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|
/*
* Argyll Color Correction System
* ChromCast support
*
* Author: Graeme W. Gill
* Date: 28/8/2014
*
* Copyright 2014 Graeme W. Gill
* All rights reserved.
*
* This material is licenced under the GNU AFFERO GENERAL PUBLIC LICENSE Version 3 :-
* see the License2.txt file for licencing details.
*
*/
/*
* This class provides simple access to the Google ChromeCast
* for the purposes of generating Video Test patches.
*/
/*
TTBD: Ideally we should use the system mDNS resource if it is available,
and fall back to our mDNS code if not.
ie. Linux may have nothing, be using avahi-daemon,
possibly Zeroconf (== Bonjour ?)
Avahi has Bonjour compatibility library ??
ie. OS X is using mDNSRespo (Bonjour ?)
MSWin may have Bonjour installed on it ?
Has dns-sd command - what's that using (SSDP/UPnP ?)
From <http://stackoverflow.com/questions/8659638/how-does-windows-know-how-to-resolve-mdns-queries>
Bonjour for Windows allows any software using the standard name resolution APIs
to resolve mDNS names; it does so by registering a DLL (mdnsnsp.dll) as a
namespace provider using WSCInstallNameSpace.
The corresponding code is included in the mDNSResponder source (in particular,
look at the mdnsNSP and NSPTool components).
To test on Linux:
To check what's listening: sudo netstat -anp | grep 5353
/etc/init.d/avahi-daemon stop
/etc/init.d/avahi-daemon start
To test on OS X:
To check what's listening: sudo netstat -an | grep 5353
launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
*/
#include <time.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>
#include <stdarg.h>
#include <math.h>
#include <assert.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include "copyright.h"
#include "aconfig.h"
#include <sys/types.h>
#ifndef SALONEINSTLIB
#include "numlib.h"
#else
#include "numsup.h"
#endif
#include "conv.h"
#include "ccmdns.h"
#undef DEBUG /* [und] */
#if defined(NT) // Windows specific
# if _WIN32_WINNT < 0x0400
# undef _WIN32_WINNT
# define _WIN32_WINNT 0x0400 // To make it link in VS2005
# endif
# define WIN32_LEAN_AND_MEAN
# include <winsock2.h>
# include <windows.h>
# include <ws2tcpip.h>
# include <process.h>
# include <direct.h>
# include <io.h>
# define ERRNO GetLastError()
# define UDP_SOCKET_TIMEOUT WSAETIMEDOUT
#else /* !NT = Unix, OS X */
# include <errno.h>
# include <sys/types.h>
# include <sys/wait.h>
# include <sys/socket.h>
# include <sys/select.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <sys/time.h>
# include <stdint.h>
# include <inttypes.h>
# include <netdb.h>
# include <pwd.h>
# include <unistd.h>
# include <dirent.h>
typedef int SOCKET;
# define ERRNO errno
# define INVALID_SOCKET -1
# define SOCKET_ERROR -1
# define UDP_SOCKET_TIMEOUT EAGAIN
#define closesocket(xxx) close(xxx);
#endif
#ifdef DEBUG
# define DBG(xxx) a1logd xxx ;
# define DBG2(xxx) a1logd xxx ;
# define DLEV 0
#else
# define DBG(xxx) ;
# define DBG2(xxx) a1logd xxx ;
# define DLEV 2
#endif /* DEBUG */
/* ================================================================ */
/* mDNS details */
#define DESTINATION_MCAST "224.0.0.251"
#define DESTINATION_MCASTV6 "FF02::FB"
#define SOURCE_PORT 5353
#define DESTINATION_PORT 5353
#define BUFSIZE 1024
/* Various DNS defines */
#define DNS_CLASS_IN 0x0001
// Used by ChromeCast
#define DNS_TYPE_PTR 12 /* Domain name pointer */
#define DNS_TYPE_TXT 16 /* Text String */
#define DNS_TYPE_SRV 33 /* Server selection (SRV) record */
#define DNS_TYPE_A 1 /* Host address (A) record */
#define DNS_TYPE_AAAA 28 /* IPv6 address ??? */
#define DNS_TYPE_NSEC 47 /* DNS Next Secure Name */
#ifdef NEVER
/* Print out a V6 address in zero compresed form */
/* (It would be nice to add zero compression) */
static char *print_IPV6_Address(ORD8 *buf) {
static char sbuf[40], *p = sbuf;
int i;
for (i = 0; i < 8; i++) {
p += sprintf(p, "%x", buf[i * 2 + 1] * 256 + buf[i * 2 + 0]);
if (i < 7)
*p++ = ':';
}
*p++ = '\000';
return sbuf;
}
#endif
/* Write a DNS string to a buffer. */
/* return the offset of the next byte after the string */
static int write_string(ORD8 *buf, int off, char *s) {
int len = strlen(s);
if (len >= 0xc0)
len = 0xc0; // Hmm.
