A generic parser for HTTP requests. More...

#include <request_parser.h>

Inheritance diagram for isc::http::HttpRequestParser:

States supported by the HttpRequestParser.
static const int	RECEIVE_START_ST = SM_DERIVED_STATE_MIN + 1
	State indicating a beginning of parsing.

static const int	HTTP_METHOD_ST = SM_DERIVED_STATE_MIN + 2
	Parsing HTTP method, e.g. GET, POST etc.

static const int	HTTP_URI_ST = SM_DERIVED_STATE_MIN + 3
	Parsing URI.

static const int	HTTP_VERSION_H_ST = SM_DERIVED_STATE_MIN + 4
	Parsing letter "H" of "HTTP".

static const int	HTTP_VERSION_T1_ST = SM_DERIVED_STATE_MIN + 5
	Parsing first occurrence of "T" in "HTTP".

static const int	HTTP_VERSION_T2_ST = SM_DERIVED_STATE_MIN + 6
	Parsing second occurrence of "T" in "HTTP".

static const int	HTTP_VERSION_P_ST = SM_DERIVED_STATE_MIN + 7
	Parsing letter "P" in "HTTP".

static const int	HTTP_VERSION_SLASH_ST = SM_DERIVED_STATE_MIN + 8
	Parsing slash character in "HTTP/Y.X".

static const int	HTTP_VERSION_MAJOR_START_ST = SM_DERIVED_STATE_MIN + 9
	Starting to parse major HTTP version number.

static const int	HTTP_VERSION_MAJOR_ST = SM_DERIVED_STATE_MIN + 10
	Parsing major HTTP version number.

static const int	HTTP_VERSION_MINOR_START_ST = SM_DERIVED_STATE_MIN + 11
	Starting to parse minor HTTP version number.

static const int	HTTP_VERSION_MINOR_ST = SM_DERIVED_STATE_MIN + 12
	Parsing minor HTTP version number.

static const int	EXPECTING_NEW_LINE1_ST = SM_DERIVED_STATE_MIN + 13
	Parsing first new line (after HTTP version number).

static const int	HEADER_LINE_START_ST = SM_DERIVED_STATE_MIN + 14
	Starting to parse a header line.

static const int	HEADER_LWS_ST = SM_DERIVED_STATE_MIN + 15
	Parsing LWS (Linear White Space), i.e.

static const int	HEADER_NAME_ST = SM_DERIVED_STATE_MIN + 16
	Parsing header name.

static const int	SPACE_BEFORE_HEADER_VALUE_ST = SM_DERIVED_STATE_MIN + 17
	Parsing space before header value.

static const int	HEADER_VALUE_ST = SM_DERIVED_STATE_MIN + 18
	Parsing header value.

static const int	EXPECTING_NEW_LINE2_ST = SM_DERIVED_STATE_MIN + 19
	Expecting new line after parsing header value.

static const int	EXPECTING_NEW_LINE3_ST = SM_DERIVED_STATE_MIN + 20
	Expecting second new line marking end of HTTP headers.

static const int	HTTP_BODY_ST = SM_DERIVED_STATE_MIN + 21
	Parsing body of a HTTP message.

	HttpRequestParser (HttpRequest &request)
	Constructor.

void	initModel ()
	Initialize the state model for parsing.

Additional Inherited Members
Public Member Functions inherited from isc::http::HttpMessageParserBase
	HttpMessageParserBase (HttpMessage &message)
	Constructor.

void	poll ()
	Run the parser as long as the amount of data is sufficient.

bool	needData () const
	Returns true if the parser needs more data to continue.

bool	httpParseOk () const
	Returns true if the message has been parsed successfully.

std::string	getErrorMessage () const
	Returns error message.

void	postBuffer (const void *buf, const size_t buf_size)
	Provides more input data to the parser.

std::string	getBufferAsString (const size_t limit=0) const
	Returns parser's input buffer as string.

Public Member Functions inherited from isc::util::StateModel
	StateModel ()
	Constructor.

virtual	~StateModel ()
	Destructor.

bool	didModelFail () const
	Returns whether or not the model failed.

void	endModel ()
	Conducts a normal transition to the end of the model.

std::string	getContextStr () const
	Convenience method which returns a string rendition of the current state and next event.

unsigned int	getCurrState () const
	Fetches the model's current state.

std::string	getEventLabel (const int event) const
	Fetches the label associated with an event value.

unsigned int	getLastEvent () const
	Fetches the model's last event.

unsigned int	getNextEvent () const
	Fetches the model's next event.

std::string	getPrevContextStr () const
	Convenience method which returns a string rendition of the previous state and last event.

unsigned int	getPrevState () const
	Fetches the model's previous state.

std::string	getStateLabel (const int state) const
	Fetches the label associated with an state value.

bool	isModelDone () const
	Returns whether or not the model has finished execution.

bool	isModelNew () const
	Returns whether or not the model is new.

bool	isModelPaused () const
	Returns whether or not the model is paused.

bool	isModelRunning () const
	Returns whether or not the model is running.

bool	isModelWaiting () const
	Returns whether or not the model is waiting.

void	nopStateHandler ()
	An empty state handler.

virtual void	runModel (unsigned int event)
	Processes events through the state model.

void	startModel (const int start_state)
	Begins execution of the model.

void	unpauseModel ()
	Unpauses state model.

