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bionic/libc/netbsd/net/getaddrinfo.c
Brad Fitzpatrick a1dbf0b453 DNS proxy: the start. proxies getaddrinfo calls. 
Will also need to do gethostinfo, but that's probably about it.

It was cleaner to do it at this level, rather than speaking in terms
of DNS packets.

Change-Id: I047cc459979ffb0170a3eb0d432a7e827fb71c26
2010-10-28 11:31:22 -07:00

2351 lines
56 KiB
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/* $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 <fcntl.h>
#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "arpa_nameser.h"
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include "resolv_private.h"
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <syslog.h>
#include <stdarg.h>
#include "nsswitch.h"
typedef union sockaddr_union {
struct sockaddr generic;
struct sockaddr_in in;
struct sockaddr_in6 in6;
} sockaddr_union;
#define SUCCESS 0
#define ANY 0
#define YES 1
#define NO 0
static const char in_addrany[] = { 0, 0, 0, 0 };
static const char in_loopback[] = { 127, 0, 0, 1 };
#ifdef INET6
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
};
#endif
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 [] = {
#ifdef INET6
{PF_INET6, sizeof(struct in6_addr),
sizeof(struct sockaddr_in6),
offsetof(struct sockaddr_in6, sin6_addr),
in6_addrany, in6_loopback, 1},
#endif
{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[] = {
#if 0
{ PF_LOCAL, 0, ANY, ANY, NULL, 0x01 },
#endif
#ifdef INET6
{ PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
{ PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
{ PF_INET6, SOCK_RAW, ANY, NULL, 0x05 },
#endif
{ 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 },
};
#ifdef INET6
#define PTON_MAX 16
#else
#define PTON_MAX 4
#endif
static const ns_src default_dns_files[] = {
{ NSSRC_FILES, NS_SUCCESS },
{ NSSRC_DNS, NS_SUCCESS },
{ 0, 0 }
};
#define MAXPACKET (64*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 **);
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);
#ifdef INET6
static int ip6_str2scopeid(char *, struct sockaddr_in6 *, u_int32_t *);
#endif
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 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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/0)
#define ERR(err) \
do { \
/* external reference: error, and label bad */ \
error = (err); \
goto bad; \
/*NOTREACHED*/ \
} while (/*CONSTCOND*/0)
#define MATCH_FAMILY(x, y, w) \
((x) == (y) || (/*CONSTCOND*/(w) && ((x) == PF_UNSPEC || \
(y) == PF_UNSPEC)))
#define MATCH(x, y, w) \
((x) == (y) || (/*CONSTCOND*/(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;
assert(ai != NULL);
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;
}
/* Determine whether IPv6 connectivity is available. */
static int
_have_ipv6() {
/*
* Connect a UDP socket to an global unicast IPv6 address. This will
* cause no network traffic, but will fail fast if the system has no or
* limited IPv6 connectivity (e.g., only a link-local address).
*/
static const struct sockaddr_in6 sin6_test = {
/* family, port, flow label */
AF_INET6, 0, 0,
/* 2000:: */
{{{ 0x20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }}},
/* scope ID */
0};
sockaddr_union addr_test;
addr_test.in6 = sin6_test;
int s = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
if (s < 0)
return 0;
int ret;
do {
ret = connect(s, &addr_test.generic, sizeof(addr_test.in6));
} while (ret < 0 && errno == EINTR);
int have_ipv6 = (ret == 0);
do {
ret = close(s);
} while (ret < 0 && errno == EINTR);
return have_ipv6;
}
// Returns 0 on success, else returns non-zero on error (in which case
// getaddrinfo should continue as normal)
static int
android_getaddrinfo_proxy(
const char *hostname, const char *servname,
const struct addrinfo *hints, struct addrinfo **res)
{
int sock;
const int one = 1;
struct sockaddr_un proxy_addr;
const char* cache_mode = getenv("ANDROID_DNS_MODE");
FILE* proxy = NULL;
int success = 0;
// Clear this at start, as we use its non-NULLness later (in the
// error path) to decide if we have to free up any memory we
// allocated in the process (before failing).
