Minimal changes to bring the resolver into the C++ era
It took surprisingly few changes, considering the leap from C with some
K&R constructs to C++17; most of the diffs are adding explicit pointer
casts and renaming variables called 'class' or 'try'.
As a result of building as C++, some of the names are now mangled,
making clashes with bionic harder. However, some names remain C due to
the __BEGIN_DECLS / __END_DECLS macros, scheduled to be removed in a
later cleanup pass.
Test: atest netd_integration_test
Change-Id: I3aefb9078421ec42f98f97d917785b365545feba
diff --git a/resolv/getaddrinfo.cpp b/resolv/getaddrinfo.cpp
new file mode 100644
index 0000000..d6912ec
--- /dev/null
+++ b/resolv/getaddrinfo.cpp
@@ -0,0 +1,2028 @@
+/* $NetBSD: getaddrinfo.c,v 1.82 2006/03/25 12:09:40 rpaulo Exp $ */
+/* $KAME: getaddrinfo.c,v 1.29 2000/08/31 17:26:57 itojun Exp $ */
+
+/*
+ * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Issues to be discussed:
+ * - Thread safe-ness must be checked.
+ * - Return values. There are nonstandard return values defined and used
+ * in the source code. This is because RFC2553 is silent about which error
+ * code must be returned for which situation.
+ * - IPv4 classful (shortened) form. RFC2553 is silent about it. XNET 5.2
+ * says to use inet_aton() to convert IPv4 numeric to binary (alows
+ * classful form as a result).
+ * current code - disallow classful form for IPv4 (due to use of inet_pton).
+ * - freeaddrinfo(NULL). RFC2553 is silent about it. XNET 5.2 says it is
+ * invalid.
+ * current code - SEGV on freeaddrinfo(NULL)
+ * Note:
+ * - We use getipnodebyname() just for thread-safeness. There's no intent
+ * to let it do PF_UNSPEC (actually we never pass PF_UNSPEC to
+ * getipnodebyname().
+ * - The code filters out AFs that are not supported by the kernel,
+ * when globbing NULL hostname (to loopback, or wildcard). Is it the right
+ * thing to do? What is the relationship with post-RFC2553 AI_ADDRCONFIG
+ * in ai_flags?
+ * - (post-2553) semantics of AI_ADDRCONFIG itself is too vague.
+ * (1) what should we do against numeric hostname (2) what should we do
+ * against NULL hostname (3) what is AI_ADDRCONFIG itself. AF not ready?
+ * non-loopback address configured? global address configured?
+ * - To avoid search order issue, we have a big amount of code duplicate
+ * from gethnamaddr.c and some other places. The issues that there's no
+ * lower layer function to lookup "IPv4 or IPv6" record. Calling
+ * gethostbyname2 from getaddrinfo will end up in wrong search order, as
+ * follows:
+ * - The code makes use of following calls when asked to resolver with
+ * ai_family = PF_UNSPEC:
+ * getipnodebyname(host, AF_INET6);
+ * getipnodebyname(host, AF_INET);
+ * This will result in the following queries if the node is configure to
+ * prefer /etc/hosts than DNS:
+ * lookup /etc/hosts for IPv6 address
+ * lookup DNS for IPv6 address
+ * lookup /etc/hosts for IPv4 address
+ * lookup DNS for IPv4 address
+ * which may not meet people's requirement.
+ * The right thing to happen is to have underlying layer which does
+ * PF_UNSPEC lookup (lookup both) and return chain of addrinfos.
+ * This would result in a bit of code duplicate with _dns_ghbyname() and
+ * friends.
+ */
+
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <net/if.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include "resolv_cache.h"
+#include "resolv_netid.h"
+#include "resolv_private.h"
+
+#include <stdarg.h>
+#include <syslog.h>
+
+#include "nsswitch.h"
+
+typedef union sockaddr_union {
+ struct sockaddr generic;
+ struct sockaddr_in in;
+ struct sockaddr_in6 in6;
+} sockaddr_union;
+
+#define ANY 0
+
+static const char in_addrany[] = {0, 0, 0, 0};
+static const char in_loopback[] = {127, 0, 0, 1};
+static const char in6_addrany[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+static const char in6_loopback[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+
+static const struct afd {
+ int a_af;
+ int a_addrlen;
+ int a_socklen;
+ int a_off;
+ const char* a_addrany;
+ const char* a_loopback;
+ int a_scoped;
+} afdl[] = {
+ {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
+ offsetof(struct sockaddr_in6, sin6_addr), in6_addrany, in6_loopback, 1},
+ {PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
+ offsetof(struct sockaddr_in, sin_addr), in_addrany, in_loopback, 0},
+ {0, 0, 0, 0, NULL, NULL, 0},
+};
+
+struct explore {
+ int e_af;
+ int e_socktype;
+ int e_protocol;
+ const char* e_protostr;
+ int e_wild;
+#define WILD_AF(ex) ((ex)->e_wild & 0x01)
+#define WILD_SOCKTYPE(ex) ((ex)->e_wild & 0x02)
+#define WILD_PROTOCOL(ex) ((ex)->e_wild & 0x04)
+};
+
+static const struct explore explore[] = {
+ {PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07},
+ {PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07},
+ {PF_INET6, SOCK_RAW, ANY, NULL, 0x05},
+ {PF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07},
+ {PF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07},
+ {PF_INET, SOCK_RAW, ANY, NULL, 0x05},
+ {PF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07},
+ {PF_UNSPEC, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07},
+ {PF_UNSPEC, SOCK_RAW, ANY, NULL, 0x05},
+ {-1, 0, 0, NULL, 0},
+};
+
+#define PTON_MAX 16
+
+static const ns_src default_dns_files[] = {
+ {NSSRC_FILES, NS_SUCCESS},
+ {NSSRC_DNS, NS_SUCCESS},
+ {0, 0}
+};
+
+#define MAXPACKET (8 * 1024)
+
+typedef union {
+ HEADER hdr;
+ u_char buf[MAXPACKET];
+} querybuf;
+
+struct res_target {
+ struct res_target* next;
+ const char* name; /* domain name */
+ int qclass, qtype; /* class and type of query */
+ u_char* answer; /* buffer to put answer */
+ int anslen; /* size of answer buffer */
+ int n; /* result length */
+};
+
+static int str2number(const char*);
+static int explore_fqdn(const struct addrinfo*, const char*, const char*, struct addrinfo**,
+ const struct android_net_context*);
+static int explore_null(const struct addrinfo*, const char*, struct addrinfo**);
+static int explore_numeric(const struct addrinfo*, const char*, const char*, struct addrinfo**,
+ const char*);
+static int explore_numeric_scope(const struct addrinfo*, const char*, const char*,
+ struct addrinfo**);
+static int get_canonname(const struct addrinfo*, struct addrinfo*, const char*);
+static struct addrinfo* get_ai(const struct addrinfo*, const struct afd*, const char*);
+static int get_portmatch(const struct addrinfo*, const char*);
+static int get_port(const struct addrinfo*, const char*, int);
+static const struct afd* find_afd(int);
+static int ip6_str2scopeid(const char*, struct sockaddr_in6*, u_int32_t*);
+
+static struct addrinfo* getanswer(const querybuf*, int, const char*, int, const struct addrinfo*);
+static int _dns_getaddrinfo(void*, void*, va_list);
+static void _sethtent(FILE**);
+static void _endhtent(FILE**);
+static struct addrinfo* _gethtent(FILE**, const char*, const struct addrinfo*);
+static int _files_getaddrinfo(void*, void*, va_list);
+static int _find_src_addr(const struct sockaddr*, struct sockaddr*, unsigned, uid_t);
+
+static int res_queryN(const char*, struct res_target*, res_state);
+static int res_searchN(const char*, struct res_target*, res_state);
+static int res_querydomainN(const char*, const char*, struct res_target*, res_state);
+
+static const char* const ai_errlist[] = {
+ "Success",
+ "Address family for hostname not supported", /* EAI_ADDRFAMILY */
+ "Temporary failure in name resolution", /* EAI_AGAIN */