buf[off] = len;
off++;
memcpy(buf + off, s, len);
off += len;
return off;
}
/* Return NZ on error */
static int init_mDNS() {
#ifdef NT
WSADATA data;
if (WSAStartup(MAKEWORD(2,2), &data)) {
DBG((g_log,0,"WSAStartup failed\n"))
return 1;
}
#endif
return 0;
}
/* Setup the send socket */
/* Return nz on error */
static int init_send_mDNS(SOCKET *psock) {
int nRet, nOptVal;
int off;
SOCKET sock;
struct sockaddr_in stSourceAddr;
DBG((g_log,0,"init_send_mDNS() called\n"))
/* get a datagram (UDP) socket */
sock = socket(PF_INET, SOCK_DGRAM, 0);
if (sock == INVALID_SOCKET) {
DBG((g_log,0,"opening send UDP socked failed with %d\n",ERRNO))
return 1;
}
/*----------------------- to send --------------------------- */
/* Theoretically, you do not need any special preparation to
* send to a multicast address. However, you may want a few
* things to overcome the limits of the default behavior
*/
// If we're doing a one-shot, we shouldn't transmit from port 5353, */
// but ChromCast won't see the packet if we don't. */
/* We can't send from port 5353 if someone else is using it, */
/* so set the SO_REUSEADDR option (which is enough for MSWin), */
/* and SO_REUSEPORT for OS X and Linux */
{
int on = 1;
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char *)&on, sizeof(on))) {
DBG((g_log,0,"setsockopt(SO_REUSEADDR) failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
/* Need this to be able to open port on Unix like systems */
#ifndef NT
# ifndef SO_REUSEPORT
# ifdef __APPLE__
# define SO_REUSEPORT 0x0200
# else /* Linux */
# define SO_REUSEPORT 15
# endif
# endif
if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, (const char *)&on, sizeof(on))) {
DBG((g_log,0,"setsockopt(SO_REUSEPORT) failed with %d\n",ERRNO))
}
#endif
}
/* init source address structure */
stSourceAddr.sin_family = PF_INET;
stSourceAddr.sin_port = htons(SOURCE_PORT);
stSourceAddr.sin_addr.s_addr = INADDR_ANY;
/*
* Calling bind() is not required, but some implementations need it
* before you can reference any multicast socket options
* and in this case we must be on port 5353 for ChromeCast to see the packet
*/
nRet = bind(sock, (struct sockaddr *)&stSourceAddr,
sizeof(struct sockaddr));
if (nRet == SOCKET_ERROR) {
DBG((g_log,0,"bind failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
/* disable loopback of multicast datagrams we send, since the
* default--according to Steve Deering--is to loopback all
* datagrams sent on any interface which is a member of the
* destination group address of that datagram.
*/
nOptVal = 0;
nRet = setsockopt (sock, IPPROTO_IP, IP_MULTICAST_LOOP,
(char *)&nOptVal, sizeof(int));
if (nRet == SOCKET_ERROR) {
/* rather than notifying the user, we make note that this option
* failed. Some WinSocks don't support this option, and default
* with loopback disabled), so this failure is of no consequence.
