tor-browser

prnetdb.c (67981B)

---

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "primpl.h"

#include <string.h>

#if defined(LINUX)
#  include <sys/un.h>
#endif

/*
* On Unix, the error code for gethostbyname() and gethostbyaddr()
* is returned in the global variable h_errno, instead of the usual
* errno.
*/
#if defined(XP_UNIX)
#  if defined(_PR_NEED_H_ERRNO)
extern int h_errno;
#  endif
#  define _MD_GETHOST_ERRNO() h_errno
#else
#  define _MD_GETHOST_ERRNO() _MD_ERRNO()
#endif

/*
* The meaning of the macros related to gethostbyname, gethostbyaddr,
* and gethostbyname2 is defined below.
* - _PR_HAVE_THREADSAFE_GETHOST: the gethostbyXXX functions return
*   the result in thread specific storage.  For example, AIX, HP-UX.
* -  _PR_HAVE_GETHOST_R: have the gethostbyXXX_r functions. See next
*   two macros.
* - _PR_HAVE_GETHOST_R_INT: the gethostbyXXX_r functions return an
*   int.  For example, Linux glibc.
* - _PR_HAVE_GETHOST_R_POINTER: the gethostbyXXX_r functions return
*   a struct hostent* pointer.  For example, Solaris.
*/
#if defined(_PR_NO_PREEMPT) || defined(_PR_HAVE_GETHOST_R) || \
   defined(_PR_HAVE_THREADSAFE_GETHOST)
#  define _PR_NO_DNS_LOCK
#endif

#if defined(_PR_NO_DNS_LOCK)
#  define LOCK_DNS()
#  define UNLOCK_DNS()
#else
PRLock* _pr_dnsLock = NULL;
#  define LOCK_DNS() PR_Lock(_pr_dnsLock)
#  define UNLOCK_DNS() PR_Unlock(_pr_dnsLock)
#endif /* defined(_PR_NO_DNS_LOCK) */

/*
* Some platforms have the reentrant getprotobyname_r() and
* getprotobynumber_r().  However, they come in three flavors.
* Some return a pointer to struct protoent, others return
* an int, and glibc's flavor takes five arguments.
*/

#if defined(SOLARIS) \
|| (defined(LINUX) && defined(_REENTRANT) && defined(__GLIBC__) && \
   __GLIBC__ < 2)
#  define _PR_HAVE_GETPROTO_R
#  define _PR_HAVE_GETPROTO_R_POINTER
#endif

#if defined(AIX4_3_PLUS) || (defined(AIX) && defined(_THREAD_SAFE)) || \
   (defined(HPUX10_10) && defined(_REENTRANT)) ||                     \
   (defined(HPUX10_20) && defined(_REENTRANT)) || defined(OPENBSD)
#  define _PR_HAVE_GETPROTO_R
#  define _PR_HAVE_GETPROTO_R_INT
#endif

#if __FreeBSD_version >= 602000
#  define _PR_HAVE_GETPROTO_R
#  define _PR_HAVE_5_ARG_GETPROTO_R
#endif

/* BeOS has glibc but not the glibc-style getprotobyxxx_r functions. */
#if (defined(__GLIBC__) && __GLIBC__ >= 2)
#  define _PR_HAVE_GETPROTO_R
#  define _PR_HAVE_5_ARG_GETPROTO_R
#endif

#if !defined(_PR_HAVE_GETPROTO_R)
       PRLock* _getproto_lock = NULL;
#endif

#if defined(_PR_INET6_PROBE)
extern PRBool _pr_ipv6_is_present(void);
#endif

#define _PR_IN6_IS_ADDR_UNSPECIFIED(a)                           \
 (((a)->pr_s6_addr32[0] == 0) && ((a)->pr_s6_addr32[1] == 0) && \
  ((a)->pr_s6_addr32[2] == 0) && ((a)->pr_s6_addr32[3] == 0))

#define _PR_IN6_IS_ADDR_LOOPBACK(a)                              \
 (((a)->pr_s6_addr32[0] == 0) && ((a)->pr_s6_addr32[1] == 0) && \
  ((a)->pr_s6_addr32[2] == 0) && ((a)->pr_s6_addr[12] == 0) &&  \
  ((a)->pr_s6_addr[13] == 0) && ((a)->pr_s6_addr[14] == 0) &&   \
  ((a)->pr_s6_addr[15] == 0x1U))

const PRIPv6Addr _pr_in6addr_any = {
   {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}};

const PRIPv6Addr _pr_in6addr_loopback = {
   {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x1U}}};
/*
* The values at bytes 10 and 11 are compared using pointers to
* 8-bit fields, and not 32-bit fields, to make the comparison work on
* both big-endian and little-endian systems
*/

#define _PR_IN6_IS_ADDR_V4MAPPED(a)                              \
 (((a)->pr_s6_addr32[0] == 0) && ((a)->pr_s6_addr32[1] == 0) && \
  ((a)->pr_s6_addr[8] == 0) && ((a)->pr_s6_addr[9] == 0) &&     \
  ((a)->pr_s6_addr[10] == 0xff) && ((a)->pr_s6_addr[11] == 0xff))

#define _PR_IN6_IS_ADDR_V4COMPAT(a)                              \
 (((a)->pr_s6_addr32[0] == 0) && ((a)->pr_s6_addr32[1] == 0) && \
  ((a)->pr_s6_addr32[2] == 0))

#define _PR_IN6_V4MAPPED_TO_IPADDR(a) ((a)->pr_s6_addr32[3])

#if defined(_PR_INET6) && defined(_PR_HAVE_GETHOSTBYNAME2)

/*
* The _pr_QueryNetIfs() function finds out if the system has
* IPv4 or IPv6 source addresses configured and sets _pr_have_inet_if
* and _pr_have_inet6_if accordingly.
*
* We have an implementation using SIOCGIFCONF ioctl and a
* default implementation that simply sets _pr_have_inet_if
* and _pr_have_inet6_if to true.  A better implementation
* would be to use the routing sockets (see Chapter 17 of
* W. Richard Stevens' Unix Network Programming, Vol. 1, 2nd. Ed.)
*/

static PRLock* _pr_query_ifs_lock = NULL;
static PRBool _pr_have_inet_if = PR_FALSE;
static PRBool _pr_have_inet6_if = PR_FALSE;

#  undef DEBUG_QUERY_IFS

#  if defined(AIX) || (defined(DARWIN) && !defined(HAVE_GETIFADDRS))

/*
* Use SIOCGIFCONF ioctl on platforms that don't have routing
* sockets.  Warning: whether SIOCGIFCONF ioctl returns AF_INET6
* network interfaces is not portable.
*
* The _pr_QueryNetIfs() function is derived from the code in
* src/lib/libc/net/getifaddrs.c in BSD Unix and the code in
* Section 16.6 of W. Richard Stevens' Unix Network Programming,
* Vol. 1, 2nd. Ed.
*/

#    include <sys/ioctl.h>
#    include <sys/socket.h>
#    include <netinet/in.h>
#    include <net/if.h>

#    ifdef DEBUG_QUERY_IFS
static void _pr_PrintIfreq(struct ifreq* ifr) {
 PRNetAddr addr;
 struct sockaddr* sa;
 const char* family;
 char addrstr[64];

 sa = &ifr->ifr_addr;
 if (sa->sa_family == AF_INET) {
   struct sockaddr_in* sin = (struct sockaddr_in*)sa;
   family = "inet";
   memcpy(&addr.inet.ip, &sin->sin_addr, sizeof(sin->sin_addr));
 } else if (sa->sa_family == AF_INET6) {
   struct sockaddr_in6* sin6 = (struct sockaddr_in6*)sa;
   family = "inet6";
   memcpy(&addr.ipv6.ip, &sin6->sin6_addr, sizeof(sin6->sin6_addr));
 } else {
   return; /* skip if not AF_INET or AF_INET6 */
 }
 addr.raw.family = sa->sa_family;
 PR_NetAddrToString(&addr, addrstr, sizeof(addrstr));
 printf("%s: %s %s\n", ifr->ifr_name, family, addrstr);
}
#    endif

static void _pr_QueryNetIfs(void) {
 int sock;
 int rv;
 struct ifconf ifc;
 struct ifreq* ifr;
 struct ifreq* lifr;
 PRUint32 len, lastlen;
 char* buf;

 if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
   return;
 }

 /* Issue SIOCGIFCONF request in a loop. */
 lastlen = 0;
 len = 100 * sizeof(struct ifreq); /* initial buffer size guess */
 for (;;) {
   buf = (char*)PR_Malloc(len);
   if (NULL == buf) {
     close(sock);
     return;
   }
   ifc.ifc_buf = buf;
   ifc.ifc_len = len;
   rv = ioctl(sock, SIOCGIFCONF, &ifc);
   if (rv < 0) {
     if (errno != EINVAL || lastlen != 0) {
       close(sock);
       PR_Free(buf);
       return;
     }
   } else {
     if (ifc.ifc_len == lastlen) {
       break; /* success, len has not changed */
     }
     lastlen = ifc.ifc_len;
   }
   len += 10 * sizeof(struct ifreq); /* increment */
   PR_Free(buf);
 }
 close(sock);

 ifr = ifc.ifc_req;
 lifr = (struct ifreq*)&ifc.ifc_buf[ifc.ifc_len];

 while (ifr < lifr) {
   struct sockaddr* sa;
   int sa_len;

#    ifdef DEBUG_QUERY_IFS
   _pr_PrintIfreq(ifr);
#    endif
   sa = &ifr->ifr_addr;
   if (sa->sa_family == AF_INET) {
     struct sockaddr_in* sin = (struct sockaddr_in*)sa;
     if (sin->sin_addr.s_addr != htonl(INADDR_LOOPBACK)) {
       _pr_have_inet_if = PR_TRUE;
     }
   } else if (sa->sa_family == AF_INET6) {
     struct sockaddr_in6* sin6 = (struct sockaddr_in6*)sa;
     if (!IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr) &&
         !IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
       _pr_have_inet6_if = PR_TRUE;
     }
   }

#    ifdef _PR_HAVE_SOCKADDR_LEN
   sa_len = PR_MAX(sa->sa_len, sizeof(struct sockaddr));
#    else
   switch (sa->sa_family) {
#      ifdef AF_LINK
     case AF_LINK:
       sa_len = sizeof(struct sockaddr_dl);
       break;
#      endif
     case AF_INET6:
       sa_len = sizeof(struct sockaddr_in6);
       break;
     default:
       sa_len = sizeof(struct sockaddr);
       break;
   }
#    endif
   ifr = (struct ifreq*)(((char*)sa) + sa_len);
 }
 PR_Free(buf);
}

