A Modern Web App in C (prophitt.me)

323 pointsby prophittcorey6 hours ago134 comments

ramses0 5 hours ago

My favorite trivia is that busybox has built-in cgi-bin support (and `rclone serve webdav` seems remiss to not mention as well). `https://elixir.bootlin.com/busybox/1.37.0/source/networking/...`

Everything the post mentions is 100% true and well-reasoned, especially with the inclusion of pledge/chroot/etc. for dropping privileges.

There's two diametrically opposed deployment mechanisms:

1) stack towers of glop on top of each other until you're running a simple `echo "hello world"` on top of a docker container inside a vm in a proxmox server as part of a k8s cluster under a hypervisor running on remote compute...

2) just run `bash -c 'echo "hello world"'` and front it with CGI (stateless, single binary, yada yada yada...)

Take a peek at https://github.com/Domain/bash.cgi ... not that i'm suggesting that 'bash over busybox using cgi-bin' is the "proper architecture", it's more trying to illustrate that the amount of code that holds you back from being nearly truly "frameworkless" is tiny and easy to reason about.

For some of the internal tooling I'm doing for work, I've been tending towards:

    some-cmd [--json|--markdown] ...yet-more-args...

When you use the process and shell environment itself as a repl, you start trending towards `[--cgi-bin]` would "just" be another output type, and the ability (nay: foresight!) to ensure that your commands are independent, reproducible, and only depend on their input arguments leads you directly towards being runnable in both "hostile" (ie: firecracker vm / lambda-style) or very "comfortable" environments (ie: shell, debuggers, unit/integration tests).

rpdillon 4 hours ago

Mirrors my experience, and it's funny you mention busybox: I just discovered busybox's ability to serve via `busybox httpd -p 9000 -h . -f -v` with a `cgi-bin` folder dropped in the current directory.

I already write Python services using Bottle that function both as a standalone server and as a CGI script, and I've been updating them to work with busybox's more constrained CGI environment (basically being able to handle the lack of .htaccess rewrite rules).

I definitely see a chance for simple deployment tools to make a resurgence as we create more one-off/disposable/personal software, and the low system requirements for something like busybox + lua stack are extremely minimal, which fits well with the current DDR4-is-good-enough zeitgeist. I'm running them on an old Raspberry Pi 2B and it's plenty performant for the ~10 people that access it regularly.

MomsAVoxell 4 hours ago

Instead of busybox+Lua, I just use TurboLua:

https://turbo.readthedocs.io/en/latest/

Event driven, fast, all the networking basics in place including http, mustache templates and encryption, light and small executable, very nice for embedded applications, signals and fd handling built-in, very easy to use…

Have used it very successfully for million-dollar projects, including some scientific applications running on limited-resource systems (512 megs of RAM) ..

Was very, very easy to add C functions to interface with the web front-end, libffi is great for this purpose, but its also very easy to extend as a standard, well-written Lua/C application ..

rpdillon 3 hours ago

This is exactly the sort of thing I'm really interested in. I'm particularly excited about various takes on Lua+batteries, have looked into designing my own (C wrapper with bindings to networking, JSON, templating, and DB libraries), but found Redbean to be almost ideal so never got past overall design to dig into code.

Turbo looks fantastic, though! It's precisely the niche I was looking to have filled, so I'll build a prototype or two in it to see what I think. Very much appreciate the pointer!

MomsAVoxell 3 hours ago

You’re welcome - we share interests, I too am interested in the Lua+batteries approach to life - I’ve used Lua very successfully in many commercial projects, so I’m quite convinced of its power in spite of the warts and thorns that many newbies in the ways of Lua tend to whine about.

TurboLua is particularly great because it really integrates about all of the I/O mechanisms you could want in a network-centric application, plus it has a pretty nice runtime loop which is easy to hook into and coordinate properly with signal handlers and fd sets and things. Can’t beat it as a very quick way to do embedded stuff too - very easy to do gpio, signal handling, etc.

Good luck, if you have time to share your thoughts after an initial first-pass, I’d be happy to hear your perspective ..

OleksandrC 5 hours ago

For people who find interest in weird web applications, I have been working on a game project, in C++, where the client is compiled to WebAssembly with Emscripten, and the application server is also implemented in C++ (behind nginx).

This is from pre-AI era also. The game is Civ-like. Custom engine from scratch (including both the 3D stuff, and all the web handling also).