* However, if we *do* get loop-backed data, we'll know why
*/
DBG((g_log,0,"[disabling loopback failed with %d]\n",ERRNO))
}
/* Is this desirable ? */
/* increase the IP TTL from the default of one to 64, so our
* multicast datagrams can get off of the local network
*/
nOptVal = 64;
nRet = setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL,
(char *)&nOptVal, sizeof(int));
if (nRet == SOCKET_ERROR) {
DBG((g_log,0,"increasing TTL failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
if (psock != NULL)
*psock = sock;
DBG((g_log,0,"init sending mDNS succeed\n",ERRNO))
return 0;
}
/* Send an mDNS quesry */
/* on some platforms if we try to transmit & recieve at the same time */
/* Return nz on error */
static int send_mDNS(SOCKET sock) {
int nRet;
int off;
ORD8 achOutBuf[BUFSIZE];
struct sockaddr_in stDestAddr;
DBG((g_log,0,"send_mDNS() called\n"))
/* Initialize the Destination Address structure and send */
stDestAddr.sin_family = PF_INET;
stDestAddr.sin_addr.s_addr = inet_addr(DESTINATION_MCAST);
stDestAddr.sin_port = htons(DESTINATION_PORT);
/* Setup the FQDN data packet to send */
write_ORD16_be(achOutBuf + 0, 0); /* ID */
write_ORD16_be(achOutBuf + 2, 0); /* Flags */
write_ORD16_be(achOutBuf + 4, 1); /* QDCOUNT - one question */
write_ORD16_be(achOutBuf + 6, 0); /* ANCOUNT */
write_ORD16_be(achOutBuf + 8, 0); /* NSCOUNT */
write_ORD16_be(achOutBuf + 10, 0); /* ARCOUNT */
off = 12;
off = write_string(achOutBuf, off, "_googlecast");
off = write_string(achOutBuf, off, "_tcp");
off = write_string(achOutBuf, off, "local");
write_ORD8(achOutBuf + off, 0); /* null string */
off += 1;
write_ORD16_be(achOutBuf + off, 0x000c); /* QCOUNT */
off += 2;
/* Set top bit to get a unicast response (not for ChromeCast though) */
write_ORD16_be(achOutBuf + off, 0x0001); /* QCLASS */
off += 2;
nRet = sendto(sock, (char *)achOutBuf, off,
0,
(struct sockaddr *) &stDestAddr,
sizeof(struct sockaddr));
if (nRet == SOCKET_ERROR) {
DBG((g_log,0,"sending mDNS query failed with %d\n",ERRNO))
return 1;
}
DBG((g_log,0,"sending mDNS query succeed\n",ERRNO))
return 0;
}
static int parse_dns(char **name, char **ip, ORD8 *buf, int size);
/* Free up what get_ccids returned */
void free_ccids(ccast_id **ids) {
if (ids != NULL) {
int i;
for (i = 0; ids[i] != NULL; i++) {
free(ids[i]->name);
free(ids[i]->ip);
free(ids[i]);
}
free(ids);
}
}
/* Spend the given time waiting for replies. */
/* (Note than on MSWin this will be a minimum of 500msec) */
/* Add any ChromeCast replies to the list. */
/* return nz on error */
static int init_receive_mDNS(SOCKET *psock) {
int nRet;
int off, size;
struct sockaddr_in stSourceAddr;
struct ip_mreq stIpMreq;
SOCKET sock;
DBG((g_log,0,"init_receive_mDNS() called\n"))
/* get a datagram (UDP) socket */
sock = socket(PF_INET, SOCK_DGRAM, 0);
if (sock == INVALID_SOCKET) {
DBG((g_log,0,"opening receive UDP socked failed with %d\n",ERRNO))
return 1;
}
/* We can't receive from port 5353 if someone else is using it, */
/* so set the SO_REUSEADDR option (which is enough for MSWin), */
/* and SO_REUSEPORT for OS X and Linux */
{
int on = 1, off = 0;
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char *) &on, sizeof(on))) {
DBG((g_log,0,"setsockopt(SO_REUSEADDR) failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
/* Need this to be able to open port on Unix like systems */
#ifndef NT
# ifndef SO_REUSEPORT
# ifdef __APPLE__
# define SO_REUSEPORT 0x0200
# else /* Linux */
# define SO_REUSEPORT 15
# endif
# endif
if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, (const char *)&on, sizeof(on))) {
DBG((g_log,0,"setsockopt(SO_REUSEPORT) failed with %d\n",ERRNO))
}
#endif
}
/* init source address structure */
stSourceAddr.sin_family = PF_INET;
stSourceAddr.sin_port = htons(SOURCE_PORT);
stSourceAddr.sin_addr.s_addr = INADDR_ANY;
/*
* Calling bind() is not required, but some implementations need it
* before you can reference any multicast socket options
* and in this case we must be on port 5353.