+ "Invalid value for ai_flags", /* EAI_BADFLAGS */
+ "Non-recoverable failure in name resolution", /* EAI_FAIL */
+ "ai_family not supported", /* EAI_FAMILY */
+ "Memory allocation failure", /* EAI_MEMORY */
+ "No address associated with hostname", /* EAI_NODATA */
+ "hostname nor servname provided, or not known", /* EAI_NONAME */
+ "servname not supported for ai_socktype", /* EAI_SERVICE */
+ "ai_socktype not supported", /* EAI_SOCKTYPE */
+ "System error returned in errno", /* EAI_SYSTEM */
+ "Invalid value for hints", /* EAI_BADHINTS */
+ "Resolved protocol is unknown", /* EAI_PROTOCOL */
+ "Argument buffer overflow", /* EAI_OVERFLOW */
+ "Unknown error", /* EAI_MAX */
+};
+
+/* XXX macros that make external reference is BAD. */
+
+#define GET_AI(ai, afd, addr) \
+ do { \
+ /* external reference: pai, error, and label free */ \
+ (ai) = get_ai(pai, (afd), (addr)); \
+ if ((ai) == NULL) { \
+ error = EAI_MEMORY; \
+ goto free; \
+ } \
+ } while (0)
+
+#define GET_PORT(ai, serv) \
+ do { \
+ /* external reference: error and label free */ \
+ error = get_port((ai), (serv), 0); \
+ if (error != 0) goto free; \
+ } while (0)
+
+#define GET_CANONNAME(ai, str) \
+ do { \
+ /* external reference: pai, error and label free */ \
+ error = get_canonname(pai, (ai), (str)); \
+ if (error != 0) goto free; \
+ } while (0)
+
+#define ERR(err) \
+ do { \
+ /* external reference: error, and label bad */ \
+ error = (err); \
+ goto bad; \
+ /*NOTREACHED*/ \
+ } while (0)
+
+#define MATCH_FAMILY(x, y, w) \
+ ((x) == (y) || ((w) && ((x) == PF_UNSPEC || (y) == PF_UNSPEC)))
+#define MATCH(x, y, w) ((x) == (y) || ((w) && ((x) == ANY || (y) == ANY)))
+
+const char* gai_strerror(int ecode) {
+ if (ecode < 0 || ecode > EAI_MAX) ecode = EAI_MAX;
+ return ai_errlist[ecode];
+}
+
+void freeaddrinfo(struct addrinfo* ai) {
+ struct addrinfo* next;
+
+ if (ai == NULL) return;
+
+ do {
+ next = ai->ai_next;
+ if (ai->ai_canonname) free(ai->ai_canonname);
+ /* no need to free(ai->ai_addr) */
+ free(ai);
+ ai = next;
+ } while (ai);
+}
+
+static int str2number(const char* p) {
+ char* ep;
+ unsigned long v;
+
+ assert(p != NULL);
+
+ if (*p == '\0') return -1;
+ ep = NULL;
+ errno = 0;
+ v = strtoul(p, &ep, 10);
+ if (errno == 0 && ep && *ep == '\0' && v <= UINT_MAX)
+ return v;
+ else
+ return -1;
+}
+
+/*
+ * The following functions determine whether IPv4 or IPv6 connectivity is
+ * available in order to implement AI_ADDRCONFIG.
+ *
+ * Strictly speaking, AI_ADDRCONFIG should not look at whether connectivity is
+ * available, but whether addresses of the specified family are "configured
+ * on the local system". However, bionic doesn't currently support getifaddrs,
+ * so checking for connectivity is the next best thing.
+ */
+static int _have_ipv6(unsigned mark, uid_t uid) {
+ static const struct sockaddr_in6 sin6_test = {
+ .sin6_family = AF_INET6,
+ .sin6_addr.s6_addr = {// 2000::
+ 0x20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+ sockaddr_union addr = {.in6 = sin6_test};
+ return _find_src_addr(&addr.generic, NULL, mark, uid) == 1;
+}
+
+static int _have_ipv4(unsigned mark, uid_t uid) {
+ static const struct sockaddr_in sin_test = {
+ .sin_family = AF_INET,
+ .sin_addr.s_addr = __constant_htonl(0x08080808L) // 8.8.8.8
+ };
+ sockaddr_union addr = {.in = sin_test};
+ return _find_src_addr(&addr.generic, NULL, mark, uid) == 1;
+}
+
+bool readBE32(FILE* fp, int32_t* result) {
+ int32_t tmp;
+ if (fread(&tmp, sizeof(tmp), 1, fp) != 1) {
+ return false;
+ }
+ *result = ntohl(tmp);
+ return true;
+}
+
+int getaddrinfo(const char* hostname, const char* servname, const struct addrinfo* hints,
+ struct addrinfo** res) {
+ return android_getaddrinfofornet(hostname, servname, hints, NETID_UNSET, MARK_UNSET, res);
+}
+
+int android_getaddrinfofornet(const char* hostname, const char* servname,
+ const struct addrinfo* hints, unsigned netid, unsigned mark,
+ struct addrinfo** res) {
+ struct android_net_context netcontext = {
+ .app_netid = netid,
+ .app_mark = mark,
+ .dns_netid = netid,
+ .dns_mark = mark,
+ .uid = NET_CONTEXT_INVALID_UID,
+ };
+ return android_getaddrinfofornetcontext(hostname, servname, hints, &netcontext, res);
+}
+
+int android_getaddrinfofornetcontext(const char* hostname, const char* servname,
+ const struct addrinfo* hints,
+ const struct android_net_context* netcontext,
+ struct addrinfo** res) {
+ struct addrinfo sentinel;
+ struct addrinfo* cur;
+ int error = 0;
+ struct addrinfo ai;
+ struct addrinfo ai0;
+ struct addrinfo* pai;
+ const struct explore* ex;
+
+ /* hostname is allowed to be NULL */
+ /* servname is allowed to be NULL */
+ /* hints is allowed to be NULL */
+ assert(res != NULL);
+ assert(netcontext != NULL);
+ memset(&sentinel, 0, sizeof(sentinel));
+ cur = &sentinel;
+ pai = &ai;
+ pai->ai_flags = 0;
+ pai->ai_family = PF_UNSPEC;
+ pai->ai_socktype = ANY;
+ pai->ai_protocol = ANY;
+ pai->ai_addrlen = 0;
+ pai->ai_canonname = NULL;
+ pai->ai_addr = NULL;
+ pai->ai_next = NULL;
+
+ if (hostname == NULL && servname == NULL) return EAI_NONAME;
+ if (hints) {
+ /* error check for hints */
+ if (hints->ai_addrlen || hints->ai_canonname || hints->ai_addr || hints->ai_next)
+ ERR(EAI_BADHINTS); /* xxx */
+ if (hints->ai_flags & ~AI_MASK) ERR(EAI_BADFLAGS);
+ switch (hints->ai_family) {
+ case PF_UNSPEC:
+ case PF_INET:
+ case PF_INET6:
+ break;
+ default:
+ ERR(EAI_FAMILY);
+ }
+ memcpy(pai, hints, sizeof(*pai));
+
+ /*
+ * if both socktype/protocol are specified, check if they
+ * are meaningful combination.
+ */
+ if (pai->ai_socktype != ANY && pai->ai_protocol != ANY) {
+ for (ex = explore; ex->e_af >= 0; ex++) {
+ if (pai->ai_family != ex->e_af) continue;
+ if (ex->e_socktype == ANY) continue;
+ if (ex->e_protocol == ANY) continue;
+ if (pai->ai_socktype == ex->e_socktype && pai->ai_protocol != ex->e_protocol) {
+ ERR(EAI_BADHINTS);
+ }
+ }
+ }
+ }
+
+ /*
+ * check for special cases. (1) numeric servname is disallowed if
+ * socktype/protocol are left unspecified. (2) servname is disallowed
+ * for raw and other inet{,6} sockets.
+ */
+ if (MATCH_FAMILY(pai->ai_family, PF_INET, 1)
+ || MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
+ ) {
+ ai0 = *pai; /* backup *pai */
+
+ if (pai->ai_family == PF_UNSPEC) {
+ pai->ai_family = PF_INET6;
+ }
+ error = get_portmatch(pai, servname);
+ if (error) ERR(error);
+
+ *pai = ai0;
+ }
+
+ ai0 = *pai;
+
+ /* NULL hostname, or numeric hostname */
+ for (ex = explore; ex->e_af >= 0; ex++) {
+ *pai = ai0;
+
+ /* PF_UNSPEC entries are prepared for DNS queries only */
+ if (ex->e_af == PF_UNSPEC) continue;
+
+ if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex))) continue;
+ if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex))) continue;
+ if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex))) continue;
+
+ if (pai->ai_family == PF_UNSPEC) pai->ai_family = ex->e_af;
+ if (pai->ai_socktype == ANY && ex->e_socktype != ANY) pai->ai_socktype = ex->e_socktype;
+ if (pai->ai_protocol == ANY && ex->e_protocol != ANY) pai->ai_protocol = ex->e_protocol;
+
+ if (hostname == NULL)
+ error = explore_null(pai, servname, &cur->ai_next);
+ else
+ error = explore_numeric_scope(pai, hostname, servname, &cur->ai_next);
+
+ if (error) goto free;
+
+ while (cur->ai_next) cur = cur->ai_next;
+ }
+
+ /*
+ * XXX
+ * If numeric representation of AF1 can be interpreted as FQDN
+ * representation of AF2, we need to think again about the code below.
