Bounded image/anchor URL scanning and relative-URL resolution. More...

#include "mdl_extract.h"
#include <stdio.h>
#include <string.h>
#include "ra8_attributes.h"
#include "mdl_extract_internal.h"

Include dependency graph for mdl_extract.c:

Enumerations
enum	mdl_scan_limits_t : uint16_t { k_authority_max = 512 }
	Local scan/resolve limits. More...

Functions
static bool	internal_authority_of (const char base, char auth, size_t cap)
	Extract "scheme://host" from base into auth (NUL-terminated).
static bool	internal_resolve_scheme_rel (const char base, const char raw, char *out, size_t out_cap)
	Resolve a scheme-relative ("//host/...") URL against base.
static bool	internal_resolve_root_rel (const char auth, const char raw, char *out, size_t out_cap)
	Resolve a root-relative ("/path") URL against authority auth.
static bool	internal_resolve_path_rel (const char base, const char auth, const char raw, char out, size_t out_cap)
	Resolve a path-relative URL against base (authority auth).
bool	mdl_extract_resolve_url (const char base, const char raw, char *out, size_t out_cap)
	Resolve raw (possibly relative) against base into out.
static bool	internal_already_have (const mdl_url_list_t list, const char url)
	True if url is already present in list.
static ra8_err_t	internal_emit_tag_url (const char base_url, const char attr1, const char attr2, const char keep, const char tag, size_t tag_len, mdl_url_list_t out)
	Read attr1 (or attr2) from one tag, resolve+filter, append.
static ra8_err_t	internal_scan_tags (const char html, size_t html_len, const char base_url, const char tagname, const char attr1, const char attr2, const char keep, mdl_url_list_t *out)
	Shared scanner for <img>/<a>: emit each tag's resolved URL.
ra8_err_t	mdl_extract_images (const char html, size_t html_len, const char base_url, const char prefer_attr, const char url_contains, mdl_url_list_t *out)
	Scan html for <img> image URLs, resolved to absolute form.
ra8_err_t	mdl_extract_anchors (const char html, size_t html_len, const char base_url, const char href_contains, mdl_url_list_t out)
	Scan html for <a href> links, resolved to absolute form.

Detailed Description

Bounded image/anchor URL scanning and relative-URL resolution.

Resolves absolute and relative URL forms, then scans bounded image or anchor tags into caller-owned URL lists. Titled-anchor extraction is isolated in mdl_extract_hits.c.

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Definition in file mdl_extract.c.

Enumeration Type Documentation

◆ mdl_scan_limits_t

enum mdl_scan_limits_t : uint16_t

Local scan/resolve limits.

Enumerator
k_authority_max	Max bytes of "scheme://host" prefix.

Definition at line 18 of file mdl_extract.c.

Function Documentation

◆ internal_already_have()

bool internal_already_have	(	const mdl_url_list_t *	list,
		const char *	url )

static

True if url is already present in list.

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	list	Existing bounded URL list.
[in]	url	NUL-terminated URL input.

Returns: True when url already occurs in list.

Return values

true	The documented predicate holds or the requested operation completed.
false	The predicate does not hold or validation rejected the operation.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 208 of file mdl_extract.c.

References mdl_url_list_t::count, RA8_INTERNAL, strcmp(), and mdl_url_list_t::urls.

Referenced by internal_emit_tag_url().

◆ internal_authority_of()

bool internal_authority_of	(	const char *	base,
		char *	auth,
		size_t	cap )

static

Extract "scheme://host" from base into auth (NUL-terminated).

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	base	NUL-terminated base URL or path.
[in,out]	auth	Bounded authority string.
[in]	cap	Destination capacity including any terminator.

Returns: True when a complete authority fits in auth; otherwise false.

Return values

true	The documented predicate holds or the requested operation completed.
false	The predicate does not hold or validation rejected the operation.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 40 of file mdl_extract.c.

References memcpy(), RA8_INTERNAL, strchr(), strlen(), and strstr().

Referenced by mdl_extract_resolve_url().

◆ internal_emit_tag_url()

ra8_err_t internal_emit_tag_url	(	const char *	base_url,
		const char *	attr1,
		const char *	attr2,
		const char *	keep,
		const char *	tag,
		size_t	tag_len,
		mdl_url_list_t *	out )

static

Read attr1 (or attr2) from one tag, resolve+filter, append.

