http_parser.h File Reference

Standalone HTTP/1.1 request parser — no transport dependency. More...

#include "DetWebServerConfig.h"
#include <Arduino.h>

Go to the source code of this file.

Classes
struct	Header
	A single HTTP header field (key: value). More...
struct	QueryParam
	A single parsed query-string parameter. More...
struct	HttpReq
	Fully-parsed HTTP/1.1 request. More...

Enumerations
enum	ParseState {   PARSE_METHOD , PARSE_PATH , PARSE_QUERY , PARSE_VERSION ,   PARSE_HEADER_KEY , PARSE_HEADER_VAL , PARSE_EXPECT_LF , PARSE_EXPECT_BODY_LF ,   PARSE_BODY , PARSE_COMPLETE , PARSE_ERROR , PARSE_ENTITY_TOO_LARGE ,   PARSE_URI_TOO_LONG }
	States of the HTTP/1.1 request parser. More...
enum	HttpVersion { HTTP_UNKNOWN = 0 , HTTP_10 , HTTP_11 }
	Parsed HTTP protocol version. More...

Functions
void	http_parser_reset (HttpReq *req)
	Reset a parser context to the initial (PARSE_METHOD) state.
void	http_parser_feed (HttpReq *req, uint8_t byte)
	Feed one byte to the parser state machine.
const char *	http_get_header (const HttpReq *req, const char *key)
	Look up a header value by name (case-insensitive).
const char *	http_get_query (const HttpReq *req, const char *key)
	Look up a query parameter value by name (case-sensitive).

Variables
HttpReq	http_pool [MAX_CONNS]
	Pool of parser contexts, one per transport slot.

Detailed Description

Standalone HTTP/1.1 request parser — no transport dependency.

The parser is a pure byte-stream state machine. It has no knowledge of ring buffers, TCP PCBs, or FreeRTOS. Feed it bytes one at a time via http_parser_feed() and inspect HttpReq::parse_state to know when the request is ready.

State machine

PARSE_METHOD       ──space──────► PARSE_PATH
PARSE_PATH         ──space──────► PARSE_VERSION
PARSE_PATH         ──'?'────────► PARSE_QUERY
PARSE_QUERY        ──space──────► PARSE_VERSION  (calls parse_query_params)
PARSE_VERSION      ──CR─────────► PARSE_EXPECT_LF
PARSE_EXPECT_LF    ──LF─────────► PARSE_HEADER_KEY
PARSE_HEADER_KEY   ──':'────────► PARSE_HEADER_VAL
PARSE_HEADER_KEY   ──CR─────────► PARSE_EXPECT_BODY_LF  (blank line)
PARSE_HEADER_VAL   ──CR─────────► PARSE_EXPECT_LF  (stores header)
PARSE_EXPECT_BODY_LF ──LF (CL=0)──► PARSE_COMPLETE
PARSE_EXPECT_BODY_LF ──LF (CL>BUF)► PARSE_ENTITY_TOO_LARGE  (→ 413)
PARSE_EXPECT_BODY_LF ──LF (else)──► PARSE_BODY
PARSE_BODY         ──(all read)──► PARSE_COMPLETE
PARSE_PATH (overflow) ───────────► PARSE_URI_TOO_LONG       (→ 414)
Any state + protocol error ──────► PARSE_ERROR             (→ 400)

Author

Douglas Quigg (dstroy0)

Date

2026

Definition in file http_parser.h.

Enumeration Type Documentation

ParseState

enum ParseState

States of the HTTP/1.1 request parser.

Advance via http_parser_feed(). The application layer inspects this after each feed call or after draining a complete chunk.

Enumerator
PARSE_METHOD	Reading the HTTP method (GET, POST, …).
PARSE_PATH	Reading the URL path component.
PARSE_QUERY	Reading the raw query string (after ?).
PARSE_VERSION	Accumulating HTTP/1.x — hashed for validation.
PARSE_HEADER_KEY	Reading a header field name.
PARSE_HEADER_VAL	Reading a header field value.
PARSE_EXPECT_LF	Consuming the LF of a header-line CRLF pair.
PARSE_EXPECT_BODY_LF	Consuming the LF of the blank-line CRLF.
PARSE_BODY	Reading the request body.
PARSE_COMPLETE	Full request parsed; ready for dispatch.
PARSE_ERROR	Unrecoverable parse failure → 400.
PARSE_ENTITY_TOO_LARGE	Content-Length > BODY_BUF_SIZE → 413.
PARSE_URI_TOO_LONG	Path exceeds MAX_PATH_LEN → 414.

