CODEWITHSUNDEEP
socketshttprequestnetwork-programminglibcurl
ageispolis
ageispolis

Reputation: 33

Why use external libraries (like libcurl) vs. sockets for sending HTTP requests?

I'm new to network programming and have recently been playing around with using sockets in C++.
I have a pretty decent handle on it at this point, and I understand HTTP/TCP/IP packets pretty well.

However, upon doing some research online it seems like the bulk of network programmers suggest using external libraries such as libcurl (or curl++ for c++) for sending HTTP requests.

Considering that HTTP is a text-based protocol, why is this more beneficial/easier than simply sending HTTP requests as text messages using socket programming?

I found a few sites that show that you can do this without too much difficulty:
HTTP Requests in C++ without external libraries?,
Simple C example of doing an HTTP POST and consuming the response

It seems like sending HTTP requests is simply a matter of getting the formatting correct and then sending it via a TCP socket. How is this made easier with external libraries?

Please bear with me as I'm new to network programming and eager to learn.

Upvotes: 1

Views: 1713

Answers (1)

Steffen Ullrich
Steffen Ullrich

Reputation: 123375

The links you've provided in your question are in a way a pretty good explanation on why you should not code HTTP yourself it: the first link only points to the socket API and does not say anything about HTTP while the second one provides some examples and code which are too much simplified for real world use and will not even work with with typical setup of multiple domains on the same host since the requests are missing the Host field. In other words: these are resources which might look useful to the inexperienced developer but they will actually lead you into trouble.

HTTP is not the simple as it might look. HTTP/0.9 was simple but is no longer supported by many clients. HTTP/1.0 is still kind of simple if restricted to the basic aspects. But there are already enough pitfalls, like using the wrong delimiter between lines and request header/body or not using a Host field when accessing multi-domain hosts.

And once you want to get efficient you want to have multiple requests per TCP connection and compression and then it gets more complex. With HTTP/1.1 it gets even more complex due to the use of chunked data encoding and with HTTP/2 it gets more efficient but way more complex with a binary protocol and interleaved requests and responses.

And this was only HTTP. With HTTPS you have the additional and not trivial TLS layer which has its own pitfalls.

Thus, if you just want to use HTTP and HTTPS it is much better to use established libraries. Of course if you want to learn the innards of HTTP it might be useful to read all the relevant standards, look at packet traces and try to implement your own.

Upvotes: 6

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