How to set the Maximum Packet Size for the UDP Socket Buffer Size ?

How to set the Maximum Packet Size for the UDP Socket Buffer Size ?

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#define UDP_TX_BUF_SIZE 32768

#define UDP_MAX_PKT_SIZE 65536

// set udp recv buffer size to at least the largest possible udp packet

//size to avoid losing data on OSes that set this too low by default.

int optlen = sizeof(tmp);

if (!getsockopt(udp_fd, SOL_SOCKET, SO_RCVBUF, &tmp, &optlen) && ( tmp <>

{ tmp = UDP_MAX_PKT_SIZE;

setsockopt(udp_fd, SOL_SOCKET, SO_RCVBUF, &tmp, sizeof(tmp));

}

UDP Server and Client application

UDPServer :
--------------
1.WSAStartup()
2.socket()
3.bind()
4.recv()
5.send()



UDPClient :
------------

1.WSAStartup()
2.gethostbyaddr()
3.socket()
4.connect()
5.send()
6.receive()



UDPServer:
----------
struct sockaddr_in local, from;
WSADATA wsaData;
SOCKET listen_socket, msgsock;


WSAStartup(0x202, &wsaData)
local.sin_family = AF_INET;
local.sin_addr.s_addr = (!ip_address) ? INADDR_ANY:inet_addr(ip_address);
local.sin_port = htons(port);

listen_socket = socket(AF_INET, SOCK_DGRAM,0);

if (listen_socket == INVALID_SOCKET){ //Error}

if (bind(listen_socket, (struct sockaddr*)&local, sizeof(local)) == SOCKET_ERROR){ //error}

msgsock = listen_socket;

retval = recvfrom(msgsock,Buffer, sizeof(Buffer), 0, (struct sockaddr *)&from, &fromlen);

if(retval == SOCKET_ERROR) {return;}

//send the received data back to the client...
retval = sendto(msgsock, Buffer, sizeof(Buffer), 0, (struct sockaddr *)&from, fromlen);



UDP client :
---------------

struct sockaddr_in server;

struct hostent *hp;

WSADATA wsaData;

SOCKET conn_socket;


if (isalpha(server_name[0]))

{ // server address is a name

hp = gethostbyname(server_name);

}

else

{ // Convert nnn.nnn address to a usable one

addr = inet_addr(server_name);

hp = gethostbyaddr((char *)&addr, 4, AF_INET);

}




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

memcpy(&(server.sin_addr), hp->h_addr, hp->h_length);

server.sin_family = hp->h_addrtype;

server.sin_port = htons(port);

conn_socket = socket(AF_INET, SOCK_DGRAM, 0);

if (connect(conn_socket, (struct sockaddr*)&server, sizeof(server)) == SOCKET_ERROR) { //Error}


retval = send(conn_socket, Buffer, sizeof(Buffer), 0);

retval = recv(conn_socket, Buffer, sizeof(Buffer), 0);

closesocket(conn_socket);

WSACleanup();