/***************************************************************************
 *                                  _   _ ____  _
 *  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: hostip4.c,v 1.12 2004/10/06 07:52:20 bagder Exp $
 ***************************************************************************/

#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"

/***********************************************************************
 * Only for plain-ipv4 builds
 **********************************************************************/
#ifdef CURLRES_IPV4 /* plain ipv4 code coming up */

/*
 * 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;
		free( ai );
		ai = next;
	}
}

/*
 * 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 */
}

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, char *hostname, int port ) {
	Curl_addrinfo *ai;
	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;
	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( (char *)h->h_name, 16, "%s", hostname );

	ai = Curl_he2ai( h, port );

	return ai;
}

#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 ) {
	Curl_addrinfo *ai = NULL;
	struct hostent *h = NULL;
	in_addr_t in;
	struct SessionHandle *data = conn->data;
	struct hostent *buf = NULL;

	(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, port );
	}

#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;

		buf = (struct hostent *)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 */
		h = gethostbyname_r( hostname,
							 (struct hostent *)buf,
							 (char *)buf + sizeof( struct hostent ),
							 CURL_HOSTENT_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 ) {
			;
		} else
#endif /* HAVE_GETHOSTBYNAME_R_5 */
#ifdef HAVE_GETHOSTBYNAME_R_6
		/* Linux */

		res = gethostbyname_r( hostname,
							   (struct hostent *)buf,
							   (char *)buf + sizeof( struct hostent ),
							   CURL_HOSTENT_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 ( !h ) /* failure */
#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 = 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 );
		}
#endif /*HAVE_GETHOSTBYNAME_R */
	}

	if ( h ) {
		ai = Curl_he2ai( h, port );

		if ( buf ) { /* used a *_r() function */
			free( buf );
		}
	}

	return ai;
}

#endif /* CURLRES_SYNCH */

/*
 * 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.

struct Curl_addrinfo {
  int     ai_flags;
  int     ai_family;
  int     ai_socktype;
  int     ai_protocol;
  size_t  ai_addrlen;
  struct sockaddr *ai_addr;
  char   *ai_canonname;
  struct addrinfo *ai_next;
};

struct hostent {
  char    *h_name;        * official name of host *
  char    **h_aliases;    * alias list *
  int     h_addrtype;     * host address type *
  int     h_length;       * length of address *
  char    **h_addr_list;  * list of addresses *
}
#define h_addr  h_addr_list[0]  * for backward compatibility *

*/

Curl_addrinfo *Curl_he2ai( struct hostent *he, int port ) {
	Curl_addrinfo *ai;
	Curl_addrinfo *prevai = NULL;
	Curl_addrinfo *firstai = NULL;
	struct sockaddr_in *addr;
	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] ); i++ ) {

		ai = calloc( 1, sizeof( Curl_addrinfo ) + sizeof( struct sockaddr_in ) );

		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 = AF_INET;          /* we only support this */
		ai->ai_socktype = SOCK_STREAM;    /* we only support this */
		ai->ai_addrlen = sizeof( struct sockaddr_in );
		/* 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 ) );

		/* leave the rest of the struct filled with zero */

		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 = he->h_addrtype;
		addr->sin_port = htons( (unsigned short)port );

		prevai = ai;
	}
	return firstai;
}

#endif /* CURLRES_IPV4 */