+ */
+ if (sentinel.ai_next) goto good;
+
+ if (hostname == NULL) ERR(EAI_NODATA);
+ if (pai->ai_flags & AI_NUMERICHOST) ERR(EAI_NONAME);
+
+ /*
+ * hostname as alphabetical name.
+ * we would like to prefer AF_INET6 than AF_INET, so we'll make a
+ * outer loop by AFs.
+ */
+ for (ex = explore; ex->e_af >= 0; ex++) {
+ *pai = ai0;
+
+ /* require exact match for family field */
+ if (pai->ai_family != ex->e_af) continue;
+
+ if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex))) {
+ continue;
+ }
+ if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex))) {
+ continue;
+ }
+
+ if (pai->ai_socktype == ANY && ex->e_socktype != ANY) pai->ai_socktype = ex->e_socktype;
+ if (pai->ai_protocol == ANY && ex->e_protocol != ANY) pai->ai_protocol = ex->e_protocol;
+
+ error = explore_fqdn(pai, hostname, servname, &cur->ai_next, netcontext);
+
+ while (cur && cur->ai_next) cur = cur->ai_next;
+ }
+
+ /* XXX */
+ if (sentinel.ai_next) error = 0;
+
+ if (error) goto free;
+ if (error == 0) {
+ if (sentinel.ai_next) {
+ good:
+ *res = sentinel.ai_next;
+ return 0;
+ } else
+ error = EAI_FAIL;
+ }
+free:
+bad:
+ if (sentinel.ai_next) freeaddrinfo(sentinel.ai_next);
+ *res = NULL;
+ return error;
+}
+
+// FQDN hostname, DNS lookup
+static int explore_fqdn(const struct addrinfo* pai, const char* hostname, const char* servname,
+ struct addrinfo** res, const struct android_net_context* netcontext) {
+ struct addrinfo* result;
+ struct addrinfo* cur;
+ int error = 0;
+ static const ns_dtab dtab[] = {
+ {NSSRC_FILES, _files_getaddrinfo, NULL},
+ {NSSRC_DNS, _dns_getaddrinfo, NULL},
+ {0, 0, 0}
+ };
+
+ assert(pai != NULL);
+ /* hostname may be NULL */
+ /* servname may be NULL */
+ assert(res != NULL);
+
+ result = NULL;
+
+ /*
+ * if the servname does not match socktype/protocol, ignore it.
+ */
+ if (get_portmatch(pai, servname) != 0) return 0;
+
+ switch (nsdispatch(&result, dtab, NSDB_HOSTS, "getaddrinfo", default_dns_files, hostname, pai,
+ netcontext)) {
+ case NS_TRYAGAIN:
+ error = EAI_AGAIN;
+ goto free;
+ case NS_UNAVAIL:
+ error = EAI_FAIL;
+ goto free;
+ case NS_NOTFOUND:
+ error = EAI_NODATA;
+ goto free;
+ case NS_SUCCESS:
+ error = 0;
+ for (cur = result; cur; cur = cur->ai_next) {
+ GET_PORT(cur, servname);
+ /* canonname should be filled already */
+ }
+ break;
+ }
+
+ *res = result;
+
+ return 0;
+
+free:
+ if (result) freeaddrinfo(result);
+ return error;
+}
+
+/*
+ * hostname == NULL.
+ * passive socket -> anyaddr (0.0.0.0 or ::)
+ * non-passive socket -> localhost (127.0.0.1 or ::1)
+ */
+static int explore_null(const struct addrinfo* pai, const char* servname, struct addrinfo** res) {
+ int s;
+ const struct afd* afd;
+ struct addrinfo* cur;
+ struct addrinfo sentinel;
+ int error;
+
+ assert(pai != NULL);
+ /* servname may be NULL */
+ assert(res != NULL);
+
+ *res = NULL;
+ sentinel.ai_next = NULL;
+ cur = &sentinel;
+
+ /*
+ * filter out AFs that are not supported by the kernel
+ * XXX errno?
+ */
+ s = socket(pai->ai_family, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+ if (s < 0) {
+ if (errno != EMFILE) return 0;
+ } else
+ close(s);
+
+ /*
+ * if the servname does not match socktype/protocol, ignore it.
+ */
+ if (get_portmatch(pai, servname) != 0) return 0;
+
+ afd = find_afd(pai->ai_family);
+ if (afd == NULL) return 0;
+
+ if (pai->ai_flags & AI_PASSIVE) {
+ GET_AI(cur->ai_next, afd, afd->a_addrany);
+ /* xxx meaningless?
+ * GET_CANONNAME(cur->ai_next, "anyaddr");
+ */
+ GET_PORT(cur->ai_next, servname);
+ } else {
+ GET_AI(cur->ai_next, afd, afd->a_loopback);
+ /* xxx meaningless?
+ * GET_CANONNAME(cur->ai_next, "localhost");
+ */
+ GET_PORT(cur->ai_next, servname);
+ }
+ cur = cur->ai_next;
+
+ *res = sentinel.ai_next;
+ return 0;
+
+free:
+ if (sentinel.ai_next) freeaddrinfo(sentinel.ai_next);
+ return error;
+}
+
+/*
+ * numeric hostname
+ */
+static int explore_numeric(const struct addrinfo* pai, const char* hostname, const char* servname,
+ struct addrinfo** res, const char* canonname) {
+ const struct afd* afd;
+ struct addrinfo* cur;
+ struct addrinfo sentinel;
+ int error;
+ char pton[PTON_MAX];
+
+ assert(pai != NULL);
+ /* hostname may be NULL */
+ /* servname may be NULL */
+ assert(res != NULL);
+
+ *res = NULL;
+ sentinel.ai_next = NULL;
+ cur = &sentinel;
+
+ /*
+ * if the servname does not match socktype/protocol, ignore it.
+ */
+ if (get_portmatch(pai, servname) != 0) return 0;
+
+ afd = find_afd(pai->ai_family);
+ if (afd == NULL) return 0;
+
+ switch (afd->a_af) {
+#if 0 /*X/Open spec*/
+ case AF_INET:
+ if (inet_aton(hostname, (struct in_addr *)pton) == 1) {
+ if (pai->ai_family == afd->a_af ||
+ pai->ai_family == PF_UNSPEC /*?*/) {
+ GET_AI(cur->ai_next, afd, pton);
+ GET_PORT(cur->ai_next, servname);
+ if ((pai->ai_flags & AI_CANONNAME)) {
+ /*
+ * Set the numeric address itself as
+ * the canonical name, based on a
+ * clarification in rfc2553bis-03.
+ */
+ GET_CANONNAME(cur->ai_next, canonname);
+ }
+ while (cur && cur->ai_next)
+ cur = cur->ai_next;
+ } else
+ ERR(EAI_FAMILY); /*xxx*/
+ }
+ break;
+#endif
+ default:
+ if (inet_pton(afd->a_af, hostname, pton) == 1) {
+ if (pai->ai_family == afd->a_af || pai->ai_family == PF_UNSPEC /*?*/) {
+ GET_AI(cur->ai_next, afd, pton);
+ GET_PORT(cur->ai_next, servname);
+ if ((pai->ai_flags & AI_CANONNAME)) {
+ /*
+ * Set the numeric address itself as
+ * the canonical name, based on a
+ * clarification in rfc2553bis-03.
+ */
+ GET_CANONNAME(cur->ai_next, canonname);
+ }
+ while (cur->ai_next) cur = cur->ai_next;
+ } else
+ ERR(EAI_FAMILY); /*xxx*/
+ }
+ break;
+ }
+
+ *res = sentinel.ai_next;
+ return 0;
+
+free:
+bad:
+ if (sentinel.ai_next) freeaddrinfo(sentinel.ai_next);
+ return error;
+}
+
+/*
+ * numeric hostname with scope
+ */
+static int explore_numeric_scope(const struct addrinfo* pai, const char* hostname,
+ const char* servname, struct addrinfo** res) {
+ const struct afd* afd;
+ struct addrinfo* cur;
+ int error;
+ const char *cp, *scope, *addr;
+ struct sockaddr_in6* sin6;
+
+ assert(pai != NULL);
+ /* hostname may be NULL */
+ /* servname may be NULL */
+ assert(res != NULL);
+
+ /*
+ * if the servname does not match socktype/protocol, ignore it.
