For the multicast_dns only mode, be very restrictive in what lookups we
try. No point in making queries and waiting for timeouts on lookups that will never succeed. Now only does lookups for linklocal addresses (v4 or v6) and "name.local" names (and dotless names, iff "local" is specified in the resolv.conf search list). Also, lower the timeout in this mode, since multicast lookups should return pretty fast or not at all.
This commit is contained in:
tsarna
parent
3c3a7b7603
commit
29822c6b8b
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@ -1,4 +1,4 @@
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/* $NetBSD: nss_mdnsd.c,v 1.1 2009/10/25 00:17:06 tsarna Exp $ */
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/* $NetBSD: nss_mdnsd.c,v 1.2 2009/10/26 00:46:19 tsarna Exp $ */
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/*-
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* Copyright (c) 2009 The NetBSD Foundation, Inc.
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@ -85,14 +85,9 @@ typedef struct addrinfo_ctx {
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#define HCTX_BUFLEFT(c) (sizeof((c)->buf) - ((c)->next - (c)->buf))
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typedef struct search_domain {
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const char *name;
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bool enabled;
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} search_domain;
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typedef struct search_iter {
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const char *name;
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search_domain *next_search;
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char **next_search;
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size_t baselen;
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bool abs_first;
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bool abs_last;
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@ -102,7 +97,7 @@ typedef struct search_iter {
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static hostent_ctx h_ctx;
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static DNSServiceFlags svc_flags = 0;
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static int ndots = 1, timeout = 1000;
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static search_domain *search_domains, *no_search;
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static char **search_domains, **no_search;
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ns_mtab *nss_module_register(const char *, u_int *, nss_module_unregister_fn *);
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static int load_config(res_state);
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@ -136,6 +131,7 @@ static char *_mdns_rdata2name(const unsigned char *, uint16_t,
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void search_init(search_iter *, const char *);
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const char *search_next(search_iter *);
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bool searchable_domain(char *);
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@ -153,8 +149,6 @@ nss_module_register(const char *source, u_int *nelems,
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{
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res_state res;
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UNUSED(unreg);
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*nelems = sizeof(mtab) / sizeof(mtab[0]);
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*unreg = NULL;
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@ -179,16 +173,27 @@ load_config(res_state res)
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int count = 0;
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char **sd;
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ndots = res->ndots;
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timeout = res->retrans * 1000; /* retrans in sec to timeout in msec */
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/* free old search list, if any */
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if ((no_search = search_domains)) {
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for (; *no_search; no_search++) {
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free(*no_search);
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}
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free(search_domains);
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}
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/* new search list */
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sd = res->dnsrch;
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while (*sd) {
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count++;
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if (searchable_domain(*sd)) {
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count++;
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}
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sd++;
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}
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search_domains = malloc(sizeof(search_domain) * (count + 1));
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search_domains = calloc(sizeof(char *), count + 1);
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if (!search_domains) {
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return -1;
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}
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@ -196,15 +201,24 @@ load_config(res_state res)
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sd = res->dnsrch;
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no_search = search_domains;
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while (*sd) {
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no_search->name = *sd;
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no_search->enabled =
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(svc_flags & kDNSServiceFlagsForceMulticast) ? true : true;
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no_search++;
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if (searchable_domain(*sd)) {
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*no_search = strdup(*sd);
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no_search++;
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}
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sd++;
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}
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/* terminate list */
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no_search->name = NULL;
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/* retrans in sec to timeout in msec */
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timeout = res->retrans * 1000;
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if (svc_flags & kDNSServiceFlagsForceMulticast) {
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ndots = 1;
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if (timeout > 2000) {
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timeout = 2000;
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}
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} else {
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ndots = res->ndots;
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}
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}
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@ -243,6 +257,14 @@ _mdns_getaddrinfo(void *cbrv, void *cbdata, va_list ap)
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return NS_UNAVAIL;
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}
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search_init(&iter, name);
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sname = search_next(&iter);
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if (!sname) {
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h_errno = HOST_NOT_FOUND;
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return NS_NOTFOUND;
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}
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/* use one connection for all searches */
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if (DNSServiceCreateConnection(&sdRef)) {
