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curl/lib/hostip.c

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C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2008, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* $Id$
***************************************************************************/
#include "setup.h"
#include <string.h>
#ifdef NEED_MALLOC_H
#include <malloc.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h> /* required for free() prototypes */
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h> /* for the close() proto */
#endif
#ifdef VMS
#include <in.h>
#include <inet.h>
#include <stdlib.h>
#endif
#ifdef HAVE_SETJMP_H
#include <setjmp.h>
#endif
#ifdef HAVE_PROCESS_H
#include <process.h>
#endif
#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "strerror.h"
#include "url.h"
#include "inet_ntop.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
#if defined(HAVE_INET_NTOA_R) && !defined(HAVE_INET_NTOA_R_DECL)
#include "inet_ntoa_r.h"
#endif
#include "memory.h"
/* The last #include file should be: */
#include "memdebug.h"
/*
* hostip.c explained
* ==================
*
* The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
* source file are these:
*
* CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
* that. The host may not be able to resolve IPv6, but we don't really have to
* take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
* defined.
*
* CURLRES_ARES - is defined if libcurl is built to use c-ares for
* asynchronous name resolves. This can be Windows or *nix.
*
* CURLRES_THREADED - is defined if libcurl is built to run under (native)
* Windows, and then the name resolve will be done in a new thread, and the
* supported API will be the same as for ares-builds.
*
* If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
* libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
* defined.
*
* The host*.c sources files are split up like this:
*
* hostip.c - method-independent resolver functions and utility functions
* hostasyn.c - functions for asynchronous name resolves
* hostsyn.c - functions for synchronous name resolves
* hostares.c - functions for ares-using name resolves
* hostthre.c - functions for threaded name resolves
* hostip4.c - ipv4-specific functions
* hostip6.c - ipv6-specific functions
*
* The hostip.h is the united header file for all this. It defines the
* CURLRES_* defines based on the config*.h and setup.h defines.
*/
/* These two symbols are for the global DNS cache */
static struct curl_hash hostname_cache;
static int host_cache_initialized;
static void freednsentry(void *freethis);
/*
* Curl_global_host_cache_init() initializes and sets up a global DNS cache.
* Global DNS cache is general badness. Do not use. This will be removed in
* a future version. Use the share interface instead!
*
* Returns a struct curl_hash pointer on success, NULL on failure.
*/
struct curl_hash *Curl_global_host_cache_init(void)
{
int rc = 0;
if(!host_cache_initialized) {
rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str,
Curl_str_key_compare, freednsentry);
if(!rc)
host_cache_initialized = 1;
}
return rc?NULL:&hostname_cache;
}
/*
* Destroy and cleanup the global DNS cache
*/
void Curl_global_host_cache_dtor(void)
{
if(host_cache_initialized) {
Curl_hash_clean(&hostname_cache);
host_cache_initialized = 0;
}
}
/*
* Return # of adresses in a Curl_addrinfo struct
*/
int Curl_num_addresses(const Curl_addrinfo *addr)
{
int i;
for (i = 0; addr; addr = addr->ai_next, i++)
; /* empty loop */
return i;
}
/*
* Curl_printable_address() returns a printable version of the 1st address
* given in the 'ip' argument. The result will be stored in the buf that is
* bufsize bytes big.
*
* If the conversion fails, it returns NULL.
*/
const char *Curl_printable_address(const Curl_addrinfo *ip,
char *buf, size_t bufsize)
{
const void *ip4 = &((const struct sockaddr_in*)ip->ai_addr)->sin_addr;
int af = ip->ai_family;
#ifdef CURLRES_IPV6
const void *ip6 = &((const struct sockaddr_in6*)ip->ai_addr)->sin6_addr;
#else
const void *ip6 = NULL;
#endif
return Curl_inet_ntop(af, af == AF_INET ? ip4 : ip6, buf, bufsize);
}
/*
* Return a hostcache id string for the providing host + port, to be used by
* the DNS caching.
*/
static char *
create_hostcache_id(const char *server, int port)
{
/* create and return the new allocated entry */
return aprintf("%s:%d", server, port);
}
struct hostcache_prune_data {
long cache_timeout;
time_t now;
};
/*
* This function is set as a callback to be called for every entry in the DNS
* cache when we want to prune old unused entries.
*
* Returning non-zero means remove the entry, return 0 to keep it in the
* cache.
*/
static int
hostcache_timestamp_remove(void *datap, void *hc)
{
struct hostcache_prune_data *data =
(struct hostcache_prune_data *) datap;
struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
if((data->now - c->timestamp < data->cache_timeout) ||
c->inuse) {
/* please don't remove */
return 0;
}
/* fine, remove */
return 1;
}
/*
* Prune the DNS cache. This assumes that a lock has already been taken.