Take a look: https://statebuilder.com/

hughw 4 hours ago

It's beautiful

nmstoker an hour ago

Nice. I know your comment was on the technical points, but it definitely under sells the game!

Transformanshen 19 minutes ago

That's cool

assimpleaspossi 2 hours ago

I started a web dev company 22 years ago after developing an online menu ordering system for a restaurant I owned. I, then we, did pretty much the same thing as talked about in the posting but we used fastcgi. I started with C because I knew C. That was my real job. It ran so well, the franchise bought the software from me--and then devolved it to all the Microsoft stuff and had issues upon issues from then on out. That's another story.

I continued to make sites for other venues that needed online ordering; such as theatre companies and restaurants. All in C, fastcgi, FreeBSD, postgresql and h2o-server cause it always did what we wanted without bending to someone else's rules. It was fast and easy to make changes while changes weren't made for us or without our consent. We did very well for ourselves.

glouwbug 2 hours ago

Feels so long ago the way you write about it, but 22 years ago was basically 2005

assimpleaspossi 2 hours ago

It was February, 2004

unixholder 42 minutes ago

The deeper you go into complex web technologies & frameworks, the more obvious it becomes that simplicity wins.

benlivengood 3 hours ago

Golang also makes it possible to serve a web site or service from a single binary. You can even avoid linking libc if you stick to core Go (CGO_ENABLED=0), and it comes with all the http and tls libraries you need to replace the traditional web server (nginx, apache, httpd) as well.

I love C and wrote some CGIs in C in the past but I don't love concurrent programming in C. While forking and execing can use shared read-only mmap on .text segments, the .bss and .data will need initialization and copying; there's unavoidable startup overhead that a threaded process avoids, and raw pthreads is kind of painful. If all you need to do is serve a low traffic site, CGI is fine.

My biggest worry would be how often the SQLite DB gets backed up because there's no way a C web server will be free of RCEs in today's world.

ncruces an hour ago

Shameless plug: if you value Go, and CGO_ENABLED=0, and SQLite, and are worried about C in a web server and RCEs, may I interest you in my SQLite driver?

https://github.com/ncruces/go-sqlite3

I just wrote up the security goals of the tool I use to translate C to Go: https://github.com/ncruces/wasm2go/blob/main/SECURITY.md

I obviously can't make any promises, as it's just a personal pet project, but those are the goals, and they do catch memory corruption bugs in practice: https://sqlite.org/bugs/forumpost/543f94984b

creatonez an hour ago

Is the CGI process opening up the SQLite database for every request...? That would have the most insane contention ever.

zbentley an hour ago

Would it? The file handle doesn’t contend for a lock IIRC; just writes.

creatonez an hour ago

I mean sure, you could still win if almost no requests are opening the database in write mode

Levitating 5 hours ago

CGI is great. Sadly nginx doesn't support it natively as opposed to lighttpd.

I like this project for adding CGI to nginx: https://github.com/pjincz/nginx-cgi

There's also methods of starting Rack applications directly form nginx via passenger[1]. Rack is the CGI like interface for ruby webapps: https://github.com/rack/rack It easily allows for writing applications and middleware with a few lines of ruby.

[1]: https://www.phusionpassenger.com/documentation/Users%20guide...

BirAdam 5 hours ago

fastcgi wrap.

assimpleaspossi 2 hours ago

Exactly what I used and wonder why the OP didn't. I'll comment at the top.

Levitating 2 hours ago

Ease of configuration, I think? I don't remember my gripes with fcgiwrap exactly.

I have used it and I've even made PR for it which led to a response from the lighttpd maintainer: https://github.com/gnosek/fcgiwrap/pull/62

Essentially I wanted fgciwrap to be able to accept arbitrary response bodies without headers, so I could use it with programs that weren't actually made for cgi. Lighttpd supports this but apparently that's an happy accident.

synergy20 4 hours ago

I just use lighttpd

Levitating 2 hours ago

I used it for a long time but the configuration of nginx just allows for more stuff.

I have my own configuration template for nginx: https://git.levitati.ng/Levitating/nginx.conf

huijzer 4 hours ago

But the real question is, does Caddy support it?

The answer is: it does but via community plugins.

Kuyawa 2 hours ago

The time is right for AI to generate a basic C web framework just like Node Express with request, response, template, cookies, auth, db, websockets and some other libs

It would be blazing fast, for use by AI itself

Just for fun

nostrademons an hour ago

Why C instead of Rust if you're using AI anyway?