*res = NULL;
if (cache_mode != NULL && strcmp(cache_mode, "local") == 0) {
// Don't use the proxy in local mode. This is used by the
// proxy itself.
return -1;
}
// Bogus things we can't serialize. Don't use the proxy.
if ((hostname != NULL &&
strcspn(hostname, " \n\r\t^'\"") != strlen(hostname)) ||
(servname != NULL &&
strcspn(servname, " \n\r\t^'\"") != strlen(servname))) {
return -1;
}
sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock < 0) {
return -1;
}
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
memset(&proxy_addr, 0, sizeof(proxy_addr));
proxy_addr.sun_family = AF_UNIX;
strlcpy(proxy_addr.sun_path, "/dev/socket/dnsproxyd",
sizeof(proxy_addr.sun_path));
if (TEMP_FAILURE_RETRY(connect(sock,
(const struct sockaddr*) &proxy_addr,
sizeof(proxy_addr))) != 0) {
close(sock);
return -1;
}
// Send the request.
proxy = fdopen(sock, "r+");
if (fprintf(proxy, "getaddrinfo %s %s %d %d %d %d",
hostname == NULL ? "^" : hostname,
servname == NULL ? "^" : servname,
hints == NULL ? -1 : hints->ai_flags,
hints == NULL ? -1 : hints->ai_family,
hints == NULL ? -1 : hints->ai_socktype,
hints == NULL ? -1 : hints->ai_protocol) < 0) {
goto exit;
}
// literal NULL byte at end, required by FrameworkListener
if (fputc(0, proxy) == EOF ||
fflush(proxy) != 0) {
goto exit;
}
int remote_rv;
if (fread(&remote_rv, sizeof(int), 1, proxy) != 1) {
goto exit;
}
if (remote_rv != 0) {
goto exit;
}
struct addrinfo* ai = NULL;
struct addrinfo** nextres = res;
while (1) {
uint32_t addrinfo_len;
if (fread(&addrinfo_len, sizeof(addrinfo_len),
1, proxy) != 1) {
break;
}
addrinfo_len = ntohl(addrinfo_len);
if (addrinfo_len == 0) {
success = 1;
break;
}
if (addrinfo_len < sizeof(struct addrinfo)) {
break;
}
struct addrinfo* ai = calloc(1, addrinfo_len +
sizeof(struct sockaddr_storage));
if (ai == NULL) {
break;
}
if (fread(ai, addrinfo_len, 1, proxy) != 1) {
// Error; fall through.
break;
}
// Zero out the pointer fields we copied which aren't
// valid in this address space.
ai->ai_addr = NULL;
ai->ai_canonname = NULL;
ai->ai_next = NULL;
// struct sockaddr
uint32_t addr_len;
if (fread(&addr_len, sizeof(addr_len), 1, proxy) != 1) {
break;
}
addr_len = ntohl(addr_len);
if (addr_len != 0) {
if (addr_len > sizeof(struct sockaddr_storage)) {
// Bogus; too big.
break;
}
struct sockaddr* addr = (struct sockaddr*)(ai + 1);
if (fread(addr, addr_len, 1, proxy) != 1) {
break;
}
ai->ai_addr = addr;
}
// cannonname
uint32_t name_len;
if (fread(&name_len, sizeof(name_len), 1, proxy) != 1) {
break;
}
if (name_len != 0) {
ai->ai_canonname = (char*) malloc(name_len);
if (fread(ai->ai_canonname, name_len, 1, proxy) != 1) {
break;
}
if (ai->ai_canonname[name_len - 1] != '\0') {
// The proxy should be returning this
// NULL-terminated.
break;
}
}
*nextres = ai;
nextres = &ai->ai_next;
ai = NULL;
}
if (ai != NULL) {
// Clean up partially-built addrinfo that we never ended up
// attaching to the response.
