www.pudn.com > dos-SDK.rar > WINUDP.C
/****************************************************************************
PROGRAM: winudp.c
PURPOSE: sample UDP application
This is a very simple application to demonstate the use of the
windows sockets dll. It creates 2 UDP sockets and does a send
from one and a receive at the other.
FUNCTIONS:
called by windows ----
WinMain() - calls initialization function, processes message loop
InitApplication() - initializes window data and registers window
InitInstance() - saves instance handle and creates main window
MainWndProc() - processes messages
AboutProc() - processes messages for "About" dialog box
internal procedures ----
udp_cmds() - Loads the windows sockets dll, creates 2 UDP
sockets, does and send and receive and calls cleanup.
cleanup() - Closes sockets and free the windows sockets dll.
inc_nI() - Increments the line number in the screen output buffer.
****************************************************************************/
#include "windows.h"
#include "winudp.h"
/* you must define WSOCKETS_DLL before including socket.h */
#define WSOCKETS_DLL
#include
#include
#include
/* Variables used in windows calls */
HANDLE hInst; /* current instance */
short xChar, yChar ;
/* variables for the screen output buffer */
char sztextarr[MAXLINES][80];
short ntextlarr[MAXLINES];
int nI;
/* send and receive buffers */
char ssendbuff[BUFFER_SIZE];
char srecvbuff[BUFFER_SIZE];
/****************************************************************************
FUNCTION: WinMain(HANDLE, HANDLE, LPSTR, int)
PURPOSE: calls initialization function, processes message loop
COMMENTS:
Windows recognizes this function by name as the initial entry point
for the program. This function calls the application initialization
routine, if no other instance of the program is running, and always
calls the instance initialization routine. It then executes a message
retrieval and dispatch loop that is the top-level control structure
for the remainder of execution. The loop is terminated when a WM_QUIT
message is received, at which time this function exits the application
instance by returning the value passed by PostQuitMessage().
If this function must abort before entering the message loop, it
returns the conventional value NULL.
****************************************************************************/
int PASCAL WinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow)
HANDLE hInstance; /* current instance */
HANDLE hPrevInstance; /* previous instance */
LPSTR lpCmdLine; /* command line */
int nCmdShow; /* show-window type (open/icon) */
{
MSG msg; /* message */
if (!hPrevInstance) /* Other instances of app running? */
if (!InitApplication(hInstance)) /* Initialize shared things */
return (FALSE); /* Exits if unable to initialize */
/* Perform initializations that apply to a specific instance */
if (!InitInstance(hInstance, nCmdShow))
return (FALSE);
/* Acquire and dispatch messages until a WM_QUIT message is received. */
while (GetMessage(&msg, /* message structure */
NULL, /* handle of window receiving the message */
NULL, /* lowest message to examine */
NULL)) /* highest message to examine */
{
TranslateMessage(&msg); /* Translates virtual key codes */
DispatchMessage(&msg); /* Dispatches message to window */
}
return (msg.wParam); /* Returns the value from PostQuitMessage */
}
/****************************************************************************
FUNCTION: InitApplication(HANDLE)
PURPOSE: Initializes window data and registers window class
COMMENTS:
This function is called at initialization time only if no other
instances of the application are running. This function performs
initialization tasks that can be done once for any number of running
instances.
In this case, we initialize a window class by filling out a data
structure of type WNDCLASS and calling the Windows RegisterClass()
function. Since all instances of this application use the same window
class, we only need to do this when the first instance is initialized.
