REMOTE, "Could not compute pairing hash!\n");
goto hash_fail;
}
DPRINTF(E_DBG, L_REMOTE, "Pairing hash for %s/%s: %s\n", ri->pi.remote_id, ri->pi.name, pairing_hash);
/* Prepare request URI */
/* The servicename variable is the mDNS service group name; currently it's
* a hash of the library name, but in iTunes the service name and the library
* ID (DbId) are different (see comment in main.c).
* Remote uses the service name to perform mDNS lookups.
*/
ret = snprintf(req_uri, sizeof(req_uri), "/pair?pairingcode=%s&servicename=%016" PRIX64, pairing_hash, libhash);
free(pairing_hash);
if ((ret < 0) || (ret >= sizeof(req_uri)))
{
DPRINTF(E_WARN, L_REMOTE, "Request URI for pairing exceeds buffer size\n");
goto req_uri_fail;
}
/* Fire up the request */
if (ri->v6_address)
{
ret = send_pairing_request(ri, req_uri, AF_INET6);
if (ret == 0)
return;
DPRINTF(E_WARN, L_REMOTE, "Could not send pairing request on IPv6\n");
}
ret = send_pairing_request(ri, req_uri, AF_INET);
if (ret < 0)
{
DPRINTF(E_WARN, L_REMOTE, "Could not send pairing request on IPv4\n");
goto pairing_fail;
}
return;
pairing_fail:
req_uri_fail:
hash_fail:
free_remote(ri);
}
/* Thread: main (pairing) */
static void
pairing_cb(int fd, short event, void *arg)
{
struct remote_info *ri;
#ifdef USE_EVENTFD
eventfd_t count;
int ret;
ret = eventfd_read(pairing_efd, &count);
if (ret < 0)
{
DPRINTF(E_LOG, L_REMOTE, "Could not read event counter: %s\n", strerror(errno));
return;
}
#else
int dummy;
/* Drain the pipe */
while (read(pairing_pipe[0], &dummy, sizeof(dummy)) >= 0)
; /* EMPTY */
#endif
for (;;)
{
pthread_mutex_lock(&remote_lck);
for (ri = remote_list; ri; ri = ri->next)
{
/* We've got both the mDNS data and the pin */
if (ri->paircode && ri->pin)
{
unlink_remote(ri);
break;
}
}
pthread_mutex_unlock(&remote_lck);
if (!ri)
break;
do_pairing(ri);
}
event_add(pairingev, NULL);
}
/* Thread: main (mdns) */
static void
touch_remote_cb(const char *name, const char *type, const char *domain, const char *hostname, int family, const char *address, int port, struct keyval *txt)
{
const char *p;
char *devname;
char *paircode;
int ret;
if (port < 0)
{
/* If Remote stops advertising itself, the pairing either succeeded or
* failed; any subsequent attempt will need a new pairing pin, so
* we can just forget everything we know about the remote.
*/
pthread_mutex_lock(&remote_lck);
remove_remote_address_byid(name, family);
pthread_mutex_unlock(&remote_lck);
}
else
{
/* Get device name (DvNm field in TXT record) */
p = keyval_get(txt, "DvNm");
if (!p)
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s: no DvNm in TXT record!\n", name);
return;
}
if (*p == '\0')
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s: DvNm has no value\n", name);
return;
}
devname = strdup(p);
if (!devname)
{
DPRINTF(E_LOG, L_REMOTE, "Out of memory for device name\n");
return;
}
/* Get pairing code (Pair field in TXT record) */
p = keyval_get(txt, "Pair");
if (!p)
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s: no Pair in TXT record!\n", name);
free(devname);
return;
}
if (*p == '\0')
{
DPRINTF(E_LOG, L_REMOTE, "Remote %s: Pair has no value\n", name);
free(devname);
return;
}
paircode = strdup(p);
if (!paircode)
{
DPRINTF(E_LOG, L_REMOTE, "Out of memory for paircode\n");
free(devname);
return;
}
DPRINTF(E_LOG, L_REMOTE, "Discovered remote '%s' (id %s) at %s:%d, paircode %s\n", devname, name, address, port, paircode);
/* Add the data to the list, adding the remote to the list if needed */
pthread_mutex_lock(&remote_lck);
ret = add_remote_mdns_data(name, family, address, port, devname, paircode);
if (ret < 0)
{
DPRINTF(E_WARN, L_REMOTE, "Could not add Remote mDNS data, id %s\n", name);