*/
nRet = bind(sock, (struct sockaddr *)&stSourceAddr,
sizeof(struct sockaddr));
if (nRet == SOCKET_ERROR) {
DBG((g_log,0,"bind failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
/* join the multicast group we want to receive datagrams from */
stIpMreq.imr_multiaddr.s_addr = inet_addr(DESTINATION_MCAST); /* group addr */
stIpMreq.imr_interface.s_addr = INADDR_ANY; /* use default */
nRet = setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
(char *)&stIpMreq, sizeof (struct ip_mreq));
if (nRet == SOCKET_ERROR) {
DBG((g_log,0,"registering for read events failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
/* Make this timeout after 100 msec second */
#ifdef NT
{
DWORD tv;
tv = 100;
if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof(tv)) < 0) {
DBG((g_log,0,"setsockopt timout failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
}
#else
{
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 100 * 1000;
if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof(tv)) < 0) {
DBG((g_log,0,"setsockopt timout failed with %d\n",ERRNO))
closesocket(sock);
return 1;
}
}
#endif
if (psock != NULL)
*psock = sock;
return 0;
}
/* Spend the given time waiting for replies. */
/* (Note than on MSWin this will be a minimum of 500msec) */
/* Add any ChromeCast replies to the list. */
/* return nz on error & free *ids */
static int receive_mDNS(SOCKET sock, ccast_id ***ids, int emsec) {
int nids = 0;
unsigned int smsec;
unsigned int nSize;
int off, size;
ORD8 achInBuf[BUFSIZE];
struct sockaddr_in stSourceAddr;
/* Count the number of current id's */
if (*ids != NULL) {
for (nids = 0; (*ids)[nids] != NULL; nids++)
;
}
DBG((g_log,0,"receive_mDNS() called with %d ids\n",nids))
for (smsec = msec_time(), emsec += smsec;msec_time() <= emsec;) {
int i;
char *name, *ip;
struct sockaddr stSockAddr;
/* Recv the available data */
nSize = sizeof(struct sockaddr);
size = recvfrom(sock, (char *)achInBuf,
BUFSIZE, 0, (struct sockaddr *) &stSockAddr, &nSize);
if (size == SOCKET_ERROR) {
if (ERRNO == UDP_SOCKET_TIMEOUT)
continue; /* Timeout */
DBG((g_log,0,"recvfrom failed with %d\n",ERRNO))
free_ccids(*ids);
*ids = NULL;
return 1;
}
DBG((g_log,0,"Got mDNS message length %d bytes\n",size))
#ifdef DEBUG
adump_bytes(g_log, " ", achInBuf, 0, size);
#endif
if (parse_dns(&name, &ip, achInBuf, size) != 0) {
DBG((g_log,0,"Failed to parse the reply\n"))
} else {
DBG((g_log,0,"Parsed reply OK\n"))
//if (*pnids > 0) {
// name = strdup("Argyll1234");
// ip = strdup("10.0.0.129");
//}
/* If we found an entry */
if (name != NULL && ip != NULL) {
DBG((g_log,0,"Got a name '%s' & IP '%s'\n",name,ip))
/* Check if it is a duplcate */
for (i = 0; i < nids; i++) {
if (strcmp((*ids)[i]->name, name) == 0
&& strcmp((*ids)[i]->ip, ip) == 0)
break; /* yes */
}
if (i < nids) {
DBG((g_log,0,"Duplicate\n"))
free(name);
free(ip);
} else {
ccast_id **tids;
if ((tids = realloc(*ids, (nids + 2) * sizeof(ccast_id *))) == NULL
|| (*ids = tids, (*ids)[nids] = malloc(sizeof(ccast_id)), (*ids)[nids]) == NULL) {