+ */
+ if (get_portmatch(pai, servname) != 0) return 0;
+
+ afd = find_afd(pai->ai_family);
+ if (afd == NULL) return 0;
+
+ if (!afd->a_scoped) return explore_numeric(pai, hostname, servname, res, hostname);
+
+ cp = strchr(hostname, SCOPE_DELIMITER);
+ if (cp == NULL) return explore_numeric(pai, hostname, servname, res, hostname);
+
+ /*
+ * Handle special case of <scoped_address><delimiter><scope id>
+ */
+ char* hostname2 = strdup(hostname);
+ if (hostname2 == NULL) return EAI_MEMORY;
+ /* terminate at the delimiter */
+ hostname2[cp - hostname] = '\0';
+ addr = hostname2;
+ scope = cp + 1;
+
+ error = explore_numeric(pai, addr, servname, res, hostname);
+ if (error == 0) {
+ u_int32_t scopeid;
+
+ for (cur = *res; cur; cur = cur->ai_next) {
+ if (cur->ai_family != AF_INET6) continue;
+ sin6 = (struct sockaddr_in6*) (void*) cur->ai_addr;
+ if (ip6_str2scopeid(scope, sin6, &scopeid) == -1) {
+ free(hostname2);
+ return (EAI_NODATA); /* XXX: is return OK? */
+ }
+ sin6->sin6_scope_id = scopeid;
+ }
+ }
+
+ free(hostname2);
+
+ return error;
+}
+
+static int get_canonname(const struct addrinfo* pai, struct addrinfo* ai, const char* str) {
+ assert(pai != NULL);
+ assert(ai != NULL);
+ assert(str != NULL);
+
+ if ((pai->ai_flags & AI_CANONNAME) != 0) {
+ ai->ai_canonname = strdup(str);
+ if (ai->ai_canonname == NULL) return EAI_MEMORY;
+ }
+ return 0;
+}
+
+static struct addrinfo* get_ai(const struct addrinfo* pai, const struct afd* afd,
+ const char* addr) {
+ char* p;
+ struct addrinfo* ai;
+
+ assert(pai != NULL);
+ assert(afd != NULL);
+ assert(addr != NULL);
+
+ ai = (struct addrinfo*) malloc(sizeof(struct addrinfo) + (afd->a_socklen));
+ if (ai == NULL) return NULL;
+
+ memcpy(ai, pai, sizeof(struct addrinfo));
+ ai->ai_addr = (struct sockaddr*) (void*) (ai + 1);
+ memset(ai->ai_addr, 0, (size_t) afd->a_socklen);
+
+ ai->ai_addrlen = afd->a_socklen;
+#if defined(__alpha__) || (defined(__i386__) && defined(_LP64)) || defined(__sparc64__)
+ ai->__ai_pad0 = 0;
+#endif
+ ai->ai_addr->sa_family = ai->ai_family = afd->a_af;
+ p = (char*) (void*) (ai->ai_addr);
+ memcpy(p + afd->a_off, addr, (size_t) afd->a_addrlen);
+ return ai;
+}
+
+static int get_portmatch(const struct addrinfo* ai, const char* servname) {
+ assert(ai != NULL);
+ /* servname may be NULL */
+
+ return get_port(ai, servname, 1);
+}
+
+static int get_port(const struct addrinfo* ai, const char* servname, int matchonly) {
+ const char* proto;
+ struct servent* sp;
+ int port;
+ int allownumeric;
+
+ assert(ai != NULL);
+ /* servname may be NULL */
+
+ if (servname == NULL) return 0;
+ switch (ai->ai_family) {
+ case AF_INET:
+ case AF_INET6:
+ break;
+ default:
+ return 0;
+ }
+
+ switch (ai->ai_socktype) {
+ case SOCK_RAW:
+ return EAI_SERVICE;
+ case SOCK_DGRAM:
+ case SOCK_STREAM:
+ allownumeric = 1;
+ break;
+ case ANY:
+ allownumeric = 1;
+ break;
+ default:
+ return EAI_SOCKTYPE;
+ }
+
+ port = str2number(servname);
+ if (port >= 0) {
+ if (!allownumeric) return EAI_SERVICE;
+ if (port < 0 || port > 65535) return EAI_SERVICE;
+ port = htons(port);
+ } else {
+ if (ai->ai_flags & AI_NUMERICSERV) return EAI_NONAME;
+
+ switch (ai->ai_socktype) {
+ case SOCK_DGRAM:
+ proto = "udp";
+ break;
+ case SOCK_STREAM:
+ proto = "tcp";
+ break;
+ default:
+ proto = NULL;
+ break;
+ }
+
+ if ((sp = getservbyname(servname, proto)) == NULL) return EAI_SERVICE;
+ port = sp->s_port;
+ }
+
+ if (!matchonly) {
+ switch (ai->ai_family) {
+ case AF_INET:
+ ((struct sockaddr_in*) (void*) ai->ai_addr)->sin_port = port;
+ break;
+ case AF_INET6:
+ ((struct sockaddr_in6*) (void*) ai->ai_addr)->sin6_port = port;
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static const struct afd* find_afd(int af) {
+ const struct afd* afd;
+
+ if (af == PF_UNSPEC) return NULL;
+ for (afd = afdl; afd->a_af; afd++) {
+ if (afd->a_af == af) return afd;
+ }
+ return NULL;
+}
+
+// Convert a string to a scope identifier.
+static int ip6_str2scopeid(const char* scope, struct sockaddr_in6* sin6, u_int32_t* scopeid) {
+ u_long lscopeid;
+ struct in6_addr* a6;
+ char* ep;
+
+ assert(scope != NULL);
+ assert(sin6 != NULL);
+ assert(scopeid != NULL);
+
+ a6 = &sin6->sin6_addr;
+
+ /* empty scopeid portion is invalid */
+ if (*scope == '\0') return -1;
+
+ if (IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) {
+ /*
+ * We currently assume a one-to-one mapping between links
+ * and interfaces, so we simply use interface indices for
+ * like-local scopes.
+ */
+ *scopeid = if_nametoindex(scope);
+ if (*scopeid == 0) goto trynumeric;
+ return 0;
+ }
+
+ /* still unclear about literal, allow numeric only - placeholder */
+ if (IN6_IS_ADDR_SITELOCAL(a6) || IN6_IS_ADDR_MC_SITELOCAL(a6)) goto trynumeric;
+ if (IN6_IS_ADDR_MC_ORGLOCAL(a6))
+ goto trynumeric;
+ else
+ goto trynumeric; /* global */
+
+ /* try to convert to a numeric id as a last resort */
+trynumeric:
+ errno = 0;
+ lscopeid = strtoul(scope, &ep, 10);
+ *scopeid = (u_int32_t)(lscopeid & 0xffffffffUL);
+ if (errno == 0 && ep && *ep == '\0' && *scopeid == lscopeid)
+ return 0;
+ else
+ return -1;
+}
+
+/* code duplicate with gethnamaddr.c */
+
+static const char AskedForGot[] = "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
+
+#define BOUNDED_INCR(x) \
+ do { \
+ BOUNDS_CHECK(cp, x); \
+ cp += (x); \
+ } while (0)
+
+#define BOUNDS_CHECK(ptr, count) \
+ do { \
+ if (eom - (ptr) < (count)) { \
+ h_errno = NO_RECOVERY; \
+ return NULL; \
+ } \
+ } while (0)
+
+static struct addrinfo* getanswer(const querybuf* answer, int anslen, const char* qname, int qtype,
+ const struct addrinfo* pai) {
+ struct addrinfo sentinel, *cur;
+ struct addrinfo ai;
+ const struct afd* afd;
+ char* canonname;
+ const HEADER* hp;
+ const u_char* cp;
+ int n;
+ const u_char* eom;
+ char *bp, *ep;
+ int type, ancount, qdcount;
+ int haveanswer, had_error;
+ char tbuf[MAXDNAME];
+ int (*name_ok)(const char*);
+ char hostbuf[8 * 1024];
+
+ assert(answer != NULL);
+ assert(qname != NULL);
+ assert(pai != NULL);
+
+ memset(&sentinel, 0, sizeof(sentinel));
+ cur = &sentinel;
+
+ canonname = NULL;
+ eom = answer->buf + anslen;
+ switch (qtype) {
+ case T_A:
+ case T_AAAA:
+ case T_ANY: /*use T_ANY only for T_A/T_AAAA lookup*/
+ name_ok = res_hnok;
+ break;
+ default:
+ return NULL; /* XXX should be abort(); */
+ }
+ /*
+ * find first satisfactory answer
+ */
+ hp = &answer->hdr;
+ ancount = ntohs(hp->ancount);
+ qdcount = ntohs(hp->qdcount);
+ bp = hostbuf;
+ ep = hostbuf + sizeof hostbuf;
+ cp = answer->buf;
+ BOUNDED_INCR(HFIXEDSZ);
+ if (qdcount != 1) {
+ h_errno = NO_RECOVERY;
+ return (NULL);
+ }
+ n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
+ if ((n < 0) || !(*name_ok)(bp)) {
+ h_errno = NO_RECOVERY;
+ return (NULL);
+ }
+ BOUNDED_INCR(n + QFIXEDSZ);
+ if (qtype == T_A || qtype == T_AAAA || qtype == T_ANY) {
+ /* res_send() has already verified that the query name is the
+ * same as the one we sent; this just gets the expanded name
+ * (i.e., with the succeeding search-domain tacked on).
