resolv.c

Axis 221 camera embedded programing interface

	j = __encode_question(&q, packet + i, maxlen - i);
	if (j < 0)
		return j;

	return i + j;
}
#endif

#ifdef L_dnslookup

#ifdef __UCLIBC_HAS_THREADS__
static pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER;
# define LOCK	__pthread_mutex_lock(&mylock)
# define UNLOCK	__pthread_mutex_unlock(&mylock);
#else
# define LOCK
# define UNLOCK
#endif

/* Just for the record, having to lock __dns_lookup() just for these two globals
 * is pretty lame.  I think these two variables can probably be de-global-ized, 
 * which should eliminate the need for doing locking here...  Needs a closer 
 * look anyways. */
static int ns=0, id=1;

int __dns_lookup(const char *name, int type, int nscount, char **nsip,
			   unsigned char **outpacket, struct resolv_answer *a)
{
	int i, j, len, fd, pos, rc;
	struct timeval tv;
	fd_set fds;
	struct resolv_header h;
	struct resolv_question q;
	int retries = 0;
	unsigned char * packet = malloc(PACKETSZ);
	char *dns, *lookup = malloc(MAXDNAME);
	int variant = -1;
	struct sockaddr_in sa;
#ifdef __UCLIBC_HAS_IPV6__
	int v6;
	struct sockaddr_in6 sa6;
#endif

	fd = -1;

	if (!packet || !lookup || !nscount)
	    goto fail;

	DPRINTF("Looking up type %d answer for '%s'\n", type, name);

	LOCK;
	ns %= nscount;
	UNLOCK;

	while (retries < MAX_RETRIES) {
		if (fd != -1)
			close(fd);

		memset(packet, 0, PACKETSZ);

		memset(&h, 0, sizeof(h));

		/* Mess with globals while under lock */
		LOCK;
		++id;
		id &= 0xffff;
		h.id = id;
		dns = nsip[ns];
		UNLOCK;

		h.qdcount = 1;
		h.rd = 1;

		DPRINTF("encoding header\n", h.rd);

		i = __encode_header(&h, packet, PACKETSZ);
		if (i < 0)
			goto fail;

		strncpy(lookup,name,MAXDNAME);
		if (variant >= 0) {
                        BIGLOCK;
                        if (variant < __searchdomains) {
                                strncat(lookup,".", MAXDNAME);
                                strncat(lookup,__searchdomain[variant], MAXDNAME);
                        }
                        BIGUNLOCK;
                }
		DPRINTF("lookup name: %s\n", lookup);
		q.dotted = (char *)lookup;
		q.qtype = type;
		q.qclass = C_IN; /* CLASS_IN */

		j = __encode_question(&q, packet+i, PACKETSZ-i);
		if (j < 0)
			goto fail;

		len = i + j;

		DPRINTF("On try %d, sending query to port %d of machine %s\n",
				retries+1, NAMESERVER_PORT, dns);

#ifdef __UCLIBC_HAS_IPV6__
		v6 = inet_pton(AF_INET6, dns, &sa6.sin6_addr) > 0;
		fd = socket(v6 ? AF_INET6 : AF_INET, SOCK_DGRAM, IPPROTO_UDP);
#else
		fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
#endif
		if (fd < 0) {
                    retries++;
		    continue;
		}

		/* Connect to the UDP socket so that asyncronous errors are returned */		 
#ifdef __UCLIBC_HAS_IPV6__
		if (v6) {
		    sa6.sin6_family = AF_INET6;
		    sa6.sin6_port = htons(NAMESERVER_PORT);
		    /* sa6.sin6_addr is already here */
		    rc = connect(fd, (struct sockaddr *) &sa6, sizeof(sa6));
		} else {
#endif
		    sa.sin_family = AF_INET;
		    sa.sin_port = htons(NAMESERVER_PORT);
		    sa.sin_addr.s_addr = inet_addr(dns);
		    rc = connect(fd, (struct sockaddr *) &sa, sizeof(sa));
#ifdef __UCLIBC_HAS_IPV6__
		}
#endif
		if (rc < 0) {
		    if (errno == ENETUNREACH) {
			/* routing error, presume not transient */
			goto tryall;
		    } else
			/* retry */
                        retries++;
			continue;
		}

		DPRINTF("Transmitting packet of length %d, id=%d, qr=%d\n",
				len, h.id, h.qr);

		send(fd, packet, len, 0);

		FD_ZERO(&fds);
		FD_SET(fd, &fds);
		tv.tv_sec = REPLY_TIMEOUT;
		tv.tv_usec = 0;
		if (select(fd + 1, &fds, NULL, NULL, &tv) <= 0) {
		    DPRINTF("Timeout\n");