#  elif (defined(DARWIN) && defined(HAVE_GETIFADDRS)) || defined(FREEBSD) || \
     defined(NETBSD) || defined(OPENBSD)

/*
* Use the BSD getifaddrs function.
*/

#    include <sys/types.h>
#    include <sys/socket.h>
#    include <ifaddrs.h>
#    include <netinet/in.h>

#    ifdef DEBUG_QUERY_IFS
static void _pr_PrintIfaddrs(struct ifaddrs* ifa) {
 struct sockaddr* sa;
 const char* family;
 void* addrp;
 char addrstr[64];

 sa = ifa->ifa_addr;
 if (sa->sa_family == AF_INET) {
   struct sockaddr_in* sin = (struct sockaddr_in*)sa;
   family = "inet";
   addrp = &sin->sin_addr;
 } else if (sa->sa_family == AF_INET6) {
   struct sockaddr_in6* sin6 = (struct sockaddr_in6*)sa;
   family = "inet6";
   addrp = &sin6->sin6_addr;
 } else {
   return; /* skip if not AF_INET or AF_INET6 */
 }
 inet_ntop(sa->sa_family, addrp, addrstr, sizeof(addrstr));
 printf("%s: %s %s\n", ifa->ifa_name, family, addrstr);
}
#    endif

static void _pr_QueryNetIfs(void) {
 struct ifaddrs* ifp;
 struct ifaddrs* ifa;

 if (getifaddrs(&ifp) == -1) {
   return;
 }
 for (ifa = ifp; ifa; ifa = ifa->ifa_next) {
   struct sockaddr* sa;

#    ifdef DEBUG_QUERY_IFS
   _pr_PrintIfaddrs(ifa);
#    endif
   sa = ifa->ifa_addr;
   if (sa->sa_family == AF_INET) {
     struct sockaddr_in* sin = (struct sockaddr_in*)sa;
     if (sin->sin_addr.s_addr != htonl(INADDR_LOOPBACK)) {
       _pr_have_inet_if = 1;
     }
   } else if (sa->sa_family == AF_INET6) {
     struct sockaddr_in6* sin6 = (struct sockaddr_in6*)sa;
     if (!IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr) &&
         !IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
       _pr_have_inet6_if = 1;
     }
   }
 }
 freeifaddrs(ifp);
}

#  else /* default */

/*
* Emulate the code in NSPR 4.2 or older.  PR_GetIPNodeByName behaves
* as if the system had both IPv4 and IPv6 source addresses configured.
*/
static void _pr_QueryNetIfs(void) {
 _pr_have_inet_if = PR_TRUE;
 _pr_have_inet6_if = PR_TRUE;
}

#  endif

#endif /* _PR_INET6 && _PR_HAVE_GETHOSTBYNAME2 */

void _PR_InitNet(void) {
#if defined(XP_UNIX)
#  ifdef HAVE_NETCONFIG
 /*
  * This one-liner prevents the endless re-open's and re-read's of
  * /etc/netconfig on EACH and EVERY call to accept(), connect(), etc.
  */
 (void)setnetconfig();
#  endif
#endif
#if !defined(_PR_NO_DNS_LOCK)
 _pr_dnsLock = PR_NewLock();
#endif
#if !defined(_PR_HAVE_GETPROTO_R)
 _getproto_lock = PR_NewLock();
#endif
#if defined(_PR_INET6) && defined(_PR_HAVE_GETHOSTBYNAME2)
 _pr_query_ifs_lock = PR_NewLock();
#endif
}

void _PR_CleanupNet(void) {
#if !defined(_PR_NO_DNS_LOCK)
 if (_pr_dnsLock) {
   PR_DestroyLock(_pr_dnsLock);
   _pr_dnsLock = NULL;
 }
#endif
#if !defined(_PR_HAVE_GETPROTO_R)
 if (_getproto_lock) {
   PR_DestroyLock(_getproto_lock);
   _getproto_lock = NULL;
 }
#endif
#if defined(_PR_INET6) && defined(_PR_HAVE_GETHOSTBYNAME2)
 if (_pr_query_ifs_lock) {
   PR_DestroyLock(_pr_query_ifs_lock);
   _pr_query_ifs_lock = NULL;
 }
#endif
}

/*
** Allocate space from the buffer, aligning it to "align" before doing
** the allocation. "align" must be a power of 2.
*/
static char* Alloc(PRIntn amount, char** bufp, PRIntn* buflenp, PRIntn align) {
 char* buf = *bufp;
 PRIntn buflen = *buflenp;

 if (align && ((long)buf & (align - 1))) {
   PRIntn skip = align - ((ptrdiff_t)buf & (align - 1));
   if (buflen < skip) {
     return 0;
   }
   buf += skip;
   buflen -= skip;
 }
 if (buflen < amount) {
   return 0;
 }
 *bufp = buf + amount;
 *buflenp = buflen - amount;
 return buf;
}

typedef enum _PRIPAddrConversion {
 _PRIPAddrNoConversion,
 _PRIPAddrIPv4Mapped,
 _PRIPAddrIPv4Compat
} _PRIPAddrConversion;

/*
** Convert an IPv4 address (v4) to an IPv4-mapped IPv6 address (v6).
*/
static void MakeIPv4MappedAddr(const char* v4, char* v6) {
 memset(v6, 0, 10);
 memset(v6 + 10, 0xff, 2);
 memcpy(v6 + 12, v4, 4);
}

/*
** Convert an IPv4 address (v4) to an IPv4-compatible IPv6 address (v6).
*/
static void MakeIPv4CompatAddr(const char* v4, char* v6) {
 memset(v6, 0, 12);
 memcpy(v6 + 12, v4, 4);
}

/*
** Copy a hostent, and all of the memory that it refers to into
** (hopefully) stacked buffers.
*/
static PRStatus CopyHostent(struct hostent* from, char** buf, PRIntn* bufsize,
                           _PRIPAddrConversion conversion, PRHostEnt* to) {
 PRIntn len, na;
 char** ap;

 if (conversion != _PRIPAddrNoConversion && from->h_addrtype == AF_INET) {
   PR_ASSERT(from->h_length == 4);
   to->h_addrtype = PR_AF_INET6;
   to->h_length = 16;
 } else {
#if defined(_PR_INET6) || defined(_PR_INET6_PROBE)
   if (AF_INET6 == from->h_addrtype) {
     to->h_addrtype = PR_AF_INET6;
   } else
#endif
     to->h_addrtype = from->h_addrtype;
   to->h_length = from->h_length;
 }

 /* Copy the official name */
 if (!from->h_name) {
   return PR_FAILURE;
 }
 len = strlen(from->h_name) + 1;
 to->h_name = Alloc(len, buf, bufsize, 0);
 if (!to->h_name) {
   return PR_FAILURE;
 }
 memcpy(to->h_name, from->h_name, len);

 /* Count the aliases, then allocate storage for the pointers */
 if (!from->h_aliases) {
   na = 1;
 } else {
   for (na = 1, ap = from->h_aliases; *ap != 0; na++, ap++) {
     ;
   } /* nothing to execute */
 }
 to->h_aliases =
     (char**)Alloc(na * sizeof(char*), buf, bufsize, sizeof(char**));
 if (!to->h_aliases) {
   return PR_FAILURE;
 }

 /* Copy the aliases, one at a time */
 if (!from->h_aliases) {
   to->h_aliases[0] = 0;
 } else {
   for (na = 0, ap = from->h_aliases; *ap != 0; na++, ap++) {
     len = strlen(*ap) + 1;
     to->h_aliases[na] = Alloc(len, buf, bufsize, 0);
     if (!to->h_aliases[na]) {
       return PR_FAILURE;
     }
     memcpy(to->h_aliases[na], *ap, len);
   }
   to->h_aliases[na] = 0;
 }

 /* Count the addresses, then allocate storage for the pointers */
 for (na = 1, ap = from->h_addr_list; *ap != 0; na++, ap++) {
   ;
 } /* nothing to execute */
 to->h_addr_list =
     (char**)Alloc(na * sizeof(char*), buf, bufsize, sizeof(char**));
 if (!to->h_addr_list) {
   return PR_FAILURE;
 }

 /* Copy the addresses, one at a time */
 for (na = 0, ap = from->h_addr_list; *ap != 0; na++, ap++) {
   to->h_addr_list[na] = Alloc(to->h_length, buf, bufsize, 0);
   if (!to->h_addr_list[na]) {
     return PR_FAILURE;
   }
   if (conversion != _PRIPAddrNoConversion && from->h_addrtype == AF_INET) {
     if (conversion == _PRIPAddrIPv4Mapped) {
       MakeIPv4MappedAddr(*ap, to->h_addr_list[na]);
     } else {
       PR_ASSERT(conversion == _PRIPAddrIPv4Compat);
       MakeIPv4CompatAddr(*ap, to->h_addr_list[na]);
     }
   } else {
     memcpy(to->h_addr_list[na], *ap, to->h_length);
   }
 }
 to->h_addr_list[na] = 0;
 return PR_SUCCESS;
}

#if !defined(_PR_HAVE_GETPROTO_R)
/*
** Copy a protoent, and all of the memory that it refers to into
** (hopefully) stacked buffers.
*/
static PRStatus CopyProtoent(struct protoent* from, char* buf, PRIntn bufsize,
                            PRProtoEnt* to) {
 PRIntn len, na;
 char** ap;

 /* Do the easy stuff */
 to->p_num = from->p_proto;

 /* Copy the official name */
 if (!from->p_name) {
   return PR_FAILURE;
 }
 len = strlen(from->p_name) + 1;
 to->p_name = Alloc(len, &buf, &bufsize, 0);
 if (!to->p_name) {
   return PR_FAILURE;
 }
 memcpy(to->p_name, from->p_name, len);

 /* Count the aliases, then allocate storage for the pointers */
 for (na = 1, ap = from->p_aliases; *ap != 0; na++, ap++) {
   ;
 } /* nothing to execute */
 to->p_aliases =
     (char**)Alloc(na * sizeof(char*), &buf, &bufsize, sizeof(char**));
 if (!to->p_aliases) {
   return PR_FAILURE;
 }

 /* Copy the aliases, one at a time */
 for (na = 0, ap = from->p_aliases; *ap != 0; na++, ap++) {
   len = strlen(*ap) + 1;
   to->p_aliases[na] = Alloc(len, &buf, &bufsize, 0);
   if (!to->p_aliases[na]) {
     return PR_FAILURE;
   }
   memcpy(to->p_aliases[na], *ap, len);
 }
 to->p_aliases[na] = 0;

 return PR_SUCCESS;
}
#endif /* !defined(_PR_HAVE_GETPROTO_R) */

/*
* #################################################################
* NOTE: tmphe, tmpbuf, bufsize, h, and h_err are local variables
* or arguments of PR_GetHostByName, PR_GetIPNodeByName, and
* PR_GetHostByAddr.  DO NOT CHANGE THE NAMES OF THESE LOCAL
* VARIABLES OR ARGUMENTS.
* #################################################################
*/
#if defined(_PR_HAVE_GETHOST_R_INT)

