netsupp.cpp

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/*
 *  This file is part of the KDE libraries
 *  Copyright (C) 2000,2001 Thiago Macieira <[e-mail]>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 **/

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <arpa/inet.h>

#include <qglobal.h>

// This is so that, if addrinfo is defined, it doesn't clobber our definition
// It might be defined in the few cases in which we are replacing the system's
// broken getaddrinfo
#include <netdb.h>

#include "config.h"
#include "kdebug.h"
#include "klocale.h"

#ifndef IN6_IS_ADDR_V4MAPPED
#define NEED_IN6_TESTS
#endif
#undef CLOBBER_IN6
#include "netsupp.h"

#if defined(__hpux) || defined(_HPUX_SOURCE)
extern int h_errno;
#endif

#include <kdemacros.h>

#if !defined(kde_sockaddr_in6)
/*
 * kde_sockaddr_in6 might have got defined even though we #undef'ed
 * CLOBBER_IN6. This happens when we are compiling under --enable-final.
 * However, in that case, if it was defined, that's because ksockaddr.cpp
 * had it defined because sockaddr_in6 didn't exist, and so sockaddr_in6
 * exists and is our kde_sockaddr_in6
 */
# define sockaddr_in6	kde_sockaddr_in6
# define in6_addr	kde_in6_addr
#endif

#ifdef offsetof
#undef offsetof
#endif
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

/*
 * These constants tell the flags in KDE::resolverFlags
 * The user could (but shouldn't) test the variable to know what kind of
 * resolution is supported
 */
#define KRF_KNOWS_AF_INET6		0x01	/* if present, the code knows about AF_INET6 */
#define KRF_USING_OWN_GETADDRINFO	0x02	/* if present, we are using our own getaddrinfo */
#define KRF_USING_OWN_INET_NTOP		0x04	/* if present, we are using our own inet_ntop */
#define KRF_USING_OWN_INET_PTON		0x08	/* if present, we are using our own inet_pton */
#define KRF_CAN_RESOLVE_UNIX		0x100	/* if present, the resolver can resolve Unix sockets */
#define KRF_CAN_RESOLVE_IPV4		0x200	/* if present, the resolver can resolve to IPv4 */
#define KRF_CAN_RESOLVE_IPV6		0x400	/* if present, the resolver can resolve to IPv6 */


static void dofreeaddrinfo(struct addrinfo *ai)
{
  while (ai)
    {
      struct addrinfo *ai2 = ai;
      if (ai->ai_canonname != NULL)
	free(ai->ai_canonname);

      if (ai->ai_addr != NULL)
	free(ai->ai_addr);

      ai = ai->ai_next;
      free(ai2);
    }
}

void kde_freeaddrinfo(struct kde_addrinfo *ai)
{
  if (ai->origin == KAI_LOCALUNIX)
    {
      struct addrinfo *p, *last = NULL;
      /* We've added one AF_UNIX socket in here, to the
       * tail of the linked list. We have to find it */
      for (p = ai->data; p; p = p->ai_next)
	{
	  if (p->ai_family == AF_UNIX)
	    {
	      if (last)
		{
		  last->ai_next = NULL;
		  freeaddrinfo(ai->data);
		}
	      dofreeaddrinfo(p);
	      break;
	    }
	  last = p;
	}
    }
  else
    freeaddrinfo(ai->data);

  free(ai);
}

static struct addrinfo*
make_unix(const char *name, const char *serv)
{
  const char *buf;
  struct addrinfo *p;
  struct sockaddr_un *_sun;
  int len;

  p = (addrinfo*)malloc(sizeof(*p));
  if (p == NULL)
    return NULL;
  memset(p, 0, sizeof(*p));

  if (name != NULL)
    buf = name;
  else
    buf = serv;

  // Calculate length of the binary representation
  len = strlen(buf) + offsetof(struct sockaddr_un, sun_path) + 1;
  if (*buf != '/')
    len += 5;			// strlen("/tmp/");

  _sun = (sockaddr_un*)malloc(len);
  if (_sun == NULL)
    {
      // Oops
      free(p);
      return NULL;
    }

