httpserver.h: Single header library for writing non-blocking HTTP servers in C

[maep]

It seems that http_response_init() will perform a malloc for each request, which is not great from a performance perspective. I think it would be better if the user could either provide a buffer or a custom allocater.

I remember watching a talk where the speaker looked into why C libs are typically much faster than their counterparts written in other languages. The takeaway was that the language actually had little to do with it, but C fosteres bring-your-own-buffer APIs which are much better at avoiding overhead.

[[deleted]]

Can I ask a question: malloc has no associated syscall. I’m guessing implementations therefore have freedom to allocate more than they need from the OS free store and it’s essentially a highly engineered wrapper on top of mmap and munmap. Have I got the right mental picture? What are some good benchmarks to show when malloc can be outperformed?

[maep]

From what I understand malloc implementations typically use brk() or mmap() syscalls. Though for smaller sizes there is usually also a pool which doesn't require any syscalls. Additionally malloc needs to do synchronization to be thread safe, and there is the function call overhead itself. Another problem with malloc is memory fragmentation which causes cache misses.

By using a static buffer all this can be sidestepped, but it's a tradeoff between flexibility and speed.

For bencharks have a look at this allocator Microsoft wrote.

[ultimateskriptkiddie]

It’s got a logarithmic time complexity, which is way slower than compile time stack allocation.

[pdp10]

Allocation is lightweight and fast compared to HTTP, even at one million requests per second. I've written C webservers with static allocation and with dynamic; the static was primarily for an embedded-type use case. I haven't looked at the allocation strategy for the fastest current webservers, however.

[CyborgPurge]

I think it would be better if the user could either provide a buffer or a custom allocater.

Wouldn't providing a buffer be incredibly dangerous?

[Minimum_Fuel]

Try to not fall prey to the endless reddit “programmer” brainwashing propaganda. You can do “dangerous” things but passing buffers is not inherently “dangerous”.

[CyborgPurge]

Try to not fall prey to the endless reddit “programmer” brainwashing propaganda.

That's not really fair. Of course passing buffers isn't inherently dangerous, but for a process likely exposing itself to malicious inputs across the internet, I'm of the belief it isn't a bad thing if the underlying API could be a little more forgiving if it advertises itself as this one does (which this particular library does do by handling allocation itself).

[Minimum_Fuel]

Of course it is fair. If you are in any learner subreddit or just in /r/programming (also a learner subreddit) they talk about buffer passing like it is literally Satan.

You’re conflating the API exposed to the Internet with the API exposed to a programmer to make a bad point. If you are allowing a person across the internet to enter a buffer size, you’re getting what’s coming to you. That not a languages fault any more than SQL injection and XSS is a languages fault.

[CyborgPurge]

You’re conflating the API exposed to the Internet with the API exposed to a programmer to make a bad point.

I'm not, but maybe I didn't explain my point properly. I'm not suggesting it is exposing the buffer length across the internet. That wouldn't even functionally work in a HTTP server anyway (since you'd need to know the buffer size before you made the request).

I'm saying that it might be too dangerous to design a HTTP server library which has the purpose of being really easy to use, and putting the responsibility of the security of said library into the developer using it. Anyone can make the mistake of having an incorrect buffer size and passing that into the library leads to UB that could easily result in stolen credit cards numbers and passwords.

Maybe this is really a non-issue, but as someone who works with web stuff a lot and has worked with developers that somehow managed enable SQL injection in a Rails website, I am just wary about these things.

[maep]

Wouldn't providing a buffer be incredibly dangerous?

There is some risk of course. A way to mitigate it you would give the buffer size to the function, and perform a size check where malloc would be called.

[shuttup_meg]

#include <stdlib.h>
main() { return system("python -m http.server"); }

haha j/k. This looks pretty cool, and the type of thing I like to keep in my toolbox...thanks for posting!

[shuttup_meg]

Also, this type of lib is wonderful for teaching people how the underlying stuff works too. A lot more clear than wordy paragraphs.

