Sender: This sample sends UDP datagrams to the specified
recipient. The -c option first calls connect() to associate the recipient’s
IP address with the socket handle so that the send() function can be used as
opposed to the sendto() call.

Compile:
cl -o Sender Sender.c ws2_32.lib
Command line options:
sender [-p:int] [-r:IP] [-c] [-n:x] [-b:x] [-d:c]
-p:int Remote port
-r:IP Recipient’s IP address or hostname
-c Connect to remote IP first
-n:x Number of times to send message
-b:x Size of buffer to send
-d:c Character to fill buffer with

Receiver: This sample receives UDP datagrams by binding to
the specified interface and port number and then blocking on a recvfrom()
call
Compile:
cl -o Receiver Receiver.c ws2_32.lib
Command line options:
sender [-p:int] [-i:IP][-n:x] [-b:x]
-p:int Local port
-i:IP Local IP address to listen on
-n:x Number of times to send message
-b:x Size of buffer to send
[sourcecode language=’cpp’]/*******************************************************
* MYCPLUS Sample Code – http://www.mycplus.com *
* *
* This code is made available as a service to our *
* visitors and is provided strictly for the *
* purpose of illustration. *
* *
* Please direct all inquiries to saqib at mycplus.com *
*******************************************************/

// Module Name: Sender.c
//
// Description:
// This sample sends UDP datagrams to the specified recipient.
// The -c option first calls connect() to associate the
// recipient’s IP address with the socket handle so that the
// send() function can be used as opposed to the sendto() call.
//
// Compile:
// cl -o Sender Sender.c ws2_32.lib
//
// Command line options:
// sender [-p:int] [-r:IP] [-c] [-n:x] [-b:x] [-d:c]
// -p:int Remote port
// -r:IP Recipient’s IP address or hostname
// -c Connect to remote IP first
// -n:x Number of times to send message
// -b:x Size of buffer to send
// -d:c Character to fill buffer with
//
#include
#include
#include

#define DEFAULT_PORT 5150
#define DEFAULT_COUNT 25
#define DEFAULT_CHAR ‘a’
#define DEFAULT_BUFFER_LENGTH 64

BOOL bConnect = FALSE; // Connect to recipient first
int iPort = DEFAULT_PORT; // Port to send data to
char cChar = DEFAULT_CHAR; // Character to fill buffer
DWORD dwCount = DEFAULT_COUNT, // Number of messages to send
dwLength = DEFAULT_BUFFER_LENGTH; // Length of buffer to send
char szRecipient[128]; // Recipient’s IP or hostname

//
// Function: usage
//
// Description:
// Print usage information and exit
//
void usage()
{
printf(“usage: sender [-p:int] [-r:IP] ”
“[-c] [-n:x] [-b:x] [-d:c]\n\n”);
printf(” -p:int Remote port\n”);
printf(” -r:IP Recipients IP address or hostname\n”);
printf(” -c Connect to remote IP first\n”);
printf(” -n:x Number of times to send message\n”);
printf(” -b:x Size of buffer to send\n”);
printf(” -d:c Character to fill buffer with\n\n”);
ExitProcess(1);
}

//
// Function: ValidateArgs
//
// Description:
// Parse the command line arguments, and set some global flags to
// indicate what actions to perform
//
void ValidateArgs(int argc, char **argv)
{
int i;

for(i = 1; i < argc; i++) { if ((argv[i][0] == '-') || (argv[i][0] == '/')) { switch (tolower(argv[i][1])) { case 'p': // Remote port if (strlen(argv[i]) > 3)
iPort = atoi(&argv[i][3]);
break;
case ‘r’: // Recipient’s IP addr
if (strlen(argv[i]) > 3)
strcpy(szRecipient, &argv[i][3]);
break;
case ‘c’: // Connect to recipients IP addr
bConnect = TRUE;
break;
case ‘n’: // Number of times to send message
if (strlen(argv[i]) > 3)
dwCount = atol(&argv[i][3]);
break;
case ‘b’: // Buffer size
if (strlen(argv[i]) > 3)
dwLength = atol(&argv[i][3]);
break;
case ‘d’: // Character to fill buffer
cChar = argv[i][3];
break;
default:
usage();
break;
}
}
}
}

//
// Function: main
//
// Description:
// Main thread of execution. Initialize Winsock, parse the command
// line arguments, create a socket, connect to the remote IP
// address if specified, and then send datagram messages to the
// recipient.
//
int main(int argc, char **argv)
{
WSADATA wsd;
SOCKET s;
char *sendbuf = NULL;
int ret,
i;
SOCKADDR_IN recipient;

// Parse the command line and load Winsock
//
ValidateArgs(argc, argv);

if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)
{
printf(“WSAStartup failed!\n”);
return 1;
}
// Create the socket
//
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s == INVALID_SOCKET)
{
printf(“socket() failed; %d\n”, WSAGetLastError());
return 1;
}
// Resolve the recipient’s IP address or hostname
//
recipient.sin_family = AF_INET;
recipient.sin_port = htons((short)iPort);
if ((recipient.sin_addr.s_addr = inet_addr(szRecipient))
== INADDR_NONE)
{
struct hostent *host=NULL;

