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Why would a blocking socket repeatedly return 0-length data?
原标题:

I m having a significant problem using a standard BSD-style socket in a C++ program. In the code below, I connect to a local web server, send a request, and simply create a loop waiting for data to return. I actually do receive the data, but then I get an endless stream of 0-length data as if it was a non-blocking socket. The web server presumably didn t kill the connection, because if so I would have received a length of -1.

Please ignore simple typos I make below, as I m writing the code from memory, not a direct copy/paste. The code produces the same result on OSX and Windows.

int sock = socket(AF_INET, SOCK_STREAM, 0);

//assume serv_addr has been created correctly
connect(sock, (sockaddr*)&serv_addr, sizeof(serv_addr)) < 0);

std::string header = "GET / HTTP/1.1
"
    "Host: 127.0.0.1:80
"
    "Keep-Alive: 300
"
    "Connection: keep-alive

";

send(sock, header.c_str(), header.length()+1, 0);

for (;;) {
    char buffer[1024];
    int len = recv(sock, buffer, 1024, 0);
    cout << len << endl;
    //this outputs two numbers around 200 and 500,
    //which are the header and html, and then it
    //outputs and endless stream of 0 s
}
最佳回答

From the man page of recv

For TCP sockets, the return value 0 means the peer has closed its half
     side of the connection.
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