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curl/lib/hostip.c
Daniel Stenberg 84fa12c885 Cris Bailiff found this flaw, gethostbyname_r() on linux returns 0 even 
when it can't lookup the name (at least in some cases) and thus we need
to make an extra check to detect failures.
2002-09-30 08:07:16 +00:00

681 lines
18 KiB
C
Raw Blame History

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2002, 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 <winsock.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 VMS
#include <in.h>
#include <inet.h>
#include <stdlib.h>
#endif
#endif
#ifdef HAVE_SETJMP_H
#include <setjmp.h>
#endif
#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.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 MALLOCDEBUG
#include "memdebug.h"
#endif
static curl_hash hostname_cache;
static int host_cache_initialized;
void Curl_global_host_cache_init(void)
{
if (!host_cache_initialized) {
Curl_hash_init(&hostname_cache, 7, Curl_freeaddrinfo);
host_cache_initialized = 1;
}
}
curl_hash *Curl_global_host_cache_get(void)
{
return &hostname_cache;
}
void Curl_global_host_cache_dtor(void)
{
if (host_cache_initialized) {
Curl_hash_clean(&hostname_cache);
host_cache_initialized = 0;
}
}
struct curl_dns_cache_entry {
Curl_addrinfo *addr;
time_t timestamp;
};
/* count the number of characters that an integer takes up */
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;
}
/* Create a hostcache id */
static char *
_create_hostcache_id(char *server, int port, ssize_t *entry_len)
{
char *id = NULL;
/* Get the length of the new entry id */
*entry_len = *entry_len + /* Hostname length */
1 + /* The ':' seperator */
_num_chars(port); /* The number of characters the port will take up */
/* Allocate the new entry id */
id = malloc(*entry_len + 1);
if (!id) {
return NULL;
}
/* Create the new entry */
/* If sprintf() doesn't return the entry length, that signals failure */
if (sprintf(id, "%s:%d", server, port) != *entry_len) {
/* Free the allocated id, set length to zero and return NULL */
*entry_len = 0;
free(id);
return NULL;
}
return id;
}
struct hostcache_prune_data {
int cache_timeout;
int now;
};
static int
_curl_hostcache_timestamp_remove(void *datap, void *hc)
{
struct hostcache_prune_data *data =
(struct hostcache_prune_data *) datap;
struct curl_dns_cache_entry *c = (struct curl_dns_cache_entry *) hc;
if (data->now - c->timestamp < data->cache_timeout) {
return 0;
}
return 1;
}
static void
hostcache_prune(curl_hash *hostcache, int cache_timeout, int now)
{
struct hostcache_prune_data user;
user.cache_timeout = cache_timeout;
user.now = now;
Curl_hash_clean_with_criterium(hostcache,
(void *) &user,
_curl_hostcache_timestamp_remove);
}
/* Macro to save redundant free'ing of entry_id */
#define _hostcache_return(__v) \
{ \
free(entry_id); \
return (__v); \
}
#ifdef HAVE_SIGSETJMP
/* Beware this is a global and unique instance */
sigjmp_buf curl_jmpenv;
#endif
Curl_addrinfo *Curl_resolv(struct SessionHandle *data,
char *hostname,
int port)
{
char *entry_id = NULL;
struct curl_dns_cache_entry *p = NULL;
ssize_t entry_len;
time_t now;
char *bufp;
#ifdef HAVE_SIGSETJMP
if(sigsetjmp(curl_jmpenv, 1) != 0) {
/* this is coming from a siglongjmp() */
failf(data, "name lookup time-outed");
return NULL;
}
#endif
/* If the host cache timeout is 0, we don't do DNS cach'ing
so fall through */
if (data->set.dns_cache_timeout == 0) {
return Curl_getaddrinfo(data, hostname, port, &bufp);
}
time(&now);
/* Remove outdated entries from the hostcache */
hostcache_prune(data->hostcache,
data->set.dns_cache_timeout,
now);
/* Create an entry id, based upon the hostname and port */
entry_len = strlen(hostname);
entry_id = _create_hostcache_id(hostname, port, &entry_len);
/* If we can't create the entry id, don't cache, just fall-through
to the plain Curl_getaddrinfo() */
if (!entry_id) {
return Curl_getaddrinfo(data, hostname, port, &bufp);
}
/* See if its already in our dns cache */
if (entry_id &&
Curl_hash_find(data->hostcache, entry_id, entry_len+1, (void **) &p)) {
_hostcache_return(p->addr);
}
/* Create a new cache entry */
p = (struct curl_dns_cache_entry *)
malloc(sizeof(struct curl_dns_cache_entry));
if (!p) {
_hostcache_return(NULL);
}
p->addr = Curl_getaddrinfo(data, hostname, port, &bufp);
if (!p->addr) {
free(p);
_hostcache_return(NULL);
}
p->timestamp = now;
/* Save it in our host cache */
Curl_hash_update(data->hostcache, entry_id, entry_len+1, (const void *) p);
_hostcache_return(p->addr);
}
/*
* This is a wrapper function for freeing name information in a protocol
* independent way. This takes care of using the appropriate underlaying
* proper function.