Definition at line 52 of file http_parser.h.

HttpVersion

enum HttpVersion

Parsed HTTP protocol version.

Populated from the request line (HTTP/1.0 or HTTP/1.1) using an FNV-1a hash accumulated during PARSE_VERSION. The application layer may use this to drive keep-alive semantics: HTTP/1.1 defaults to persistent connections; HTTP/1.0 defaults to close.

Enumerator
HTTP_UNKNOWN	Version string did not match any known token.
HTTP_10	HTTP/1.0 — close semantics by default.
HTTP_11	HTTP/1.1 — persistent connection by default.

Definition at line 77 of file http_parser.h.

Function Documentation

http_parser_reset()

void http_parser_reset

(

HttpReq *

req

)

Reset a parser context to the initial (PARSE_METHOD) state.

Zeroes all fields and sets parse_state = PARSE_METHOD. Call before the first use, after each completed or failed request, and on connection events.

Parameters

req	Parser context to reset. Must not be null.

Definition at line 150 of file http_parser.cpp.

References HttpReq::_version_hash, PARSE_METHOD, HttpReq::parse_state, and HttpReq::slot_id.

Referenced by http_reset().

http_parser_feed()

void http_parser_feed	(	HttpReq *	req,
		uint8_t	byte
	)

Feed one byte to the parser state machine.

Returns immediately without modifying state when parse_state is already PARSE_COMPLETE, PARSE_ERROR, PARSE_ENTITY_TOO_LARGE, or PARSE_URI_TOO_LONG.

Parameters

req	Parser context for this request.
byte	Next byte from the HTTP stream.

Definition at line 159 of file http_parser.cpp.

References HttpReq::_version_hash, HttpReq::body, BODY_BUF_SIZE, HttpReq::body_bytes_read, HttpReq::body_len, HttpReq::content_length, HttpReq::current_token_idx, HttpReq::header_count, HttpReq::headers, HTTP_10, HTTP_11, HTTP_UNKNOWN, Header::key, MAX_HEADERS, MAX_KEY_LEN, MAX_PATH_LEN, MAX_QUERY_LEN, MAX_VAL_LEN, HttpReq::method, PARSE_BODY, PARSE_COMPLETE, PARSE_ENTITY_TOO_LARGE, PARSE_ERROR, PARSE_EXPECT_BODY_LF, PARSE_EXPECT_LF, PARSE_HEADER_KEY, PARSE_HEADER_VAL, PARSE_METHOD, PARSE_PATH, PARSE_QUERY, HttpReq::parse_state, PARSE_URI_TOO_LONG, PARSE_VERSION, HttpReq::path, HttpReq::path_idx, HttpReq::query, HttpReq::query_idx, Header::val, and HttpReq::version.

Referenced by http_parse().

http_get_header()

const char * http_get_header	(	const HttpReq *	req,
		const char *	key
	)

Look up a header value by name (case-insensitive).

Parameters

req	Parsed request.
key	Header field name (e.g. "Content-Type").

Returns

Pointer to the null-terminated value, or nullptr if not found.

Definition at line 389 of file http_parser.cpp.

References HttpReq::header_count, HttpReq::headers, Header::key, and Header::val.

Referenced by multipart_parse().

http_get_query()

const char * http_get_query	(	const HttpReq *	req,
		const char *	key
	)

Look up a query parameter value by name (case-sensitive).

Parameters

req	Parsed request.
key	Parameter name.

Returns

Pointer to the null-terminated value (empty string if key= with no value), or nullptr if the key is absent.

Definition at line 399 of file http_parser.cpp.

References QueryParam::key, HttpReq::query_count, HttpReq::query_params, and QueryParam::val.

Variable Documentation

http_pool

HttpReq http_pool[MAX_CONNS]

extern

Pool of parser contexts, one per transport slot.

Definition at line 15 of file http_parser.cpp.

Referenced by DetWebServer::handle(), http_parse(), and http_reset().