#  define GETHOSTBYNAME(name) \
   (gethostbyname_r(name, &tmphe, tmpbuf, bufsize, &h, &h_err), h)
#  define GETHOSTBYNAME2(name, af) \
   (gethostbyname2_r(name, af, &tmphe, tmpbuf, bufsize, &h, &h_err), h)
#  define GETHOSTBYADDR(addr, addrlen, af) \
   (gethostbyaddr_r(addr, addrlen, af, &tmphe, tmpbuf, bufsize, &h, &h_err), h)

#elif defined(_PR_HAVE_GETHOST_R_POINTER)

#  define GETHOSTBYNAME(name) \
   gethostbyname_r(name, &tmphe, tmpbuf, bufsize, &h_err)
#  define GETHOSTBYNAME2(name, af) \
   gethostbyname2_r(name, af, &tmphe, tmpbuf, bufsize, &h_err)
#  define GETHOSTBYADDR(addr, addrlen, af) \
   gethostbyaddr_r(addr, addrlen, af, &tmphe, tmpbuf, bufsize, &h_err)

#else

#  define GETHOSTBYNAME(name) gethostbyname(name)
#  define GETHOSTBYNAME2(name, af) gethostbyname2(name, af)
#  define GETHOSTBYADDR(addr, addrlen, af) gethostbyaddr(addr, addrlen, af)

#endif /* definition of GETHOSTBYXXX */

PR_IMPLEMENT(PRStatus)
PR_GetHostByName(const char* name, char* buf, PRIntn bufsize, PRHostEnt* hp) {
 struct hostent* h;
 PRStatus rv = PR_FAILURE;
#if defined(_PR_HAVE_GETHOST_R)
 char localbuf[PR_NETDB_BUF_SIZE];
 char* tmpbuf;
 struct hostent tmphe;
 int h_err;
#endif

 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

#if defined(_PR_HAVE_GETHOST_R)
 tmpbuf = localbuf;
 if (bufsize > sizeof(localbuf)) {
   tmpbuf = (char*)PR_Malloc(bufsize);
   if (NULL == tmpbuf) {
     PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
     return rv;
   }
 }
#endif

 LOCK_DNS();

 h = GETHOSTBYNAME(name);

 if (NULL == h) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_GETHOST_ERRNO());
 } else {
   _PRIPAddrConversion conversion = _PRIPAddrNoConversion;
   rv = CopyHostent(h, &buf, &bufsize, conversion, hp);
   if (PR_SUCCESS != rv) {
     PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
   }
 }
 UNLOCK_DNS();
#if defined(_PR_HAVE_GETHOST_R)
 if (tmpbuf != localbuf) {
   PR_Free(tmpbuf);
 }
#endif
 return rv;
}

#if !defined(_PR_INET6) && defined(_PR_INET6_PROBE) && \
   defined(_PR_HAVE_GETIPNODEBYNAME)
typedef struct hostent* (*_pr_getipnodebyname_t)(const char*, int, int, int*);
typedef struct hostent* (*_pr_getipnodebyaddr_t)(const void*, size_t, int,
                                                int*);
typedef void (*_pr_freehostent_t)(struct hostent*);
static void* _pr_getipnodebyname_fp;
static void* _pr_getipnodebyaddr_fp;
static void* _pr_freehostent_fp;

/*
* Look up the addresses of getipnodebyname, getipnodebyaddr,
* and freehostent.
*/
PRStatus _pr_find_getipnodebyname(void) {
 PRLibrary* lib;
 PRStatus rv;
#  define GETIPNODEBYNAME "getipnodebyname"
#  define GETIPNODEBYADDR "getipnodebyaddr"
#  define FREEHOSTENT "freehostent"

 _pr_getipnodebyname_fp = PR_FindSymbolAndLibrary(GETIPNODEBYNAME, &lib);
 if (NULL != _pr_getipnodebyname_fp) {
   _pr_freehostent_fp = PR_FindSymbol(lib, FREEHOSTENT);
   if (NULL != _pr_freehostent_fp) {
     _pr_getipnodebyaddr_fp = PR_FindSymbol(lib, GETIPNODEBYADDR);
     if (NULL != _pr_getipnodebyaddr_fp) {
       rv = PR_SUCCESS;
     } else {
       rv = PR_FAILURE;
     }
   } else {
     rv = PR_FAILURE;
   }
   (void)PR_UnloadLibrary(lib);
 } else {
   rv = PR_FAILURE;
 }
 return rv;
}
#endif

#if defined(_PR_INET6) && defined(_PR_HAVE_GETHOSTBYNAME2)
/*
** Append the V4 addresses to the end of the list
*/
static PRStatus AppendV4AddrsToHostent(struct hostent* from, char** buf,
                                      PRIntn* bufsize, PRHostEnt* to) {
 PRIntn na, na_old;
 char** ap;
 char** new_addr_list;

 /* Count the addresses, then grow storage for the pointers */
 for (na_old = 0, ap = to->h_addr_list; *ap != 0; na_old++, ap++) {
   ;
 } /* nothing to execute */
 for (na = na_old + 1, ap = from->h_addr_list; *ap != 0; na++, ap++) {
   ;
 } /* nothing to execute */
 new_addr_list =
     (char**)Alloc(na * sizeof(char*), buf, bufsize, sizeof(char**));
 if (!new_addr_list) {
   return PR_FAILURE;
 }

 /* Copy the V6 addresses, one at a time */
 for (na = 0, ap = to->h_addr_list; *ap != 0; na++, ap++) {
   new_addr_list[na] = to->h_addr_list[na];
 }
 to->h_addr_list = new_addr_list;

 /* Copy the V4 addresses, one at a time */
 for (ap = from->h_addr_list; *ap != 0; na++, ap++) {
   to->h_addr_list[na] = Alloc(to->h_length, buf, bufsize, 0);
   if (!to->h_addr_list[na]) {
     return PR_FAILURE;
   }
   MakeIPv4MappedAddr(*ap, to->h_addr_list[na]);
 }
 to->h_addr_list[na] = 0;
 return PR_SUCCESS;
}
#endif

PR_IMPLEMENT(PRStatus)
PR_GetIPNodeByName(const char* name, PRUint16 af, PRIntn flags, char* buf,
                  PRIntn bufsize, PRHostEnt* hp) {
 struct hostent* h = 0;
 PRStatus rv = PR_FAILURE;
#if defined(_PR_HAVE_GETHOST_R)
 char localbuf[PR_NETDB_BUF_SIZE];
 char* tmpbuf;
 struct hostent tmphe;
 int h_err;
#endif
#if defined(_PR_HAVE_GETIPNODEBYNAME)
 PRUint16 md_af = af;
 int error_num;
 int tmp_flags = 0;
#endif
#if defined(_PR_HAVE_GETHOSTBYNAME2)
 PRBool did_af_inet = PR_FALSE;
#endif

 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

 if (af != PR_AF_INET && af != PR_AF_INET6) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   return PR_FAILURE;
 }

#if defined(_PR_INET6) && defined(_PR_HAVE_GETHOSTBYNAME2)
 PR_Lock(_pr_query_ifs_lock);
 /*
  * Keep querying the presence of IPv4 and IPv6 interfaces until
  * at least one is up.  This allows us to detect the local
  * machine going from offline to online.
  */
 if (!_pr_have_inet_if && !_pr_have_inet6_if) {
   _pr_QueryNetIfs();
#  ifdef DEBUG_QUERY_IFS
   if (_pr_have_inet_if) {
     printf("Have IPv4 source address\n");
   }
   if (_pr_have_inet6_if) {
     printf("Have IPv6 source address\n");
   }
#  endif
 }
 PR_Unlock(_pr_query_ifs_lock);
#endif

#if defined(_PR_HAVE_GETIPNODEBYNAME)
 if (flags & PR_AI_V4MAPPED) {
   tmp_flags |= AI_V4MAPPED;
 }
 if (flags & PR_AI_ADDRCONFIG) {
   tmp_flags |= AI_ADDRCONFIG;
 }
 if (flags & PR_AI_ALL) {
   tmp_flags |= AI_ALL;
 }
 if (af == PR_AF_INET6) {
   md_af = AF_INET6;
 } else {
   md_af = af;
 }
#endif

#if defined(_PR_HAVE_GETHOST_R)
 tmpbuf = localbuf;
 if (bufsize > sizeof(localbuf)) {
   tmpbuf = (char*)PR_Malloc(bufsize);
   if (NULL == tmpbuf) {
     PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
     return rv;
   }
 }
#endif

 /* Do not need to lock the DNS lock if getipnodebyname() is called */
#ifdef _PR_INET6
#  ifdef _PR_HAVE_GETHOSTBYNAME2
 LOCK_DNS();
 if (af == PR_AF_INET6) {
   if ((flags & PR_AI_ADDRCONFIG) == 0 || _pr_have_inet6_if) {
#    ifdef _PR_INET6_PROBE
     if (_pr_ipv6_is_present())
#    endif
       h = GETHOSTBYNAME2(name, AF_INET6);
   }
   if ((NULL == h) && (flags & PR_AI_V4MAPPED) &&
       ((flags & PR_AI_ADDRCONFIG) == 0 || _pr_have_inet_if)) {
     did_af_inet = PR_TRUE;
     h = GETHOSTBYNAME2(name, AF_INET);
   }
 } else {
   if ((flags & PR_AI_ADDRCONFIG) == 0 || _pr_have_inet_if) {
     did_af_inet = PR_TRUE;
     h = GETHOSTBYNAME2(name, af);
   }
 }
#  elif defined(_PR_HAVE_GETIPNODEBYNAME)
 h = getipnodebyname(name, md_af, tmp_flags, &error_num);
#  else
#    error "Unknown name-to-address translation function"
#  endif /* _PR_HAVE_GETHOSTBYNAME2 */
#elif defined(_PR_INET6_PROBE) && defined(_PR_HAVE_GETIPNODEBYNAME)
 if (_pr_ipv6_is_present()) {
#  ifdef PR_GETIPNODE_NOT_THREADSAFE
   LOCK_DNS();
#  endif
   h = (*((_pr_getipnodebyname_t)_pr_getipnodebyname_fp))(
       name, md_af, tmp_flags, &error_num);
 } else {
   LOCK_DNS();
   h = GETHOSTBYNAME(name);
 }
#else  /* _PR_INET6 */
 LOCK_DNS();
 h = GETHOSTBYNAME(name);
#endif /* _PR_INET6 */