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h_errno = NETDB_INTERNAL;
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@ -250,9 +272,7 @@ _mdns_getaddrinfo(void *cbrv, void *cbdata, va_list ap)
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}
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_mdns_addrinfo_init(&ctx, pai);
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search_init(&iter, name);
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sname = search_next(&iter);
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while (sname && (err != NS_SUCCESS)) {
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err = _mdns_getaddrinfo_abs(sname, proto, sdRef, &ctx);
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if (err != NS_SUCCESS) {
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@ -279,7 +299,7 @@ _mdns_getaddrinfo_abs(const char *name, DNSServiceProtocol proto,
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err = DNSServiceGetAddrInfo(
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&sdRef,
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svc_flags,
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svc_flags | kDNSServiceFlagsReturnIntermediates,
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kDNSServiceInterfaceIndexAny,
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proto,
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name,
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@ -291,7 +311,6 @@ _mdns_getaddrinfo_abs(const char *name, DNSServiceProtocol proto,
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h_errno = NETDB_INTERNAL;
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return NS_UNAVAIL;
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}
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_mdns_eventloop(sdRef, (void *)ctx);
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DNSServiceRefDeallocate(sdRef);
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@ -324,12 +343,28 @@ _mdns_gethtbyaddr(void *cbrv, void *cbdata, va_list ap)
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switch (af) {
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case AF_INET:
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/* if mcast-only don't bother for non-LinkLocal addrs) */
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if (svc_flags & kDNSServiceFlagsForceMulticast) {
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if ((addr[0] != 169) || (addr[1] != 254)) {
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h_errno = HOST_NOT_FOUND;
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return NS_NOTFOUND;
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}
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}
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(void)snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa",
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(addr[3] & 0xff), (addr[2] & 0xff),
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(addr[1] & 0xff), (addr[0] & 0xff));
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break;
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case AF_INET6:
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/* if mcast-only don't bother for non-LinkLocal addrs) */
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if (svc_flags & kDNSServiceFlagsForceMulticast) {
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if ((addr[0] != 0xfe) || ((addr[1] & 0xc0) != 0x80)) {
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h_errno = HOST_NOT_FOUND;
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return NS_NOTFOUND;
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}
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}
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qp = qbuf;
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ep = qbuf + sizeof(qbuf) - 1;
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for (n = IN6ADDRSZ - 1; n >= 0; n--) {
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@ -417,7 +452,15 @@ _mdns_gethtbyname(void *cbrv, void *cbdata, va_list ap)
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break;
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default:
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h_errno = NETDB_INTERNAL;
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h_errno = NO_RECOVERY;
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return NS_UNAVAIL;
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}
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search_init(&iter, name);
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sname = search_next(&iter);
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if (!sname) {
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h_errno = HOST_NOT_FOUND;
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return NS_NOTFOUND;
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}
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@ -428,9 +471,7 @@ _mdns_gethtbyname(void *cbrv, void *cbdata, va_list ap)
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}
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_mdns_hostent_init(&h_ctx, af, addrlen);
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search_init(&iter, name);
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sname = search_next(&iter);
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while (sname && (err != NS_SUCCESS)) {
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err = _mdns_gethtbyname_abs(sname, rrtype, sdRef);
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if (err != NS_SUCCESS) {
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@ -458,7 +499,7 @@ _mdns_gethtbyname_abs(const char *name, int rrtype, DNSServiceRef sdRef)
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err = DNSServiceQueryRecord(
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&sdRef,
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svc_flags,
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svc_flags | kDNSServiceFlagsReturnIntermediates,
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kDNSServiceInterfaceIndexAny,
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name,
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rrtype,
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@ -642,7 +683,6 @@ _mdns_addrinfo_cb(
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UNUSED(sdRef);
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UNUSED(interfaceIndex);
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UNUSED(hostname);
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UNUSED(ttl);
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if (errorCode == kDNSServiceErr_NoError) {
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@ -723,6 +763,8 @@ _mdns_hostent_cb(
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}
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break;
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}
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} else if (errorCode == kDNSServiceErr_NoSuchRecord) {
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ctx->cb_ctx.done = true;
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}
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}
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@ -820,35 +862,52 @@ _mdns_rdata2name(const unsigned char *rdata, uint16_t rdlen, char *buf, size_t b
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void
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search_init(search_iter *iter, const char *name)
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{
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const char *c = name;
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bool enddot = false;
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int dots = 0;
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const char *c = name, *cmp;
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int dots = 0, enddot = 0;
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size_t len, cl;
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iter->name = name;
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iter->baselen = 0;
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iter->abs_first = iter->abs_last = false;