C introduces the possibility of memory-safety issues, which are deadly in server software that's exposed to the Internet. And AI, from what I've seen, is not all that great at writing software with zero memory bugs.

Rust closes the memory safety holes, at the cost of making the programmer think through ownership and architecture much more carefully. Those are exactly the skills that AI is good at. So if you want something fast and are writing it with AI anyway, why not have the AI generate Rust code?

joshheitzman 4 minutes ago

Because the memory safety Rust offers isn't worth the supply chain risks: https://safeguard.sh/resources/blog/rust-supply-chain-securi...

ok123456 4 hours ago

A Go binary with CGO=0 and all templates/documents embedded gives you a better overall tooling and deployment experience. Put it in a scratch container for complete isolation.

doublepg23 4 hours ago

CGO=0 came in clutch at previous job when we were deploying Go apps compiled on builders that had a newer glibc than the actual prod server.

Panzerschrek 5 hours ago

> There's no separate database server. You open the database file through SQLite's C API.

> Every request spawns a fresh process.

How does it work when multiple concurrent requests are possible? Does SQLite allow simultaneous write access from multiple processes?

prophittcorey 5 hours ago

SQLite can handle multiple concurrent requests if it's set to WAL mode. Reading is all non-blocking/concurrent but writing is still synchronous. You should also set the "busy timeout" or else your blocked writes will timeout immediately.

warkdarrior 5 hours ago

Users who send concurrent requests will be summarily banned and their data deleted. It's the only way to be sure.

citrin_ru 5 hours ago

SQLite does allow write access from mulitple processes - file locks (fcntl) are used to ensure at any given moment only one of processes modifies the database (or WAL if WAL is enabled).

huijzer 4 hours ago

SQLite is a database. The main idea of a database is to support concurrent reads/writes although databases differ in how much concurrency they allow

td521534f12 4 hours ago

The answer is more complicated for SQLite: https://sqlite.org/isolation.html

> There can only be a single writer at a time to an SQLite database. There can be multiple database connections open at the same time, and all of those database connections can write to the database file, but they have to take turns.

However, it can also be configured in WAL mode where the single writer is applying WALs while the applications append to the log.

sophacles 3 hours ago

The main idea of a database is to support storing data in a structured and queryable way. Concurrency came later.

tomjen3 an hour ago

In Wal mode you can have multiple readers. Writers block, but because there is no network traffic, the writers finish very quickly, so in practice you don't usually wait that long.

hughw 4 hours ago

I disagree with the first sentence. In 199x the first people I knew making web pages dropped perl scripts, not C programs, into cgi-bin.

nkozyra 4 hours ago

May have pre-dated you by a bit. Perl definitely took foot not long after but the earliest cgi-bin days were dominated by C before people got tired of fighting compilation for web apps.

IIRC the spec itself says it was built for C applications.

mod-perl was a godsend, of course.

minaguib 4 hours ago

Perl's CGI.pm was updated as recently as 5 months ago :)

https://metacpan.org/pod/CGI

rjrjrjrj 3 hours ago

I started using Perl in 1996.

But the very first CGI scripts I wrote were in C, late 95 or early 96. Apache on Slackware Linux.

PaulDavisThe1st 3 hours ago

We did the CGI-bin in C thing at amzn in 1994.

layer8 2 hours ago

I still have such Perl scripts deployed, though using FastCGI.

icedchai an hour ago

Same. My first "web app" was a Perl CGI that saved data to mSQL (not MySQL), probably early 1995.

wainstead 26 minutes ago

Same!

forinti an hour ago

I learnt Perl because I had to make a page with a form that would then be turned into Postscript and printed. My only options were C, which I knew well, and Perl, which I had never seen before. So I got to learning Perl. Doing it in C just seemed like too much work for the task.

jjuel 3 hours ago

I just really wish it had some examples of code in there to get a better idea of what is really going on. It sounds interesting.

tomcam 2 hours ago

They use this framework: https://learnbchs.org

Their example is:

    #include <err.h> /* err(3) */
    #include <stdlib.h> /* EXIT_xxxx */
    #include <stdio.h> /* puts(3) */
    #include <unistd.h> /* pledge(2) */ 
    int main(void)
    {
      if (pledge("stdio", NULL) == -1) 
        err(EXIT_FAILURE, "pledge");
        puts("Status: 200 OK\r");
        puts("Content-Type: text/html\r");
        puts("\r");
        puts("Hello, world!\n");
        return EXIT_SUCCESS;
      }