 if (NULL == h) {
#if defined(_PR_INET6) && defined(_PR_HAVE_GETIPNODEBYNAME)
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, error_num);
#elif defined(_PR_INET6_PROBE) && defined(_PR_HAVE_GETIPNODEBYNAME)
   if (_pr_ipv6_is_present()) {
     PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, error_num);
   } else {
     PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_GETHOST_ERRNO());
   }
#else
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_GETHOST_ERRNO());
#endif
 } else {
   _PRIPAddrConversion conversion = _PRIPAddrNoConversion;

   if (af == PR_AF_INET6) {
     conversion = _PRIPAddrIPv4Mapped;
   }
   rv = CopyHostent(h, &buf, &bufsize, conversion, hp);
   if (PR_SUCCESS != rv) {
     PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
   }
#if defined(_PR_INET6) && defined(_PR_HAVE_GETIPNODEBYNAME)
   freehostent(h);
#elif defined(_PR_INET6_PROBE) && defined(_PR_HAVE_GETIPNODEBYNAME)
   if (_pr_ipv6_is_present()) {
     (*((_pr_freehostent_t)_pr_freehostent_fp))(h);
   }
#endif
#if defined(_PR_INET6) && defined(_PR_HAVE_GETHOSTBYNAME2)
   if ((PR_SUCCESS == rv) && (flags & PR_AI_V4MAPPED) &&
       ((flags & PR_AI_ALL) ||
        ((flags & PR_AI_ADDRCONFIG) && _pr_have_inet_if)) &&
       !did_af_inet && (h = GETHOSTBYNAME2(name, AF_INET)) != 0) {
     rv = AppendV4AddrsToHostent(h, &buf, &bufsize, hp);
     if (PR_SUCCESS != rv) {
       PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
     }
   }
#endif
 }

 /* Must match the convoluted logic above for LOCK_DNS() */
#ifdef _PR_INET6
#  ifdef _PR_HAVE_GETHOSTBYNAME2
 UNLOCK_DNS();
#  endif /* _PR_HAVE_GETHOSTBYNAME2 */
#elif defined(_PR_INET6_PROBE) && defined(_PR_HAVE_GETIPNODEBYNAME)
#  ifdef PR_GETIPNODE_NOT_THREADSAFE
 UNLOCK_DNS();
#  else
 if (!_pr_ipv6_is_present()) {
   UNLOCK_DNS();
 }
#  endif
#else  /* _PR_INET6 */
 UNLOCK_DNS();
#endif /* _PR_INET6 */

#if defined(_PR_HAVE_GETHOST_R)
 if (tmpbuf != localbuf) {
   PR_Free(tmpbuf);
 }
#endif

 return rv;
}

PR_IMPLEMENT(PRStatus)
PR_GetHostByAddr(const PRNetAddr* hostaddr, char* buf, PRIntn bufsize,
                PRHostEnt* hostentry) {
 struct hostent* h;
 PRStatus rv = PR_FAILURE;
 const void* addr;
 PRUint32 tmp_ip;
 int addrlen;
 PRInt32 af;
#if defined(_PR_HAVE_GETHOST_R)
 char localbuf[PR_NETDB_BUF_SIZE];
 char* tmpbuf;
 struct hostent tmphe;
 int h_err;
#endif
#if defined(_PR_HAVE_GETIPNODEBYADDR)
 int error_num;
#endif

 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

 if (hostaddr->raw.family == PR_AF_INET6) {
#if defined(_PR_INET6_PROBE)
   af = _pr_ipv6_is_present() ? AF_INET6 : AF_INET;
#elif defined(_PR_INET6)
   af = AF_INET6;
#else
   af = AF_INET;
#endif
#if defined(_PR_GHBA_DISALLOW_V4MAPPED)
   if (_PR_IN6_IS_ADDR_V4MAPPED(&hostaddr->ipv6.ip)) {
     af = AF_INET;
   }
#endif
 } else {
   PR_ASSERT(hostaddr->raw.family == AF_INET);
   af = AF_INET;
 }
 if (hostaddr->raw.family == PR_AF_INET6) {
#if defined(_PR_INET6) || defined(_PR_INET6_PROBE)
   if (af == AF_INET6) {
     addr = &hostaddr->ipv6.ip;
     addrlen = sizeof(hostaddr->ipv6.ip);
   } else
#endif
   {
     PR_ASSERT(af == AF_INET);
     if (!_PR_IN6_IS_ADDR_V4MAPPED(&hostaddr->ipv6.ip)) {
       PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
       return rv;
     }
     tmp_ip = _PR_IN6_V4MAPPED_TO_IPADDR((PRIPv6Addr*)&hostaddr->ipv6.ip);
     addr = &tmp_ip;
     addrlen = sizeof(tmp_ip);
   }
 } else {
   PR_ASSERT(hostaddr->raw.family == AF_INET);
   PR_ASSERT(af == AF_INET);
   addr = &hostaddr->inet.ip;
   addrlen = sizeof(hostaddr->inet.ip);
 }

#if defined(_PR_HAVE_GETHOST_R)
 tmpbuf = localbuf;
 if (bufsize > sizeof(localbuf)) {
   tmpbuf = (char*)PR_Malloc(bufsize);
   if (NULL == tmpbuf) {
     PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
     return rv;
   }
 }
#endif

 /* Do not need to lock the DNS lock if getipnodebyaddr() is called */
#if defined(_PR_HAVE_GETIPNODEBYADDR) && defined(_PR_INET6)
 h = getipnodebyaddr(addr, addrlen, af, &error_num);
#elif defined(_PR_HAVE_GETIPNODEBYADDR) && defined(_PR_INET6_PROBE)
 if (_pr_ipv6_is_present()) {
#  ifdef PR_GETIPNODE_NOT_THREADSAFE
   LOCK_DNS();
#  endif
   h = (*((_pr_getipnodebyaddr_t)_pr_getipnodebyaddr_fp))(addr, addrlen, af,
                                                          &error_num);
 } else {
   LOCK_DNS();
   h = GETHOSTBYADDR(addr, addrlen, af);
 }
#else  /* _PR_HAVE_GETIPNODEBYADDR */
 LOCK_DNS();
 h = GETHOSTBYADDR(addr, addrlen, af);
#endif /* _PR_HAVE_GETIPNODEBYADDR */
 if (NULL == h) {
#if defined(_PR_INET6) && defined(_PR_HAVE_GETIPNODEBYADDR)
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, error_num);
#elif defined(_PR_INET6_PROBE) && defined(_PR_HAVE_GETIPNODEBYADDR)
   if (_pr_ipv6_is_present()) {
     PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, error_num);
   } else {
     PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_GETHOST_ERRNO());
   }
#else
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_GETHOST_ERRNO());
#endif
 } else {
   _PRIPAddrConversion conversion = _PRIPAddrNoConversion;
   if (hostaddr->raw.family == PR_AF_INET6) {
     if (af == AF_INET) {
       if (_PR_IN6_IS_ADDR_V4MAPPED((PRIPv6Addr*)&hostaddr->ipv6.ip)) {
         conversion = _PRIPAddrIPv4Mapped;
       } else if (_PR_IN6_IS_ADDR_V4COMPAT((PRIPv6Addr*)&hostaddr->ipv6.ip)) {
         conversion = _PRIPAddrIPv4Compat;
       }
     }
   }
   rv = CopyHostent(h, &buf, &bufsize, conversion, hostentry);
   if (PR_SUCCESS != rv) {
     PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
   }
#if defined(_PR_INET6) && defined(_PR_HAVE_GETIPNODEBYADDR)
   freehostent(h);
#elif defined(_PR_INET6_PROBE) && defined(_PR_HAVE_GETIPNODEBYADDR)
   if (_pr_ipv6_is_present()) {
     (*((_pr_freehostent_t)_pr_freehostent_fp))(h);
   }
#endif
 }

 /* Must match the convoluted logic above for LOCK_DNS() */
#if defined(_PR_HAVE_GETIPNODEBYADDR) && defined(_PR_INET6)
#elif defined(_PR_HAVE_GETIPNODEBYADDR) && defined(_PR_INET6_PROBE)
#  ifdef PR_GETIPNODE_NOT_THREADSAFE
 UNLOCK_DNS();
#  else
 if (!_pr_ipv6_is_present()) {
   UNLOCK_DNS();
 }
#  endif
#else  /* _PR_HAVE_GETIPNODEBYADDR */
 UNLOCK_DNS();
#endif /* _PR_HAVE_GETIPNODEBYADDR */

#if defined(_PR_HAVE_GETHOST_R)
 if (tmpbuf != localbuf) {
   PR_Free(tmpbuf);
 }
#endif

 return rv;
}

/******************************************************************************/
/*
* Some systems define a reentrant version of getprotobyname(). Too bad
* the signature isn't always the same. But hey, they tried. If there
* is such a definition, use it. Otherwise, grab a lock and do it here.
*/
/******************************************************************************/

#if !defined(_PR_HAVE_GETPROTO_R)
/*
* This may seem like a silly thing to do, but the compiler SHOULD
* complain if getprotobyname_r() is implemented on some system and
* we're not using it. For sure these signatures are different than
* any usable implementation.
*/

#  if defined(ANDROID)
/* Android's Bionic libc system includes prototypes for these in netdb.h,
* but doesn't actually include implementations.  It uses the 5-arg form,
* so these functions end up not matching the prototype.  So just rename
* them if not found.
*/
#    define getprotobyname_r _pr_getprotobyname_r
#    define getprotobynumber_r _pr_getprotobynumber_r
#  endif

static struct protoent* getprotobyname_r(const char* name) {
 return getprotobyname(name);
} /* getprotobyname_r */

static struct protoent* getprotobynumber_r(PRInt32 number) {
 return getprotobynumber(number);
} /* getprotobynumber_r */

#endif /* !defined(_PR_HAVE_GETPROTO_R) */

PR_IMPLEMENT(PRStatus)
PR_GetProtoByName(const char* name, char* buffer, PRInt32 buflen,
                 PRProtoEnt* result) {
 PRStatus rv = PR_SUCCESS;
#if defined(_PR_HAVE_GETPROTO_R)
 struct protoent* res = (struct protoent*)result;
#endif