host = gethostbyname(szRecipient);
if (host)
CopyMemory(&recipient.sin_addr, host->h_addr_list[0],
host->h_length);
else
{
printf(“gethostbyname() failed: %d\n”, WSAGetLastError());
WSACleanup();
return 1;
}
}
// Allocate the send buffer
//
sendbuf = GlobalAlloc(GMEM_FIXED, dwLength);
if (!sendbuf)
{
printf(“GlobalAlloc() failed: %d\n”, GetLastError());
return 1;
}
memset(sendbuf, cChar, dwLength);
//
// If the connect option is set, “connect” to the recipient
// and send the data with the send() function
//
if (bConnect)
{
if (connect(s, (SOCKADDR *)&recipient,
sizeof(recipient)) == SOCKET_ERROR)
{
printf(“connect() failed: %d\n”, WSAGetLastError());
GlobalFree(sendbuf);
WSACleanup();
return 1;
}
for(i = 0; i < dwCount; i++) { ret = send(s, sendbuf, dwLength, 0); if (ret == SOCKET_ERROR) { printf("send() failed: %d\n", WSAGetLastError()); break; } else if (ret == 0) break; // send() succeeded! } } else { // Otherwise, use the sendto() function // for(i = 0; i < dwCount; i++) { ret = sendto(s, sendbuf, dwLength, 0, (SOCKADDR *)&recipient, sizeof(recipient)); if (ret == SOCKET_ERROR) { printf("sendto() failed; %d\n", WSAGetLastError()); break; } else if (ret == 0) break; // sendto() succeeded! } } closesocket(s); GlobalFree(sendbuf); WSACleanup(); return 0; } /************************* End of Sender ***********************/ /************************************************************/ /************************** Receiver *************************/ // Module Name: Receiver.c // // Description: // This sample receives UDP datagrams by binding to the specified // interface and port number and then blocking on a recvfrom() // call // // Compile: // cl -o Receiver Receiver.c ws2_32.lib // // Command line options: // sender [-p:int] [-i:IP][-n:x] [-b:x] // -p:int Local port // -i:IP Local IP address to listen on // -n:x Number of times to send message // -b:x Size of buffer to send // #include #include #include #define DEFAULT_PORT 5150 #define DEFAULT_COUNT 25 #define DEFAULT_BUFFER_LENGTH 4096 int iPort = DEFAULT_PORT; // Port to receive on DWORD dwCount = DEFAULT_COUNT, // Number of messages to read dwLength = DEFAULT_BUFFER_LENGTH; // Length of receiving buffer BOOL bInterface = FALSE; // Use an interface other than // default char szInterface[32]; // Interface to read datagrams from // // Function: usage: // // Description: // Print usage information and exit // void usage() { printf("usage: sender [-p:int] [-i:IP][-n:x] [-b:x]\n\n"); printf(" -p:int Local port\n"); printf(" -i:IP Local IP address to listen on\n"); printf(" -n:x Number of times to send message\n"); printf(" -b:x Size of buffer to send\n\n"); ExitProcess(1); } // // Function: ValidateArgs // // Description: // Parse the command line arguments, and set some global flags to // indicate what actions to perform // void ValidateArgs(int argc, char **argv) { int i; for(i = 1; i < argc; i++) { if ((argv[i][0] == '-') || (argv[i][0] == '/')) { switch (tolower(argv[i][1])) { case 'p': // Local port if (strlen(argv[i]) > 3)
iPort = atoi(&argv[i][3]);
break;
case ‘n’: // Number of times to receive message
if (strlen(argv[i]) > 3)
dwCount = atol(&argv[i][3]);
break;
case ‘b’: // Buffer size
if (strlen(argv[i]) > 3)
dwLength = atol(&argv[i][3]);
break;
case ‘i’: // Interface to receive datagrams on
if (strlen(argv[i]) > 3)
{
bInterface = TRUE;
strcpy(szInterface, &argv[i][3]);
}
break;
default:
usage();
break;
}
}
}
}

//
// Function: main
//
// Description:
// Main thread of execution. Initialize Winsock, parse the command
// line arguments, create a socket, bind it to a local interface
// and port, and then read datagrams.
//
int main(int argc, char **argv)
{
WSADATA wsd;
SOCKET s;
char *recvbuf = NULL;
int ret,
i;
DWORD dwSenderSize;
SOCKADDR_IN sender,
local;

// Parse arguments and load Winsock
//
ValidateArgs(argc, argv);

if (WSAStartup(MAKEWORD(2,2), &wsd) != 0)
{
printf(“WSAStartup failed!\n”);
return 1;
}
// Create the socket and bind it to a local interface and port
//
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s == INVALID_SOCKET)
{
printf(“socket() failed; %d\n”, WSAGetLastError());
return 1;
}
local.sin_family = AF_INET;
local.sin_port = htons((short)iPort);
if (bInterface)
local.sin_addr.s_addr = inet_addr(szInterface);
else
local.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(s, (SOCKADDR *)&local, sizeof(local)) == SOCKET_ERROR)
{
printf(“bind() failed: %d\n”, WSAGetLastError());
return 1;
}
// Allocate the receive buffer
//
recvbuf = GlobalAlloc(GMEM_FIXED, dwLength);
if (!recvbuf)
{
printf(“GlobalAlloc() failed: %d\n”, GetLastError());
return 1;
}
// Read the datagrams
//
for(i = 0; i < dwCount; i++) { dwSenderSize = sizeof(sender); ret = recvfrom(s, recvbuf, dwLength, 0, (SOCKADDR *)&sender, &dwSenderSize); if (ret == SOCKET_ERROR) { printf("recvfrom() failed; %d\n", WSAGetLastError()); break; } else if (ret == 0) break; else { recvbuf[ret] = '\0'; printf("[%s] sent me: '%s'\n", inet_ntoa(sender.sin_addr), recvbuf); } } closesocket(s); GlobalFree(recvbuf); WSACleanup(); return 0; } /************************* End of Receiver **********************/[/sourcecode]

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