*/
void Curl_freeaddrinfo(void *freethis)
{
struct curl_dns_cache_entry *p = (struct curl_dns_cache_entry *) freethis;
#ifdef ENABLE_IPV6
freeaddrinfo(p->addr);
#else
free(p->addr);
#endif
free(p);
}
/* --- resolve name or IP-number --- */
#ifdef ENABLE_IPV6
#ifdef MALLOCDEBUG
/* These two are strictly for memory tracing and are using the same
* style as the family otherwise present in memdebug.c. I put these ones
* here since they require a bunch of struct types I didn't wanna include
* in memdebug.c
*/
int curl_getaddrinfo(char *hostname, char *service,
struct addrinfo *hints,
struct addrinfo **result,
int line, const char *source)
{
int res=(getaddrinfo)(hostname, service, hints, result);
if(0 == res) {
/* success */
if(logfile)
fprintf(logfile, "ADDR %s:%d getaddrinfo() = %p\n",
source, line, (void *)*result);
}
else {
if(logfile)
fprintf(logfile, "ADDR %s:%d getaddrinfo() failed\n",
source, line);
}
return res;
}
void curl_freeaddrinfo(struct addrinfo *freethis,
int line, const char *source)
{
(freeaddrinfo)(freethis);
if(logfile)
fprintf(logfile, "ADDR %s:%d freeaddrinfo(%p)\n",
source, line, (void *)freethis);
}
#endif
/*
* Return name information about the given hostname and port number. If
* successful, the 'addrinfo' is returned and the forth argument will point to
* memory we need to free after use. That meory *MUST* be freed with
* Curl_freeaddrinfo(), nothing else.
*/
Curl_addrinfo *Curl_getaddrinfo(struct SessionHandle *data,
char *hostname,
int port,
char **bufp)
{
struct addrinfo hints, *res;
int error;
char sbuf[NI_MAXSERV];
int s, pf = PF_UNSPEC;
/* see if we have an IPv6 stack */
s = socket(PF_INET6, SOCK_DGRAM, 0);
if (s < 0)
/* Some non-IPv6 stacks have been found to make very slow name resolves
* when PF_UNSPEC is used, so thus we switch to a mere PF_INET lookup if
* the stack seems to be a non-ipv6 one. */
pf = PF_INET;
else
/* This seems to be an IPv6-capable stack, use PF_UNSPEC for the widest
* possible checks. And close the socket again.
*/
sclose(s);
memset(&hints, 0, sizeof(hints));
hints.ai_family = pf;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_CANONNAME;
snprintf(sbuf, sizeof(sbuf), "%d", port);
error = getaddrinfo(hostname, sbuf, &hints, &res);
if (error) {
infof(data, "getaddrinfo(3) failed for %s:%d\n", hostname, port);
return NULL;
}
*bufp=(char *)res; /* make it point to the result struct */
return res;
}
#else /* following code is IPv4-only */
#ifndef HAVE_GETHOSTBYNAME_R
static void hostcache_fixoffset(struct hostent *h, int offset);
/**
* Performs a "deep" copy of a hostent into a buffer (returns a pointer to the
* copy). Make absolutely sure the destination buffer is big enough!
