httpd: fix the misspelled access handler callback typedef

[denys-i-didww]

Summary

The httpd module declares its access handler callback as httpd_acces_handler_cb,
missing an s. It is the last misspelled identifier left in the tree, and since 5 August
it is also a contradiction: the README spells the callback correctly and the header does
not, so the published Developer Guide names a type that does not compile.

Correcting it opened two older defects in the same three lines of the same page. All three
are fixed here.

#	Defect	Since
1	httpd_acces_handler_cb is misspelled in the header and the implementation	9e86d39d9, 2012
2	httpd_load.h declares register_httpdcb(), a function that has never existed	9e86d39d9, 2012
3	The Developer Guide documents that dead prototype, one parameter short	02638044d, 2013

Details

1. The typedef. Five occurrences: httpd_load.h:68 (the typedef), :115 (the
struct httpd_cb member), :130 and :134 (two declarations), and httpd.c:240 (the
implementation's signature). A sixth is the error message beside the check that uses it,
httpd.c:255 — "NULL acces handler cb".

For fourteen years the documentation matched the code. e941906dd9 (docs: fix README.md
typos, 5 Aug 2026) corrected the page, which is right about English and leaves the two
sides disagreeing: docs.opensips.org/manual/devel/modules/httpd/ and /manual/4-1/
publish httpd_access_handler_cb today, and a module written from that page does not
build. This PR closes the gap from the other side rather than reverting that commit.

It is the last one of its kind. Sweeping .c and .h for the usual misspellings —
lenght, recieve, seperat, occured, sucess, paramater, treshold, adress,
priviledge, notifiy, defualt — every surviving hit is in a comment or a log string.
treshold, adress and paramater were removed from identifiers years ago;
httpd_acces_handler_cb is the only one still in an identifier.

2. A prototype with no function. httpd_load.h:129-133 declared

int register_httpdcb(const char *mod, str *root_path,
			httpd_acces_handler_cb f1,
			httpd_flush_data_cb f2,
			httpd_init_proc_cb f3);

No such function exists, and none ever has. The implementation is httpd_register_httpdcb
(httpd.c:240), assigned to the api struct at httpd.c:302, and the five consumers reach
it as httpd_api.register_httpdcb(...). nm -D on httpd.so lists
httpd_register_httpdcb and no register_httpdcb, so nothing could ever have linked
against the declaration.

3. The documented signature is one parameter short. 02638044d (2013) added
enum HTTPD_CONTENT_TYPE type to the register_httpdcb_f pointer that modules actually
call, and updated neither the prototype above nor the page. The Developer Guide section
was written in 2012 against the dead five-parameter prototype — it is unchanged since,
including through the move from doc/httpd_devel.xml to README.md. All five call sites
in the tree pass six arguments.

Solution

Rename the typedef to httpd_access_handler_cb and fix the same word in the error
message. Remove the dead prototype rather than correct it: a corrected prototype would
still be a declaration with no definition. Document type in its real position, between
f2 and f3; the callback's name on that page is already correct and is left alone.

Reproduced

Debian 12, opensips 4.1.0-dev built from this branch:

• the core and every module that uses the API — httpd, mi_http, mi_html,
  mi_xmlrpc, pi_http, prometheus — compile with no warning and no error;
• the exported symbols do not change. nm -D --defined-only httpd.so, built from
  master and from this branch, is identical — 31 symbols. A typedef exists only at
  compile time, so there is no ABI effect to weigh;
• it still works at runtime. httpd + mi_http, MI over HTTP:

$ curl -s -X POST -d '{"jsonrpc":"2.0","id":1,"method":"version"}' http://127.0.0.1:8888/mi/
{"jsonrpc":"2.0","result":{"Server":"OpenSIPS (4.1.0-dev (aarch64/linux))"},"id":1}

$ curl -s -o /dev/null -D - -X POST -d '...' http://127.0.0.1:8888/mi/ | grep -i content-type
Content-Type: application/json

That header is what the newly documented type parameter selects — mi_http registers
with HTTPD_APPLICATION_JSON_CNT_TYPE.

Where else this text appears

master only. On 4.0 and 3.6 the header and the README both say acces, so the
contradiction this PR resolves does not exist there, and renaming a type mid-release
branch would be a change without a reason. Defects 2 and 3 are on those branches as well;
whether they are worth the same patch is the maintainers' call, not something I have
assumed.

Compatibility

Nothing breaks. The typedef is compile-time only, no module outside httpd names it, and
make install does not install module headers — no package exposes the old spelling to
anything built out of tree. No compatibility #define is kept, following 36a09ee7ab
(dispatcher: Fix modparam typo), which renamed the C variable outright and kept the old
spelling only for the script-facing modparam; there is no script-facing name here. If
you would rather have one, say so and I will add it.

This is a functional change, so CI runs on it — no [skip ci].

---

AI assistance disclosure. This change and its wording were produced with AI assistance.
Every item was checked against the source before submission:

• the five occurrences and the log message — httpd_load.h:68, :115, :130, :134,
  httpd.c:240 and :255;
• the typo dates to the module's first commit — the header has fifteen commits in its full
  history and 9e86d39d9 (2012-01-25) already carries it;
• the documentation matched the code until e941906dd9 — at its parent commit
  README.md:374 and :387 read acces;
• what the site serves today — docs.opensips.org/manual/devel/modules/httpd/ and
  /manual/4-1/ show access, /manual/4-0/ still shows acces;
• the census of surviving misspellings — repository-wide grep over *.c and *.h for
  eleven common misspellings, each hit classified as identifier or prose;
• register_httpdcb has never been defined — git log -S over the full history returns
  only the 2012 commit that added the declaration, and nm -D confirms it is not
  exported;
• the missing parameter and its date — 02638044d (2013); the original 2012
  doc/httpd_devel.xml documents the same five parameters as the page does now;
• the builds, the symbol comparison and the HTTP request were run, not inferred — the
  output is quoted above;
• the precedent, including that it kept no alias for the C identifier — 36a09ee7ab.