			/* timed out, so retry send and receive, 
			 * to next nameserver on queue */
			goto tryall;
		}

		len = recv(fd, packet, 512, 0);
		if (len < HFIXEDSZ) {
			/* too short ! */
			goto again;
		}

		__decode_header(packet, &h);

		DPRINTF("id = %d, qr = %d\n", h.id, h.qr);

		LOCK;
		if ((h.id != id) || (!h.qr)) {
			UNLOCK;
			/* unsolicited */
			goto again;
		}
		UNLOCK;


		DPRINTF("Got response %s\n", "(i think)!");
		DPRINTF("qrcount=%d,ancount=%d,nscount=%d,arcount=%d\n",
				h.qdcount, h.ancount, h.nscount, h.arcount);
		DPRINTF("opcode=%d,aa=%d,tc=%d,rd=%d,ra=%d,rcode=%d\n",
				h.opcode, h.aa, h.tc, h.rd, h.ra, h.rcode);

		if ((h.rcode) || (h.ancount < 1)) {
			/* negative result, not present */
			goto again;
		}

		pos = HFIXEDSZ;

		for (j = 0; j < h.qdcount; j++) {
			DPRINTF("Skipping question %d at %d\n", j, pos);
			i = __length_question(packet, pos);
			DPRINTF("Length of question %d is %d\n", j, i);
			if (i < 0)
				goto again;
			pos += i;
		}
		DPRINTF("Decoding answer at pos %d\n", pos);

		for (j=0;j<h.ancount;j++)
		{
		    i = __decode_answer(packet, pos, a);

		    if (i<0) {
			DPRINTF("failed decode %d\n", i);
			goto again;
		    }
		    /* For all but T_SIG, accept first answer */
		    if (a->atype != T_SIG)
			break;

		    DPRINTF("skipping T_SIG %d\n", i);
		    free(a->dotted);
		    pos += i;
		}

		DPRINTF("Answer name = |%s|\n", a->dotted);
		DPRINTF("Answer type = |%d|\n", a->atype);

		close(fd);

		if (outpacket)
			*outpacket = packet;
		else
			free(packet);
		free(lookup);
		return (len);				/* success! */

	  tryall:
		/* if there are other nameservers, give them a go,
		   otherwise return with error */
		{
		    variant = -1;
                    LOCK;
                    ns = (ns + 1) % nscount;
                    if (ns == 0)
                      retries++;

                    UNLOCK;
                    continue;
		}

	  again:
		/* if there are searchdomains, try them or fallback as passed */
		{
		    int sdomains;
		    BIGLOCK;
		    sdomains=__searchdomains;
		    BIGUNLOCK;

		    if (variant < sdomains - 1) {
			/* next search */
			variant++;
		    } else {
			/* next server, first search */
			LOCK;
			ns = (ns + 1) % nscount;
                        if (ns == 0)
                          retries++;

			UNLOCK;
			variant = -1;
		    }
		}
	}

fail:
	if (fd != -1)
	    close(fd);
	if (lookup)
	    free(lookup);
	if (packet)
	    free(packet);
	h_errno = NETDB_INTERNAL;
	return -1;
}
#endif

#ifdef L_opennameservers

int __nameservers;
char * __nameserver[MAX_SERVERS];
int __searchdomains;
char * __searchdomain[MAX_SEARCH];
#ifdef __UCLIBC_HAS_THREADS__
pthread_mutex_t __resolv_lock = PTHREAD_MUTEX_INITIALIZER;
#endif

/*
 *	we currently read formats not quite the same as that on normal
 *	unix systems, we can have a list of nameservers after the keyword.
 */

int __open_nameservers()
{
	FILE *fp;
	int i;
#define RESOLV_ARGS 5
	char szBuffer[128], *p, *argv[RESOLV_ARGS];
	int argc;

	BIGLOCK;
	if (__nameservers > 0) { 
	    BIGUNLOCK;
	    return 0;
	}

	if ((fp = fopen("/etc/resolv.conf", "r")) ||
			(fp = fopen("/etc/config/resolv.conf", "r")))
	{

		while (fgets(szBuffer, sizeof(szBuffer), fp) != NULL) {

			for (p = szBuffer; *p && isspace(*p); p++)
				/* skip white space */;
			if (*p == '\0' || *p == '\n' || *p == '#') /* skip comments etc */
				continue;
			argc = 0;
			while (*p && argc < RESOLV_ARGS) {
				argv[argc++] = p;
				while (*p && !isspace(*p) && *p != '\n')
					p++;
				while (*p && (isspace(*p) || *p == '\n')) /* remove spaces */
					*p++ = '\0';
			}

			if (strcmp(argv[0], "nameserver") == 0) {
				for (i = 1; i < argc && __nameservers < MAX_SERVERS; i++) {
					__nameserver[__nameservers++] = strdup(argv[i]);
					DPRINTF("adding nameserver %s\n", argv[i]);
				}
			}