****************************************************************************/
BOOL InitApplication(hInstance)
HANDLE hInstance; /* current instance */
{
HANDLE hMemory;
PWNDCLASS pWndClass;
BOOL bSuccess;
hMemory = LocalAlloc((LMEM_FIXED | LMEM_ZEROINIT), sizeof(WNDCLASS));
pWndClass = (PWNDCLASS) LocalLock(hMemory);
/* Fill in window class structure with parameters that describe the */
/* main window. */
pWndClass->style = NULL; /* Class style(s). */
pWndClass->lpfnWndProc = MainWndProc; /* Function to retrieve messages */
/* windows of this class. */
pWndClass->cbClsExtra = 0; /* No per-class extra data. */
pWndClass->cbWndExtra = 0; /* No per-window extra data */
pWndClass->hInstance = hInstance; /* Application that owns the class. */
pWndClass->hIcon = LoadIcon(NULL, IDI_APPLICATION);
pWndClass->hCursor = LoadCursor(NULL, IDC_ARROW);
pWndClass->hbrBackground = GetStockObject(WHITE_BRUSH);
pWndClass->lpszMenuName = "UDPMenu"; /* Name of menu resource in .RC file. */
pWndClass->lpszClassName = "UDPWClass"; /* Name used in call to CreateWindow. */
/* Register the window class and return success/failure code. */
bSuccess= (RegisterClass(pWndClass));
LocalUnlock(hMemory);
LocalFree(hMemory);
return (bSuccess);
}
/****************************************************************************
FUNCTION: InitInstance(HANDLE, int)
PURPOSE: Saves instance handle and creates main window
COMMENTS:
This function is called at initialization time for every instance of
this application. This function performs initialization tasks that
cannot be shared by multiple instances.
In this case, we save the instance handle in a static variable and
create and display the main program window.
****************************************************************************/
BOOL InitInstance(hInstance, nCmdShow)
HANDLE hInstance; /* Current instance identifier. */
int nCmdShow; /* Param for first ShowWindow() call. */
{
HWND hWnd; /* Main window handle. */
/* Save the instance handle in static variable, which will be used in */
/* many subsequence calls from this application to Windows. */
hInst = hInstance;
/* Create a main window for this application instance. */
hWnd = CreateWindow(
"UDPWClass", /* See RegisterClass() call. */
"UDP Sample Application", /* Text for window title bar. */
WS_OVERLAPPEDWINDOW, /* Window style. */
CW_USEDEFAULT, /* Default horizontal position. */
CW_USEDEFAULT, /* Default vertical position. */
CW_USEDEFAULT, /* Default width. */
CW_USEDEFAULT, /* Default height. */
NULL, /* Overlapped windows have no parent. */
NULL, /* Use the window class menu. */
hInstance, /* This instance owns this window. */
NULL /* Pointer not needed. */
);
/* If window could not be created, return "failure" */
if (!hWnd)
return (FALSE);
/* Make the window visible; update its client area; and return "success" */
ShowWindow(hWnd, nCmdShow); /* Show the window */
UpdateWindow(hWnd); /* sends WM_PAINT message */
return (TRUE); /* Returns the value from PostQuitMessage */
}
/****************************************************************************
FUNCTION: MainWndProc(HWND, unsigned, WORD, LONG)
PURPOSE: Processes messages
MESSAGES:
WM_CREATE - create window
WM_PAINT - repaints the window
WM_DESTROY - destroy window
WM_COMMAND messages:
IDM_UDP - do some UDP commands.
COMMENTS:
****************************************************************************/
long FAR PASCAL MainWndProc(hWnd, message, wParam, lParam)
HWND hWnd;
unsigned message;
WORD wParam;
LONG lParam;
{
FARPROC lpProcAbout;
HMENU hMenu;
HDC hDC;
PAINTSTRUCT ps;
TEXTMETRIC tm;
int nJ;
switch (message) {
case WM_CREATE:
hDC =GetDC(hWnd);
GetTextMetrics (hDC,&tm);
xChar = tm.tmAveCharWidth;
yChar = tm.tmHeight +tm.tmExternalLeading;
ReleaseDC (hWnd,hDC);
break;
case WM_PAINT:
/* This program has a simplistic output method. It repaints
* the entire screen for every WM_PAINT message. Each time
* it adds a line of output it calls inc_nI() to increment the
* line number in the output buffer, and it calls InvalidateRect()
* so the screen will be repainted.
