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* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
* Copyright (C) 1998 - 2008, Daniel Stenberg, <>, 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
* 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>
#include <malloc.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <stdlib.h> /* required for free() prototypes */
#include <unistd.h> /* for the close() proto */
#ifdef VMS
#include <in.h>
#include <inet.h>
#include <stdlib.h>
#include <process.h>
#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "strerror.h"
#include "url.h"
#include "inet_pton.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
#include "memory.h"
/* The last #include file should be: */
#include "memdebug.h"
* Only for plain-ipv4 builds
#ifdef CURLRES_IPV4 /* plain ipv4 code coming up */
* Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
* been set and returns TRUE if they are OK.
bool Curl_ipvalid(struct SessionHandle *data)
if(data->set.ip_version == CURL_IPRESOLVE_V6)
/* an ipv6 address was requested and we can't get/use one */
return FALSE;
return TRUE; /* OK, proceed */
#ifdef CURLRES_SYNCH /* the functions below are for synchronous resolves */
* Curl_getaddrinfo() - the ipv4 synchronous version.
* The original code to this function was from the Dancer source code, written
* by Bjorn Reese, it has since been patched and modified considerably.
* gethostbyname_r() is the thread-safe version of the gethostbyname()
* function. When we build for plain IPv4, we attempt to use this
* function. There are _three_ different gethostbyname_r() versions, and we
* detect which one this platform supports in the configure script and set up
* HAVE_GETHOSTBYNAME_R_6 defines accordingly. Note that HAVE_GETADDRBYNAME
* has the corresponding rules. This is primarily on *nix. Note that some unix
* flavours have thread-safe versions of the plain gethostbyname() etc.
Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
const char *hostname,
int port,
int *waitp)
int res;
Curl_addrinfo *ai = NULL;
struct hostent *h = NULL;
struct in_addr in;
struct hostent *buf = NULL;
*waitp = 0; /* don't wait, we act synchronously */
if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
/* This is a dotted IP address */
return Curl_ip2addr(AF_INET, &in, hostname, port);
* gethostbyname_r() is the preferred resolve function for many platforms.
* Since there are three different versions of it, the following code is
* somewhat #ifdef-ridden.
else {
int h_errnop;
buf = calloc(CURL_HOSTENT_SIZE, 1);
return NULL; /* major failure */
* The clearing of the buffer is a workaround for a gethostbyname_r bug in
* qnx nto and it is also _required_ for some of these functions on some
* platforms.
/* Solaris, IRIX and more */
h = gethostbyname_r(hostname,
(struct hostent *)buf,
(char *)buf + sizeof(struct hostent),
CURL_HOSTENT_SIZE - sizeof(struct hostent),
/* If the buffer is too small, it returns NULL and sets errno to
* ERANGE. The errno is thread safe if this is compiled with
* -D_REENTRANT as then the 'errno' variable is a macro defined to get
* used properly for threads.
if(h) {
/* Linux */
(struct hostent *)buf,
(char *)buf + sizeof(struct hostent),
CURL_HOSTENT_SIZE - sizeof(struct hostent),
&h, /* DIFFERENCE */
/* Redhat 8, using glibc 2.2.93 changed the behavior. Now all of a
* sudden this function returns EAGAIN if the given buffer size is too
* small. Previous versions are known to return ERANGE for the same
* problem.
* This wouldn't be such a big problem if older versions wouldn't
* sometimes return EAGAIN on a common failure case. Alas, we can't
* assume that EAGAIN *or* ERANGE means ERANGE for any given version of
* glibc.
* For now, we do that and thus we may call the function repeatedly and
* fail for older glibc versions that return EAGAIN, until we run out of
* buffer size (step_size grows beyond CURL_HOSTENT_SIZE).
* If anyone has a better fix, please tell us!
* -------------------------------------------------------------------
* On October 23rd 2003, Dan C dug up more details on the mysteries of
* gethostbyname_r() in glibc:
* In glibc 2.2.5 the interface is different (this has also been
* discovered in glibc 2.1.1-6 as shipped by Redhat 6). What I can't
* explain, is that tests performed on glibc 2.2.4-34 and 2.2.4-32
* (shipped/upgraded by Redhat 7.2) don't show this behavior!
* In this "buggy" version, the return code is -1 on error and 'errno'
* is set to the ERANGE or EAGAIN code. Note that 'errno' is not a
* thread-safe variable.
if(!h) /* failure */
/* AIX, Digital Unix/Tru64, HPUX 10, more? */
/* For AIX 4.3 or later, we don't use gethostbyname_r() at all, because of
* the plain fact that it does not return unique full buffers on each
* call, but instead several of the pointers in the hostent structs will
* point to the same actual data! This have the unfortunate down-side that
* our caching system breaks down horribly. Luckily for us though, AIX 4.3
* and more recent versions have a "completely thread-safe"[*] libc where
* all the data is stored in thread-specific memory areas making calls to
* the plain old gethostbyname() work fine even for multi-threaded
* programs.
* This AIX 4.3 or later detection is all made in the configure script.
* Troels Walsted Hansen helped us work this out on March 3rd, 2003.
* [*] = much later we've found out that it isn't at all "completely
* thread-safe", but at least the gethostbyname() function is.
(sizeof(struct hostent)+sizeof(struct hostent_data))) {
/* August 22nd, 2000: Albert Chin-A-Young brought an updated version
* that should work! September 20: Richard Prescott worked on the buffer
* size dilemma.
res = gethostbyname_r(hostname,
(struct hostent *)buf,
(struct hostent_data *)((char *)buf +
sizeof(struct hostent)));
h_errnop = SOCKERRNO; /* we don't deal with this, but set it anyway */
res = -1; /* failure, too smallish buffer size */
if(!res) { /* success */
h = buf; /* result expected in h */
/* This is the worst kind of the different gethostbyname_r() interfaces.
* Since we don't know how big buffer this particular lookup required,
* we can't realloc down the huge alloc without doing closer analysis of
* the returned data. Thus, we always use CURL_HOSTENT_SIZE for every
* name lookup. Fixing this would require an extra malloc() and then
* calling Curl_addrinfo_copy() that subsequent realloc()s down the new
* memory area to the actually used amount.
infof(conn->data, "gethostbyname_r(2) failed for %s\n", hostname);
h = NULL; /* set return code to NULL */
* Here is code for platforms that don't have gethostbyname_r() or for
* which the gethostbyname() is the preferred() function.
else {
#if (defined(NETWARE) && !defined(__NOVELL_LIBC__))
h = gethostbyname((char*)hostname);
h = gethostbyname(hostname);
infof(conn->data, "gethostbyname(2) failed for %s\n", hostname);
if(h) {
ai = Curl_he2ai(h, port);
if(buf) /* used a *_r() function */
return ai;
#endif /* CURLRES_SYNCH */
#endif /* CURLRES_IPV4 */
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