DBG((g_log,0,"realloc/malloc fail\n"))
free(name);
free(ip);
free_ccids(*ids);
*ids = NULL;
return 1;
} else {
DBG((g_log,0,"Adding entry\n"))
(*ids)[nids]->name = name;
(*ids)[nids]->ip = ip;
(*ids)[++nids] = NULL; /* End marker */
}
}
}
}
}
DBG((g_log,0,"receive_mDNS() returning %d in list\n",nids))
return 0;
}
/* ==================================================================== */
/* Get a list of Chromecasts. Return NULL on error */
/* Last pointer in array is NULL */
/* Takes 1.0 second to return */
ccast_id **get_ccids() {
ccast_id **ids = NULL;
int i, j, k;
unsigned int smsec;
int waittime = 100;
SOCKET ssock, rsock;
DBG2((g_log,DLEV,"get_ccids: called\n"))
if (init_mDNS()) {
DBG2((g_log,0,"get_ccids: init_mDNS() failed\n"))
return NULL;
}
if (init_send_mDNS(&ssock)) {
DBG2((g_log,0,"get_ccids: init_send_mDNS() failed\n"))
return NULL;
}
if (init_receive_mDNS(&rsock)) {
DBG2((g_log,0,"get_ccids: init_receive_mDNS() failed\n"))
closesocket(ssock);
return NULL;
}
smsec = msec_time();
/* Try a few times, with increasing response wait time */
for (k = 1; ids == NULL && (msec_time() - smsec) < 1000; k++) {
DBG2((g_log,DLEV,"get_ccids: Sending mDNS query #%d:\n",k))
if (send_mDNS(ssock)) {
DBG2((g_log,0,"get_ccids: send_mDNS() #1 failed\n"))
closesocket(ssock);
closesocket(rsock);
return NULL;
}
DBG2((g_log,DLEV,"get_ccids: Waiting for mDNS reply #%d:\n",k))
if (receive_mDNS(rsock, &ids, waittime)) {
DBG2((g_log,0,"get_ccids: receive_mDNS() #%d failed\n",k))
closesocket(ssock);
closesocket(rsock);
return NULL;
}
if (ids != NULL)
DBG2((g_log,DLEV,"get_ccids: Got reply\n"))
waittime *= 2;
}
closesocket(ssock);
closesocket(rsock);
/* If no ChromCasts found, return an empty list */
if (ids == NULL) {
DBG2((g_log,DLEV,"get_ccids: no devices found\n"))
if ((ids = calloc(sizeof(ccast_id *), 1)) == NULL) {
DBG2((g_log,0,"get_ccids: calloc fail\n"))
return NULL;
}
}
/* Sort the results so that it is stable */
for (i = 0; ids[i] != NULL && ids[i+1] != NULL; i++) {
for (j = i+1; ids[j] != NULL; j++) {
if (strcmp(ids[i]->name, ids[j]->name) > 0) {
ccast_id *tmp;
tmp = ids[i];
ids[i] = ids[j];
ids[j] = tmp;
}
}
}
for (i = 0; ids[i] != NULL; i++) {
DBG2((g_log,DLEV," Entry %d:\n",i))
DBG2((g_log,DLEV," Name: %s\n",ids[i]->name))
DBG2((g_log,DLEV," IP: %s\n",ids[i]->ip))
}
DBG2((g_log,DLEV,"get_ccids: Returning %d devices\n",i))
return ids;
}
void ccast_id_copy(ccast_id *dst, ccast_id *src) {
dst->name = strdup(src->name);
dst->ip = strdup(src->ip);
}
ccast_id *ccast_id_clone(ccast_id *src) {
ccast_id *dst;
if ((dst = calloc(sizeof(ccast_id), 1)) == NULL)
return dst;
if (src->name != NULL && (dst->name = strdup(src->name)) == NULL) {
free(dst);
return NULL;
}
if (src->ip != NULL && (dst->ip = strdup(src->ip)) == NULL) {
free(dst->name);
free(dst);
return NULL;
}
return dst;
}
void ccast_id_del(ccast_id *id) {
free(id->name);
free(id->ip);
free(id);
}
/* ==================================================================== */
/* Read a string with a trailing '.' added. */