*/
if (nI==0) {
return (DefWindowProc(hWnd, message, wParam, lParam));
}
BeginPaint(hWnd,&ps);
for (nJ=1;nJ<=nI;nJ++) {
TextOut(ps.hdc,xChar,yChar * nJ,&sztextarr[nJ-1][0],ntextlarr[nJ-1]);
}
EndPaint (hWnd, &ps);
break;
case WM_COMMAND:
switch (wParam) {
case IDM_UDP:
nI=0;
udp_cmds(hWnd);
break;
case IDM_ABOUT:
lpProcAbout = MakeProcInstance(About, hInst);
DialogBox(hInst, "AboutBox", hWnd, lpProcAbout);
FreeProcInstance(lpProcAbout);
break;
}
break;
case WM_DESTROY:
PostQuitMessage(NULL);
break;
default:
return (DefWindowProc(hWnd, message, wParam, lParam));
}
return (NULL);
}
/****************************************************************************
FUNCTION: udp_cmds(HWND)
PURPOSE: Creates 2 sockets, binds address and send and receives a
packet. When complete, or if and error occurs cleanup is called.
****************************************************************************/
VOID PASCAL udp_cmds(hWnd)
HWND hWnd;
{
int nJ;
int nFromLen;
int nSd1,nSd2;
int nRc, nLen;
struct hostent far *hp;
struct sockaddr_in nSd1_addr, nSd2_addr, from;
char far * szIP;
ntextlarr[nI]=sprintf(&sztextarr[nI][0],"Starting UDP sample application");
inc_nI();
InvalidateRect(hWnd,NULL,TRUE);
/* create nSd1 socket */
nSd1= socket( AF_INET, SOCK_DGRAM, 0);
if (nSd1 < 0) {
ntextlarr[nI]=sprintf(&sztextarr[nI][0],"1st socket call failed, error=%d ",errno);
inc_nI();
InvalidateRect(hWnd,NULL,TRUE);
return;
}
/* create nSd2 socket */
nSd2= socket( AF_INET, SOCK_DGRAM, 0);
if (nSd2 < 0) {
ntextlarr[nI]=sprintf(&sztextarr[nI][0],"2nd socket call failed, error=%d",errno);
inc_nI();
InvalidateRect(hWnd,NULL,TRUE);
cleanup(hWnd, nSd1, nSd2);
return;
}
/* get IP address of local node */
hp = gethostbyname( "local_node");
if (hp ==NULL) {
ntextlarr[nI]=sprintf(&sztextarr[nI][0],"can't continue, 'local_node' not found in hosts table");
inc_nI();
InvalidateRect(hWnd,NULL,TRUE);
cleanup(hWnd, nSd1, nSd2);
return;
}
/* bind both sockets to hard coded ports */
nSd1_addr.sin_family=AF_INET;
nSd1_addr.sin_port=htons(PORT1);
nSd1_addr.sin_addr.s_addr=
*( (unsigned long far *) hp->h_addr_list[0]);
nRc=bind( nSd1, (struct sockaddr far *) &nSd1_addr,
sizeof(nSd1_addr));
if (nRc <0) {
ntextlarr[nI]=sprintf(&sztextarr[nI][0],"bind of socket nSd1=%d failed, error=%d",nSd1,errno);
inc_nI();
InvalidateRect(hWnd,NULL,TRUE);
cleanup(hWnd, nSd1, nSd2);
return;
}
nSd2_addr.sin_family=AF_INET;
nSd2_addr.sin_port=htons(PORT2);
nSd2_addr.sin_addr.s_addr =
*( (unsigned long far *) hp->h_addr_list[0]);
nRc=bind( nSd2, (struct sockaddr far *) &nSd2_addr,
sizeof(nSd2_addr));
if (nRc <0) {
ntextlarr[nI]=sprintf(&sztextarr[nI][0],"bind of socket nSd2=%d failed, error=%d",nSd1,errno);
inc_nI();
InvalidateRect(hWnd,NULL,TRUE);
cleanup(hWnd, nSd1, nSd2);
return;
}
/* initialize buffer */
for (nJ=0; nJ