			/* domain and search are mutually exclusive, the last one wins */
			if (strcmp(argv[0],"domain")==0 || strcmp(argv[0],"search")==0) {
				while (__searchdomains > 0) {
					free(__searchdomain[--__searchdomains]);
					__searchdomain[__searchdomains] = NULL;
				}
				for (i=1; i < argc && __searchdomains < MAX_SEARCH; i++) {
					__searchdomain[__searchdomains++] = strdup(argv[i]);
					DPRINTF("adding search %s\n", argv[i]);
				}
			}
		}
		fclose(fp);
		DPRINTF("nameservers = %d\n", __nameservers);
		BIGUNLOCK;
		return 0;
	}
	DPRINTF("failed to open %s\n", "resolv.conf");
	h_errno = NO_RECOVERY;
	BIGUNLOCK;
	return -1;
}
#endif


#ifdef L_closenameservers

void __close_nameservers(void)
{
	BIGLOCK;
	while (__nameservers > 0) {
		free(__nameserver[--__nameservers]);
		__nameserver[__nameservers] = NULL;
	}
	while (__searchdomains > 0) {
		free(__searchdomain[--__searchdomains]);
		__searchdomain[__searchdomains] = NULL;
	}
	BIGUNLOCK;
}
#endif

#ifdef L_gethostbyname

struct hostent *gethostbyname(const char *name)
{
	static struct hostent h;
	static char buf[sizeof(struct in_addr) +
			sizeof(struct in_addr *)*2 +
			sizeof(char *)*(ALIAS_DIM) + 256/*namebuffer*/ + 32/* margin */];
	struct hostent *hp;

	gethostbyname_r(name, &h, buf, sizeof(buf), &hp, &h_errno);

	return hp;
}
#endif

#ifdef L_gethostbyname2

struct hostent *gethostbyname2(const char *name, int family)
{
#ifndef __UCLIBC_HAS_IPV6__
	return family == AF_INET ? gethostbyname(name) : (struct hostent*)0;
#else /* __UCLIBC_HAS_IPV6__ */
	static struct hostent h;
	static char buf[sizeof(struct in6_addr) +
			sizeof(struct in6_addr *)*2 +
			sizeof(char *)*(ALIAS_DIM) + 256/*namebuffer*/ + 32/* margin */];
	struct hostent *hp;

	gethostbyname2_r(name, family, &h, buf, sizeof(buf), &hp, &h_errno);

	return hp;
#endif /* __UCLIBC_HAS_IPV6__ */
}
#endif



#ifdef L_res_init
struct __res_state _res;

int res_init(void)
{
	struct __res_state *rp = &(_res);

	__close_nameservers();
	__open_nameservers();
	rp->retrans = RES_TIMEOUT;
	rp->retry = 4;
	rp->options = RES_INIT;
	rp->id = (u_int) random();
	rp->nsaddr.sin_addr.s_addr = INADDR_ANY;
	rp->nsaddr.sin_family = AF_INET;
	rp->nsaddr.sin_port = htons(NAMESERVER_PORT);
	rp->ndots = 1;
	/** rp->pfcode = 0; **/
	rp->_vcsock = -1;
	/** rp->_flags = 0; **/
	/** rp->qhook = NULL; **/
	/** rp->rhook = NULL; **/
	/** rp->_u._ext.nsinit = 0; **/

	BIGLOCK;
	if(__searchdomains) {
		int i;
		for(i=0; i<__searchdomains; i++) {
			rp->dnsrch[i] = __searchdomain[i];
		}
	}

	if(__nameservers) {
		int i;
		struct in_addr a;
		for(i=0; i<__nameservers; i++) {
			if (inet_aton(__nameserver[i], &a)) {
				rp->nsaddr_list[i].sin_addr = a;
				rp->nsaddr_list[i].sin_family = AF_INET;
				rp->nsaddr_list[i].sin_port = htons(NAMESERVER_PORT);
			}
		}
	}
	rp->nscount = __nameservers;
	BIGUNLOCK;

	return(0);
}

void res_close( void )
{
	return;
}

#endif


#ifdef L_res_query

#ifndef MIN
#define MIN(x, y)	((x) < (y) ? (x) : (y))
#endif

int res_query(const char *dname, int class, int type,
              unsigned char *answer, int anslen)
{
	int i;
	unsigned char * packet = 0;
	struct resolv_answer a;
	int __nameserversXX;
	char ** __nameserverXX;