/* Return the next offset or -1 and *rv = NULL on error */
static int read_string_imp(char **rv, int *slen, ORD8 *buf, int off, int size, int rec) {
int len;
int d1 = 0;
//printf("~1 read_string_imp called for off 0x%x rec %d\n",off,rec);
if (rec > 10) /* Too many recursions */
return -1; /* Error */
if (off >= size)
return -1; /* Error */
for (;;) {
//printf("~1 top of loop at off 0x%x\n",off);
len = buf[off];
if (len == 0xc0) { /* Is it an offset marker */
int poff;
//printf("~1 got pointer\n");
if ((size - off) < 2)
return -1;
poff = read_ORD16_be(buf + off); off += 2;
poff -= 0xc000;
if (poff < 0 || poff >= size)
return -1;
read_string_imp(rv, slen, buf, poff, size, rec+1);
//if (slen != NULL) printf("~1 after recurse, slen = %d, off = 0x%x\n",*slen,off);
break; /* we're done */
} else {
//printf("~1 got string length %d\n",len);
off++;
if ((off + len) >= size)
return -1;
if (len == 0)
break; /* we're done */
if (rv != NULL) {
memcpy(*rv, buf + off, len);
//(*rv)[len] = '\000'; printf("Copied string %p = '%s'\n",*rv,*rv);
*rv += len;
}
off += len;
if (slen != NULL) {
(*slen) += len;
//printf("~1 slen now = %d\n",*slen);
}
}
d1 = 1;
if (slen != NULL)
(*slen)++;
if (rv != NULL) {
(*rv)[0] = '.';
(*rv)++;
}
}
//if (slen != NULL) printf("~1 returning slen = %d\n",*slen);
return off;
}
/* Read a string */
/* Return the next offset or -1 and *rv = NULL on error */
static int read_string(char **rv, ORD8 *buf, int off, int size) {
int len = 0, toff = off;
char *trv;
//printf("~1 read_string called for off 0x%x\n",off);
/* See how long it will be */
if ((toff = read_string_imp(NULL, &len, buf, off, size, 0)) < 0) {
//printf("~1 read_string_imp length returned error\n");
return toff;
}
//printf("~1 read_string_imp got length %d\n",len);
if (len == 0) {
//printf("~1 Got zero length string\n");
len++; /* Room for null string */
}
if ((*rv = trv = malloc(len)) == NULL) {
return -1;
}
//printf("Malloced %p\n",*rv);
off = read_string_imp(&trv, NULL, buf, off, size, 0);
if (off >= 0) {
(*rv)[len-1] = '\000';
//printf("~1 read string ok: %p = '%s'\n",*rv, *rv);
}
//else printf("~1 reading string failed\n");
return off;
}
/* Parse an mDNS query */
/* Return updated off value or -1 on error */
int parse_query(ORD8 *buf, int off, int size) {
char *sv;
int qtype, qclass;
DBG((g_log,0,"Parsing query at 0x%x:\n",off))
if ((off = read_string(&sv, buf, off, size)) < 0)
return -1;
DBG((g_log,0," Got string '%s'\n",sv))
free(sv);
if ((size - off) < 2)
return -1;
qtype = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," QTYPE = 0x%04x\n",qtype))
if ((size - off) < 2)
return -1;
qclass = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," QCLASS = 0x%04x\n",qtype))
return off;
}
/* Parse an mDNS reply */
/* Return updated off value or -1 on error */
int parse_reply(char **pname, char **pip, ORD8 *buf, int off, int size) {
char *sv;
int rtype, rclass, rdlength;
unsigned int ttl;
DBG((g_log,0,"Parsing reply at 0x%x:\n",off))
if ((off = read_string(&sv, buf, off, size)) < 0)
return -1;
