Clients/BonjourExample/BonjourExample.cpp

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  */
  17
  18 #include        "stdafx.h"
  19
  20 #include        <assert.h>
  21 #include        <stdio.h>
  22
  23 #include        "dns_sd.h"
  24
  25 // Constants
  26
  27 #define BONJOUR_EVENT           ( WM_USER + 0x100 )     // Message sent to the Window when a Bonjour event occurs.
  28
  29 // Prototypes
  30
  31 static LRESULT CALLBACK WndProc( HWND inWindow, UINT inMsg, WPARAM inWParam, LPARAM inLParam );
  32
  33 static void DNSSD_API
  34         BrowserCallBack(
  35                 DNSServiceRef           inServiceRef,
  36                 DNSServiceFlags         inFlags,
  37                 uint32_t                        inIFI,
  38                 DNSServiceErrorType     inError,
  39                 const char *            inName,
  40                 const char *            inType,
  41                 const char *            inDomain,
  42                 void *                          inContext );
  43
  44 // Globals
  45
  46 DNSServiceRef           gServiceRef = NULL;
  47
  48 // Main entry point for application.
  49
  50 int _tmain( int argc, _TCHAR *argv[] )
  51 {
  52         HINSTANCE                               instance;
  53         WNDCLASSEX                              wcex;
  54         HWND                                    wind;
  55         MSG                                             msg;
  56         DNSServiceErrorType             err;
  57
  58         (void) argc; // Unused
  59         (void) argv; // Unused
  60
  61         // Create the window. This window won't actually be shown, but it demonstrates how to use Bonjour
  62         // with Windows GUI applications by having Bonjour events processed as messages to a Window.
  63
  64         instance = GetModuleHandle( NULL );
  65         assert( instance );
  66
  67         wcex.cbSize                     = sizeof( wcex );
  68         wcex.style                      = 0;
  69         wcex.lpfnWndProc        = (WNDPROC) WndProc;
  70         wcex.cbClsExtra         = 0;
  71         wcex.cbWndExtra         = 0;
  72         wcex.hInstance          = instance;
  73         wcex.hIcon                      = NULL;
  74         wcex.hCursor            = NULL;
  75         wcex.hbrBackground      = NULL;
  76         wcex.lpszMenuName       = NULL;
  77         wcex.lpszClassName      = TEXT( "BonjourExample" );
  78         wcex.hIconSm            = NULL;
  79         RegisterClassEx( &wcex );
  80
  81         wind = CreateWindow( wcex.lpszClassName, wcex.lpszClassName, 0, CW_USEDEFAULT, 0, CW_USEDEFAULT,
  82                 0, NULL, NULL, instance, NULL );
  83         assert( wind );
  84
  85         // Start browsing for services and associate the Bonjour browser with our window using the
  86         // WSAAsyncSelect mechanism. Whenever something related to the Bonjour browser occurs, our
  87         // private Windows message will be sent to our window so we can give Bonjour a chance to
  88         // process it. This allows Bonjour to avoid using a secondary thread (and all the issues
  89         // with synchronization that would introduce), but still process everything asynchronously.
  90         // This also simplifies app code because Bonjour will only run when we explicitly call it.
  91
  92         err = DNSServiceBrowse(
  93                 &gServiceRef,                                   // Receives reference to Bonjour browser object.
  94                 0,                                                              // No flags.
  95                 kDNSServiceInterfaceIndexAny,   // Browse on all network interfaces.
  96                 "_http._tcp",                                   // Browse for HTTP service types.
  97                 NULL,                                                   // Browse on the default domain (e.g. local.).
  98                 BrowserCallBack,                                // Callback function when Bonjour events occur.
  99                 NULL );                                                 // No callback context needed.
 100         assert( err == kDNSServiceErr_NoError );
 101
 102         err = WSAAsyncSelect( (SOCKET) DNSServiceRefSockFD( gServiceRef ), wind, BONJOUR_EVENT, FD_READ | FD_CLOSE );
 103         assert( err == kDNSServiceErr_NoError );
 104
 105         fprintf( stderr, "Browsing for _http._tcp\n" );
 106
 107         // Main event loop for the application. All Bonjour events are dispatched while in this loop.