*/
static void
hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
{
struct hostcache_prune_data user;
user.cache_timeout = cache_timeout;
user.now = now;
Curl_hash_clean_with_criterium(hostcache,
(void *) &user,
hostcache_timestamp_remove);
}
/*
* Library-wide function for pruning the DNS cache. This function takes and
* returns the appropriate locks.
*/
void Curl_hostcache_prune(struct SessionHandle *data)
{
time_t now;
if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
/* cache forever means never prune, and NULL hostcache means
we can't do it */
return;
if(data->share)
Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
time(&now);
/* Remove outdated and unused entries from the hostcache */
hostcache_prune(data->dns.hostcache,
data->set.dns_cache_timeout,
now);
if(data->share)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
}
/*
* Check if the entry should be pruned. Assumes a locked cache.
*/
static int
remove_entry_if_stale(struct SessionHandle *data, struct Curl_dns_entry *dns)
{
struct hostcache_prune_data user;
if( !dns || (data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
/* cache forever means never prune, and NULL hostcache means
we can't do it */
return 0;
time(&user.now);
user.cache_timeout = data->set.dns_cache_timeout;
if( !hostcache_timestamp_remove(&user,dns) )
return 0;
Curl_hash_clean_with_criterium(data->dns.hostcache,
(void *) &user,
hostcache_timestamp_remove);
return 1;
}
#ifdef HAVE_SIGSETJMP
/* Beware this is a global and unique instance. This is used to store the
return address that we can jump back to from inside a signal handler. This
is not thread-safe stuff. */
sigjmp_buf curl_jmpenv;
#endif
/*
* Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
*
* When calling Curl_resolv() has resulted in a response with a returned
* address, we call this function to store the information in the dns
* cache etc
*
* Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
*/
struct Curl_dns_entry *
Curl_cache_addr(struct SessionHandle *data,
Curl_addrinfo *addr,
const char *hostname,
int port)
{
char *entry_id;
size_t entry_len;
struct Curl_dns_entry *dns;
struct Curl_dns_entry *dns2;
time_t now;
/* Create an entry id, based upon the hostname and port */
entry_id = create_hostcache_id(hostname, port);
/* If we can't create the entry id, fail */
if(!entry_id)
return NULL;
entry_len = strlen(entry_id);
/* Create a new cache entry */
dns = (struct Curl_dns_entry *) calloc(sizeof(struct Curl_dns_entry), 1);
if(!dns) {
free(entry_id);
return NULL;
}
dns->inuse = 0; /* init to not used */
dns->addr = addr; /* this is the address(es) */
/* Store the resolved data in our DNS cache. This function may return a
pointer to an existing struct already present in the hash, and it may
return the same argument we pass in. Make no assumptions. */
dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1,
(void *)dns);
if(!dns2) {
/* Major badness, run away. */
free(dns);
free(entry_id);
return NULL;
}
time(&now);
dns = dns2;
dns->timestamp = now; /* used now */
dns->inuse++; /* mark entry as in-use */
/* free the allocated entry_id again */
free(entry_id);
return dns;
}
/*
* Curl_resolv() is the main name resolve function within libcurl. It resolves
* a name and returns a pointer to the entry in the 'entry' argument (if one
* is provided). This function might return immediately if we're using asynch
* resolves. See the return codes.
*
* The cache entry we return will get its 'inuse' counter increased when this
* function is used. You MUST call Curl_resolv_unlock() later (when you're
* done using this struct) to decrease the counter again.
*
* Return codes:
*
* CURLRESOLV_ERROR (-1) = error, no pointer
* CURLRESOLV_RESOLVED (0) = OK, pointer provided
* CURLRESOLV_PENDING (1) = waiting for response, no pointer
*/
int Curl_resolv(struct connectdata *conn,
const char *hostname,
int port,
struct Curl_dns_entry **entry)
{
char *entry_id = NULL;
struct Curl_dns_entry *dns = NULL;
size_t entry_len;
struct SessionHandle *data = conn->data;
CURLcode result;
int rc = CURLRESOLV_ERROR; /* default to failure */
*entry = NULL;
#ifdef HAVE_SIGSETJMP
/* this allows us to time-out from the name resolver, as the timeout
will generate a signal and we will siglongjmp() from that here */
if(!data->set.no_signal) {
if(sigsetjmp(curl_jmpenv, 1)) {
/* this is coming from a siglongjmp() */
failf(data, "name lookup timed out");
return rc;
}
}
#endif
/* Create an entry id, based upon the hostname and port */
entry_id = create_hostcache_id(hostname, port);
/* If we can't create the entry id, fail */
if(!entry_id)
return rc;
entry_len = strlen(entry_id);
if(data->share)
Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
/* See if its already in our dns cache */
dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
/* See whether the returned entry is stale. Done before we release lock */
if( remove_entry_if_stale(data, dns) )
dns = NULL; /* the memory deallocation is being handled by the hash */
if(dns) {
dns->inuse++; /* we use it! */
rc = CURLRESOLV_RESOLVED;
}
if(data->share)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
/* free the allocated entry_id again */
free(entry_id);
if(!dns) {
/* The entry was not in the cache. Resolve it to IP address */
Curl_addrinfo *addr;
int respwait;
/* Check what IP specifics the app has requested and if we can provide it.
