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curl/lib/hostip.c

642 lines
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C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2004, 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>
#include <errno.h>
#define _REENTRANT
#if defined(WIN32) && !defined(__GNUC__) || defined(__MINGW32__)
#include <malloc.h>
#else
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.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
#endif
#ifdef HAVE_SETJMP_H
#include <setjmp.h>
#endif
#ifdef WIN32
#include <process.h>
#endif
#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
#undef in_addr_t
#define in_addr_t unsigned long
#endif
#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "strerror.h"
#include "url.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. It cannot have ENABLE_IPV6 defined at the same
* time, as c-ares has no ipv6 support. 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 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!
*/
void Curl_global_host_cache_init(void)
{
if (!host_cache_initialized) {
Curl_hash_init(&hostname_cache, 7, freednsentry);
host_cache_initialized = 1;
}
}
/*
* Return a pointer to the global cache
*/
curl_hash *Curl_global_host_cache_get(void)
{
return &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;
}
}
/*
* Count the number of characters that an integer would use in a string
* (base 10).
*/
static int _num_chars(int i)
{
int chars = 0;
/* While the number divided by 10 is greater than one,
* re-divide the number by 10, and increment the number of
* characters by 1.
*
* this relies on the fact that for every multiple of 10,
* a new digit is added onto every number
*/
do {
chars++;
i = (int) i / 10;
} while (i >= 1);
return chars;
}
/*
* Return a hostcache id string for the providing host + port, to be used by
* the DNS caching.
*/
static char *
create_hostcache_id(char *server, int port, size_t *entry_len)
{
char *id = NULL;
/* Get the length of the new entry id */
*entry_len = strlen(server) + /* Hostname length */
1 + /* ':' seperator */
_num_chars(port); /* number of characters the port will take up */
/* Allocate the new entry id */
id = malloc(*entry_len + 1); /* 1 extra for the zero terminator */
if (!id)
return NULL;
/* Create the new entry */
sprintf(id, "%s:%d", server, port);
return id; /* return pointer to the string */
}
struct hostcache_prune_data {
int 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(curl_hash *hostcache, int 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)
/* cache forever means never prune! */
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->hostcache,
data->set.dns_cache_timeout,
now);
if(data->share)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
}
#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,
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, &entry_len);
/* If we can't create the entry id, fail */
if (!entry_id)
return NULL;
/* Create a new cache entry */
dns = (struct Curl_dns_entry *) malloc(sizeof(struct Curl_dns_entry));
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->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,
char *hostname,
int port,
struct Curl_dns_entry **entry)
{
char *entry_id = NULL;
struct Curl_dns_entry *dns = NULL;
size_t entry_len;
int wait;
struct SessionHandle *data = conn->data;
CURLcode result;
/* default to failure */
int rc = CURLRESOLV_ERROR;
*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 && sigsetjmp(curl_jmpenv, 1)) {
/* this is coming from a siglongjmp() */
failf(data, "name lookup timed out");
return CURLRESOLV_ERROR;
}
#endif
/* Create an entry id, based upon the hostname and port */
entry_id = create_hostcache_id(hostname, port, &entry_len);
/* If we can't create the entry id, fail */
if (!entry_id)
return CURLRESOLV_ERROR;
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->hostcache, entry_id, entry_len+1);
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;
/* 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, 'wait' 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, &wait);
if (!addr) {
if(wait) {
/* 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;
}
}
else {
dns->inuse++; /* we use it! */
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)
{
curlassert(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.
*/
curl_hash *Curl_mk_dnscache(void)
{
return Curl_hash_alloc(7, freednsentry);
}
#ifdef CURLRES_HOSTENT_RELOCATE
/*
* Curl_hostent_relocate() ajusts all pointers in the given hostent struct
* according to the offset. This is typically used when a hostent has been
* reallocated and needs to be setup properly on the new address.
*/
void Curl_hostent_relocate(struct hostent *h, long offset)
{
int i=0;
h->h_name=(char *)((long)h->h_name+offset);
if(h->h_aliases) {
/* only relocate aliases if there are any! */
h->h_aliases=(char **)((long)h->h_aliases+offset);
while(h->h_aliases[i]) {
h->h_aliases[i]=(char *)((long)h->h_aliases[i]+offset);
i++;
}
}
h->h_addr_list=(char **)((long)h->h_addr_list+offset);
i=0;
while(h->h_addr_list[i]) {
h->h_addr_list[i]=(char *)((long)h->h_addr_list[i]+offset);
i++;
}
}
#endif /* CURLRES_HOSTENT_RELOCATE */
#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(Curl_addrinfo *orig)
{
char *newbuf;
Curl_addrinfo *copy;
int i;
char *str;
size_t len;
char *aptr = (char *)malloc(CURL_HOSTENT_SIZE);
char *bufptr = aptr;
if(!bufptr)
return NULL; /* major bad */
copy = (Curl_addrinfo *)bufptr;
bufptr += sizeof(Curl_addrinfo);
copy->h_name = bufptr;
len = strlen(orig->h_name) + 1;
strncpy(bufptr, orig->h_name, len);
bufptr += len;
/* This must be aligned properly to work on many CPU architectures! */
bufptr = MEMALIGN(bufptr);
copy->h_aliases = (char**)bufptr;
/* Figure out how many aliases there are */
for (i = 0; orig->h_aliases && orig->h_aliases[i]; ++i);
/* Reserve room for the array */
bufptr += (i + 1) * sizeof(char*);
/* Clone all known aliases */
if(orig->h_aliases) {
for(i = 0; (str = orig->h_aliases[i]); i++) {
len = strlen(str) + 1;
strncpy(bufptr, str, len);
copy->h_aliases[i] = bufptr;
bufptr += len;
}
}
/* if(!orig->h_aliases) i was already set to 0 */
/* Terminate the alias list with a NULL */
copy->h_aliases[i] = NULL;
copy->h_addrtype = orig->h_addrtype;
copy->h_length = orig->h_length;
/* align it for (at least) 32bit accesses */
bufptr = MEMALIGN(bufptr);
copy->h_addr_list = (char**)bufptr;
/* Figure out how many addresses there are */
for (i = 0; orig->h_addr_list[i] != NULL; ++i);
/* Reserve room for the array */
bufptr += (i + 1) * sizeof(char*);
i = 0;
len = orig->h_length;
str = orig->h_addr_list[i];
while (str != NULL) {
memcpy(bufptr, str, len);
copy->h_addr_list[i] = bufptr;
bufptr += len;
str = orig->h_addr_list[++i];
}
copy->h_addr_list[i] = NULL;
/* now, shrink the allocated buffer to the size we actually need, which
most often is only a fraction of the original alloc */
newbuf=(char *)realloc(aptr, (long)(bufptr-aptr));
if(!newbuf) {
/* serious error, but since this is shrinking only requested, we can
still use the previous memory block */
newbuf = aptr;
}
/* if the alloc moved, we need to adjust the hostent struct */
else if(newbuf != aptr)
Curl_hostent_relocate((struct hostent*)newbuf, (long)(newbuf-aptr));
/* setup the return */
copy = (Curl_addrinfo *)newbuf;
return copy;
}
#endif /* CURLRES_ADDRINFO_COPY */
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