CODEWITHSUNDEEP
chttptcp
YoavKlein
YoavKlein

Reputation: 2705

Reading HTTP headers from socket C

My question is mainly educational so please don't tell me you shouldn't do that or you should do that. Thanks.

This is basically about how TCP works.

I'm implementing a HTTP client in C that basically just sends a HTTP GET and reads the response from ths server. Now I want to separate the headers from the body. The question is, is it possible to read from the socket byte-by-byte:


while(recv(sockfd, buffer, 1, 0))
{
  // do whatever with buffer[0]
}

or is it so that: once the server wrote to the socket, say, 1000 bytes, so once the client reads even 1 bytes than all this message is "wasted" and cannot be read anymore?

Because I remember that when dealing with sockets sometime in the past that was how I understood that it is working.

Upvotes: 0

Views: 947

Answers (2)

Criticize SE actions means ban
Criticize SE actions means ban

Reputation: 58848

Yes, in TCP that is possible. TCP does not have messages, only bytes, like a file. You can send 1000 bytes and then receive 1 byte 1000 times.

In fact that is a convenient way to start out, because if you try to receive more than 1 byte, you might not get the same number of bytes you asked for, you could get any number down to 1 byte. If you only ask to receive 1 byte, then you always get exactly 1 byte (unless the connection is closed).

It is inefficient, however, because the receive function uses a certain amount of CPU time just to process the fact that you want to receive - i.e. the function call itself costs a bit of CPU time. If you ask for, say, 100000 bytes at once, then you don't have to call the receive function 100000 times to get it. It's probably fast enough for you, just not as fast as it could be.

Upvotes: 1

Merty
Merty

Reputation: 61

Although it is not good practice, it isn't "wasted". Most socket implementations on OS's do use a socket buffer, ranging from 4K till 6MB. So yes you can, as long as you read it fast engough. But still, it is saver to just copy the stuf to your own memory-managed buffer..

Upvotes: 0

Related Questions