Client API Functions

TCP States

code:

#include<winsock2.h>
#include<stdio.h>
#pragma   comment(lib,   "ws2_32.lib")
int main(int argc,char**argv)
{
    WSADATA wsaData;
    SOCKET SendingSocket;
    SOCKADDR_IN ServerAddr;
    unsigned int Port=80;
    int RetCode;
    //Initialize Winsock version 2.2
    WSAStartup(MAKEWORD(2,2),&wsaData);
    printf("Client:Winsock DLL status is %s.\n",wsaData.szSystemStatus);
    //Create a new socket to make a client connection.
    //AF_INET=2,The Internet Protocol version 4(IPv4)address family,TCP protocpl
    SendingSocket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
    if(SendingSocket==INVALID_SOCKET)
    {
        printf("Client:socket()failed !Error code:%ld\n",WSAGetLastError());
        WSACleanup();
        return -1;
    }
    else
        printf("Client:socket () is OK!\n");
    //Set up a SOCKETADDR_IN structure that will be used to connect to a listening server on port 5150,For demonstration purposes ,let's assume our server IP address is 127.0.0.1 or localhost.
    //IPv4
    ServerAddr.sin_family=AF_INET;
    //Port no.
    ServerAddr.sin_port=htons(Port);
    //The IPaddress
    ServerAddr.sin_addr.S_un.S_addr=inet_addr("209.131.36.158");
    RetCode=connect(SendingSocket,(SOCKADDR*)&ServerAddr,sizeof(ServerAddr));
    if(RetCode!=0)
    {
        printf("Client:connect() failed!Error code :%ld\n",WSAGetLastError());
        closesocket(SendingSocket);
        WSACleanup();
        return -1;
    }
    else
    {
        printf("Client connect() is OK,got connected ...\n");
        printf("Client Ready for sending and receiving data..\n");
    }
    // At this point you can start sending or receiving data on

     // the socket SendingSocket. We will describe sending and receiving data

     // later in the chapter.

     // When you are finished sending and receiving data on socket SendingSocket,

     // you should close the socket using the closesocket API. We will

     // describe socket closure later in the chapter.
    if(closesocket(SendingSocket)!=0)
        printf("Client :Cannot close \"Sending Socket .Error code:%ld\n",WSAGetLastError());
    else
        printf("Client :Closing \"SendingSocket\"socket..\n");
    if(WSACleanup()!=0)
         printf("Client: WSACleanup() failed!...\n");
     else
         printf("Client: WSACleanup() is OK...\n");
     return 0;
}