	__open_nameservers();
	if (!dname || class != 1 /* CLASS_IN */) {
		h_errno = NO_RECOVERY;
		return(-1);
	}

	memset((char *) &a, '\0', sizeof(a));

	BIGLOCK;
	__nameserversXX=__nameservers;
	__nameserverXX=__nameserver;
	BIGUNLOCK;
	i = __dns_lookup(dname, type, __nameserversXX, __nameserverXX, &packet, &a);

	if (i < 0) {
		h_errno = TRY_AGAIN;
		return(-1);
	}

	free(a.dotted);

	if (a.atype == type) { /* CNAME*/
		int len = MIN(anslen, i);
		memcpy(answer, packet, len);
		if (packet)
			free(packet);
		return(len);
	}
	if (packet)
		free(packet);
	return i;
}

/*
 * Formulate a normal query, send, and retrieve answer in supplied buffer.
 * Return the size of the response on success, -1 on error.
 * If enabled, implement search rules until answer or unrecoverable failure
 * is detected.  Error code, if any, is left in h_errno.
 */
int res_search(name, class, type, answer, anslen)
	const char *name;	/* domain name */
	int class, type;	/* class and type of query */
	u_char *answer;		/* buffer to put answer */
	int anslen;		/* size of answer */
{
	const char *cp, * const *domain;
	HEADER *hp = (HEADER *)(void *)answer;
	u_int dots;
	int trailing_dot, ret, saved_herrno;
	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;

	if ((!name || !answer) || ((_res.options & RES_INIT) == 0 && res_init() == -1)) {
		h_errno = NETDB_INTERNAL;
		return (-1);
	}

	errno = 0;
	h_errno = HOST_NOT_FOUND;	/* default, if we never query */
	dots = 0;
	for (cp = name; *cp; cp++)
		dots += (*cp == '.');
	trailing_dot = 0;
	if (cp > name && *--cp == '.')
		trailing_dot++;

	/*
	 * If there are dots in the name already, let's just give it a try
	 * 'as is'.  The threshold can be set with the "ndots" option.
	 */
	saved_herrno = -1;
	if (dots >= _res.ndots) {
		ret = res_querydomain(name, NULL, class, type, answer, anslen);
		if (ret > 0)
			return (ret);
		saved_herrno = h_errno;
		tried_as_is++;
	}

	/*
	 * We do at least one level of search if
	 *	- there is no dot and RES_DEFNAME is set, or
	 *	- there is at least one dot, there is no trailing dot,
	 *	  and RES_DNSRCH is set.
	 */
	if ((!dots && (_res.options & RES_DEFNAMES)) ||
	    (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
		int done = 0;

		for (domain = (const char * const *)_res.dnsrch;
		   *domain && !done;
		   domain++) {

			ret = res_querydomain(name, *domain, class, type,
			    answer, anslen);
			if (ret > 0)
				return (ret);

			/*
			 * If no server present, give up.
			 * If name isn't found in this domain,
			 * keep trying higher domains in the search list
			 * (if that's enabled).
			 * On a NO_DATA error, keep trying, otherwise
			 * a wildcard entry of another type could keep us
			 * from finding this entry higher in the domain.
			 * If we get some other error (negative answer or
			 * server failure), then stop searching up,
			 * but try the input name below in case it's
			 * fully-qualified.
			 */
			if (errno == ECONNREFUSED) {
				h_errno = TRY_AGAIN;
				return (-1);
			}

			switch (h_errno) {
			case NO_DATA:
				got_nodata++;
				/* FALLTHROUGH */
			case HOST_NOT_FOUND:
				/* keep trying */
				break;
			case TRY_AGAIN:
				if (hp->rcode == SERVFAIL) {
					/* try next search element, if any */
					got_servfail++;
					break;
				}
				/* FALLTHROUGH */
			default:
				/* anything else implies that we're done */
				done++;
			}
			/*
			 * if we got here for some reason other than DNSRCH,
			 * we only wanted one iteration of the loop, so stop.
			 */
			if (!(_res.options & RES_DNSRCH))
				done++;
		}
	}

	/*
	 * if we have not already tried the name "as is", do that now.
	 * note that we do this regardless of how many dots were in the
	 * name or whether it ends with a dot.
	 */
	if (!tried_as_is) {
		ret = res_querydomain(name, NULL, class, type, answer, anslen);
		if (ret > 0)
			return (ret);
	}