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iter->next_search = search_domains;
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while (*c) {
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if (*c == '.') {
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dots++;
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enddot = true;
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enddot = 1;
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} else {
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enddot = false;
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enddot = 0;
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}
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c++;
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}
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if (dots >= ndots) {
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iter->abs_first = true;
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iter->abs_last = false;
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if (svc_flags & kDNSServiceFlagsForceMulticast) {
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if (dots) {
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iter->next_search = no_search;
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if ((dots - enddot) == 1) {
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len = strlen(iter->name);
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cl = strlen(".local") + enddot;
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if (len > cl) {
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cmp = enddot ? ".local." : ".local";
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c = iter->name + len - cl;
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if (!strcasecmp(c, cmp)) {
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iter->abs_first = true;
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}
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}
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}
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}
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} else {
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iter->abs_first = false;
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iter->abs_last = true;
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}
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if (dots >= ndots) {
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iter->abs_first = true;
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} else {
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iter->abs_last = true;
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}
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if (enddot) {
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iter->next_search = no_search;
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} else {
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iter->next_search = search_domains;
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if (enddot) {
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/* absolute; don't search */
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iter->next_search = no_search;
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}
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}
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}
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@ -866,34 +925,30 @@ search_next(search_iter *iter)
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return iter->name;
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}
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while (iter->next_search->name) {
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if (iter->next_search->enabled) {
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if (!iter->baselen) {
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iter->baselen = strlcpy(iter->buf, iter->name, sizeof(iter->buf));
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if (iter->baselen >= sizeof(iter->buf) - 1) {
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/* original is too long, don't try any search domains */
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iter->next_search = no_search;
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break;
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}
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iter->buf[iter->baselen++] = '.';
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while (*(iter->next_search)) {
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if (!iter->baselen) {
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iter->baselen = strlcpy(iter->buf, iter->name, sizeof(iter->buf));
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if (iter->baselen >= sizeof(iter->buf) - 1) {
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/* original is too long, don't try any search domains */
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iter->next_search = no_search;
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break;
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}
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len = strlcpy(&(iter->buf[iter->baselen]),
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iter->next_search->name,
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sizeof(iter->buf) - iter->baselen);
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iter->next_search++;
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if (len >= sizeof(iter->buf) - iter->baselen) {
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/* result would be too long */
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continue;
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}
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return iter->buf;
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} else {
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iter->next_search++;
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iter->buf[iter->baselen++] = '.';
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}
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len = strlcpy(&(iter->buf[iter->baselen]),
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*(iter->next_search),
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sizeof(iter->buf) - iter->baselen);
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iter->next_search++;
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if (len >= sizeof(iter->buf) - iter->baselen) {
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/* result was too long */
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continue;
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}
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return iter->buf;
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}
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if (iter->abs_last) {
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@ -903,3 +958,24 @@ search_next(search_iter *iter)
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return NULL;
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}
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/*
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* Is domain appropriate to be in the domain search list?
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* For mdnsd, take everything. For multicast_dns, only "local"
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* if present.
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*/
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bool
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searchable_domain(char *d)
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{
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if (!(svc_flags & kDNSServiceFlagsForceMulticast)) {
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return true;
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}
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if (!strcasecmp(d, "local") || !strcasecmp(d, "local.")) {
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return true;
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}
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return false;
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}
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