 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

#if defined(_PR_HAVE_GETPROTO_R_INT)
 {
   /*
   ** The protoent_data has a pointer as the first field.
   ** That implies the buffer better be aligned, and char*
   ** doesn't promise much.
   */
   PRUptrdiff aligned = (PRUptrdiff)buffer;
   if (0 != (aligned & (sizeof(struct protoent_data*) - 1))) {
     aligned += sizeof(struct protoent_data*) - 1;
     aligned &= ~(sizeof(struct protoent_data*) - 1);
     buflen -= (aligned - (PRUptrdiff)buffer);
     buffer = (char*)aligned;
   }
 }
#endif /* defined(_PR_HAVE_GETPROTO_R_INT) */

 if (PR_MIN_NETDB_BUF_SIZE > buflen) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   return PR_FAILURE;
 }

#if defined(_PR_HAVE_GETPROTO_R_POINTER)
 if (NULL == getprotobyname_r(name, res, buffer, buflen)) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   return PR_FAILURE;
 }
#elif defined(_PR_HAVE_GETPROTO_R_INT)
 /*
 ** The buffer needs to be zero'd, and it should be
 ** at least the size of a struct protoent_data.
 */
 memset(buffer, 0, buflen);
 if (-1 == getprotobyname_r(name, res, (struct protoent_data*)buffer)) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   return PR_FAILURE;
 }
#elif defined(_PR_HAVE_5_ARG_GETPROTO_R)
 /* The 5th argument for getprotobyname_r() cannot be NULL */
 if (-1 == getprotobyname_r(name, res, buffer, buflen, &res)) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   return PR_FAILURE;
 }
#else  /* do it the hard way */
 {
   struct protoent* staticBuf;
   PR_Lock(_getproto_lock);
   staticBuf = getprotobyname_r(name);
   if (NULL == staticBuf) {
     rv = PR_FAILURE;
     PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   } else {
     rv = CopyProtoent(staticBuf, buffer, buflen, result);
     if (PR_FAILURE == rv) {
       PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
     }
   }
   PR_Unlock(_getproto_lock);
 }
#endif /* all that */
 return rv;
}

PR_IMPLEMENT(PRStatus)
PR_GetProtoByNumber(PRInt32 number, char* buffer, PRInt32 buflen,
                   PRProtoEnt* result) {
 PRStatus rv = PR_SUCCESS;
#if defined(_PR_HAVE_GETPROTO_R)
 struct protoent* res = (struct protoent*)result;
#endif

 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

#if defined(_PR_HAVE_GETPROTO_R_INT)
 {
   /*
   ** The protoent_data has a pointer as the first field.
   ** That implies the buffer better be aligned, and char*
   ** doesn't promise much.
   */
   PRUptrdiff aligned = (PRUptrdiff)buffer;
   if (0 != (aligned & (sizeof(struct protoent_data*) - 1))) {
     aligned += sizeof(struct protoent_data*) - 1;
     aligned &= ~(sizeof(struct protoent_data*) - 1);
     buflen -= (aligned - (PRUptrdiff)buffer);
     buffer = (char*)aligned;
   }
 }
#endif /* defined(_PR_HAVE_GETPROTO_R_INT) */

 if (PR_MIN_NETDB_BUF_SIZE > buflen) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   return PR_FAILURE;
 }

#if defined(_PR_HAVE_GETPROTO_R_POINTER)
 if (NULL == getprotobynumber_r(number, res, buffer, buflen)) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   return PR_FAILURE;
 }

#elif defined(_PR_HAVE_GETPROTO_R_INT)
 /*
 ** The buffer needs to be zero'd for these OS's.
 */
 memset(buffer, 0, buflen);
 if (-1 == getprotobynumber_r(number, res, (struct protoent_data*)buffer)) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   return PR_FAILURE;
 }
#elif defined(_PR_HAVE_5_ARG_GETPROTO_R)
 /* The 5th argument for getprotobynumber_r() cannot be NULL */
 if (-1 == getprotobynumber_r(number, res, buffer, buflen, &res)) {
   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   return PR_FAILURE;
 }
#else  /* do it the hard way */
 {
   struct protoent* staticBuf;
   PR_Lock(_getproto_lock);
   staticBuf = getprotobynumber_r(number);
   if (NULL == staticBuf) {
     rv = PR_FAILURE;
     PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, _MD_ERRNO());
   } else {
     rv = CopyProtoent(staticBuf, buffer, buflen, result);
     if (PR_FAILURE == rv) {
       PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
     }
   }
   PR_Unlock(_getproto_lock);
 }
#endif /* all that crap */
 return rv;
}

PRUintn _PR_NetAddrSize(const PRNetAddr* addr) {
 PRUintn addrsize;

 /*
  * RFC 2553 added a new field (sin6_scope_id) to
  * struct sockaddr_in6.  PRNetAddr's ipv6 member has a
  * scope_id field to match the new field.  In order to
  * work with older implementations supporting RFC 2133,
  * we take the size of struct sockaddr_in6 instead of
  * addr->ipv6.
  */
 if (AF_INET == addr->raw.family) {
   addrsize = sizeof(addr->inet);
 } else if (PR_AF_INET6 == addr->raw.family)
#if defined(_PR_INET6)
   addrsize = sizeof(struct sockaddr_in6);
#else
   addrsize = sizeof(addr->ipv6);
#endif
#if defined(XP_UNIX)
 else if (AF_UNIX == addr->raw.family) {
#  if defined(LINUX)
   if (addr->local.path[0] == 0)
     /* abstract socket address is supported on Linux only */
     addrsize = strnlen(addr->local.path + 1, sizeof(addr->local.path)) +
                offsetof(struct sockaddr_un, sun_path) + 1;
   else
#  endif
     addrsize = sizeof(addr->local);
 }
#endif
 else {
   addrsize = 0;
 }

 return addrsize;
} /* _PR_NetAddrSize */

PR_IMPLEMENT(PRIntn)
PR_EnumerateHostEnt(PRIntn enumIndex, const PRHostEnt* hostEnt, PRUint16 port,
                   PRNetAddr* address) {
 void* addr = hostEnt->h_addr_list[enumIndex++];
 memset(address, 0, sizeof(PRNetAddr));
 if (NULL == addr) {
   enumIndex = 0;
 } else {
   address->raw.family = hostEnt->h_addrtype;
   if (PR_AF_INET6 == hostEnt->h_addrtype) {
     address->ipv6.port = htons(port);
     address->ipv6.flowinfo = 0;
     address->ipv6.scope_id = 0;
     memcpy(&address->ipv6.ip, addr, hostEnt->h_length);
   } else {
     PR_ASSERT(AF_INET == hostEnt->h_addrtype);
     address->inet.port = htons(port);
     memcpy(&address->inet.ip, addr, hostEnt->h_length);
   }
 }
 return enumIndex;
} /* PR_EnumerateHostEnt */

PR_IMPLEMENT(PRStatus)
PR_InitializeNetAddr(PRNetAddrValue val, PRUint16 port, PRNetAddr* addr) {
 PRStatus rv = PR_SUCCESS;
 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

 if (val != PR_IpAddrNull) {
   memset(addr, 0, sizeof(*addr));
 }
 addr->inet.family = AF_INET;
 addr->inet.port = htons(port);
 switch (val) {
   case PR_IpAddrNull:
     break; /* don't overwrite the address */
   case PR_IpAddrAny:
     addr->inet.ip = htonl(INADDR_ANY);
     break;
   case PR_IpAddrLoopback:
     addr->inet.ip = htonl(INADDR_LOOPBACK);
     break;
   default:
     PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
     rv = PR_FAILURE;
 }
 return rv;
} /* PR_InitializeNetAddr */

PR_IMPLEMENT(PRStatus)
PR_SetNetAddr(PRNetAddrValue val, PRUint16 af, PRUint16 port, PRNetAddr* addr) {
 PRStatus rv = PR_SUCCESS;
 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

 if (af == PR_AF_INET6) {
   if (val != PR_IpAddrNull) {
     memset(addr, 0, sizeof(addr->ipv6));
   }
   addr->ipv6.family = af;
   addr->ipv6.port = htons(port);
   addr->ipv6.flowinfo = 0;
   addr->ipv6.scope_id = 0;
   switch (val) {
     case PR_IpAddrNull:
       break; /* don't overwrite the address */
     case PR_IpAddrAny:
       addr->ipv6.ip = _pr_in6addr_any;
       break;
     case PR_IpAddrLoopback:
       addr->ipv6.ip = _pr_in6addr_loopback;
       break;
     default:
       PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
       rv = PR_FAILURE;
   }
 } else {
   if (val != PR_IpAddrNull) {
     memset(addr, 0, sizeof(addr->inet));
   }
   addr->inet.family = af;
   addr->inet.port = htons(port);
   switch (val) {
     case PR_IpAddrNull:
       break; /* don't overwrite the address */
     case PR_IpAddrAny:
       addr->inet.ip = htonl(INADDR_ANY);
       break;
     case PR_IpAddrLoopback:
       addr->inet.ip = htonl(INADDR_LOOPBACK);
       break;
     default:
       PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
       rv = PR_FAILURE;
   }
 }
 return rv;
} /* PR_SetNetAddr */

PR_IMPLEMENT(PRBool)
PR_IsNetAddrType(const PRNetAddr* addr, PRNetAddrValue val) {
 if (addr->raw.family == PR_AF_INET6) {
   if (val == PR_IpAddrAny) {
     if (_PR_IN6_IS_ADDR_UNSPECIFIED((PRIPv6Addr*)&addr->ipv6.ip)) {
       return PR_TRUE;
     }
     if (_PR_IN6_IS_ADDR_V4MAPPED((PRIPv6Addr*)&addr->ipv6.ip) &&
         _PR_IN6_V4MAPPED_TO_IPADDR((PRIPv6Addr*)&addr->ipv6.ip) ==
             htonl(INADDR_ANY)) {
       return PR_TRUE;
     }
   } else if (val == PR_IpAddrLoopback) {
     if (_PR_IN6_IS_ADDR_LOOPBACK((PRIPv6Addr*)&addr->ipv6.ip)) {
       return PR_TRUE;
     }
     if (_PR_IN6_IS_ADDR_V4MAPPED((PRIPv6Addr*)&addr->ipv6.ip) &&
         _PR_IN6_V4MAPPED_TO_IPADDR((PRIPv6Addr*)&addr->ipv6.ip) ==
             htonl(INADDR_LOOPBACK)) {
       return PR_TRUE;
     }
   } else if (val == PR_IpAddrV4Mapped &&
              _PR_IN6_IS_ADDR_V4MAPPED((PRIPv6Addr*)&addr->ipv6.ip)) {
     return PR_TRUE;
   }
 } else {
   if (addr->raw.family == AF_INET) {
     if (val == PR_IpAddrAny && addr->inet.ip == htonl(INADDR_ANY)) {
       return PR_TRUE;
     }
     if (val == PR_IpAddrLoopback && addr->inet.ip == htonl(INADDR_LOOPBACK)) {
       return PR_TRUE;
     }
   }
 }
 return PR_FALSE;
}

extern int pr_inet_aton(const char* cp, PRUint32* addr);