* If not, bail out. */
if(!Curl_ipvalid(data))
return CURLRESOLV_ERROR;
/* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
non-zero value indicating that we need to wait for the response to the
resolve call */
addr = Curl_getaddrinfo(conn, hostname, port, &respwait);
if(!addr) {
if(respwait) {
/* the response to our resolve call will come asynchronously at
a later time, good or bad */
/* First, check that we haven't received the info by now */
result = Curl_is_resolved(conn, &dns);
if(result) /* error detected */
return CURLRESOLV_ERROR;
if(dns)
rc = CURLRESOLV_RESOLVED; /* pointer provided */
else
rc = CURLRESOLV_PENDING; /* no info yet */
}
}
else {
if(data->share)
Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
/* we got a response, store it in the cache */
dns = Curl_cache_addr(data, addr, hostname, port);
if(data->share)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
if(!dns)
/* returned failure, bail out nicely */
Curl_freeaddrinfo(addr);
else
rc = CURLRESOLV_RESOLVED;
}
}
*entry = dns;
return rc;
}
/*
* Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
* made, the struct may be destroyed due to pruning. It is important that only
* one unlock is made for each Curl_resolv() call.
*/
void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns)
{
DEBUGASSERT(dns && (dns->inuse>0));
if(data->share)
Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
dns->inuse--;
if(data->share)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
}
/*
* File-internal: free a cache dns entry.
*/
static void freednsentry(void *freethis)
{
struct Curl_dns_entry *p = (struct Curl_dns_entry *) freethis;
Curl_freeaddrinfo(p->addr);
free(p);
}
/*
* Curl_mk_dnscache() creates a new DNS cache and returns the handle for it.
*/
struct curl_hash *Curl_mk_dnscache(void)
{
return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry);
}
#ifdef CURLRES_ADDRINFO_COPY
/* align on even 64bit boundaries */
#define MEMALIGN(x) ((x)+(8-(((unsigned long)(x))&0x7)))
/*
* Curl_addrinfo_copy() performs a "deep" copy of a hostent into a buffer and
* returns a pointer to the malloc()ed copy. You need to call free() on the
* returned buffer when you're done with it.
*/
Curl_addrinfo *Curl_addrinfo_copy(const void *org, int port)
{
const struct hostent *orig = org;
return Curl_he2ai(orig, port);
}
#endif /* CURLRES_ADDRINFO_COPY */
/***********************************************************************
* Only for plain-ipv4 and c-ares builds (NOTE: c-ares builds can be IPv6
* enabled)
**********************************************************************/
#if defined(CURLRES_IPV4) || defined(CURLRES_ARES)
/*
* This is a function for freeing name information in a protocol independent
* way.
*/
void Curl_freeaddrinfo(Curl_addrinfo *ai)
{
Curl_addrinfo *next;
/* walk over the list and free all entries */
while(ai) {
next = ai->ai_next;
if(ai->ai_canonname)
free(ai->ai_canonname);
free(ai);
ai = next;
}
}
struct namebuf {
struct hostent hostentry;
char *h_addr_list[2];
struct in_addr addrentry;
char h_name[16]; /* 123.123.123.123 = 15 letters is maximum */
};
/*
* Curl_ip2addr() takes a 32bit ipv4 internet address as input parameter
* together with a pointer to the string version of the address, and it
* returns a Curl_addrinfo chain filled in correctly with information for this
* address/host.
*
* The input parameters ARE NOT checked for validity but they are expected
* to have been checked already when this is called.