Static Public Member Functions inherited from isc::http::HttpMessageParserBase
static std::string	logFormatHttpMessage (const std::string &message, const size_t limit=0)
	Formats provided HTTP message for logging.

Static Public Attributes inherited from isc::http::HttpMessageParserBase
static const int	HTTP_PARSE_OK_ST = SM_DERIVED_STATE_MIN + 1000
	Parsing successfully completed.

static const int	HTTP_PARSE_FAILED_ST = SM_DERIVED_STATE_MIN + 1001
	Parsing failed.

static const int	DATA_READ_OK_EVT = SM_DERIVED_EVENT_MIN + 1
	Chunk of data successfully read and parsed.

static const int	NEED_MORE_DATA_EVT = SM_DERIVED_EVENT_MIN + 2
	Unable to proceed with parsing until new data is provided.

static const int	MORE_DATA_PROVIDED_EVT = SM_DERIVED_EVENT_MIN + 3
	New data provided and parsing should continue.

static const int	HTTP_PARSE_OK_EVT = SM_DERIVED_EVENT_MIN + 1000
	Parsing HTTP request successful.

static const int	HTTP_PARSE_FAILED_EVT = SM_DERIVED_EVENT_MIN + 1001
	Parsing HTTP request failed.

Static Public Attributes inherited from isc::util::StateModel
static const int	END_EVT = 2
	Event issued to end the model execution.

static const int	END_ST = 1
	Final state, all the state model has reached its conclusion.

static const int	FAIL_EVT = 3
	Event issued to abort the model execution.

static const int	NEW_ST = 0
	State that a state model is in immediately after construction.

static const int	NOP_EVT = 0
	Signifies that no event has occurred.

static const int	SM_DERIVED_EVENT_MIN = 11
	Value at which custom events in a derived class should begin.

static const int	SM_DERIVED_STATE_MIN = 11
	Value at which custom states in a derived class should begin.

static const int	START_EVT = 1
	Event issued to start the model execution.

Protected Member Functions inherited from isc::http::HttpMessageParserBase
virtual void	defineEvents () override
	Define events used by the parser.

virtual void	verifyEvents () override
	Verifies events used by the parser.

void	stateWithReadHandler (const std::string &handler_name, std::function< void(const char c)> after_read_logic)
	Generic parser handler which reads a single byte of data and parses it using specified callback function.

void	stateWithMultiReadHandler (const std::string &handler_name, std::function< void(const std::string &)> after_read_logic)
	Generic parser handler which reads multiple bytes of data and parses it using specified callback function.

void	parseFailure (const std::string &error_msg)
	Transition parser to failure state.

virtual void	onModelFailure (const std::string &explanation) override
	A method called when parsing fails.

void	getNextFromBuffer (std::string &bytes, const size_t limit=1)
	Retrieves next bytes of data from the buffer.

void	invalidEventError (const std::string &handler_name, const unsigned int event)
	This method is called when invalid event occurred in a particular parser state.

void	parseEndedHandler ()
	Handler for HTTP_PARSE_OK_ST and HTTP_PARSE_FAILED_ST.

bool	popNextFromBuffer (std::string &next, const size_t limit=1)
	Tries to read next byte from buffer.

bool	isChar (const signed char c) const
	Checks if specified value is a character.

bool	isCtl (const signed char c) const
	Checks if specified value is a control value.

bool	isSpecial (const signed char c) const
	Checks if specified value is a special character.

Protected Member Functions inherited from isc::util::StateModel
void	abortModel (const std::string &explanation)
	Aborts model execution.

void	defineEvent (unsigned int value, const std::string &label)
	Adds an event value and associated label to the set of events.

void	defineState (unsigned int value, const std::string &label, StateHandler handler, const StatePausing &state_pausing=STATE_PAUSE_NEVER)
	Adds an state value and associated label to the set of states.

bool	doOnEntry ()
	Checks if on entry flag is true.

bool	doOnExit ()
	Checks if on exit flag is true.

const EventPtr &	getEvent (unsigned int value)
	Fetches the event referred to by value.

const StatePtr	getState (unsigned int value)
	Fetches the state referred to by value.

const StatePtr	getStateInternal (unsigned int value)
	Fetches the state referred to by value.

void	initDictionaries ()
	Initializes the event and state dictionaries.

void	postNextEvent (unsigned int event)
	Sets the next event to the given event value.

void	setState (unsigned int state)
	Sets the current state to the given state value.

void	transition (unsigned int state, unsigned int event)
	Sets up the model to transition into given state with a given event.

virtual void	verifyStates ()
	Validates the contents of the set of states.

