building simple http client in c

Question

sprintf(send_data,"GET / HTTP/1.1\r\nHost: %s\r\n\r\n",hoststr);
printf("%s",send_data);
send(sock,send_data,strlen(send_data), 0);
while(bytes_recieved)
  {
    bytes_recieved=recv(sock,recv_data,1024,0);
    printf("%d\n",bytes_recieved);
    if(bytes_recieved==0){ break; }
    recv_data[bytes_recieved] = '\0';
    printf("%s" , recv_data);
  }

When I request for example "www.example.com", I get the whole page and then at the end after two or three seconds I get bytes_received printed ('0') and then the loop breaks.

Why it takes 2-3 seconds to break the loop?

Is there a better way to implement simple http client then this?

Thanks.

By default, HTTP 1.1 uses "Connection: Keep-Alive". This is because most web pages have more than one file that needs to be downloaded from the server; you don't have to reconnect to get the CSS for example. I believe you can get this behavior in HTTP 1.1 by specifying "Connection: Close" in the headers. — Jess
– Jess, Commented Feb 21, 2014 at 19:33
Also, if you're going to use 1.1 you should probably add an "Accept" header. See also HTTP pipelining and persistent connection. — Elliott Frisch
– Elliott Frisch, Commented Feb 21, 2014 at 19:37

Some programmer dude · Accepted Answer · 2014-02-21 19:31:55Z

1

When recv returns 0 it means that the other end of the connection has nicely closed the connection.

HTTP is, from the beginning, a pure request-response protocol, where each request got a response followed by a closed connection.

What you're seeing here is that first you receive the requested page, then after a timeout (due to the newer versions of the HTTP protocol (that you say you support) keeps the connection open) a closed connection from the server.

answered Feb 21, 2014 at 19:31

Some programmer dude

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Elliott Frisch · Accepted Answer · 2014-02-21 19:40:54Z

1

As an optimization for the HTTP protocol, version 1.1 adds default persistent connections (aka Connection: Keep-Alive). The keep-alive holds the connection open so that you can send additional requests over the "reliable" channel; you can find additional information about that portion of the HTTP protocol in RFC2616 Section 8.1 - Persistent Connections.

answered Feb 21, 2014 at 19:40

Elliott Frisch

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