http: refactor http auth into static functions

[Gottox]

Based on #12262 I factored the auth functions out into its own functions. While doing that I noticed that the auth code could be turned into a abstract interface with multiple implementors. Are you peps interested in this?

The changes I currently did are purely cosmetic (given, that the compiler is smart enough to do proper inlining/dead code elimination), but if I'm implementing an abstract interface, this would introduce an indirection between the http code and the http-auth code.

This PR is opened as a draft for now to discuss if my approach makes sense.

[bagder]

1. Needs a rebase
2. Seems to have broken test 1204

[bagder]

We use TRUE and FALSE (uppercase).

[bagder]

Suggested change

	if(handle_spnego(&authinfo)) {}
	else if(handle_ntlm(&authinfo)) {}
	else if(handle_digest(&authinfo)) {}
	else if(handle_basic(&authinfo)) {}
	else if(handle_bearer(&authinfo)) {}
	if(handle_spnego(&authinfo) ||
	handle_ntlm(&authinfo) ||
	handle_digest(&authinfo) ||
	handle_basic(&authinfo) ||
	handle_bearer(&authinfo))
	{}

Saves having to use {} so many times.

[Gottox]

in that case, even the if is not needed:

handle_spnego(&authinfo) || 
       handle_ntlm(&authinfo) ||
       handle_digest(&authinfo) ||
       handle_basic(&authinfo) ||
       handle_bearer(&authinfo);

[Gottox]

@bagder Generally speaking would you support factoring out all the authentication specific code into its own interface?

For start, I'm thinking of a simple interface like this: (pseudocode)

struct authimpl {
  const char *name;
  bool (*handle)(struct authdata *);
};

// ...

static bool handle_auth_basic(struct authdata *) {
  // ...
}

static struct authimpl authimpls[] {
  { "Basic", 5, handle_auth_basic },
  { "Bearer", 5, handle_auth_bearer },
  // ...
}

// ...

struct authdata ad = { ... };
for(int i = 0; i < LENGTH(authimpls); i++) {
  if (checkauth(authimpls[i].name, auth)) {
    authimpls[i].handle(&ad);
    break;
  }
}

In the second iteration I'd like to move the auth methods to their own files and let them build conditionally. This would reduce #ifdef clutter even more at the cost compile time inlining.

[bagder]

This returns an error code, not a boolean! You probably need to propagate the error code.

[bagder]

@bagder Generally speaking would you support factoring out all the authentication specific code into its own interface?

I would. I think that could clean things up nicely!

[bagder]

Stalled