freeaddrinfo(ai);
}
exit:
if (proxy != NULL) {
fclose(proxy);
}
if (success) {
return 0;
}
// Proxy failed; fall through to local
// resolver case. But first clean up any
// memory we might've allocated.
if (*res) {
freeaddrinfo(*res);
*res = NULL;
}
return -1;
}
int
getaddrinfo(const char *hostname, const char *servname,
const struct addrinfo *hints, 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);
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:
#ifdef INET6
case PF_INET6:
#endif
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)
#ifdef PF_INET6
|| MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
#endif
) {
ai0 = *pai; /* backup *pai */
if (pai->ai_family == PF_UNSPEC) {
#ifdef PF_INET6
pai->ai_family = PF_INET6;
#else
pai->ai_family = PF_INET;
#endif
}
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);
/*
* BEGIN ANDROID CHANGES; proxying to the cache
*/
if (android_getaddrinfo_proxy(hostname, servname, hints, res) == 0) {
return 0;
}
/*
* 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);
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 SUCCESS;
} 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)
{
struct addrinfo *result;
struct addrinfo *cur;
int error = 0;
static const ns_dtab dtab[] = {
NS_FILES_CB(_files_getaddrinfo, NULL)
{ NSSRC_DNS, _dns_getaddrinfo, NULL }, /* force -DHESIOD */
NS_NIS_CB(_yp_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)) {
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, 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)
{
#if !defined(SCOPE_DELIMITER) || !defined(INET6)
return explore_numeric(pai, hostname, servname, res, hostname);
#else
const struct afd *afd;
struct addrinfo *cur;
int error;
char *cp, *hostname2 = NULL, *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>
*/
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;
#endif
}
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);
#ifdef HAVE_SA_LEN
ai->ai_addr->sa_len = afd->a_socklen;
#endif
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:
#ifdef AF_INET6
case AF_INET6:
#endif
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:
#if 1 /* ANDROID-SPECIFIC CHANGE TO MATCH GLIBC */
allownumeric = 1;
#else
allownumeric = 0;
#endif
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;
#ifdef INET6
case AF_INET6:
((struct sockaddr_in6 *)(void *)
ai->ai_addr)->sin6_port = port;
break;
#endif
}
}
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;
}
#ifdef INET6
/* convert a string to a scope identifier. XXX: IPv6 specific */
static int
ip6_str2scopeid(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;
}
#endif
/* code duplicate with gethnamaddr.c */
static const char AskedForGot[] =
"gethostby*.getanswer: asked for \"%s\", got \"%s\"";
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, class, 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 + 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);
}
cp += 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 */
type = _getshort(cp);
cp += INT16SZ; /* type */
class = _getshort(cp);
cp += INT16SZ + INT32SZ; /* class, TTL */
n = _getshort(cp);
cp += INT16SZ; /* len */
if (class != 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;
};
/*ARGSUSED*/
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 if ((na & 0xff000000) == 0x0a000000 || /* 10.0.0.0/8 */
(na & 0xfff00000) == 0xac100000 || /* 172.16.0.0/12 */
(na & 0xffff0000) == 0xc0a80000) { /* 192.168.0.0/16 */
return IPV6_ADDR_SCOPE_SITELOCAL;
} else {
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))
/*
* Get the label for a given IPv4/IPv6 address.
* RFC 3484, section 2.1, plus Teredo added in with label 5.
*/
/*ARGSUSED*/
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_V4COMPAT(&addr6->sin6_addr)) {
return 3;
} else if (IN6_IS_ADDR_TEREDO(&addr6->sin6_addr)) {
return 5;
} else if (IN6_IS_ADDR_6TO4(&addr6->sin6_addr)) {
return 2;
} else {
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 3484, section 2.1, plus Teredo added in with precedence 25.