+ */
+ n = strlen(bp) + 1; /* for the \0 */
+ if (n >= MAXHOSTNAMELEN) {
+ h_errno = NO_RECOVERY;
+ return (NULL);
+ }
+ canonname = bp;
+ bp += n;
+ /* The qname can be abbreviated, but h_name is now absolute. */
+ qname = canonname;
+ }
+ haveanswer = 0;
+ had_error = 0;
+ while (ancount-- > 0 && cp < eom && !had_error) {
+ n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
+ if ((n < 0) || !(*name_ok)(bp)) {
+ had_error++;
+ continue;
+ }
+ cp += n; /* name */
+ BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
+ type = _getshort(cp);
+ cp += INT16SZ; /* type */
+ int cl = _getshort(cp);
+ cp += INT16SZ + INT32SZ; /* class, TTL */
+ n = _getshort(cp);
+ cp += INT16SZ; /* len */
+ BOUNDS_CHECK(cp, n);
+ if (cl != C_IN) {
+ /* XXX - debug? syslog? */
+ cp += n;
+ continue; /* XXX - had_error++ ? */
+ }
+ if ((qtype == T_A || qtype == T_AAAA || qtype == T_ANY) && type == T_CNAME) {
+ n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
+ if ((n < 0) || !(*name_ok)(tbuf)) {
+ had_error++;
+ continue;
+ }
+ cp += n;
+ /* Get canonical name. */
+ n = strlen(tbuf) + 1; /* for the \0 */
+ if (n > ep - bp || n >= MAXHOSTNAMELEN) {
+ had_error++;
+ continue;
+ }
+ strlcpy(bp, tbuf, (size_t)(ep - bp));
+ canonname = bp;
+ bp += n;
+ continue;
+ }
+ if (qtype == T_ANY) {
+ if (!(type == T_A || type == T_AAAA)) {
+ cp += n;
+ continue;
+ }
+ } else if (type != qtype) {
+ if (type != T_KEY && type != T_SIG)
+ syslog(LOG_NOTICE | LOG_AUTH,
+ "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"", qname,
+ p_class(C_IN), p_type(qtype), p_type(type));
+ cp += n;
+ continue; /* XXX - had_error++ ? */
+ }
+ switch (type) {
+ case T_A:
+ case T_AAAA:
+ if (strcasecmp(canonname, bp) != 0) {
+ syslog(LOG_NOTICE | LOG_AUTH, AskedForGot, canonname, bp);
+ cp += n;
+ continue; /* XXX - had_error++ ? */
+ }
+ if (type == T_A && n != INADDRSZ) {
+ cp += n;
+ continue;
+ }
+ if (type == T_AAAA && n != IN6ADDRSZ) {
+ cp += n;
+ continue;
+ }
+ if (type == T_AAAA) {
+ struct in6_addr in6;
+ memcpy(&in6, cp, IN6ADDRSZ);
+ if (IN6_IS_ADDR_V4MAPPED(&in6)) {
+ cp += n;
+ continue;
+ }
+ }
+ if (!haveanswer) {
+ int nn;
+
+ canonname = bp;
+ nn = strlen(bp) + 1; /* for the \0 */
+ bp += nn;
+ }
+
+ /* don't overwrite pai */
+ ai = *pai;
+ ai.ai_family = (type == T_A) ? AF_INET : AF_INET6;
+ afd = find_afd(ai.ai_family);
+ if (afd == NULL) {
+ cp += n;
+ continue;
+ }
+ cur->ai_next = get_ai(&ai, afd, (const char*) cp);
+ if (cur->ai_next == NULL) had_error++;
+ while (cur && cur->ai_next) cur = cur->ai_next;
+ cp += n;
+ break;
+ default:
+ abort();
+ }
+ if (!had_error) haveanswer++;
+ }
+ if (haveanswer) {
+ if (!canonname)
+ (void) get_canonname(pai, sentinel.ai_next, qname);
+ else
+ (void) get_canonname(pai, sentinel.ai_next, canonname);
+ h_errno = NETDB_SUCCESS;
+ return sentinel.ai_next;
+ }
+
+ h_errno = NO_RECOVERY;
+ return NULL;
+}
+
+struct addrinfo_sort_elem {
+ struct addrinfo* ai;
+ int has_src_addr;
+ sockaddr_union src_addr;
+ int original_order;
+};
+
+static int _get_scope(const struct sockaddr* addr) {
+ if (addr->sa_family == AF_INET6) {
+ const struct sockaddr_in6* addr6 = (const struct sockaddr_in6*) addr;
+ if (IN6_IS_ADDR_MULTICAST(&addr6->sin6_addr)) {
+ return IPV6_ADDR_MC_SCOPE(&addr6->sin6_addr);
+ } else if (IN6_IS_ADDR_LOOPBACK(&addr6->sin6_addr) ||
+ IN6_IS_ADDR_LINKLOCAL(&addr6->sin6_addr)) {
+ /*
+ * RFC 4291 section 2.5.3 says loopback is to be treated as having
+ * link-local scope.
+ */
+ return IPV6_ADDR_SCOPE_LINKLOCAL;
+ } else if (IN6_IS_ADDR_SITELOCAL(&addr6->sin6_addr)) {
+ return IPV6_ADDR_SCOPE_SITELOCAL;
+ } else {
+ return IPV6_ADDR_SCOPE_GLOBAL;
+ }
+ } else if (addr->sa_family == AF_INET) {
+ const struct sockaddr_in* addr4 = (const struct sockaddr_in*) addr;
+ unsigned long int na = ntohl(addr4->sin_addr.s_addr);
+
+ if (IN_LOOPBACK(na) || /* 127.0.0.0/8 */
+ (na & 0xffff0000) == 0xa9fe0000) { /* 169.254.0.0/16 */
+ return IPV6_ADDR_SCOPE_LINKLOCAL;
+ } else {
+ /*
+ * RFC 6724 section 3.2. Other IPv4 addresses, including private addresses
+ * and shared addresses (100.64.0.0/10), are assigned global scope.
+ */
+ return IPV6_ADDR_SCOPE_GLOBAL;
+ }
+ } else {
+ /*
+ * This should never happen.
+ * Return a scope with low priority as a last resort.
+ */
+ return IPV6_ADDR_SCOPE_NODELOCAL;
+ }
+}
+
+/* These macros are modelled after the ones in <netinet/in6.h>. */
+
+/* RFC 4380, section 2.6 */
+#define IN6_IS_ADDR_TEREDO(a) \
+ ((*(const uint32_t*) (const void*) (&(a)->s6_addr[0]) == ntohl(0x20010000)))
+
+/* RFC 3056, section 2. */
+#define IN6_IS_ADDR_6TO4(a) (((a)->s6_addr[0] == 0x20) && ((a)->s6_addr[1] == 0x02))
+
+/* 6bone testing address area (3ffe::/16), deprecated in RFC 3701. */
+#define IN6_IS_ADDR_6BONE(a) (((a)->s6_addr[0] == 0x3f) && ((a)->s6_addr[1] == 0xfe))
+
+/*
+ * Get the label for a given IPv4/IPv6 address.
+ * RFC 6724, section 2.1.
