/*
 *	FILE
 *		win32.c
 *
 *	DESCRIPTION
 *		Win32 support functions.
 *
 * Contains table and functions for looking up win32 socket error
 * descriptions. But will/may contain other win32 helper functions
 * for libpq.
 *
 * The error constants are taken from the Frambak Bakfram LGSOCKET 
 * library guys who in turn took them from the Winsock FAQ.
 *
 * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 */

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <winsock.h>
#include <stdio.h>
#include "win32.h"

static struct WSErrorEntry {
    DWORD 	 error;
    const char*  description;
} WSErrors [] = {
    {0,                  "No error"},
    {WSAEINTR,           "Interrupted system call"},
    {WSAEBADF,           "Bad file number"},
    {WSAEACCES,          "Permission denied"},
    {WSAEFAULT,          "Bad address"},
    {WSAEINVAL,          "Invalid argument"},
    {WSAEMFILE,          "Too many open sockets"},
    {WSAEWOULDBLOCK,     "Operation would block"},
    {WSAEINPROGRESS,     "Operation now in progress"},
    {WSAEALREADY,        "Operation already in progress"},
    {WSAENOTSOCK,        "Socket operation on non-socket"},
    {WSAEDESTADDRREQ,    "Destination address required"},
    {WSAEMSGSIZE,        "Message too long"},
    {WSAEPROTOTYPE,      "Protocol wrong type for socket"},
    {WSAENOPROTOOPT,     "Bad protocol option"},
    {WSAEPROTONOSUPPORT, "Protocol not supported"},
    {WSAESOCKTNOSUPPORT, "Socket type not supported"},
    {WSAEOPNOTSUPP,      "Operation not supported on socket"},
    {WSAEPFNOSUPPORT,    "Protocol family not supported"},
    {WSAEAFNOSUPPORT,    "Address family not supported"},
    {WSAEADDRINUSE,      "Address already in use"},
    {WSAEADDRNOTAVAIL,   "Can't assign requested address"},
    {WSAENETDOWN,        "Network is down"},
    {WSAENETUNREACH,     "Network is unreachable"},
    {WSAENETRESET,       "Net connection reset"},
    {WSAECONNABORTED,    "Software caused connection abort"},
    {WSAECONNRESET,      "Connection reset by peer"},
    {WSAENOBUFS,         "No buffer space available"},
    {WSAEISCONN,         "Socket is already connected"},
    {WSAENOTCONN,        "Socket is not connected"},
    {WSAESHUTDOWN,       "Can't send after socket shutdown"},
    {WSAETOOMANYREFS,    "Too many references, can't splice"},
    {WSAETIMEDOUT,       "Connection timed out"},
    {WSAECONNREFUSED,    "Connection refused"},
    {WSAELOOP,           "Too many levels of symbolic links"},
    {WSAENAMETOOLONG,    "File name too long"},
    {WSAEHOSTDOWN,       "Host is down"},
    {WSAEHOSTUNREACH,    "No route to host"},
    {WSAENOTEMPTY,       "Directory not empty"},
    {WSAEPROCLIM,        "Too many processes"},
    {WSAEUSERS,          "Too many users"},
    {WSAEDQUOT,          "Disc quota exceeded"},
    {WSAESTALE,          "Stale NFS file handle"},
    {WSAEREMOTE,         "Too many levels of remote in path"},
    {WSASYSNOTREADY,     "Network system is unavailable"},
    {WSAVERNOTSUPPORTED, "Winsock version out of range"},
    {WSANOTINITIALISED,  "WSAStartup not yet called"},
    {WSAEDISCON,         "Graceful shutdown in progress"},
    {WSAHOST_NOT_FOUND,  "Host not found"},
    {WSATRY_AGAIN,       "NA Host not found / SERVFAIL"},
    {WSANO_RECOVERY,     "Non recoverable FORMERR||REFUSED||NOTIMP"},
    {WSANO_DATA,         "No host data of that type was found"},
    {0,0} /* End of table */
};


/* 
 * Returns 0 if not found, linear but who cares, at this moment
 * we're already in pain :)
 */

static int LookupWSErrorMessage(DWORD err,char*dest)
{   
  struct WSErrorEntry *e;
  for (e = WSErrors;e->description;e++)
  {
    if (e->error == err)
    {
      strcpy(dest,e->description);
      return 1;
    }
  }
  return 0;
}


struct MessageDLL{
    const char *dll_name;
    void       *handle;
    int         loaded; /* BOOL */
}dlls[]={
  {"netmsg.dll",0,0},
  {"winsock.dll",0,0},
  {"wsock32.dll",0,0},
  {"ws2_32.dll",0,0},
  {"wsock32n.dll",0,0},
  {"mswsock.dll",0,0},
  {"ws2help.dll",0,0},
  {"ws2thk.dll",0,0},
  {0,0,1}             /* Last one, no dll, always loaded */
};

#define DLLS_SIZE (sizeof(dlls)/sizeof(struct MessageDLL))

/*
 * Returns a description of the socket error by first trying
 * to find it in the lookup table, and if that fails, tries
 * to load any of the winsock dlls to find that message.
 * The DLL thing works from Nt4 (spX ?) up, but some special 
 * versions of winsock might have this aswell (seen on Win98 SE
 * special install)            / Magnus Naeslund (mag@fbab.net)
 *
 */

const char *winsock_strerror(int err){
  static char   buf[512]; /* Not threadsafe */
  unsigned long flags;
  int           offs,i;
  int           success = LookupWSErrorMessage(err,buf);
  
  for (i=0;!success && i<DLLS_SIZE;i++)
  {
      
      if (!dlls[i].loaded)
      {
	dlls[i].loaded = 1; /* Only load once */
	dlls[i].handle = (void*)LoadLibraryEx(
					      dlls[i].dll_name,
					      0,
					      LOAD_LIBRARY_AS_DATAFILE);
      }
      
      if (dlls[i].dll_name && !dlls[i].handle)
	continue; /* Didn't load */
      
      flags = FORMAT_MESSAGE_FROM_SYSTEM 
	    | FORMAT_MESSAGE_IGNORE_INSERTS
	    | (dlls[i].handle?FORMAT_MESSAGE_FROM_HMODULE:0);
      
      success = 0 != FormatMessage( 
				   flags,
				   dlls[i].handle,err,
				   MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
				   buf,sizeof(buf)-64,
				   0
				   );
  }
  
  if (!success)
  {
    sprintf(buf,"Unknown socket error (0x%08X/%lu)",err,err);
  }
  else
  {
    buf[sizeof(buf)-1]='\0';
    offs = strlen(buf);
    if (offs>sizeof(buf)-64)
      offs = sizeof(buf)-64;
    sprintf(buf+offs," (0x%08X/%lu)",err,err);
  }
  return buf;  
}