6c696e7578 10 minutes ago

fcgi tends to be overlooked

macleginn 3 hours ago

"A modern web application typically puts a web server like nginx in front and reverse-proxies to an application server written in another language like Ruby, Python, Go, or Rust. That always felt a bit strange to me: you essentially have two web servers, and one of them is also responsible for your business logic." -- Is the fundamental difference here that the business-logic binary is not always running but gets spun out with each request? This looks like a relatively minor thing, to be honest.

prophittcorey an hour ago

I meant to express the layers of abstraction feel strange to me in a typical setup.

A typical setup today looks like:

nginx -> puma/unicorn/gunicorn/etc -> your code

With cgi that middle layer is gone. It's just:

nginx -> your code

The layer reduction is nice when it comes to things like debugging. You don't have to guess if the middle server is removing a header, failing to forward a header, etc.

It's obvious who does that with cgi.

bijowo1676 4 hours ago

Author described good ole PHP 3.

Early PHP (3 and 4) were the thin layer over the C libraries and were pretty fast and easy. it came about right when CGI was deprecated and it solved CGI's problems

mc007 3 hours ago

came back to C/C++ for same reasons, no supply chain trouble, fits in my head, runs forever, ... here a playground for win32, using partially webview2, all batteries included, openai client , tts, stt, vpl, images, audio, video, ... comes with webview2 apps, settings (and encryption), config, rest server, ipc, testing, CLI11, postgres, installer, doc gen, modbus, OpenCV, daemon, computer use, agent memory, image tools, mcp server/client, experimental flow editor - what a fun and exciting times :) https://github.com/polymech-info/win32-boilerplate

rietta 37 minutes ago

It's been a long time since I have tried to do Windows work in C/C++. Is this Win32 the actual Win32 API of yesteryear or something else. I thought CMoke was a Unix tooling.

codazoda 36 minutes ago

I agree on "fits in my head". I haven't used C++ but I used to love ANSI C. I had a reference manual for it that was something like 30 pages and basically covered the entire language. There's something magical about the compact size of regular C.

fmo91 5 hours ago

It's not very clear to me why the author has chosen C in the first place. I appreciate the effort of sharing the experience with us, anyway.

EGreg 5 hours ago

I'm old enough to remember when the OKCupid guys wrote their own webserver in C++!

I took the concept of "slots" in requests, from it: https://github.com/okws/okws

uecker 5 hours ago

Yesterday or so there was a post about using Zig. When I read it I thought that using C would work equally well.

christoff12 5 hours ago

Yeah, I thought it was interesting that both of these[0] were on the front page.

[0] - the other one: https://news.ycombinator.com/item?id=50051573

Kevin_Flynn 5 hours ago

I can never figure out why everything isn't in C. :|

ricardobeat an hour ago

Is it because you segfault before reaching the answer?

prophittcorey 5 hours ago

I didn't want to state why C and not "X" because the comments would have devolved into an all out language war.

christoff12 5 hours ago

Fair enough. But I am also curious if you'd like to share your rationale.

kanbankaren 4 hours ago

As someone who works on C compilers, I find the obession with C language insane.

For any greenfield project, pick up C++ in lieu of C if you want a C language.

There is no runtime penalty for using C++ if you stick to plain structs and don't use virtual functions, but you get better static type safety, lvalue references, namespaces, etc. even if you don't use the OO features.

Even for virtual functions, the overhead is minimal that it is just noise.

C compilers themselves are written in C++ for the last 15 years. Oh, the irony!

prophittcorey 4 hours ago

I generally like "C-style C++", but I find it difficult to draw the line between C and C++. It's too easy to keep reaching into C++ for "just one more thing."

That may be a me problem.

kevin_thibedeau 3 hours ago

T> here is no runtime penalty for using C++

Large portions of the standard lib depend on heap allocations. C is a much safer target for environments with limited resources.

PaulDavisThe1st 3 hours ago

It's what we did at amzn in 1994 ...

bigbuppo an hour ago

Wasn't amazon running on tandem back then?