+ */
+
+static int _get_label(const struct sockaddr* addr) {
+ if (addr->sa_family == AF_INET) {
+ return 4;
+ } else if (addr->sa_family == AF_INET6) {
+ const struct sockaddr_in6* addr6 = (const struct sockaddr_in6*) addr;
+ if (IN6_IS_ADDR_LOOPBACK(&addr6->sin6_addr)) {
+ return 0;
+ } else if (IN6_IS_ADDR_V4MAPPED(&addr6->sin6_addr)) {
+ return 4;
+ } else if (IN6_IS_ADDR_6TO4(&addr6->sin6_addr)) {
+ return 2;
+ } else if (IN6_IS_ADDR_TEREDO(&addr6->sin6_addr)) {
+ return 5;
+ } else if (IN6_IS_ADDR_ULA(&addr6->sin6_addr)) {
+ return 13;
+ } else if (IN6_IS_ADDR_V4COMPAT(&addr6->sin6_addr)) {
+ return 3;
+ } else if (IN6_IS_ADDR_SITELOCAL(&addr6->sin6_addr)) {
+ return 11;
+ } else if (IN6_IS_ADDR_6BONE(&addr6->sin6_addr)) {
+ return 12;
+ } else {
+ /* All other IPv6 addresses, including global unicast addresses. */
+ return 1;
+ }
+ } else {
+ /*
+ * This should never happen.
+ * Return a semi-random label as a last resort.
+ */
+ return 1;
+ }
+}
+
+/*
+ * Get the precedence for a given IPv4/IPv6 address.
+ * RFC 6724, section 2.1.
+ */
+
+static int _get_precedence(const struct sockaddr* addr) {
+ if (addr->sa_family == AF_INET) {
+ return 35;
+ } else if (addr->sa_family == AF_INET6) {
+ const struct sockaddr_in6* addr6 = (const struct sockaddr_in6*) addr;
+ if (IN6_IS_ADDR_LOOPBACK(&addr6->sin6_addr)) {
+ return 50;
+ } else if (IN6_IS_ADDR_V4MAPPED(&addr6->sin6_addr)) {
+ return 35;
+ } else if (IN6_IS_ADDR_6TO4(&addr6->sin6_addr)) {
+ return 30;
+ } else if (IN6_IS_ADDR_TEREDO(&addr6->sin6_addr)) {
+ return 5;
+ } else if (IN6_IS_ADDR_ULA(&addr6->sin6_addr)) {
+ return 3;
+ } else if (IN6_IS_ADDR_V4COMPAT(&addr6->sin6_addr) ||
+ IN6_IS_ADDR_SITELOCAL(&addr6->sin6_addr) ||
+ IN6_IS_ADDR_6BONE(&addr6->sin6_addr)) {
+ return 1;
+ } else {
+ /* All other IPv6 addresses, including global unicast addresses. */
+ return 40;
+ }
+ } else {
+ return 1;
+ }
+}
+
+/*
+ * Find number of matching initial bits between the two addresses a1 and a2.
+ */
+
+static int _common_prefix_len(const struct in6_addr* a1, const struct in6_addr* a2) {
+ const char* p1 = (const char*) a1;
+ const char* p2 = (const char*) a2;
+ unsigned i;
+
+ for (i = 0; i < sizeof(*a1); ++i) {
+ int x, j;
+
+ if (p1[i] == p2[i]) {
+ continue;
+ }
+ x = p1[i] ^ p2[i];
+ for (j = 0; j < CHAR_BIT; ++j) {
+ if (x & (1 << (CHAR_BIT - 1))) {
+ return i * CHAR_BIT + j;
+ }
+ x <<= 1;
+ }
+ }
+ return sizeof(*a1) * CHAR_BIT;
+}
+
+/*
+ * Compare two source/destination address pairs.
+ * RFC 6724, section 6.
+ */
+
+static int _rfc6724_compare(const void* ptr1, const void* ptr2) {
+ const struct addrinfo_sort_elem* a1 = (const struct addrinfo_sort_elem*) ptr1;
+ const struct addrinfo_sort_elem* a2 = (const struct addrinfo_sort_elem*) ptr2;
+ int scope_src1, scope_dst1, scope_match1;
+ int scope_src2, scope_dst2, scope_match2;
+ int label_src1, label_dst1, label_match1;
+ int label_src2, label_dst2, label_match2;
+ int precedence1, precedence2;
+ int prefixlen1, prefixlen2;
+
+ /* Rule 1: Avoid unusable destinations. */
+ if (a1->has_src_addr != a2->has_src_addr) {
+ return a2->has_src_addr - a1->has_src_addr;
+ }
+
+ /* Rule 2: Prefer matching scope. */
+ scope_src1 = _get_scope(&a1->src_addr.generic);
+ scope_dst1 = _get_scope(a1->ai->ai_addr);
+ scope_match1 = (scope_src1 == scope_dst1);
+
+ scope_src2 = _get_scope(&a2->src_addr.generic);
+ scope_dst2 = _get_scope(a2->ai->ai_addr);
+ scope_match2 = (scope_src2 == scope_dst2);
+
+ if (scope_match1 != scope_match2) {
+ return scope_match2 - scope_match1;
+ }
+
+ /*
+ * Rule 3: Avoid deprecated addresses.
+ * TODO(sesse): We don't currently have a good way of finding this.
+ */
+
+ /*
+ * Rule 4: Prefer home addresses.
+ * TODO(sesse): We don't currently have a good way of finding this.
+ */
+
+ /* Rule 5: Prefer matching label. */
+ label_src1 = _get_label(&a1->src_addr.generic);
+ label_dst1 = _get_label(a1->ai->ai_addr);
+ label_match1 = (label_src1 == label_dst1);
+
+ label_src2 = _get_label(&a2->src_addr.generic);
+ label_dst2 = _get_label(a2->ai->ai_addr);
+ label_match2 = (label_src2 == label_dst2);
+
+ if (label_match1 != label_match2) {
+ return label_match2 - label_match1;
+ }
+
+ /* Rule 6: Prefer higher precedence. */
+ precedence1 = _get_precedence(a1->ai->ai_addr);
+ precedence2 = _get_precedence(a2->ai->ai_addr);
+ if (precedence1 != precedence2) {
+ return precedence2 - precedence1;
+ }
+
+ /*
+ * Rule 7: Prefer native transport.
+ * TODO(sesse): We don't currently have a good way of finding this.
+ */
+
+ /* Rule 8: Prefer smaller scope. */
+ if (scope_dst1 != scope_dst2) {
+ return scope_dst1 - scope_dst2;
+ }
+
+ /*
+ * Rule 9: Use longest matching prefix.
+ * We implement this for IPv6 only, as the rules in RFC 6724 don't seem
+ * to work very well directly applied to IPv4. (glibc uses information from
+ * the routing table for a custom IPv4 implementation here.)
+ */
+ if (a1->has_src_addr && a1->ai->ai_addr->sa_family == AF_INET6 && a2->has_src_addr &&
+ a2->ai->ai_addr->sa_family == AF_INET6) {
+ const struct sockaddr_in6* a1_src = &a1->src_addr.in6;
+ const struct sockaddr_in6* a1_dst = (const struct sockaddr_in6*) a1->ai->ai_addr;
+ const struct sockaddr_in6* a2_src = &a2->src_addr.in6;
+ const struct sockaddr_in6* a2_dst = (const struct sockaddr_in6*) a2->ai->ai_addr;
+ prefixlen1 = _common_prefix_len(&a1_src->sin6_addr, &a1_dst->sin6_addr);
+ prefixlen2 = _common_prefix_len(&a2_src->sin6_addr, &a2_dst->sin6_addr);
+ if (prefixlen1 != prefixlen2) {
+ return prefixlen2 - prefixlen1;
+ }
+ }
+
+ /*
+ * Rule 10: Leave the order unchanged.
+ * We need this since qsort() is not necessarily stable.
+ */
+ return a1->original_order - a2->original_order;
+}
+
+/*
+ * Find the source address that will be used if trying to connect to the given
+ * address. src_addr must be large enough to hold a struct sockaddr_in6.
+ *
+ * Returns 1 if a source address was found, 0 if the address is unreachable,
+ * and -1 if a fatal error occurred. If 0 or -1, the contents of src_addr are
+ * undefined.