*/
Curl_addrinfo *Curl_ip2addr(in_addr_t num, const char *hostname, int port)
{
Curl_addrinfo *ai;
#if defined(VMS) && \
defined(__INITIAL_POINTER_SIZE) && (__INITIAL_POINTER_SIZE == 64)
#pragma pointer_size save
#pragma pointer_size short
#pragma message disable PTRMISMATCH
#endif
struct hostent *h;
struct in_addr *addrentry;
struct namebuf buffer;
struct namebuf *buf = &buffer;
h = &buf->hostentry;
h->h_addr_list = &buf->h_addr_list[0];
addrentry = &buf->addrentry;
#ifdef _CRAYC
/* On UNICOS, s_addr is a bit field and for some reason assigning to it
* doesn't work. There must be a better fix than this ugly hack.
*/
memcpy(addrentry, &num, SIZEOF_in_addr);
#else
addrentry->s_addr = num;
#endif
h->h_addr_list[0] = (char*)addrentry;
h->h_addr_list[1] = NULL;
h->h_addrtype = AF_INET;
h->h_length = sizeof(*addrentry);
h->h_name = &buf->h_name[0];
h->h_aliases = NULL;
/* Now store the dotted version of the address */
snprintf((char *)h->h_name, 16, "%s", hostname);
#if defined(VMS) && \
defined(__INITIAL_POINTER_SIZE) && (__INITIAL_POINTER_SIZE == 64)
#pragma pointer_size restore
#pragma message enable PTRMISMATCH
#endif
ai = Curl_he2ai(h, port);
return ai;
}
/*
* Curl_he2ai() translates from a hostent struct to a Curl_addrinfo struct.
* The Curl_addrinfo is meant to work like the addrinfo struct does for IPv6
* stacks, but for all hosts and environments.
*
* Curl_addrinfo defined in "lib/hostip.h"
*
* struct Curl_addrinfo {
* int ai_flags;
* int ai_family;
* int ai_socktype;
* int ai_protocol;
* socklen_t ai_addrlen; * Follow rfc3493 struct addrinfo *
* char *ai_canonname;
* struct sockaddr *ai_addr;
* struct Curl_addrinfo *ai_next;
* };
*
* hostent defined in <netdb.h>
*
* struct hostent {
* char *h_name;
* char **h_aliases;
* int h_addrtype;
* int h_length;
* char **h_addr_list;
* };
*
* for backward compatibility:
*
* #define h_addr h_addr_list[0]
*/
Curl_addrinfo *Curl_he2ai(const struct hostent *he, int port)
{
Curl_addrinfo *ai;
Curl_addrinfo *prevai = NULL;
Curl_addrinfo *firstai = NULL;
struct sockaddr_in *addr;
#ifdef CURLRES_IPV6
struct sockaddr_in6 *addr6;
#endif /* CURLRES_IPV6 */
int i;
struct in_addr *curr;
if(!he)
/* no input == no output! */
return NULL;
for(i=0; (curr = (struct in_addr *)he->h_addr_list[i]) != NULL; i++) {
int ss_size;
#ifdef CURLRES_IPV6
if (he->h_addrtype == AF_INET6)
ss_size = sizeof (struct sockaddr_in6);
else
#endif /* CURLRES_IPV6 */
ss_size = sizeof (struct sockaddr_in);
ai = calloc(1, sizeof(Curl_addrinfo) + ss_size);
if(!ai)
break;
if(!firstai)
/* store the pointer we want to return from this function */
firstai = ai;
if(prevai)
/* make the previous entry point to this */
prevai->ai_next = ai;
ai->ai_family = he->h_addrtype;
/* we return all names as STREAM, so when using this address for TFTP
the type must be ignored and conn->socktype be used instead! */
ai->ai_socktype = SOCK_STREAM;
ai->ai_addrlen = ss_size;
/* make the ai_addr point to the address immediately following this struct
and use that area to store the address */
ai->ai_addr = (struct sockaddr *) ((char*)ai + sizeof(Curl_addrinfo));
/* need to free this eventually */
ai->ai_canonname = strdup(he->h_name);
/* leave the rest of the struct filled with zero */
switch (ai->ai_family) {
case AF_INET:
addr = (struct sockaddr_in *)ai->ai_addr; /* storage area for this info */
memcpy((char *)&(addr->sin_addr), curr, sizeof(struct in_addr));
addr->sin_family = (unsigned short)(he->h_addrtype);
addr->sin_port = htons((unsigned short)port);
break;
#ifdef CURLRES_IPV6
case AF_INET6:
addr6 = (struct sockaddr_in6 *)ai->ai_addr; /* storage area for this info */
memcpy((char *)&(addr6->sin6_addr), curr, sizeof(struct in6_addr));
addr6->sin6_family = (unsigned short)(he->h_addrtype);
addr6->sin6_port = htons((unsigned short)port);
break;
#endif /* CURLRES_IPV6 */
}
prevai = ai;
}
return firstai;
}
#endif /* CURLRES_IPV4 || CURLRES_ARES */
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