Return values

k_ra8_ok	Appended, filtered out, or attr absent (all non-fatal).
k_ra8_err_no_mem	List already at k_mdl_max_urls.

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	base_url	NUL-terminated base URL.
[in]	attr1	Preferred attribute name.
[in]	attr2	Fallback attribute name, if any.
[in]	keep	Optional substring filter.
[in]	tag	Readable tag byte span.
[in]	tag_len	Readable tag length.
[out]	out	Caller-owned result storage.

Returns: Operation status.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 240 of file mdl_extract.c.

References abs(), mdl_url_list_t::count, internal_already_have(), internal_contains_ok(), internal_copy_fits(), internal_find_attr_value(), k_mdl_max_urls, k_mdl_url_max, k_ra8_err_no_mem, k_ra8_ok, mdl_extract_resolve_url(), RA8_INTERNAL, and mdl_url_list_t::urls.

Referenced by internal_scan_tags().

◆ internal_resolve_path_rel()

bool internal_resolve_path_rel	(	const char *	base,
		const char *	auth,
		const char *	raw,
		char *	out,
		size_t	out_cap )

static

Resolve a path-relative URL against base (authority auth).

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	base	NUL-terminated base URL or path.
[in]	auth	Bounded authority string.
[in]	raw	Untrusted source text to validate or resolve.
[out]	out	Caller-owned result storage.
[in]	out_cap	Destination capacity including any terminator.

Returns: True when the path-relative URL resolves completely into out.

Return values

true	The documented predicate holds or the requested operation completed.
false	The predicate does not hold or validation rejected the operation.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 134 of file mdl_extract.c.

References memcpy(), RA8_INTERNAL, and strlen().

Referenced by mdl_extract_resolve_url().

◆ internal_resolve_root_rel()

bool internal_resolve_root_rel	(	const char *	auth,
		const char *	raw,
		char *	out,
		size_t	out_cap )

static

Resolve a root-relative ("/path") URL against authority auth.

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	auth	Bounded authority string.
[in]	raw	Untrusted source text to validate or resolve.
[out]	out	Caller-owned result storage.
[in]	out_cap	Destination capacity including any terminator.

Returns: True when the root-relative URL resolves completely into out.

Return values

true	The documented predicate holds or the requested operation completed.
false	The predicate does not hold or validation rejected the operation.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 106 of file mdl_extract.c.

Referenced by mdl_extract_resolve_url().

◆ internal_resolve_scheme_rel()

bool internal_resolve_scheme_rel	(	const char *	base,
		const char *	raw,
		char *	out,
		size_t	out_cap )

static

Resolve a scheme-relative ("//host/...") URL against base.

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	base	NUL-terminated base URL or path.
[in]	raw	Untrusted source text to validate or resolve.
[out]	out	Caller-owned result storage.
[in]	out_cap	Destination capacity including any terminator.

Returns: True when the scheme-relative URL resolves completely into out.

Return values

true	The documented predicate holds or the requested operation completed.
false	The predicate does not hold or validation rejected the operation.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 75 of file mdl_extract.c.

References memcpy(), strlen(), and strstr().

Referenced by mdl_extract_resolve_url().

◆ internal_scan_tags()

ra8_err_t internal_scan_tags	(	const char *	html,
		size_t	html_len,
		const char *	base_url,
		const char *	tagname,
		const char *	attr1,
		const char *	attr2,
		const char *	keep,
		mdl_url_list_t *	out )

static

Shared scanner for <img>/<a>: emit each tag's resolved URL.

Scans caller-supplied markup and URLs without allocation. Only fully resolved values that fit bounded result storage are appended.

Parameters

[in]	html	Readable markup bytes.
[in]	html_len	Readable markup length.
[in]	base_url	NUL-terminated base URL.
[in]	tagname	Tag-name prefix to scan for.
[in]	attr1	Preferred attribute name.
[in]	attr2	Fallback attribute name, if any.
[in]	keep	Optional substring filter.
[out]	out	Caller-owned result storage.

Returns: Operation status.

Return values

k_ra8_ok	The operation completed successfully.
other	The originating validation, storage, stream, or network error.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 292 of file mdl_extract.c.