  _sun->sun_family = AF_UNIX;
# ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
  _sun->sun_len = len;
# endif
  if (*buf == '/')
    *_sun->sun_path = '\0';	// empty it
  else
    strcpy(_sun->sun_path, "/tmp/");
  strcat(_sun->sun_path, buf);

  // Set the addrinfo
  p->ai_family = AF_UNIX;
  p->ai_addrlen = len;
  p->ai_addr = (sockaddr*)_sun;
  p->ai_canonname = strdup(buf);

  return p;
}

// Ugh. I hate #ifdefs
// Anyways, here's what this does:
// KDE_IPV6_LOOKUP_MODE != 1, this function doesn't exist
// AF_INET6 not defined, we say there is no IPv6 stack
// otherwise, we try to create a socket.
// returns: 1 for IPv6 stack available, 2 for not available
#if defined(KDE_IPV6_LOOKUP_MODE) && KDE_IPV6_LOOKUP_MODE == 1
static int check_ipv6_stack()
{
# ifndef AF_INET6
  return 2;			// how can we check?
# else
  if (getenv("KDE_NO_IPV6"))
     return 2;
  int fd = ::socket(AF_INET6, SOCK_STREAM, 0);
  if (fd == -1)
     return 2;
     
  ::close(fd);
  return 1;
# endif
}
#endif


/*
 * Reason for using this function: kde_getaddrinfo
 *
 * I decided to add this wrapper function for getaddrinfo
 * and have this be called by KExtendedSocket instead of
 * the real getaddrinfo so that we can make sure that the
 * behavior is the desired one.
 *
 * Currently, the only "undesired" behavior is getaddrinfo
 * not returning PF_UNIX sockets in some implementations.
 *
 * getaddrinfo and family are defined in POSIX 1003.1g
 * (Protocol Independent Interfaces) and in RFC 2553
 * (Basic Socket Interface for IPv6). Whereas the RFC is ambiguosly
 * vague whether this family of functions should return Internet
 * sockets only or not, the name of the POSIX draft says
 * otherwise: it should be independent of protocol.
 *
 * So, my interpretation is that they should return every
 * kind of socket available and known and that's how I
 * designed KExtendedSocket on top of it.
 *
 * That's why there's this wrapper, to make sure PF_UNIX
 * sockets are returned when expected.
 */

int kde_getaddrinfo(const char *name, const char *service,
		    const struct addrinfo* hint,
		    struct kde_addrinfo** result)
{
  struct kde_addrinfo* res;
  struct addrinfo* p;
  int err = EAI_SERVICE;
#if defined(KDE_IPV6_LOOKUP_MODE) && KDE_IPV6_LOOKUP_MODE == 1
  // mode 1: do a check on whether we have an IPv6 stack
  static int ipv6_stack = 0;	// 0: unknown, 1: yes, 2: no
#endif

  // allocate memory for results
  res = (kde_addrinfo*)malloc(sizeof(*res));
  if (res == NULL)
    return EAI_MEMORY;
  res->data = NULL;
  res->origin = KAI_SYSTEM;	// at first, it'll be only system data

  struct addrinfo* last = NULL;
  
  // Skip the getaddrinfo call and the ipv6 check for a UNIX socket.
  if (hint && (hint->ai_family == PF_UNIX))
  {
     if (service == NULL || *service == '\0')
       goto out;		// can't be Unix if no service was requested

     // Unix sockets must be localhost
     // That is, either name is NULL or, if it's not, it must be empty,
     // "*" or "localhost"
     if (name != NULL && !(name[0] == '\0' || (name[0] == '*' && name[1] == '\0') ||
		strcmp("localhost", name) == 0))
       goto out;		// isn't localhost

     goto do_unix;
  }
  
#if defined(KDE_IPV6_LOOKUP_MODE) && KDE_IPV6_LOOKUP_MODE != 0
# if KDE_IPV6_LOOKUP_MODE == 1
  // mode 1: do a check on whether we have an IPv6 stack
  if (ipv6_stack == 0)
    ipv6_stack = check_ipv6_stack();

  if (ipv6_stack == 2)
    {
# endif
      // here we have modes 1 and 2 (no lookups)
      // this is shared code
      struct addrinfo our_hint;
      if (hint != NULL)
	{
	  memcpy(&our_hint, hint, sizeof(our_hint));
	  if (our_hint.ai_family == AF_UNSPEC)
	    our_hint.ai_family = AF_INET;
	}
      else
	{
	  memset(&our_hint, 0, sizeof(our_hint));
	  our_hint.ai_family = AF_INET;
	}