#define XX 127
static const unsigned char index_hex[256] = {
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, 0,  1,  2,  3,  4,  5,  6,  7,  8,
   9,  XX, XX, XX, XX, XX, XX, XX, 10, 11, 12, 13, 14, 15, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, 10, 11, 12, 13, 14, 15, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
   XX, XX, XX, XX, XX, XX, XX, XX, XX,
};

/*
* StringToV6Addr() returns 1 if the conversion succeeds,
* or 0 if the input is not a valid IPv6 address string.
* (Same as inet_pton(AF_INET6, string, addr).)
*/
static int StringToV6Addr(const char* string, PRIPv6Addr* addr) {
 const unsigned char* s = (const unsigned char*)string;
 int section = 0;       /* index of the current section (a 16-bit
                         * piece of the address */
 int double_colon = -1; /* index of the section after the first
                         * 16-bit group of zeros represented by
                         * the double colon */
 unsigned int val;
 int len;

 /* Handle initial (double) colon */
 if (*s == ':') {
   if (s[1] != ':') {
     return 0;
   }
   s += 2;
   addr->pr_s6_addr16[0] = 0;
   section = double_colon = 1;
 }

 while (*s) {
   if (section == 8) {
     return 0; /* too long */
   }
   if (*s == ':') {
     if (double_colon != -1) {
       return 0; /* two double colons */
     }
     addr->pr_s6_addr16[section++] = 0;
     double_colon = section;
     s++;
     continue;
   }
   for (len = val = 0; len < 4 && index_hex[*s] != XX; len++) {
     val = (val << 4) + index_hex[*s++];
   }
   if (*s == '.') {
     if (len == 0) {
       return 0; /* nothing between : and . */
     }
     break;
   }
   if (*s == ':') {
     s++;
     if (!*s) {
       return 0; /* cannot end with single colon */
     }
   } else if (*s) {
     return 0; /* bad character */
   }
   addr->pr_s6_addr16[section++] = htons((unsigned short)val);
 }

 if (*s == '.') {
   /* Have a trailing v4 format address */
   if (section > 6) {
     return 0; /* not enough room */
   }

   /*
    * The number before the '.' is decimal, but we parsed it
    * as hex.  That means it is in BCD.  Check it for validity
    * and convert it to binary.
    */
   if (val > 0x0255 || (val & 0xf0) > 0x90 || (val & 0xf) > 9) {
     return 0;
   }
   val = (val >> 8) * 100 + ((val >> 4) & 0xf) * 10 + (val & 0xf);
   addr->pr_s6_addr[2 * section] = val;

   s++;
   val = index_hex[*s++];
   if (val > 9) {
     return 0;
   }
   while (*s >= '0' && *s <= '9') {
     val = val * 10 + *s++ - '0';
     if (val > 255) {
       return 0;
     }
   }
   if (*s != '.') {
     return 0; /* must have exactly 4 decimal numbers */
   }
   addr->pr_s6_addr[2 * section + 1] = val;
   section++;

   s++;
   val = index_hex[*s++];
   if (val > 9) {
     return 0;
   }
   while (*s >= '0' && *s <= '9') {
     val = val * 10 + *s++ - '0';
     if (val > 255) {
       return 0;
     }
   }
   if (*s != '.') {
     return 0; /* must have exactly 4 decimal numbers */
   }
   addr->pr_s6_addr[2 * section] = val;

   s++;
   val = index_hex[*s++];
   if (val > 9) {
     return 0;
   }
   while (*s >= '0' && *s <= '9') {
     val = val * 10 + *s++ - '0';
     if (val > 255) {
       return 0;
     }
   }
   if (*s) {
     return 0; /* must have exactly 4 decimal numbers */
   }
   addr->pr_s6_addr[2 * section + 1] = val;
   section++;
 }

 if (double_colon != -1) {
   /* Stretch the double colon */
   int tosection;
   int ncopy = section - double_colon;
   for (tosection = 7; ncopy--; tosection--) {
     addr->pr_s6_addr16[tosection] = addr->pr_s6_addr16[double_colon + ncopy];
   }
   while (tosection >= double_colon) {
     addr->pr_s6_addr16[tosection--] = 0;
   }
 } else if (section != 8) {
   return 0; /* too short */
 }
 return 1;
}
#undef XX

#ifndef _PR_HAVE_INET_NTOP
static const char* basis_hex = "0123456789abcdef";

/*
* V6AddrToString() returns a pointer to the buffer containing
* the text string if the conversion succeeds, and NULL otherwise.
* (Same as inet_ntop(AF_INET6, addr, buf, size), except that errno
* is not set on failure.)
*/
static const char* V6AddrToString(const PRIPv6Addr* addr, char* buf,
                                 PRUint32 size) {
#  define STUFF(c)              \
   do {                        \
     if (!size--) return NULL; \
     *buf++ = (c);             \
   } while (0)

 int double_colon = -1;       /* index of the first 16-bit
                               * group of zeros represented
                               * by the double colon */
 int double_colon_length = 1; /* use double colon only if
                               * there are two or more 16-bit
                               * groups of zeros */
 int zero_length;
 int section;
 unsigned int val;
 const char* bufcopy = buf;

 /* Scan to find the placement of the double colon */
 for (section = 0; section < 8; section++) {
   if (addr->pr_s6_addr16[section] == 0) {
     zero_length = 1;
     section++;
     while (section < 8 && addr->pr_s6_addr16[section] == 0) {
       zero_length++;
       section++;
     }
     /* Select the longest sequence of zeros */
     if (zero_length > double_colon_length) {
       double_colon = section - zero_length;
       double_colon_length = zero_length;
     }
   }
 }

 /* Now start converting to a string */
 section = 0;

 if (double_colon == 0) {
   if (double_colon_length == 6 ||
       (double_colon_length == 5 && addr->pr_s6_addr16[5] == 0xffff)) {
     /* ipv4 format address */
     STUFF(':');
     STUFF(':');
     if (double_colon_length == 5) {
       STUFF('f');
       STUFF('f');
       STUFF('f');
       STUFF('f');
       STUFF(':');
     }
     if (addr->pr_s6_addr[12] > 99) {
       STUFF(addr->pr_s6_addr[12] / 100 + '0');
     }
     if (addr->pr_s6_addr[12] > 9) {
       STUFF((addr->pr_s6_addr[12] % 100) / 10 + '0');
     }
     STUFF(addr->pr_s6_addr[12] % 10 + '0');
     STUFF('.');
     if (addr->pr_s6_addr[13] > 99) {
       STUFF(addr->pr_s6_addr[13] / 100 + '0');
     }
     if (addr->pr_s6_addr[13] > 9) {
       STUFF((addr->pr_s6_addr[13] % 100) / 10 + '0');
     }
     STUFF(addr->pr_s6_addr[13] % 10 + '0');
     STUFF('.');
     if (addr->pr_s6_addr[14] > 99) {
       STUFF(addr->pr_s6_addr[14] / 100 + '0');
     }
     if (addr->pr_s6_addr[14] > 9) {
       STUFF((addr->pr_s6_addr[14] % 100) / 10 + '0');
     }
     STUFF(addr->pr_s6_addr[14] % 10 + '0');
     STUFF('.');
     if (addr->pr_s6_addr[15] > 99) {
       STUFF(addr->pr_s6_addr[15] / 100 + '0');
     }
     if (addr->pr_s6_addr[15] > 9) {
       STUFF((addr->pr_s6_addr[15] % 100) / 10 + '0');
     }
     STUFF(addr->pr_s6_addr[15] % 10 + '0');
     STUFF('\0');
     return bufcopy;
   }
 }

 while (section < 8) {
   if (section == double_colon) {
     STUFF(':');
     STUFF(':');
     section += double_colon_length;
     continue;
   }
   val = ntohs(addr->pr_s6_addr16[section]);
   if (val > 0xfff) {
     STUFF(basis_hex[val >> 12]);
   }
   if (val > 0xff) {
     STUFF(basis_hex[(val >> 8) & 0xf]);
   }
   if (val > 0xf) {
     STUFF(basis_hex[(val >> 4) & 0xf]);
   }
   STUFF(basis_hex[val & 0xf]);
   section++;
   if (section < 8 && section != double_colon) {
     STUFF(':');
   }
 }
 STUFF('\0');
 return bufcopy;
#  undef STUFF
}
#endif /* !_PR_HAVE_INET_NTOP */

/*
* Convert an IPv4 addr to an (IPv4-mapped) IPv6 addr
*/
PR_IMPLEMENT(void)
PR_ConvertIPv4AddrToIPv6(PRUint32 v4addr, PRIPv6Addr* v6addr) {
 PRUint8* dstp;
 dstp = v6addr->pr_s6_addr;
 memset(dstp, 0, 10);
 memset(dstp + 10, 0xff, 2);
 memcpy(dstp + 12, (char*)&v4addr, 4);
}

PR_IMPLEMENT(PRUint16) PR_ntohs(PRUint16 n) { return ntohs(n); }
PR_IMPLEMENT(PRUint32) PR_ntohl(PRUint32 n) { return ntohl(n); }
PR_IMPLEMENT(PRUint16) PR_htons(PRUint16 n) { return htons(n); }
PR_IMPLEMENT(PRUint32) PR_htonl(PRUint32 n) { return htonl(n); }
PR_IMPLEMENT(PRUint64) PR_ntohll(PRUint64 n) {
#ifdef IS_BIG_ENDIAN
 return n;
#else
 PRUint32 hi, lo;
 lo = (PRUint32)n;
 hi = (PRUint32)(n >> 32);
 hi = PR_ntohl(hi);
 lo = PR_ntohl(lo);
 return ((PRUint64)lo << 32) + (PRUint64)hi;
#endif
} /* ntohll */

PR_IMPLEMENT(PRUint64) PR_htonll(PRUint64 n) {
#ifdef IS_BIG_ENDIAN
 return n;
#else
 PRUint32 hi, lo;
 lo = (PRUint32)n;
 hi = (PRUint32)(n >> 32);
 hi = htonl(hi);
 lo = htonl(lo);
 return ((PRUint64)lo << 32) + (PRUint64)hi;
#endif
} /* htonll */