*/
/*ARGSUSED*/
static int
_get_precedence(const struct sockaddr *addr)
{
if (addr->sa_family == AF_INET) {
return 10;
} 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_V4COMPAT(&addr6->sin6_addr)) {
return 20;
} else if (IN6_IS_ADDR_TEREDO(&addr6->sin6_addr)) {
return 25;
} else if (IN6_IS_ADDR_6TO4(&addr6->sin6_addr)) {
return 30;
} else {
return 40;
}
} else {
return 5;
}
}
/*
* Find number of matching initial bits between the two addresses a1 and a2.
*/
/*ARGSUSED*/
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 3484, section 6.
*/
/*ARGSUSED*/
static int
_rfc3484_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 3484 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.
*/
/*ARGSUSED*/
static int
_find_src_addr(const struct sockaddr *addr, struct sockaddr *src_addr)
{
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, IPPROTO_UDP);
if (sock == -1) {
if (errno == EAFNOSUPPORT) {
return 0;
} else {
return -1;
}
}
do {
ret = connect(sock, addr, len);
} while (ret == -1 && errno == EINTR);
if (ret == -1) {
close(sock);
return 0;
}
if (getsockname(sock, src_addr, &len) == -1) {
close(sock);
return -1;
}
close(sock);
return 1;
}
/*
* Sort the linked list starting at sentinel->ai_next in RFC3484 order.
* Will leave the list unchanged if an error occurs.
*/
/*ARGSUSED*/
static void
_rfc3484_sort(struct addrinfo *list_sentinel)
{
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);
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), _rfc3484_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);
}
/*ARGSUSED*/
static int
_dns_getaddrinfo(void *rv, void *cb_data, va_list ap)
{
struct addrinfo *ai;
querybuf *buf, *buf2;
const char *name;
const struct addrinfo *pai;
struct addrinfo sentinel, *cur;
struct res_target q, q2;
res_state res;
name = va_arg(ap, char *);
pai = va_arg(ap, const struct addrinfo *);
//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;
buf = malloc(sizeof(*buf));
if (buf == NULL) {
h_errno = NETDB_INTERNAL;
return NS_NOTFOUND;
}
buf2 = 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);
/* If AI_ADDRCONFIG, lookup IPv6 only if we have connectivity */
if (!(pai->ai_flags & AI_ADDRCONFIG) || _have_ipv6()) {
q.qtype = T_AAAA;
q.next = &q2;
q2.name = name;
q2.qclass = C_IN;
q2.qtype = T_A;
q2.answer = buf2->buf;
q2.anslen = sizeof(buf2->buf);
} else {
q.qtype = T_A;
}
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;
}
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;
}
}
_rfc3484_sort(&sentinel);
__res_put_state(res);
*((struct addrinfo **)rv) = sentinel.ai_next;
return NS_SUCCESS;
}
static void
_sethtent(FILE **hostf)
{
if (!*hostf)
*hostf = fopen(_PATH_HOSTS, "r" );
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, "r" )))
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;
}
/*ARGSUSED*/
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) {
int class, type;
u_char *answer;
int anslen;
hp = (HEADER *)(void *)t->answer;
hp->rcode = NOERROR; /* default */
/* make it easier... */
class = t->qclass;
type = t->qtype;
answer = t->answer;
anslen = t->anslen;
#ifdef DEBUG
if (res->options & RES_DEBUG)
printf(";; res_nquery(%s, %d, %d)\n", name, class, type);
#endif
n = res_nmkquery(res, QUERY, name, class, type, NULL, 0, NULL,
buf, sizeof(buf));
#ifdef RES_USE_EDNS0
if (n > 0 && (res->options & RES_USE_EDNS0) != 0)
n = res_nopt(res, n, buf, sizeof(buf), anslen);
#endif
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 0
if (n < 0) {
#ifdef DEBUG
if (res->options & RES_DEBUG)
printf(";; res_query: send error\n");
#endif
h_errno = TRY_AGAIN;
return n;
}
#endif
if (n < 0 || hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
rcode = hp->rcode; /* record most recent error */
#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;
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);
}
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