      // do the actual resolution
      err = getaddrinfo(name, service, &our_hint, &res->data);
# if KDE_IPV6_LOOKUP_MODE == 1
    }
  else
# endif
#endif
#if defined(KDE_IPV6_LOOKUP_MODE) && KDE_IPV6_LOOKUP_MODE != 2
      // do the IPV6 resolution
      err = getaddrinfo(name, service, hint, &res->data);
#endif

  // Now we have to check whether the user could want a Unix socket

  if (service == NULL || *service == '\0')
    goto out;			// can't be Unix if no service was requested

  // Unix sockets must be localhost
  // That is, either name is NULL or, if it's not, it must be empty,
  // "*" or "localhost"
  if (name != NULL && !(name[0] == '\0' || (name[0] == '*' && name[1] == '\0') ||
			strcmp("localhost", name) == 0))
    goto out;			// isn't localhost

  // Unix sockets can only be returned if the user asked for a PF_UNSPEC
  // or PF_UNIX socket type or gave us a NULL hint
  if (hint != NULL && (hint->ai_family != PF_UNSPEC && hint->ai_family != PF_UNIX))
    goto out;			// user doesn't want Unix

  // If we got here, then it means that the user might be expecting Unix
  // sockets. The user wants a local socket, with a non-null service and
  // has told us that they accept PF_UNIX sockets
  // Check whether the system implementation returned Unix
  if (err == 0)
    for (p = res->data; p; p = p->ai_next)
      {
	last = p;			// we have to find out which one is last anyways
	if (p->ai_family == AF_UNIX)
	  // there is an Unix node
	  goto out;
      }

 do_unix:
  // So, give the user a PF_UNIX socket
  p = make_unix(NULL, service);
  if (p == NULL)
    {
      err = EAI_MEMORY;
      goto out;
    }
  if (hint != NULL)
    p->ai_socktype = hint->ai_socktype;
  if (p->ai_socktype == 0)
    p->ai_socktype = SOCK_STREAM; // default

  if (last)
    last->ai_next = p;
  else
    res->data = p;
  res->origin = KAI_LOCALUNIX;
  *result = res;
  return 0;

 out:
  // Normal exit of the function
  if (err == 0)
    *result = res;
  else
    {
      if (res->data != NULL)
	freeaddrinfo(res->data);
      free(res);
    }
  return err;
}

#if defined(HAVE_GETADDRINFO) && !defined(HAVE_BROKEN_GETADDRINFO)

#define KRF_getaddrinfo		0
#define KRF_resolver		0

#else  // !defined(HAVE_GETADDRINFO) || defined(HAVE_BROKEN_GETADDRINFO)

#define KRF_getaddrinfo			KRF_USING_OWN_GETADDRINFO
#define KRF_resolver			KRF_CAN_RESOLVE_UNIX | KRF_CAN_RESOLVE_IPV4

/*
 * No getaddrinfo() in this system.
 * We shall provide our own
 */

/** TODO
 * Try and use gethostbyname2_r before gethostbyname2 and gethostbyname
 */
static int inet_lookup(const char *name, int portnum, int protonum,
		       struct addrinfo *p, const struct addrinfo *hint,
		       struct addrinfo** result)
{
  struct addrinfo *q;
  struct hostent *h;
  struct sockaddr **psa = NULL;
  int len;

  // TODO
  // Currently, this never resolves IPv6 (need gethostbyname2, etc.)
# ifdef AF_INET6
  if (hint->ai_family == AF_INET6)
    {
      if (p != NULL)
	{
	  *result = p;
	  return 0;
	}
      return EAI_FAIL;
    }
# endif

  q = (addrinfo*)malloc(sizeof(*q));
  if (q == NULL)
    {
      freeaddrinfo(p);
      return EAI_MEMORY;
    }

  h = gethostbyname(name);