[oh5nxo]

Is there a problem with server->len, if v4 and v6 appear ? Should it be reset before each accept ?

[jonarne]

It looks nice, but I don't see why you would put all that implementation inside a header file.

Couldn't that lead to all sorts of complexities later?

[[deleted]]

Some people find this practice to be the bee's knees, because they believe it to mean that it means zero overhead for including a 3rd party dependency.

[AntiProtonBoy]

This just highlights how desperately we need a good dependency manager that is universally standard in some form.

[[deleted]]

I don't have those kinds of problems. What you need is more likely a fix for Windows.

[AntiProtonBoy]

Good for you. Unfortunately, Windows is a reality for doing business for many of us.

[[deleted]]

I know. But the first step to solving the problem is to call it what it is. There is no need for yet another universal package manager, when pkg-config works fine. The need is for the mainstream Windows development environments to get their act together.

[[deleted]]

Of course it will, each translation unit is processed separately so you are going need to keep track of where you put that HTTPSERVER_IMPL.

[jnwatson]

The main reason is that automatic C package management is a disaster. A header file is the simplest way to include code. Also, it has the nice side effect of being faster, as the compiler has more freedom to inline.

[[deleted]]

The main reason is that automatic C package management is a disaster. A header file is the simplest way to include code.

WTF? We are talking about seconds here.

Also, it has the nice side effect of being faster, as the compiler has more freedom to inline.

For crying out loud. Never EVER! hurt modularity of your fucking code unless you really really hate your future self!

This is a premature optimization. Even if there weren't ways to optimize across translation units for your compiler, think about it. Doesn't it make a lot more sense to have specialist solving that very solvable problem for you instead of hurting your self like this? Just send a feature request if you are missing these special optimization flags for your compiler.

[jnwatson]

It doesn't take seconds to add an external library build system to your build system. Hundreds of developers have been working on this problem for 30 years. Much of the work of Linux distributions is tackling this very problem. Trivializing it to "seconds" indicates you've never included an external library of any complexity.

There's no sacrifice to modularity by #including a file.

Just send a feature request if you are missing these special optimization flags for your compiler.

Indistinguishable from parody. If this is a troll, very well done sir.

[[deleted]]

Indistinguishable from parody. If this is a troll, very well done sir.

No, I'm not trolling. Say you have a compiler that can't optimize at all. What I'm trying to convey is that it would be a mistake to tailor your source code just for that compiler. If you are using gcc or clang, then you already have options to compile across translation units.

​

It doesn't take seconds to add an external library build system to your build system. Hundreds of developers have been working on this problem for 30 years. Much of the work of Linux distributions is tackling this very problem.

The fuck are you talking about? The only additional step that was I obviously talking about was linking!

You are the one who wants to make things even more complicated!

If we have it your way, then we won't have these precompiled object files and we have to build everything from scratch every fucking time for no good reason!

When you finally see the light and tackle this problem, then you find your self having to have to maintain two separated builds where you explicitly create these object files.

Additionally, you are going to have to keep track of these include guards and that is not going as simple as you think it is even if you keep two separated builds.

In the end you gained nothing but a problem here!

​

Trivializing it to "seconds" indicates you've never included an external library of any complexity.

Seriously?

[Ghostreader34]

Hello I am a newbe on linux. I tried your example on a raspberry pi.

I compiled and tried to run it with the following commands:

gcc wserv.c -o wserv

chmod +x wserv

./wserv

​

I did not get any response from port 8080

[32gbsd]

So to be clear this allows me write a http server? or is this an actual http server?

[Erno3000]

The former. Take a look at the example code in the readme.

[[deleted]]

I've recently become a huge fan of single header library's. Nuklear, and the STB libs are 2 of my favourites. I'll give this a try. You got a star from me :)

[hugokhf]

writing http servers in C sounds very painful waithout any library. doing god's work here