free(devname);
free(paircode);
}
else if (ret == 1)
kickoff_pairing();
pthread_mutex_unlock(&remote_lck);
}
}
/* Thread: filescanner */
void
remote_pairing_read_pin(char *path)
{
char buf[256];
FILE *fp;
char *devname;
char *pin;
int len;
int ret;
fp = fopen(path, "rb");
if (!fp)
{
DPRINTF(E_LOG, L_REMOTE, "Could not open Remote pairing file %s: %s\n", path, strerror(errno));
return;
}
devname = fgets(buf, sizeof(buf), fp);
if (!devname)
{
DPRINTF(E_LOG, L_REMOTE, "Empty Remote pairing file %s\n", path);
fclose(fp);
return;
}
len = strlen(devname);
if (buf[len - 1] != '\n')
{
DPRINTF(E_LOG, L_REMOTE, "Invalid Remote pairing file %s: device name too long or missing pin\n", path);
fclose(fp);
return;
}
while (len)
{
if ((buf[len - 1] == '\r') || (buf[len - 1] == '\n'))
{
buf[len - 1] = '\0';
len--;
}
else
break;
}
if (!len)
{
DPRINTF(E_LOG, L_REMOTE, "Invalid Remote pairing file %s: empty line where device name expected\n", path);
fclose(fp);
return;
}
devname = strdup(buf);
if (!devname)
{
DPRINTF(E_LOG, L_REMOTE, "Out of memory for device name while reading %s\n", path);
fclose(fp);
return;
}
pin = fgets(buf, sizeof(buf), fp);
fclose(fp);
if (!pin)
{
DPRINTF(E_LOG, L_REMOTE, "Invalid Remote pairing file %s: no pin\n", path);
free(devname);
return;
}
len = strlen(pin);
while (len)
{
if ((buf[len - 1] == '\r') || (buf[len - 1] == '\n'))
{
buf[len - 1] = '\0';
len--;
}
else
break;
}
if (len != 4)
{
DPRINTF(E_LOG, L_REMOTE, "Invalid pin in Remote pairing file %s: pin length should be 4, got %d\n", path, len);
free(devname);
return;
}
pin = strdup(buf);
if (!pin)
{
DPRINTF(E_LOG, L_REMOTE, "Out of memory for device pin while reading %s\n", path);
free(devname);
return;
}
DPRINTF(E_LOG, L_REMOTE, "Read Remote pairing data (name '%s', pin '%s') from %s\n", devname, pin, path);
pthread_mutex_lock(&remote_lck);
ret = add_remote_pin_data(devname, pin);
free(devname);
if (ret < 0)
free(pin);
else
kickoff_pairing();
pthread_mutex_unlock(&remote_lck);
}
/* Thread: main */
int
remote_pairing_init(void)
{
int ret;
remote_list = NULL;
#ifdef USE_EVENTFD
pairing_efd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
if (pairing_efd < 0)
{
DPRINTF(E_FATAL, L_REMOTE, "Could not create eventfd: %s\n", strerror(errno));
return -1;
}
#else
# ifdef HAVE_PIPE2
ret = pipe2(pairing_pipe, O_CLOEXEC | O_NONBLOCK);
# else
if ( pipe(pairing_pipe) < 0 ||
fcntl(pairing_pipe[0], F_SETFL, O_CLOEXEC | O_NONBLOCK) < 0 ||
fcntl(pairing_pipe[1], F_SETFL, O_CLOEXEC | O_NONBLOCK) < 0 )
ret = -1;
else
ret = 0;
# endif
if (ret < 0)
{
DPRINTF(E_FATAL, L_REMOTE, "Could not create pairing pipe: %s\n", strerror(errno));
return -1;
}
#endif /* USE_EVENTFD */
// No ipv6 for remote at the moment
ret = mdns_browse("_touch-remote._tcp", AF_INET, touch_remote_cb);
if (ret < 0)
{
DPRINTF(E_FATAL, L_REMOTE, "Could not browse for Remote services\n");
goto mdns_browse_fail;
}
#ifdef USE_EVENTFD
pairingev = event_new(evbase_main, pairing_efd, EV_READ, pairing_cb, NULL);
#else
pairingev = event_new(evbase_main, pairing_pipe[0], EV_READ, pairing_cb, NULL);
#endif
if (!pairingev)
{
DPRINTF(E_FATAL, L_REMOTE, "Out of memory for pairing event\n");
goto pairingev_fail;
}
event_add(pairingev, NULL);
return 0;
pairingev_fail:
mdns_browse_fail:
#ifdef USE_EVENTFD
close(pairing_efd);
#else
close(pairing_pipe[0]);
close(pairing_pipe[1]);
#endif
return -1;
}
/* Thread: main */
void
remote_pairing_deinit(void)
{
struct remote_info *ri;
for (ri = remote_list; remote_list; ri = remote_list)
{
remote_list = ri->next;
free_remote(ri);
}
#ifdef USE_EVENTFD
close(pairing_efd);
#else
close(pairing_pipe[0]);
close(pairing_pipe[1]);
#endif
}