*
* Keith McGuigan
* 10/3/2001 */
static struct hostent* pack_hostent(char** buf, struct hostent* orig)
{
char *bufptr;
char *newbuf;
struct hostent* copy;
int i;
char *str;
int len;
bufptr = *buf;
copy = (struct hostent*)bufptr;
bufptr += sizeof(struct hostent);
copy->h_name = bufptr;
len = strlen(orig->h_name) + 1;
strncpy(bufptr, orig->h_name, len);
bufptr += len;
/* we align on even 64bit boundaries for safety */
#define MEMALIGN(x) ((x)+(8-(((unsigned long)(x))&0x7)))
/* 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[i] != NULL; ++i);
/* Reserve room for the array */
bufptr += (i + 1) * sizeof(char*);
/* Clone all known 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;
}
/* 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(*buf, (int)bufptr-(int)(*buf));
/* if the alloc moved, we need to adjust things again */
if(newbuf != *buf)
hostcache_fixoffset((struct hostent*)newbuf, (int)newbuf-(int)*buf);
/* setup the return */
*buf = newbuf;
copy = (struct hostent*)newbuf;
return copy;
}
#endif
static char *MakeIP(unsigned long num,char *addr, int addr_len)
{
#if defined(HAVE_INET_NTOA) || defined(HAVE_INET_NTOA_R)
struct in_addr in;
in.s_addr = htonl(num);
#if defined(HAVE_INET_NTOA_R)
inet_ntoa_r(in,addr,addr_len);
#else
strncpy(addr,inet_ntoa(in),addr_len);
#endif
#else
unsigned char *paddr;
num = htonl(num); /* htonl() added to avoid endian probs */
paddr = (unsigned char *)&num;
sprintf(addr, "%u.%u.%u.%u", paddr[0], paddr[1], paddr[2], paddr[3]);
#endif
return (addr);
}
#ifndef INADDR_NONE
#define INADDR_NONE (in_addr_t) ~0
#endif
static void hostcache_fixoffset(struct hostent *h, int offset)
{
int i=0;
h->h_name=(char *)((long)h->h_name+offset);
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++;
}
}
/* 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. */
Curl_addrinfo *Curl_getaddrinfo(struct SessionHandle *data,
char *hostname,
int port,
char **bufp)
{
struct hostent *h = NULL;
in_addr_t in;
int ret; /* this variable is unused on several platforms but used on some */
#define CURL_NAMELOOKUP_SIZE 9000
/* Allocate enough memory to hold the full name information structs and
* everything. OSF1 is known to require at least 8872 bytes. The buffer
* required for storing all possible aliases and IP numbers is according to
* Stevens' Unix Network Programming 2nd editor, p. 304: 8192 bytes! */
port=0; /* unused in IPv4 code */
ret = 0; /* to prevent the compiler warning */
if ( (in=inet_addr(hostname)) != INADDR_NONE ) {
struct in_addr *addrentry;
struct namebuf {
struct hostent hostentry;
char *h_addr_list[2];
struct in_addr addrentry;
char h_name[128];
} *buf = (struct namebuf *)malloc(sizeof(struct namebuf));
if(!buf)
return NULL; /* major failure */
*bufp = (char *)buf;
h = &buf->hostentry;
h->h_addr_list = &buf->h_addr_list[0];
addrentry = &buf->addrentry;
addrentry->s_addr = in;
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];
MakeIP(ntohl(in), h->h_name, sizeof(buf->h_name));
}
#if defined(HAVE_GETHOSTBYNAME_R)
else {
int h_errnop;
int res=ERANGE;
int step_size=200;
int *buf = (int *)malloc(CURL_NAMELOOKUP_SIZE);
if(!buf)
return NULL; /* major failure */
*bufp=(char *)buf;
/* Workaround for gethostbyname_r bug in qnx nto. It is also _required_
for some of these functions. */
memset(buf, 0, CURL_NAMELOOKUP_SIZE);
#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 MALLOCDEBUG
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;
hostcache_fixoffset(h, offset);
buf=(int *)h;
*bufp=(char *)buf;
}
else
#endif
#ifdef HAVE_GETHOSTBYNAME_R_6
/* Linux */
while((res=gethostbyname_r(hostname,
(struct hostent *)buf,
(char *)buf + sizeof(struct hostent),
step_size - sizeof(struct hostent),
&h, /* DIFFERENCE */
&h_errnop))==ERANGE) {
step_size+=200;
}
if(!h) /* failure */
res=1;
#ifdef MALLOCDEBUG
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;
hostcache_fixoffset(h, offset);
buf=(int *)h;
*bufp=(char *)buf;
}
else
#endif
#ifdef HAVE_GETHOSTBYNAME_R_3
/* AIX, Digital Unix, HPUX 10, more? */
if(CURL_NAMELOOKUP_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. */
ret = gethostbyname_r(hostname,
(struct hostent *)buf,
(struct hostent_data *)((char *)buf + sizeof(struct hostent)));
else
ret = -1; /* failure, too smallish buffer size */
/* result expected in h */
h = (struct hostent*)buf;
h_errnop= errno; /* we don't deal with this, but set it anyway */
if(ret)
#endif
{
infof(data, "gethostbyname_r(2) failed for %s\n", hostname);
h = NULL; /* set return code to NULL */
free(buf);
*bufp=NULL;
}
#else
else {
if ((h = gethostbyname(hostname)) == NULL ) {
infof(data, "gethostbyname(2) failed for %s\n", hostname);
*bufp=NULL;
}
else
{
char *buf=(char *)malloc(CURL_NAMELOOKUP_SIZE);
/* we make a copy of the hostent right now, right here, as the
static one we got a pointer to might get removed when we don't
want/expect that */
h = pack_hostent(&buf, h);
*bufp=(char *)buf;
}
#endif
}
return (h);
}
#endif /* end of IPv4-specific code */
/*
* local variables:
* eval: (load-file "../curl-mode.el")
* end:
* vim600: fdm=marker
* vim: et sw=2 ts=2 sts=2 tw=78
*/
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