/*
* Implementation of PR_GetAddrInfoByName and friends
*
* Compile-time options:
*
*  _PR_HAVE_GETADDRINFO  Define this macro if the target system provides
*                        getaddrinfo. With this defined, NSPR will require
*                        getaddrinfo at run time. If this if not defined,
*                        then NSPR will attempt to dynamically resolve
*                        getaddrinfo, falling back to PR_GetHostByName if
*                        getaddrinfo does not exist on the target system.
*
* Since getaddrinfo is a relatively new system call on many systems,
* we are forced to dynamically resolve it at run time in most cases.
* The exception includes any system (such as Mac OS X) that is known to
* provide getaddrinfo in all versions that NSPR cares to support.
*/

#if defined(_PR_HAVE_GETADDRINFO)

#  if defined(_PR_INET6)

typedef struct addrinfo PRADDRINFO;
#    define GETADDRINFO getaddrinfo
#    define FREEADDRINFO freeaddrinfo
#    define GETNAMEINFO getnameinfo

#  elif defined(_PR_INET6_PROBE)

typedef struct addrinfo PRADDRINFO;

/* getaddrinfo/freeaddrinfo/getnameinfo prototypes */
#    if defined(WIN32)
#      define FUNC_MODIFIER __stdcall
#    else
#      define FUNC_MODIFIER
#    endif
typedef int(FUNC_MODIFIER* FN_GETADDRINFO)(const char* nodename,
                                          const char* servname,
                                          const PRADDRINFO* hints,
                                          PRADDRINFO** res);
typedef int(FUNC_MODIFIER* FN_FREEADDRINFO)(PRADDRINFO* ai);
typedef int(FUNC_MODIFIER* FN_GETNAMEINFO)(const struct sockaddr* addr,
                                          int addrlen, char* host, int hostlen,
                                          char* serv, int servlen, int flags);

/* global state */
static FN_GETADDRINFO _pr_getaddrinfo = NULL;
static FN_FREEADDRINFO _pr_freeaddrinfo = NULL;
static FN_GETNAMEINFO _pr_getnameinfo = NULL;

#    define GETADDRINFO_SYMBOL "getaddrinfo"
#    define FREEADDRINFO_SYMBOL "freeaddrinfo"
#    define GETNAMEINFO_SYMBOL "getnameinfo"

PRStatus _pr_find_getaddrinfo(void) {
 PRLibrary* lib;
#    ifdef WIN32
 /*
  * On windows, we need to search ws2_32.dll or wship6.dll
  * (Microsoft IPv6 Technology Preview for Windows 2000) for
  * getaddrinfo and freeaddrinfo.  These libraries might not
  * be loaded yet.
  */
 const char* libname[] = {"ws2_32.dll", "wship6.dll"};
 int i;

 for (i = 0; i < sizeof(libname) / sizeof(libname[0]); i++) {
   lib = PR_LoadLibrary(libname[i]);
   if (!lib) {
     continue;
   }
   _pr_getaddrinfo =
       (FN_GETADDRINFO)PR_FindFunctionSymbol(lib, GETADDRINFO_SYMBOL);
   if (!_pr_getaddrinfo) {
     PR_UnloadLibrary(lib);
     continue;
   }
   _pr_freeaddrinfo =
       (FN_FREEADDRINFO)PR_FindFunctionSymbol(lib, FREEADDRINFO_SYMBOL);
   _pr_getnameinfo =
       (FN_GETNAMEINFO)PR_FindFunctionSymbol(lib, GETNAMEINFO_SYMBOL);
   if (!_pr_freeaddrinfo || !_pr_getnameinfo) {
     PR_UnloadLibrary(lib);
     continue;
   }
   /* Keep the library loaded. */
   return PR_SUCCESS;
 }
 return PR_FAILURE;
#    else
 /*
  * Resolve getaddrinfo by searching all loaded libraries.  Then
  * search library containing getaddrinfo for freeaddrinfo.
  */
 _pr_getaddrinfo =
     (FN_GETADDRINFO)PR_FindFunctionSymbolAndLibrary(GETADDRINFO_SYMBOL, &lib);
 if (!_pr_getaddrinfo) {
   return PR_FAILURE;
 }
 _pr_freeaddrinfo =
     (FN_FREEADDRINFO)PR_FindFunctionSymbol(lib, FREEADDRINFO_SYMBOL);
 _pr_getnameinfo =
     (FN_GETNAMEINFO)PR_FindFunctionSymbol(lib, GETNAMEINFO_SYMBOL);
 PR_UnloadLibrary(lib);
 if (!_pr_freeaddrinfo || !_pr_getnameinfo) {
   return PR_FAILURE;
 }
 return PR_SUCCESS;
#    endif
}

#    define GETADDRINFO (*_pr_getaddrinfo)
#    define FREEADDRINFO (*_pr_freeaddrinfo)
#    define GETNAMEINFO (*_pr_getnameinfo)

#  endif /* _PR_INET6 */

#endif /* _PR_HAVE_GETADDRINFO */

#if !defined(_PR_HAVE_GETADDRINFO) || defined(_PR_INET6_PROBE)
/*
* If getaddrinfo does not exist, then we will fall back on
* PR_GetHostByName, which requires that we allocate a buffer for the
* PRHostEnt data structure and its members.
*/
typedef struct PRAddrInfoFB {
 char buf[PR_NETDB_BUF_SIZE];
 PRHostEnt hostent;
 PRBool has_cname;
} PRAddrInfoFB;

static PRAddrInfo* pr_GetAddrInfoByNameFB(const char* hostname, PRUint16 af,
                                         PRIntn flags) {
 PRStatus rv;
 PRAddrInfoFB* ai;
 /* fallback on PR_GetHostByName */
 ai = PR_NEW(PRAddrInfoFB);
 if (!ai) {
   PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
   return NULL;
 }
 rv = PR_GetHostByName(hostname, ai->buf, sizeof ai->buf, &ai->hostent);
 if (rv == PR_FAILURE) {
   PR_Free(ai);
   return NULL;
 }
 ai->has_cname = !(flags & PR_AI_NOCANONNAME);

 return (PRAddrInfo*)ai;
}
#endif /* !_PR_HAVE_GETADDRINFO || _PR_INET6_PROBE */

PR_IMPLEMENT(PRAddrInfo*)
PR_GetAddrInfoByName(const char* hostname, PRUint16 af, PRIntn flags) {
 /* restrict input to supported values */
 if ((af != PR_AF_INET && af != PR_AF_UNSPEC) ||
     (flags & ~PR_AI_NOCANONNAME) != PR_AI_ADDRCONFIG) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   return NULL;
 }

 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

#if !defined(_PR_HAVE_GETADDRINFO)
 return pr_GetAddrInfoByNameFB(hostname, af, flags);
#else
#  if defined(_PR_INET6_PROBE)
 if (!_pr_ipv6_is_present()) {
   return pr_GetAddrInfoByNameFB(hostname, af, flags);
 }
#  endif
 {
   PRADDRINFO *res, hints;
   int rv;

   /*
    * we assume a RFC 2553 compliant getaddrinfo.  this may at some
    * point need to be customized as platforms begin to adopt the
    * RFC 3493.
    */

   memset(&hints, 0, sizeof(hints));
   if (!(flags & PR_AI_NOCANONNAME)) {
     hints.ai_flags |= AI_CANONNAME;
   }
#  ifdef AI_ADDRCONFIG
   /*
    * Propagate AI_ADDRCONFIG to the GETADDRINFO call if PR_AI_ADDRCONFIG
    * is set.
    *
    * Need a workaround for loopback host addresses:
    * The problem is that in glibc and Windows, AI_ADDRCONFIG applies the
    * existence of an outgoing network interface to IP addresses of the
    * loopback interface, due to a strict interpretation of the
    * specification.  For example, if a computer does not have any
    * outgoing IPv6 network interface, but its loopback network interface
    * supports IPv6, a getaddrinfo call on "localhost" with AI_ADDRCONFIG
    * won't return the IPv6 loopback address "::1", because getaddrinfo
    * thinks the computer cannot connect to any IPv6 destination,
    * ignoring the remote vs. local/loopback distinction.
    */
   if ((flags & PR_AI_ADDRCONFIG) && strcmp(hostname, "localhost") != 0 &&
       strcmp(hostname, "localhost.localdomain") != 0 &&
       strcmp(hostname, "localhost6") != 0 &&
       strcmp(hostname, "localhost6.localdomain6") != 0) {
     hints.ai_flags |= AI_ADDRCONFIG;
   }
#  endif
   hints.ai_family = (af == PR_AF_INET) ? AF_INET : AF_UNSPEC;

   /*
    * it is important to select a socket type in the hints, otherwise we
    * will get back repetitive entries: one for each socket type.  since
    * we do not expose ai_socktype through our API, it is okay to do this
    * here.  the application may still choose to create a socket of some
    * other type.
    */
   hints.ai_socktype = SOCK_STREAM;

   rv = GETADDRINFO(hostname, NULL, &hints, &res);
#  ifdef AI_ADDRCONFIG
   if (rv == EAI_BADFLAGS && (hints.ai_flags & AI_ADDRCONFIG)) {
     hints.ai_flags &= ~AI_ADDRCONFIG;
     rv = GETADDRINFO(hostname, NULL, &hints, &res);
   }
#  endif
   if (rv == 0) {
     return (PRAddrInfo*)res;
   }

   PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, rv);
 }
 return NULL;
#endif
}

PR_IMPLEMENT(PRStatus)
PR_GetPrefLoopbackAddrInfo(PRNetAddr* result, PRUint16 port) {
 char tmpBuf[40];
 const int tmpBufSize = sizeof(tmpBuf);

 if (!result) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   return PR_FAILURE;
 }

 if (!_pr_initialized) _PR_ImplicitInitialization();

 PR_snprintf(tmpBuf, tmpBufSize, "%u", port);

#if !defined(_PR_HAVE_GETADDRINFO) || !defined(AI_PASSIVE)
 PR_SetError(PR_NOT_IMPLEMENTED_ERROR, 0);
 return PR_FAILURE;
#else

 PRADDRINFO *res, hints;
 PRStatus rv;

 memset(&hints, 0, sizeof(hints));

 rv = GETADDRINFO(NULL, tmpBuf, &hints, &res);
 if (rv == 0) {
   PRBool result_still_empty = PR_TRUE;
   PRADDRINFO* ai = res;
   do {
     PRNetAddr aNetAddr;

     while (ai && ai->ai_addrlen > sizeof(PRNetAddr)) ai = ai->ai_next;

     if (ai) {
       /* copy sockaddr to PRNetAddr */
       memcpy(&aNetAddr, ai->ai_addr, ai->ai_addrlen);
       aNetAddr.raw.family = ai->ai_addr->sa_family;
#  ifdef _PR_INET6
       if (AF_INET6 == aNetAddr.raw.family) aNetAddr.raw.family = PR_AF_INET6;
#  endif
       if (ai->ai_addrlen < sizeof(PRNetAddr))
         memset(((char*)result) + ai->ai_addrlen, 0,
                sizeof(PRNetAddr) - ai->ai_addrlen);
     }