DBG((g_log,0," Got string '%s'\n",sv))
if ((size - off) < 2) {
free(sv);
return -1;
}
rtype = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," RTYPE = %d\n",rtype))
if ((size - off) < 2) {
free(sv);
return -1;
}
rclass = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," RCLASS = 0x%04x\n",rclass))
/* rclass top bit is cache flush bit */
if ((rclass & 0x7fff) != DNS_CLASS_IN) {
DBG((g_log,0," response has RCLASS != 0x%04x\n",DNS_CLASS_IN))
free(sv);
return -1;
}
if ((size - off) < 4)
return -1;
ttl = read_ORD32_be(buf + off); off += 4;
DBG((g_log,0," TTL = %u\n",ttl))
if ((size - off) < 2)
return -1;
rdlength = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," RDLENGTH = %d\n",rdlength))
if ((off + rdlength) > size) {
DBG((g_log,0," response RDLENGTH is longer than remaining buffer (%d)\n",size - off))
free(sv);
return -1;
}
/* Just decode the replies we need */
if (rtype == DNS_TYPE_TXT) { /* Check it's a ChromeCast & get its name */
char *cp;
if ((cp = strchr(sv, '.')) == NULL) {
free(sv);
return -1;
}
*cp = '\000';
if (strcmp(cp+1, "_googlecast._tcp.local") != 0) {
DBG((g_log,0,"Not a chromecast (got '%s')\n",cp+1))
free(sv);
return -1;
}
DBG((g_log,0," Chromacast '%s'\n", sv))
if ((*pname = strdup(sv)) == NULL) {
DBG((g_log,0,"strdup failed\n"))
free(sv);
return -1;
}
} else if (rtype == DNS_TYPE_A) {
/* Should we check name matches ? */
if ((*pip = malloc(3 * 4 + 3 + 1)) == NULL) {
DBG((g_log,0,"malloc failed\n"))
free(*pname);
free(sv);
}
sprintf(*pip, "%d.%d.%d.%d", buf[off], buf[off+1], buf[off+2], buf[off+3]);
DBG((g_log,0," V4 address = %s\n",*pip))
} else if (rtype == DNS_TYPE_AAAA) { /* The IPV6 address */
/* Should we check name matches ? */
if ((*pip = malloc(8 * 4 + 7 + 1)) == NULL) {
DBG((g_log,0,"malloc failed\n"))
free(*pname);
free(sv);
}
sprintf(*pip, "%x:%x:%x:%x:%x:%x:%x:%x",
buf[off+0] * 245 + buf[off+1],
buf[off+2] * 245 + buf[off+3],
buf[off+4] * 245 + buf[off+5],
buf[off+6] * 245 + buf[off+7],
buf[off+8] * 245 + buf[off+9],
buf[off+10] * 245 + buf[off+11],
buf[off+12] * 245 + buf[off+13],
buf[off+14] * 245 + buf[off+15]);
DBG((g_log,0," V6 address = %s\n",*pip))
} else {
DBG((g_log,0," Skipping reply at 0x%x\n",off))
}
off += rdlength;
free(sv);
return off;
}
/* Parse an mDNS reply into a ChromCast name & IP address */
/* Allocate and return name and IP on finding ChromeCast reply, NULL otherwise */
/* Return nz on failure */
static int parse_dns(char **pname, char **pip, ORD8 *buf, int size) {
int i, off = 0;
int id, flags, qdcount, ancount, nscount, arcount;
DBG((g_log,0,"Parsing mDNS reply:\n"))
*pname = NULL;
*pip = NULL;
// Parse reply header
if ((size - off) < 2) return 1;
id = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," ID = %d\n",id))
if ((size - off) < 2) return 1;
flags = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," FLAGS = 0x%04x\n",flags))
if ((size - off) < 2) return 1;
qdcount = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," QDCOUNT = %d\n",qdcount))
if ((size - off) < 2) return 1;