 108
 109         while( GetMessage( &msg, NULL, 0, 0 ) )
 110         {
 111                 TranslateMessage( &msg );
 112                 DispatchMessage( &msg );
 113         }
 114
 115         // Clean up Bonjour. This is not strictly necessary since the normal process cleanup will
 116         // close Bonjour socket(s) and release memory, but it's here to demonstrate how to do it.
 117
 118         if( gServiceRef )
 119         {
 120                 WSAAsyncSelect( (SOCKET) DNSServiceRefSockFD( gServiceRef ), wind, BONJOUR_EVENT, 0 );
 121                 DNSServiceRefDeallocate( gServiceRef );
 122         }
 123         return( 0 );
 124 }
 125
 126 // Callback for the Window. Bonjour events are delivered here.
 127
 128 static LRESULT CALLBACK WndProc( HWND inWindow, UINT inMsg, WPARAM inWParam, LPARAM inLParam )
 129 {
 130         LRESULT                                 result;
 131         DNSServiceErrorType             err;
 132
 133         switch( inMsg )
 134         {
 135                 case BONJOUR_EVENT:
 136
 137                         // Process the Bonjour event. All Bonjour callbacks occur from within this function.
 138                         // If an error occurs while trying to process the result, it most likely means that
 139                         // something serious has gone wrong with Bonjour, such as it being terminated. This
 140                         // does not normally occur, but code should be prepared to handle it. If the error
 141                         // is ignored, the window will receive a constant stream of BONJOUR_EVENT messages so
 142                         // if an error occurs, we disassociate the DNSServiceRef from the window, deallocate
 143                         // it, and invalidate the reference so we don't try to deallocate it again on quit.
 144                         // Since this is a simple example app, if this error occurs, we quit the app too.
 145
 146                         err = DNSServiceProcessResult( gServiceRef );
 147                         if( err != kDNSServiceErr_NoError )
 148                         {
 149                                 fprintf( stderr, "### ERROR! serious Bonjour error: %d\n", err );
 150
 151                                 WSAAsyncSelect( (SOCKET) DNSServiceRefSockFD( gServiceRef ), inWindow, BONJOUR_EVENT, 0 );
 152                                 DNSServiceRefDeallocate( gServiceRef );
 153                                 gServiceRef = NULL;
 154
 155                                 PostQuitMessage( 0 );
 156                         }
 157                         result = 0;
 158                         break;
 159
 160                 default:
 161                         result = DefWindowProc( inWindow, inMsg, inWParam, inLParam );
 162                         break;
 163         }
 164         return( result );
 165 }
 166
 167 // Callback for Bonjour browser events. Called when services are added or removed.
 168
 169 static void DNSSD_API
 170         BrowserCallBack(
 171                 DNSServiceRef           inServiceRef,
 172                 DNSServiceFlags         inFlags,
 173                 uint32_t                        inIFI,
 174                 DNSServiceErrorType     inError,
 175                 const char *            inName,
 176                 const char *            inType,
 177                 const char *            inDomain,
 178                 void *                          inContext )
 179 {
 180         (void) inServiceRef;    // Unused
 181         (void) inContext;               // Unused
 182
 183         if( inError == kDNSServiceErr_NoError )
 184         {
 185                 const char *            action;
 186                 const char *            more;
 187
 188                 if( inFlags & kDNSServiceFlagsAdd )                     action  = "ADD";
 189                 else                                                                            action  = "RMV";
 190                 if( inFlags & kDNSServiceFlagsMoreComing )      more    = " (MORE)";
 191                 else                                                                            more    = "";
 192
 193                 fprintf( stderr, "%s %30s.%s%s on interface %d%s\n", action, inName, inType, inDomain, (int) inIFI, more );
 194         }
 195         else
 196         {
 197                 fprintf( stderr, "Bonjour browser error occurred: %d\n", inError );
 198         }
 199 }