Socket Client

9/8/2008

O seguinte amostra de código mostra como implementar um cliente sockets do Windows (Winsock). Ele envia dados para o servidor e obtém os dados echoed voltar a partir de servidor. Este exemplo pode ser executar no mesmo dispositivo com o aplicativo Socket Server. Neste maiúsculas e minúsculas, use "localhost" como parâmetro do aplicativo. Caso contrário, use um nome completo servidor ou endereço.

#include <winsock2.h>
#include <ws2tcpip.h>
#include <windows.h>
#include <tchar.h>
#include <strsafe.h>

char pBuf[] = "WinCE Echo Test Packet";

#define DEFAULT_FAMILY        AF_UNSPEC
#define DEFAULT_SOCKTYPE    SOCK_STREAM
#define DEFAULT_PORT        "1234"
#define BUFFER_SIZE            23                // length of "WinCE Echo Test Packet"

#define TIMEOUT_SECS        2
#define TIMEOUT_USECS        0

void
Print(
    TCHAR *pFormat, 
    ...)
{
    va_list ArgList;
    TCHAR    Buffer[256];

    va_start (ArgList, pFormat);

   (void)StringCchPrintf(Buffer, 256, pFormat, ArgList);
#ifndef UNDER_CE
    _putts(Buffer);
#else
    printf("%s",Buffer);
#endif

    va_end(ArgList);
}

int _tmain (int argc, TCHAR* argv[])
{
    SOCKET sock = INVALID_SOCKET;
    int nFamily = DEFAULT_FAMILY;
    int nSockType = DEFAULT_SOCKTYPE;
    char szRemoteName[64];
    char *szPort = DEFAULT_PORT;
    SOCKADDR_STORAGE ssRemoteAddr;
    int cbXfer, cbTotalRecvd, cbRemoteAddrSize;
    WSADATA wsaData;
    ADDRINFO Hints, *AddrInfo = NULL, *AI;
    char szRemoteAddrString[128];
    fd_set fdReadSet;
    TIMEVAL timeout = {TIMEOUT_SECS, TIMEOUT_USECS};
    char pRecvBuf[BUFFER_SIZE];

    if(WSAStartup(MAKEWORD(2,2), &wsaData))
    {
        // WSAStartup failed
        return 1;
    }

    if(argc < 2)
    {
        Print(TEXT("Server name/address parameter required.  Ex: clnt 123.45.67.89"));
        goto Cleanup;
    }
    else
    {
        // we use the first argument as the server name/address
#if defined UNICODE
        wcstombs(szRemoteName, argv[1], sizeof(szRemoteName));
#else
        strncpy(szRemoteName, argv[1], sizeof(szRemoteName));
#endif
        szRemoteName[63] = _T('\0');
        Print(TEXT("Communicating with server - %hs\r\n"), szRemoteName);
    }

    //
    // Resolve the server name/address
    //

    memset(&Hints, 0, sizeof(Hints));
    Hints.ai_family = nFamily;
    Hints.ai_socktype = nSockType;

    if(getaddrinfo(szRemoteName, szPort, &Hints, &AddrInfo))
    {
        Print(TEXT("ERROR: Couldn't get resolve the server name/address!"));
        goto Cleanup;
    }

    //
    // Attempt to connect to each address until we find one that succeeds
    //

    for(AI = AddrInfo; AI != NULL; AI = AI->ai_next) 
    {
        if((AI->ai_family == PF_INET) || (AI->ai_family == PF_INET6)) // only want PF_INET or PF_INET6
        {
            sock = socket(AI->ai_family, AI->ai_socktype, AI->ai_protocol);
            if (sock != INVALID_SOCKET)
            {
                if (AI->ai_socktype == SOCK_STREAM)
                {
                    if(connect(sock, AI->ai_addr, AI->ai_addrlen) == SOCKET_ERROR)
                    {
                        // Connect failed, let's close this socket and try again on the next address in the list
                        closesocket(sock);
                        continue;
                    }
                }

                // connect() succeeded or we're a UDP socket
                break;
            }
        }
    }
    
    if (AI == NULL) 
    {
        Print(TEXT("ERROR: Unable to connect to any of the server's addresses!\r\n"));
        goto Cleanup;
    }

    //
    // Send data to the server
    //

    cbXfer = 0;
    cbXfer = sendto(sock, pBuf, sizeof(pBuf), 0, AI->ai_addr, AI->ai_addrlen);

    if(cbXfer != sizeof(pBuf))
    {
        Print(TEXT("ERROR: Couldn't send the data! error = %d\r\n"), WSAGetLastError());
        goto Cleanup;
    }

    if (getnameinfo(AI->ai_addr, AI->ai_addrlen,
        szRemoteAddrString, sizeof(szRemoteAddrString), NULL, 0, NI_NUMERICHOST) != 0)
        strcpy(szRemoteAddrString, "");
    
    Print(TEXT("SUCCESS - Sent %d bytes to address %hs\r\n"), cbXfer, szRemoteAddrString);

    //
    // Receive the echo'd data back from the server
    //

    FD_ZERO(&fdReadSet);
    FD_SET(sock, &fdReadSet);

    if(select(0, &fdReadSet, NULL, NULL, &timeout) != 1)
    {
        Print(TEXT("ERROR: Server hasn't responded in %d milliseconds\r\n"), 
            ((timeout.tv_sec * 1000) + (timeout.tv_sec / 1000)));
        goto Cleanup;
    }

    cbTotalRecvd = 0;
    do
    {
        cbRemoteAddrSize = sizeof(ssRemoteAddr);
        cbXfer = recvfrom(sock, pRecvBuf + cbTotalRecvd, sizeof(pRecvBuf) - cbTotalRecvd, 0, 
            (SOCKADDR *)&ssRemoteAddr, &cbRemoteAddrSize);
        cbTotalRecvd += cbXfer;
    } while(cbXfer > 0 && cbTotalRecvd < sizeof(pRecvBuf));

    if(cbXfer == SOCKET_ERROR)
    {
        Print(TEXT("ERROR: Couldn't receive the data! Error = %d\r\n"), WSAGetLastError());
        goto Cleanup;
    }
    else if(cbTotalRecvd != sizeof(pRecvBuf))
    {
        Print(TEXT("ERROR: Server didn't send back all the expected data!\r\n"));
        goto Cleanup;
    }

    if(nSockType == SOCK_STREAM)
    {
        memset(&ssRemoteAddr, 0, sizeof(ssRemoteAddr));
        cbRemoteAddrSize = sizeof(ssRemoteAddr);
        getpeername(sock, (SOCKADDR *)&ssRemoteAddr, &cbRemoteAddrSize);
    }

    if (getnameinfo((SOCKADDR *)&ssRemoteAddr, cbRemoteAddrSize,
        szRemoteAddrString, sizeof(szRemoteAddrString), NULL, 0, NI_NUMERICHOST) != 0)
        strcpy(szRemoteAddrString, "");

    Print(TEXT("SUCCESS - Received %d bytes back from address %hs\r\n"), cbTotalRecvd, szRemoteAddrString);

Cleanup:

    if(sock != INVALID_SOCKET)
    {
        shutdown(sock, SD_BOTH);
        closesocket(sock);
    }

    if(AddrInfo)
        freeaddrinfo(AddrInfo);

    WSACleanup();

    return 0;
} 

See Also

Tasks

Creating a Socket Client Application

Concepts

Creating a Socket Server Application
Socket Server
Stream Socket Application