     /* If we obtain more than one result, prefer IPv6. */
     if (result_still_empty || aNetAddr.raw.family == PR_AF_INET6) {
       memcpy(result, &aNetAddr, sizeof(PRNetAddr));
     }
     result_still_empty = PR_FALSE;
     ai = ai->ai_next;
   } while (ai);

   FREEADDRINFO(res);
   return PR_SUCCESS;
 }

 PR_SetError(PR_DIRECTORY_LOOKUP_ERROR, rv);
 return PR_FAILURE;
#endif
}

PR_IMPLEMENT(void) PR_FreeAddrInfo(PRAddrInfo* ai) {
#if defined(_PR_HAVE_GETADDRINFO)
#  if defined(_PR_INET6_PROBE)
 if (!_pr_ipv6_is_present()) {
   PR_Free((PRAddrInfoFB*)ai);
 } else
#  endif
   FREEADDRINFO((PRADDRINFO*)ai);
#else
 PR_Free((PRAddrInfoFB*)ai);
#endif
}

PR_IMPLEMENT(void*)
PR_EnumerateAddrInfo(void* iterPtr, const PRAddrInfo* base, PRUint16 port,
                    PRNetAddr* result) {
#if defined(_PR_HAVE_GETADDRINFO)
 PRADDRINFO* ai;
#  if defined(_PR_INET6_PROBE)
 if (!_pr_ipv6_is_present()) {
   /* using PRAddrInfoFB */
   PRIntn iter = (PRIntn)(PRPtrdiff)iterPtr;
   iter = PR_EnumerateHostEnt(iter, &((PRAddrInfoFB*)base)->hostent, port,
                              result);
   if (iter < 0) {
     iter = 0;
   }
   return (void*)(PRPtrdiff)iter;
 }
#  endif

 if (iterPtr) {
   ai = ((PRADDRINFO*)iterPtr)->ai_next;
 } else {
   ai = (PRADDRINFO*)base;
 }

 while (ai && ai->ai_addrlen > sizeof(PRNetAddr)) {
   ai = ai->ai_next;
 }

 if (ai) {
   /* copy sockaddr to PRNetAddr */
   memcpy(result, ai->ai_addr, ai->ai_addrlen);
   result->raw.family = ai->ai_addr->sa_family;
#  ifdef _PR_INET6
   if (AF_INET6 == result->raw.family) {
     result->raw.family = PR_AF_INET6;
   }
#  endif
   if (ai->ai_addrlen < sizeof(PRNetAddr)) {
     memset(((char*)result) + ai->ai_addrlen, 0,
            sizeof(PRNetAddr) - ai->ai_addrlen);
   }

   if (result->raw.family == PR_AF_INET) {
     result->inet.port = htons(port);
   } else {
     result->ipv6.port = htons(port);
   }
 }

 return ai;
#else
 /* using PRAddrInfoFB */
 PRIntn iter = (PRIntn)iterPtr;
 iter =
     PR_EnumerateHostEnt(iter, &((PRAddrInfoFB*)base)->hostent, port, result);
 if (iter < 0) {
   iter = 0;
 }
 return (void*)iter;
#endif
}

PR_IMPLEMENT(const char*) PR_GetCanonNameFromAddrInfo(const PRAddrInfo* ai) {
#if defined(_PR_HAVE_GETADDRINFO)
#  if defined(_PR_INET6_PROBE)
 if (!_pr_ipv6_is_present()) {
   const PRAddrInfoFB* fb = (const PRAddrInfoFB*)ai;
   return fb->has_cname ? fb->hostent.h_name : NULL;
 }
#  endif
 return ((const PRADDRINFO*)ai)->ai_canonname;
#else
 const PRAddrInfoFB* fb = (const PRAddrInfoFB*)ai;
 return fb->has_cname ? fb->hostent.h_name : NULL;
#endif
}

#if defined(_PR_HAVE_GETADDRINFO)
static PRStatus pr_StringToNetAddrGAI(const char* string, PRNetAddr* addr) {
 PRADDRINFO *res, hints;
 int rv; /* 0 for success, or the error code EAI_xxx */
 PRNetAddr laddr;
 PRStatus status = PR_SUCCESS;

 memset(&hints, 0, sizeof(hints));
 hints.ai_flags = AI_NUMERICHOST;
 hints.ai_family = AF_UNSPEC;
 hints.ai_socktype = SOCK_STREAM;

 rv = GETADDRINFO(string, NULL, &hints, &res);
 if (rv != 0) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, rv);
   return PR_FAILURE;
 }

 /* pick up the first addr */
 memcpy(&laddr, res->ai_addr, res->ai_addrlen);
 if (AF_INET6 == res->ai_addr->sa_family) {
   addr->ipv6.family = PR_AF_INET6;
   addr->ipv6.ip = laddr.ipv6.ip;
   addr->ipv6.scope_id = laddr.ipv6.scope_id;
 } else if (AF_INET == res->ai_addr->sa_family) {
   addr->inet.family = PR_AF_INET;
   addr->inet.ip = laddr.inet.ip;
 } else {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   status = PR_FAILURE;
 }

 FREEADDRINFO(res);
 return status;
}
#endif /* _PR_HAVE_GETADDRINFO */

static PRStatus pr_StringToNetAddrFB(const char* string, PRNetAddr* addr) {
 PRIntn rv;

 rv = pr_inet_aton(string, &addr->inet.ip);
 if (1 == rv) {
   addr->raw.family = AF_INET;
   return PR_SUCCESS;
 }

 PR_ASSERT(0 == rv);
 /* clean up after the failed call */
 memset(&addr->inet.ip, 0, sizeof(addr->inet.ip));

 rv = StringToV6Addr(string, &addr->ipv6.ip);
 if (1 == rv) {
   addr->raw.family = PR_AF_INET6;
   return PR_SUCCESS;
 }

 PR_ASSERT(0 == rv);
 PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
 return PR_FAILURE;
}

PR_IMPLEMENT(PRStatus) PR_StringToNetAddr(const char* string, PRNetAddr* addr) {
 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

 if (!addr || !string || !*string) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
   return PR_FAILURE;
 }

#if !defined(_PR_HAVE_GETADDRINFO)
 return pr_StringToNetAddrFB(string, addr);
#else
 /*
  * getaddrinfo with AI_NUMERICHOST is much slower than pr_inet_aton on some
  * platforms, such as Mac OS X (bug 404399), Linux glibc 2.10 (bug 344809),
  * and most likely others. So we only use it to convert literal IP addresses
  * that contain IPv6 scope IDs, which pr_inet_aton cannot convert.
  */
 if (!strchr(string, '%')) {
   return pr_StringToNetAddrFB(string, addr);
 }

#  if defined(_PR_INET6_PROBE)
 if (!_pr_ipv6_is_present()) {
   return pr_StringToNetAddrFB(string, addr);
 }
#  endif

 return pr_StringToNetAddrGAI(string, addr);
#endif
}

#if defined(_PR_HAVE_GETADDRINFO)
static PRStatus pr_NetAddrToStringGNI(const PRNetAddr* addr, char* string,
                                     PRUint32 size) {
 int addrlen;
 const PRNetAddr* addrp = addr;
#  if defined(_PR_HAVE_SOCKADDR_LEN) || defined(_PR_INET6)
 PRUint16 md_af = addr->raw.family;
 PRNetAddr addrcopy;
#  endif
 int rv; /* 0 for success, or the error code EAI_xxx */

#  ifdef _PR_INET6
 if (addr->raw.family == PR_AF_INET6) {
   md_af = AF_INET6;
#    ifndef _PR_HAVE_SOCKADDR_LEN
   addrcopy = *addr;
   addrcopy.raw.family = md_af;
   addrp = &addrcopy;
#    endif
 }
#  endif

 addrlen = PR_NETADDR_SIZE(addr);
#  ifdef _PR_HAVE_SOCKADDR_LEN
 addrcopy = *addr;
 ((struct sockaddr*)&addrcopy)->sa_len = addrlen;
 ((struct sockaddr*)&addrcopy)->sa_family = md_af;
 addrp = &addrcopy;
#  endif
 rv = GETNAMEINFO((const struct sockaddr*)addrp, addrlen, string, size, NULL,
                  0, NI_NUMERICHOST);
 if (rv != 0) {
   PR_SetError(PR_INVALID_ARGUMENT_ERROR, rv);
   return PR_FAILURE;
 }
 return PR_SUCCESS;
}
#endif /* _PR_HAVE_GETADDRINFO */

#if !defined(_PR_HAVE_GETADDRINFO) || defined(_PR_INET6_PROBE)
static PRStatus pr_NetAddrToStringFB(const PRNetAddr* addr, char* string,
                                    PRUint32 size) {
 if (PR_AF_INET6 == addr->raw.family) {
#  if defined(_PR_HAVE_INET_NTOP)
   if (NULL == inet_ntop(AF_INET6, &addr->ipv6.ip, string, size))
#  else
   if (NULL == V6AddrToString(&addr->ipv6.ip, string, size))
#  endif
   {
     /* the size of the result buffer is inadequate */
     PR_SetError(PR_BUFFER_OVERFLOW_ERROR, 0);
     return PR_FAILURE;
   }
 } else {
   if (size < 16) {
     goto failed;
   }
   if (AF_INET != addr->raw.family) {
     goto failed;
   } else {
     unsigned char* byte = (unsigned char*)&addr->inet.ip;
     PR_snprintf(string, size, "%u.%u.%u.%u", byte[0], byte[1], byte[2],
                 byte[3]);
   }
 }

 return PR_SUCCESS;

failed:
 PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
 return PR_FAILURE;

} /* pr_NetAddrToStringFB */
#endif /* !_PR_HAVE_GETADDRINFO || _PR_INET6_PROBE */

PR_IMPLEMENT(PRStatus)
PR_NetAddrToString(const PRNetAddr* addr, char* string, PRUint32 size) {
 if (!_pr_initialized) {
   _PR_ImplicitInitialization();
 }

#if !defined(_PR_HAVE_GETADDRINFO)
 return pr_NetAddrToStringFB(addr, string, size);
#else
#  if defined(_PR_INET6_PROBE)
 if (!_pr_ipv6_is_present()) {
   return pr_NetAddrToStringFB(addr, string, size);
 }
#  endif
 return pr_NetAddrToStringGNI(addr, string, size);
#endif
} /* PR_NetAddrToString */