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curl/lib/hostip4.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
/* The last #include file should be: */
#ifdef CURLDEBUG
#include "memdebug.h"
#endif
/***********************************************************************
* Only for plain-ipv4 builds
**********************************************************************/
#ifdef CURLRES_IPV4 /* plain ipv4 code coming up */
/*
* This is a wrapper function for freeing name information in a protocol
* independent way. This takes care of using the appropriate underlying
* function.
*/
void Curl_freeaddrinfo(Curl_addrinfo *p)
{
free(p); /* works fine for the ARES case too */
}
/*
* 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 */
}
/*
* Curl_ip2addr() takes a 32bit ipv4 internet address as input parameter
* together with a pointer to the string version of the address, and it
* retruns a malloc()ed version of a hostent struct 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, char *hostname)
{
struct hostent *h;
struct in_addr *addrentry;
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 */
} *buf = (struct namebuf *)malloc(sizeof(struct namebuf));
if(!buf)
return NULL; /* major failure */
h = &buf->hostentry;
h->h_addr_list = &buf->h_addr_list[0];
addrentry = &buf->addrentry;
addrentry->s_addr = num;
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(h->h_name, 16, "%s", hostname);
return h;
}
#ifdef CURLRES_SYNCH /* the functions below are for synchronous resolves */
/*
* Curl_getaddrinfo() - the ipv4 synchronous version.
*
* The original code to this function was once stolen 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
* the HAVE_GETHOSTBYNAME_R_3, HAVE_GETHOSTBYNAME_R_5 or
* 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,
char *hostname,
int port,
int *waitp)
{
struct hostent *h = NULL;
in_addr_t in;
struct SessionHandle *data = conn->data;
(void)port; /* unused in IPv4 code */
*waitp = 0; /* don't wait, we act synchronously */
in=inet_addr(hostname);
if (in != CURL_INADDR_NONE)
/* This is a dotted IP address 123.123.123.123-style */
return Curl_ip2addr(in, hostname);
#if defined(HAVE_GETHOSTBYNAME_R)
/*
* 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;
int res=ERANGE;
int step_size=200;
int *buf = (int *)calloc(CURL_HOSTENT_SIZE, 1);
if(!buf)
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.
*/
#ifdef HAVE_GETHOSTBYNAME_R_5
/* Solaris, IRIX and more */
(void)res; /* prevent compiler warning */
while(!h) {
h = gethostbyname_r(hostname,
(struct hostent *)buf,
(char *)buf + sizeof(struct hostent),
step_size - sizeof(struct hostent),
&h_errnop);
/* 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 || (errno != ERANGE))
break;
step_size+=200;
}
#ifdef CURLDEBUG
infof(data, "gethostbyname_r() uses %d bytes\n", step_size);
#endif
if(h) {
int offset;
h=(struct hostent *)realloc(buf, step_size);
offset=(long)h-(long)buf;
Curl_hostent_relocate(h, offset);
buf=(int *)h;
}
else
#endif /* HAVE_GETHOSTBYNAME_R_5 */
#ifdef HAVE_GETHOSTBYNAME_R_6
/* Linux */
do {
res=gethostbyname_r(hostname,
(struct hostent *)buf,
(char *)buf + sizeof(struct hostent),
step_size - sizeof(struct hostent),
&h, /* DIFFERENCE */
&h_errnop);
/* 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(((ERANGE == res) || (EAGAIN == res)) ||
((res<0) && ((ERANGE == errno) || (EAGAIN == errno))))
step_size+=200;
else
break;
} while(step_size <= CURL_HOSTENT_SIZE);
if(!h) /* failure */
res=1;
#ifdef CURLDEBUG
infof(data, "gethostbyname_r() uses %d bytes\n", step_size);
#endif
if(!res) {
int offset;
h=(struct hostent *)realloc(buf, step_size);
offset=(long)h-(long)buf;
Curl_hostent_relocate(h, offset);
buf=(int *)h;
}
else
#endif/* HAVE_GETHOSTBYNAME_R_6 */
#ifdef HAVE_GETHOSTBYNAME_R_3
/* 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.
*/
if(CURL_HOSTENT_SIZE >=
(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= errno; /* we don't deal with this, but set it anyway */
}
else
res = -1; /* failure, too smallish buffer size */
if(!res) { /* success */
h = (struct hostent*)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.
*/
}
else
#endif /* HAVE_GETHOSTBYNAME_R_3 */
{
infof(data, "gethostbyname_r(2) failed for %s\n", hostname);
h = NULL; /* set return code to NULL */
free(buf);
}
#else /* HAVE_GETHOSTBYNAME_R */
/*
* Here is code for platforms that don't have gethostbyname_r() or for
* which the gethostbyname() is the preferred() function.
*/
else {
h = gethostbyname(hostname);
if (!h)
infof(data, "gethostbyname(2) failed for %s\n", hostname);
else {
/*
* Copy the hostent struct right here, as the static one we got a
* pointer to might get removed when we don't want/expect that. Windows
* (other platforms?) also doesn't allow passing of the returned data
* between threads, which thus the copying here them allows the app to
* do.
*/
h = Curl_addrinfo_copy(h);
}
#endif /*HAVE_GETHOSTBYNAME_R */
}
return h;
}
#endif /* CURLRES_SYNCH */
#endif /* CURLRES_IPV4 */
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