+ */
+
+static int _find_src_addr(const struct sockaddr* addr, struct sockaddr* src_addr, unsigned mark,
+ uid_t uid) {
+ int sock;
+ int ret;
+ socklen_t len;
+
+ switch (addr->sa_family) {
+ case AF_INET:
+ len = sizeof(struct sockaddr_in);
+ break;
+ case AF_INET6:
+ len = sizeof(struct sockaddr_in6);
+ break;
+ default:
+ /* No known usable source address for non-INET families. */
+ return 0;
+ }
+
+ sock = socket(addr->sa_family, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
+ if (sock == -1) {
+ if (errno == EAFNOSUPPORT) {
+ return 0;
+ } else {
+ return -1;
+ }
+ }
+ if (mark != MARK_UNSET && setsockopt(sock, SOL_SOCKET, SO_MARK, &mark, sizeof(mark)) < 0) {
+ close(sock);
+ return 0;
+ }
+ if (uid > 0 && uid != NET_CONTEXT_INVALID_UID && fchown(sock, uid, (gid_t) -1) < 0) {
+ close(sock);
+ return 0;
+ }
+ do {
+ ret = connect(sock, addr, len);
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret == -1) {
+ close(sock);
+ return 0;
+ }
+
+ if (src_addr && getsockname(sock, src_addr, &len) == -1) {
+ close(sock);
+ return -1;
+ }
+ close(sock);
+ return 1;
+}
+
+/*
+ * Sort the linked list starting at sentinel->ai_next in RFC6724 order.
+ * Will leave the list unchanged if an error occurs.
+ */
+
+static void _rfc6724_sort(struct addrinfo* list_sentinel, unsigned mark, uid_t uid) {
+ struct addrinfo* cur;
+ int nelem = 0, i;
+ struct addrinfo_sort_elem* elems;
+
+ cur = list_sentinel->ai_next;
+ while (cur) {
+ ++nelem;
+ cur = cur->ai_next;
+ }
+
+ elems = (struct addrinfo_sort_elem*) malloc(nelem * sizeof(struct addrinfo_sort_elem));
+ if (elems == NULL) {
+ goto error;
+ }
+
+ /*
+ * Convert the linked list to an array that also contains the candidate
+ * source address for each destination address.
+ */
+ for (i = 0, cur = list_sentinel->ai_next; i < nelem; ++i, cur = cur->ai_next) {
+ int has_src_addr;
+ assert(cur != NULL);
+ elems[i].ai = cur;
+ elems[i].original_order = i;
+
+ has_src_addr = _find_src_addr(cur->ai_addr, &elems[i].src_addr.generic, mark, uid);
+ if (has_src_addr == -1) {
+ goto error;
+ }
+ elems[i].has_src_addr = has_src_addr;
+ }
+
+ /* Sort the addresses, and rearrange the linked list so it matches the sorted order. */
+ qsort((void*) elems, nelem, sizeof(struct addrinfo_sort_elem), _rfc6724_compare);
+
+ list_sentinel->ai_next = elems[0].ai;
+ for (i = 0; i < nelem - 1; ++i) {
+ elems[i].ai->ai_next = elems[i + 1].ai;
+ }
+ elems[nelem - 1].ai->ai_next = NULL;
+
+error:
+ free(elems);
+}
+
+static int _dns_getaddrinfo(void* rv, void* /*cb_data*/, va_list ap) {
+ struct addrinfo* ai;
+ const char* name;
+ const struct addrinfo* pai;
+ struct addrinfo sentinel, *cur;
+ struct res_target q, q2;
+ res_state res;
+ const struct android_net_context* netcontext;
+
+ name = va_arg(ap, char*);
+ pai = va_arg(ap, const struct addrinfo*);
+ netcontext = va_arg(ap, const struct android_net_context*);
+ // fprintf(stderr, "_dns_getaddrinfo() name = '%s'\n", name);
+
+ memset(&q, 0, sizeof(q));
+ memset(&q2, 0, sizeof(q2));
+ memset(&sentinel, 0, sizeof(sentinel));
+ cur = &sentinel;
+
+ querybuf* buf = (querybuf*) malloc(sizeof(*buf));
+ if (buf == NULL) {
+ h_errno = NETDB_INTERNAL;
+ return NS_NOTFOUND;
+ }
+ querybuf* buf2 = (querybuf*) malloc(sizeof(*buf2));
+ if (buf2 == NULL) {
+ free(buf);
+ h_errno = NETDB_INTERNAL;
+ return NS_NOTFOUND;
+ }
+
+ switch (pai->ai_family) {
+ case AF_UNSPEC: {
+ /* prefer IPv6 */
+ q.name = name;
+ q.qclass = C_IN;
+ q.answer = buf->buf;
+ q.anslen = sizeof(buf->buf);
+ int query_ipv6 = 1, query_ipv4 = 1;
+ if (pai->ai_flags & AI_ADDRCONFIG) {
+ query_ipv6 = _have_ipv6(netcontext->app_mark, netcontext->uid);
+ query_ipv4 = _have_ipv4(netcontext->app_mark, netcontext->uid);
+ }
+ if (query_ipv6) {
+ q.qtype = T_AAAA;
+ if (query_ipv4) {
+ q.next = &q2;
+ q2.name = name;
+ q2.qclass = C_IN;
+ q2.qtype = T_A;
+ q2.answer = buf2->buf;
+ q2.anslen = sizeof(buf2->buf);
+ }
+ } else if (query_ipv4) {
+ q.qtype = T_A;
+ } else {
+ free(buf);
+ free(buf2);
+ return NS_NOTFOUND;
+ }
+ break;
+ }
+ case AF_INET:
+ q.name = name;
+ q.qclass = C_IN;
+ q.qtype = T_A;
+ q.answer = buf->buf;
+ q.anslen = sizeof(buf->buf);
+ break;
+ case AF_INET6:
+ q.name = name;
+ q.qclass = C_IN;
+ q.qtype = T_AAAA;
+ q.answer = buf->buf;
+ q.anslen = sizeof(buf->buf);
+ break;
+ default:
+ free(buf);
+ free(buf2);
+ return NS_UNAVAIL;
+ }
+
+ res = __res_get_state();
+ if (res == NULL) {
+ free(buf);
+ free(buf2);
+ return NS_NOTFOUND;
+ }
+
+ /* this just sets our netid val in the thread private data so we don't have to
+ * modify the api's all the way down to res_send.c's res_nsend. We could
+ * fully populate the thread private data here, but if we get down there
+ * and have a cache hit that would be wasted, so we do the rest there on miss
+ */
+ res_setnetcontext(res, netcontext);
+ if (res_searchN(name, &q, res) < 0) {
+ __res_put_state(res);
+ free(buf);
+ free(buf2);
+ return NS_NOTFOUND;
+ }
+ ai = getanswer(buf, q.n, q.name, q.qtype, pai);
+ if (ai) {
+ cur->ai_next = ai;
+ while (cur && cur->ai_next) cur = cur->ai_next;
+ }
+ if (q.next) {
+ ai = getanswer(buf2, q2.n, q2.name, q2.qtype, pai);
+ if (ai) cur->ai_next = ai;
+ }
+ free(buf);
+ free(buf2);
+ if (sentinel.ai_next == NULL) {
+ __res_put_state(res);
+ switch (h_errno) {
+ case HOST_NOT_FOUND:
+ return NS_NOTFOUND;
+ case TRY_AGAIN:
+ return NS_TRYAGAIN;
+ default:
+ return NS_UNAVAIL;
+ }
+ }
+
+ _rfc6724_sort(&sentinel, netcontext->app_mark, netcontext->uid);
+
+ __res_put_state(res);
+
+ *((struct addrinfo**) rv) = sentinel.ai_next;
+ return NS_SUCCESS;
+}
+
+static void _sethtent(FILE** hostf) {
+ if (!*hostf)
+ *hostf = fopen(_PATH_HOSTS, "re");
+ else
+ rewind(*hostf);
+}
+
+static void _endhtent(FILE** hostf) {
+ if (*hostf) {
+ (void) fclose(*hostf);
+ *hostf = NULL;
+ }
+}
+
+static struct addrinfo* _gethtent(FILE** hostf, const char* name, const struct addrinfo* pai) {
+ char* p;
+ char *cp, *tname, *cname;
+ struct addrinfo hints, *res0, *res;
+ int error;
+ const char* addr;
+ char hostbuf[8 * 1024];
+
+ // fprintf(stderr, "_gethtent() name = '%s'\n", name);
+ assert(name != NULL);
+ assert(pai != NULL);
+
+ if (!*hostf && !(*hostf = fopen(_PATH_HOSTS, "re"))) return (NULL);
+again:
+ if (!(p = fgets(hostbuf, sizeof hostbuf, *hostf))) return (NULL);
+ if (*p == '#') goto again;
+ if (!(cp = strpbrk(p, "#\n"))) goto again;
+ *cp = '\0';
+ if (!(cp = strpbrk(p, " \t"))) goto again;
+ *cp++ = '\0';
+ addr = p;
+ /* if this is not something we're looking for, skip it. */
+ cname = NULL;
+ while (cp && *cp) {
+ if (*cp == ' ' || *cp == '\t') {
+ cp++;
+ continue;
+ }
+ if (!cname) cname = cp;
+ tname = cp;
+ if ((cp = strpbrk(cp, " \t")) != NULL) *cp++ = '\0';
+ // fprintf(stderr, "\ttname = '%s'", tname);
+ if (strcasecmp(name, tname) == 0) goto found;
+ }
+ goto again;
+
+found:
+ hints = *pai;
+ hints.ai_flags = AI_NUMERICHOST;
+ error = getaddrinfo(addr, NULL, &hints, &res0);
+ if (error) goto again;
+ for (res = res0; res; res = res->ai_next) {
+ /* cover it up */
+ res->ai_flags = pai->ai_flags;
+
+ if (pai->ai_flags & AI_CANONNAME) {
+ if (get_canonname(pai, res, cname) != 0) {
+ freeaddrinfo(res0);
+ goto again;
+ }
+ }
+ }
+ return res0;
+}
+
+static int _files_getaddrinfo(void* rv, void* /*cb_data*/, va_list ap) {
+ const char* name;
+ const struct addrinfo* pai;
+ struct addrinfo sentinel, *cur;
+ struct addrinfo* p;
+ FILE* hostf = NULL;
+
+ name = va_arg(ap, char*);
+ pai = va_arg(ap, struct addrinfo*);
+
+ // fprintf(stderr, "_files_getaddrinfo() name = '%s'\n", name);
+ memset(&sentinel, 0, sizeof(sentinel));
+ cur = &sentinel;
+
+ _sethtent(&hostf);
+ while ((p = _gethtent(&hostf, name, pai)) != NULL) {
+ cur->ai_next = p;
+ while (cur && cur->ai_next) cur = cur->ai_next;
+ }
+ _endhtent(&hostf);
+
+ *((struct addrinfo**) rv) = sentinel.ai_next;
+ if (sentinel.ai_next == NULL) return NS_NOTFOUND;
+ return NS_SUCCESS;
+}
+
+/* resolver logic */
+
+/*
+ * Formulate a normal query, send, and await answer.