References mdl_url_list_t::count, internal_emit_tag_url(), internal_find_ci(), internal_is_name_end(), k_ra8_err_invalid_arg, k_ra8_err_no_mem, k_ra8_ok, memchr(), RA8_INTERNAL, and strlen().

Referenced by mdl_extract_anchors(), and mdl_extract_images().

◆ mdl_extract_anchors()

ra8_err_t mdl_extract_anchors	(	const char *	html,
		size_t	html_len,
		const char *	base_url,
		const char *	href_contains,
		mdl_url_list_t *	out )

Scan html for <a href> links, resolved to absolute form.

Parameters

[in]	html	HTML bytes (need not be NUL-terminated).
[in]	html_len	Length of html in bytes.
[in]	base_url	Absolute URL of the page.
[in]	href_contains	If non-NULL and non-empty, keep only hrefs whose absolute URL contains this substring.
[out]	out	List to fill; out->count is reset first.

Return values

k_ra8_ok	Scan complete (count may be 0).
k_ra8_err_invalid_arg	NULL argument.
k_ra8_err_no_mem	Reached k_mdl_max_urls; remainder skipped.

Uses caller-owned fixed-capacity results and performs no allocation. Inputs stay borrowed and appended values are complete and terminated.

Returns: Operation status.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Note: Thread safety follows ownership of the supplied context; no synchronization is added.

Since: Version 0.1.0

Definition at line 342 of file mdl_extract.c.

References internal_scan_tags().

Referenced by priv_mdl_app_prepare_chapters().

◆ mdl_extract_images()

ra8_err_t mdl_extract_images	(	const char *	html,
		size_t	html_len,
		const char *	base_url,
		const char *	prefer_attr,
		const char *	url_contains,
		mdl_url_list_t *	out )

Scan html for <img> image URLs, resolved to absolute form.

Parameters

[in]	html	HTML bytes (need not be NUL-terminated).
[in]	html_len	Length of html in bytes.
[in]	base_url	Absolute URL of the page (for relative resolution).
[in]	prefer_attr	"data-src" or "src"; the other is tried as fallback.
[in]	url_contains	If non-NULL and non-empty, keep only URLs that contain this substring (drops loaders/ads/nav icons).
[out]	out	List to fill; out->count is reset first.

Return values

k_ra8_ok	Scan complete (count may be 0).
k_ra8_err_invalid_arg	NULL argument.
k_ra8_err_no_mem	Reached k_mdl_max_urls; remainder skipped.

Note: Duplicate URLs are dropped. Values longer than k_mdl_url_max are skipped rather than truncated.

Uses caller-owned fixed-capacity results and performs no allocation. Inputs stay borrowed and appended values are complete and terminated.

Returns: Operation status.

Precondition: Every required pointer is non-null and remains valid for the call.; Lengths and capacities describe complete referenced objects without overflow.

Postcondition: Documented outputs and the return value describe the same outcome.; A rejected or failed operation is never reported as successful.

Since: Version 0.1.0

Definition at line 330 of file mdl_extract.c.

References internal_scan_tags(), and strcmp().

Referenced by internal_extract_page_images(), and internal_mdl_fetch_chapter_html().

◆ mdl_extract_resolve_url()

bool mdl_extract_resolve_url	(	const char *	base,
		const char *	raw,
		char *	out,
		size_t	out_cap )

Resolve raw (possibly relative) against base into out.

Resolve a possibly relative HTTP(S) URL against an absolute base URL.

Definition at line 164 of file mdl_extract.c.

References internal_authority_of(), internal_copy_fits(), internal_resolve_path_rel(), internal_resolve_root_rel(), internal_resolve_scheme_rel(), k_authority_max, and strncmp().

Referenced by internal_emit_hit(), internal_emit_tag_url(), and internal_extract_cover().

Enumerations

Functions

Detailed Description

Enumeration Type Documentation

◆ mdl_scan_limits_t

Function Documentation

◆ internal_already_have()

◆ internal_authority_of()

◆ internal_emit_tag_url()

◆ internal_resolve_path_rel()

◆ internal_resolve_root_rel()

◆ internal_resolve_scheme_rel()

◆ internal_scan_tags()

◆ mdl_extract_anchors()

◆ mdl_extract_images()

◆ mdl_extract_resolve_url()