ancount = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," ANCOUNT = %d\n",ancount))
if ((size - off) < 2) return 1;
nscount = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," NSCOUNT = %d\n",nscount))
if ((size - off) < 2) return 1;
arcount = read_ORD16_be(buf + off); off += 2;
DBG((g_log,0," ARCOUNT = %d\n",arcount))
//printf("~1 after strings, off = 0x%x\n",off);
// Parse all the queries (QDCOUNT)
for (i = 0; i < qdcount; i++) {
if ((off = parse_query(buf, off, size)) < 0) {
DBG((g_log,0," ### Parsing query failed ###\n"))
return 1;
}
}
// Parse all the answers (ANCOUNT)
for (i = 0; i < ancount; i++) {
if ((off = parse_reply(pname, pip, buf, off, size)) < 0) {
DBG((g_log,0," ### Parsing answer failed ###\n"))
return 1;
}
}
// Parse all the NS records (NSCOUNT)
for (i = 0; i < nscount; i++) {
if ((off = parse_reply(pname, pip, buf, off, size)) < 0) {
DBG((g_log,0," ### Parsing NS record failed ###\n"))
return 1;
}
}
// Parse all the addition RR answers (ARCOUNT)
for (i = 0; i < arcount; i++) {
if ((off = parse_reply(pname, pip, buf, off, size)) < 0) {
DBG((g_log,0," ### Parsing additional records failed ###\n"))
return 1;
}
}
return 0;
}
/*
Analysis of ChromeCast reply
0000: 00 00 84 00 00 00 00 01 00 00 00 05 0b 5f 67 6f ............._go
ID 0x0000 // ID 0
Flags 0x8400 // Standard query response, No error
QDCOUNT 0x0000 // No queries
ANCOUNT 0x0001 // 1 Answer
NSCOUNT 0x0000
ARCOUNT 0x0005 // 5 Additional records
// Answer
0b 5f 67 6f _go
0010: 6f 67 6c 65 63 61 73 74 oglecast
0010: 04 5f 74 63 70 _tcp
0010: 05 6c 6f lo
0020: 63 61 6c 00 cal.
"_googlecast" "_tcp" "cal" "" //TLD
0020: 00 0c 00 01 00 00 11 94 00 11 0e 43 ...........C
RTYPE 0x000c
RCLASS 0x0001
TTL 0x00001194
RDLENGTH 0x0011
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0000: 00 00 84 00 00 00 00 01 00 00 00 05 0b 5f 67 6f ............._go
0010: 6f 67 6c 65 63 61 73 74 04 5f 74 63 70 05 6c 6f oglecast._tcp.lo
0020: 63 61 6c 00 00 0c 00 01 00 00 11 94 00 11 0e 43 cal............C
0030: 68 72 6f 6d 65 63 61 73 74 36 38 39 32 c0 0c c0 hromecast6892...
0040: 2e 00 10 80 01 00 00 11 94 00 67 23 69 64 3d 63 ..........g#id=c
0050: 31 37 61 65 38 38 32 65 37 65 31 38 37 35 64 30 17ae882e7e1875d0
0060: 31 33 65 64 32 31 32 63 31 36 62 62 64 34 30 05 13ed212c16bbd40.
0070: 76 65 3d 30 32 0d 6d 64 3d 43 68 72 6f 6d 65 63 ve=02.md=Chromec
0080: 61 73 74 12 69 63 3d 2f 73 65 74 75 70 2f 69 63 ast.ic=/setup/ic
0090: 6f 6e 2e 70 6e 67 11 66 6e 3d 43 68 72 6f 6d 65 on.png.fn=Chrome
00a0: 63 61 73 74 36 38 39 32 04 63 61 3d 35 04 73 74 cast6892.ca=5.st
00b0: 3d 30 c0 2e 00 21 80 01 00 00 00 78 00 17 00 00 =0...!.....x....
00c0: 00 00 1f 49 0e 43 68 72 6f 6d 65 63 61 73 74 36 ...I.Chromecast6
00d0: 38 39 32 c0 1d c0 c4 00 01 80 01 00 00 00 78 00 892...........x.
00e0: 04 0a 00 00 80 c0 2e 00 2f 80 01 00 00 11 94 00 ......../.......
00f0: 09 c0 2e 00 05 00 00 80 00 40 c0 c4 00 2f 80 01 .........@.../..
0100: 00 00 00 78 00 05 c0 c4 00 01 40 ...x......@
*/
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