+ * Returned answer is placed in supplied buffer "answer".
+ * Perform preliminary check of answer, returning success only
+ * if no error is indicated and the answer count is nonzero.
+ * Return the size of the response on success, -1 on error.
+ * Error number is left in h_errno.
+ *
+ * Caller must parse answer and determine whether it answers the question.
+ */
+static int res_queryN(const char* name, /* domain name */ struct res_target* target,
+ res_state res) {
+ u_char buf[MAXPACKET];
+ HEADER* hp;
+ int n;
+ struct res_target* t;
+ int rcode;
+ int ancount;
+
+ assert(name != NULL);
+ /* XXX: target may be NULL??? */
+
+ rcode = NOERROR;
+ ancount = 0;
+
+ for (t = target; t; t = t->next) {
+ u_char* answer;
+ int anslen;
+ u_int oflags;
+
+ hp = (HEADER*) (void*) t->answer;
+ oflags = res->_flags;
+
+ again:
+ hp->rcode = NOERROR; /* default */
+
+ /* make it easier... */
+ int cl = t->qclass;
+ int type = t->qtype;
+ answer = t->answer;
+ anslen = t->anslen;
+#ifdef DEBUG
+ if (res->options & RES_DEBUG) printf(";; res_nquery(%s, %d, %d)\n", name, cl, type);
+#endif
+
+ n = res_nmkquery(res, QUERY, name, cl, type, NULL, 0, NULL, buf, sizeof(buf));
+ if (n > 0 && (res->_flags & RES_F_EDNS0ERR) == 0 &&
+ (res->options & (RES_USE_EDNS0 | RES_USE_DNSSEC)) != 0)
+ n = res_nopt(res, n, buf, sizeof(buf), anslen);
+ if (n <= 0) {
+#ifdef DEBUG
+ if (res->options & RES_DEBUG) printf(";; res_nquery: mkquery failed\n");
+#endif
+ h_errno = NO_RECOVERY;
+ return n;
+ }
+ n = res_nsend(res, buf, n, answer, anslen);
+
+ if (n < 0 || hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
+ rcode = hp->rcode; /* record most recent error */
+ /* if the query choked with EDNS0, retry without EDNS0 */
+ if ((res->options & (RES_USE_EDNS0 | RES_USE_DNSSEC)) != 0 &&
+ ((oflags ^ res->_flags) & RES_F_EDNS0ERR) != 0) {
+ res->_flags |= RES_F_EDNS0ERR;
+#ifdef DEBUG
+ if (res->options & RES_DEBUG) printf(";; res_nquery: retry without EDNS0\n");
+#endif
+ goto again;
+ }
+#ifdef DEBUG
+ if (res->options & RES_DEBUG)
+ printf(";; rcode = %u, ancount=%u\n", hp->rcode, ntohs(hp->ancount));
+#endif
+ continue;
+ }
+
+ ancount += ntohs(hp->ancount);
+
+ t->n = n;
+ }
+
+ if (ancount == 0) {
+ switch (rcode) {
+ case NXDOMAIN:
+ h_errno = HOST_NOT_FOUND;
+ break;
+ case SERVFAIL:
+ h_errno = TRY_AGAIN;
+ break;
+ case NOERROR:
+ h_errno = NO_DATA;
+ break;
+ case FORMERR:
+ case NOTIMP:
+ case REFUSED:
+ default:
+ h_errno = NO_RECOVERY;
+ break;
+ }
+ return -1;
+ }
+ return ancount;
+}
+
+/*
+ * 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.
+ */
+static int res_searchN(const char* name, struct res_target* target, res_state res) {
+ const char *cp, *const *domain;
+ HEADER* hp;
+ u_int dots;
+ int trailing_dot, ret, saved_herrno;
+ int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
+
+ assert(name != NULL);
+ assert(target != NULL);
+
+ hp = (HEADER*) (void*) target->answer; /*XXX*/
+
+ 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++;
+
+ // fprintf(stderr, "res_searchN() name = '%s'\n", name);
+
+ /*
+ * if there aren't any dots, it could be a user-level alias
+ */
+ if (!dots && (cp = __hostalias(name)) != NULL) {
+ ret = res_queryN(cp, target, res);
+ return ret;
+ }
+
+ /*
+ * 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_querydomainN(name, NULL, target, res);
+ 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;
+
+ /* Unfortunately we need to set stuff up before
+ * the domain stuff is tried. Will have a better
+ * fix after thread pools are used.
+ */
+ _resolv_populate_res_for_net(res);
+
+ for (domain = (const char* const*) res->dnsrch; *domain && !done; domain++) {
+ ret = res_querydomainN(name, *domain, target, res);
+ 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_querydomainN(name, NULL, target, res);
+ if (ret > 0) return ret;
+ }
+
+ /*
+ * if we got here, we didn't satisfy the search.
+ * if we did an initial full query, return that query's h_errno
+ * (note that we wouldn't be here if that query had succeeded).
+ * else if we ever got a nodata, send that back as the reason.
+ * else send back meaningless h_errno, that being the one from
+ * the last DNSRCH we did.
+ */
+ if (saved_herrno != -1)
+ h_errno = saved_herrno;
+ else if (got_nodata)
+ h_errno = NO_DATA;
+ else if (got_servfail)
+ h_errno = TRY_AGAIN;
+ return -1;
+}
+
+/*
+ * Perform a call on res_query on the concatenation of name and domain,
+ * removing a trailing dot from name if domain is NULL.
+ */
+static int res_querydomainN(const char* name, const char* domain, struct res_target* target,
+ res_state res) {
+ char nbuf[MAXDNAME];
+ const char* longname = nbuf;
+ size_t n, d;
+
+ assert(name != NULL);
+ /* XXX: target may be NULL??? */
+
+#ifdef DEBUG
+ if (res->options & RES_DEBUG)
+ printf(";; res_querydomain(%s, %s)\n", name, domain ? domain : "<Nil>");
+#endif
+ if (domain == NULL) {
+ /*
+ * Check for trailing '.';
+ * copy without '.' if present.
+ */
+ n = strlen(name);
+ if (n + 1 > sizeof(nbuf)) {
+ h_errno = NO_RECOVERY;
+ return -1;
+ }
+ if (n > 0 && name[--n] == '.') {
+ strncpy(nbuf, name, n);
+ nbuf[n] = '\0';
+ } else
+ longname = name;
+ } else {
+ n = strlen(name);
+ d = strlen(domain);
+ if (n + 1 + d + 1 > sizeof(nbuf)) {
+ h_errno = NO_RECOVERY;
+ return -1;
+ }
+ snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain);
+ }
+ return res_queryN(longname, target, res);
+}