PaulDavisThe1st an hour ago

In 1994, amzn ran on a single solaris workstation. Same at the beginning of 1995. I can't comment after that.

glouwbug 2 hours ago

Because in practice it’s really hard to not succumb to C++ feature creep. You start with good intentions and limit yourself to namespaces and structs, but then the “this will benefit from a vector, or this from a map” appears, then you realize you’d like a templated use case, and a single raw pointer or resource handle from a call to something like fopen() suddenly is not releasing its resource on a linked list pop and now you’re writing move semantics on top of copy semantics because a destructor declaration silently enforces copies on a std::move without move semantics. You reach for a unique pointer and, and all of a sudden, you have most of modern C++ without a single virtual call.

So people obsess over C because you’re hard limited by the upper feature bound. And that’s not so bad because C gets feature updates too - microscopic but effective feature updates; see C29 for the poor man’s RAII: defer

ricardobeat an hour ago

C3 lang gives you defer + a lot of significant ergonomic improvements right now: https://c3-lang.org

feelamee 11 minutes ago

and what it does take away? most "better C" languages basically looks like C++ (except zig, maybe). Nobody write something real in them, so nobody knows about their pitfalls.

ricardobeat an hour ago

There is a huge mental overhead penalty...

layer8 2 hours ago

The underlying libraries you use tend to be in C anyway, so it simplifies things to just use them with their native interface, and not having to add another language runtime and its idiosyncrasies.

rietta 3 hours ago

There is Boost in C++. It is very mature and honestly modern C++ has a lot of extremely powerful stdlib functionality and classes that will still be orders of magnitude more performant that the vast majority of the web app languages we use today. See https://www.boost.org/

Surac 3 hours ago

i also do that way, but i also have written my own webserver so i have no cgi interface. it serves files and provides "special" sites for the application written in. I use html and css as a frontend. nealy no js code in the html. Things i hate: - applicatin status handling - mixing html, css, js and c in one file - having no web "widgets" - having to make them by myself

codazoda 5 hours ago

It hasn't been touched in a long time, maybe that's because it's "complete", but here's a quick CGI library:

https://github.com/codazoda/cgi-lib

hollowonepl 4 hours ago

I was not thinking about vanilla C and CGI but I wrote my own modern web api server app in C++ (std+boost only) and I found it extremely pleasant experience. very reliable and little supply chain/dependency hell problematic too.

It’s for intranet business app so although it’s not yet production ready yet, definitively winning against many other modern approaches in web development in my consideration, and quite refreshing POC project.

whizzter an hour ago

Yeah, shuddering at trying to manage memory vs static strings (with OOB risks) in plain C, modern C++ does give so much.

I'm actually also rewriting a header-only server (std c++ and sockets) I wrote a few years back to take advantage of C++26 reflections and similar to give it something similar in capability to AspNetCore+EFCore.

lilbigdoot 5 hours ago

I'm still in the middle of reading but I wanted to comment first that I had a pleasantly surprising experience a few years ago with CGI. I hadn't thought about CGI since I was a kid and I was tasked with adding a simple dynamic page to a server that had nothing running yet except apache. For whatever reason I though to try out CGI because of how simple the page was going to be, and yeah. Would recommend

I just got C FFI working in my LLVM based language last night so I'll need to take a look at playing around with BCHS :)

Quitschquat 5 hours ago

I worked on a FORTRAN 77 CGI application in the early 00s. I think the host was Apache httpd, on some old HPUX version.

dhuan_ 4 hours ago

How about modern web apps in shell scripts only:

https://dhuan.github.io/mock/latest/examples.html

chihuahua 41 minutes ago

Ideally, it should be a shell script for CMD.EXE, using the finest scripting language ever invented. The elegance of using FOR for such diverse tasks as enumerating files, file contents, string splitting, lists of numbers, and parsing the output of another command, is unmatched.

Scubabear68 5 hours ago

From the article, "WRITING HTML AND CSS IN C ISN'T TOO BAD".

Um, any and all string handling in C is pretty miserable.

prophittcorey 5 hours ago

To be fair, the HTML and CSS in C wasn't too bad.. the Youtube scraper was also written in C and that was a lot more painful :)

sam1r 5 hours ago

I can empathize entirely. After writing a scraper for html in C, outputting html in C is a piece of cake.

Joker_vD 5 hours ago

If you do it with the string functions from the standard library then yes, it is.

prophittcorey 5 hours ago

The standard string functionality is painful. I wrote my own string view and string builder that work with fixed size strings. No memory allocations, etc.

PhilipRoman 5 hours ago

Emitting strings is fine, it's the parsing that sucks.