Protected Attributes inherited from isc::http::HttpMessageParserBase
HttpMessage &	message_
	Reference to the parsed HTTP message.

std::string	buffer_
	Internal buffer from which parser reads data.

size_t	buffer_pos_
	Position of the next character to read from the buffer.

std::string	error_message_
	Error message set by onModelFailure.

Detailed Description

A generic parser for HTTP requests.

This class implements a parser for HTTP requests. The parser derives from HttpMessageParserBase class and implements its own state machine on top of it. The states of the parser reflect various parts of the HTTP message being parsed, e.g. parsing HTTP method, parsing URI, parsing message body etc. The descriptions of all parser states are provided below together with the constants defining these states.

The request parser validates the syntax of the received message as it progresses with parsing the data. Though, it doesn't interpret the received data until the whole message is parsed. In most cases we want to apply some restrictions on the message content, e.g. Kea Control API requires that commands are sent using HTTP POST, with a JSON command being carried in a message body. The parser doesn't verify if the message meets these restrictions until the whole message is parsed, i.e. stored in the HttpRequestContext object. This object is associated with a HttpRequest object (or its derivation). When the parsing is completed, the HttpRequest::create method is called to retrieve the data from the HttpRequestContext and interpret the data. In particular, the HttpRequest or its derivation checks if the received message meets desired restrictions.

Kea Control API uses PostHttpRequestJson class (which derives from the HttpRequest) to interpret received request. This class requires that the HTTP request uses POST method and contains the following headers:

Content-Type: application/json,
Content-Length

If any of these restrictions is not met in the received message, an exception will be thrown, thereby HttpRequestParser will fail parsing the message.

Definition at line 54 of file request_parser.h.

Constructor & Destructor Documentation

◆ HttpRequestParser()

isc::http::HttpRequestParser::HttpRequestParser ( HttpRequest & request )

explicit

Constructor.

Creates new instance of the parser.

Parameters

request Reference to the HttpRequest object or its derivation that should be used to validate the parsed request and to be used as a container for the parsed request.

Definition at line 40 of file request_parser.cc.

Member Function Documentation

◆ initModel()

void isc::http::HttpRequestParser::initModel ( )

Initialize the state model for parsing.

This method must be called before parsing the request, i.e. before calling HttpRequestParser::poll. It initializes dictionaries of states and events, and sets the initial model state to RECEIVE_START_ST.

Definition at line 46 of file request_parser.cc.

References isc::util::StateModel::initDictionaries(), isc::util::StateModel::postNextEvent(), RECEIVE_START_ST, isc::util::StateModel::setState(), and isc::util::StateModel::START_EVT.

Here is the call graph for this function:

Member Data Documentation

◆ EXPECTING_NEW_LINE1_ST

const int isc::http::HttpRequestParser::EXPECTING_NEW_LINE1_ST = SM_DERIVED_STATE_MIN + 13

static

Parsing first new line (after HTTP version number).

Definition at line 98 of file request_parser.h.

◆ EXPECTING_NEW_LINE2_ST

const int isc::http::HttpRequestParser::EXPECTING_NEW_LINE2_ST = SM_DERIVED_STATE_MIN + 19

static

Expecting new line after parsing header value.

Definition at line 117 of file request_parser.h.

◆ EXPECTING_NEW_LINE3_ST

const int isc::http::HttpRequestParser::EXPECTING_NEW_LINE3_ST = SM_DERIVED_STATE_MIN + 20

static

Expecting second new line marking end of HTTP headers.

Definition at line 120 of file request_parser.h.

◆ HEADER_LINE_START_ST

const int isc::http::HttpRequestParser::HEADER_LINE_START_ST = SM_DERIVED_STATE_MIN + 14

static

Starting to parse a header line.

Definition at line 101 of file request_parser.h.

◆ HEADER_LWS_ST

const int isc::http::HttpRequestParser::HEADER_LWS_ST = SM_DERIVED_STATE_MIN + 15

static

Parsing LWS (Linear White Space), i.e.

new line with a space or tab character while parsing a HTTP header.

Definition at line 105 of file request_parser.h.

◆ HEADER_NAME_ST

const int isc::http::HttpRequestParser::HEADER_NAME_ST = SM_DERIVED_STATE_MIN + 16

static

Parsing header name.

Definition at line 108 of file request_parser.h.

◆ HEADER_VALUE_ST

const int isc::http::HttpRequestParser::HEADER_VALUE_ST = SM_DERIVED_STATE_MIN + 18

static

Parsing header value.

Definition at line 114 of file request_parser.h.

◆ HTTP_BODY_ST

const int isc::http::HttpRequestParser::HTTP_BODY_ST = SM_DERIVED_STATE_MIN + 21

static

Parsing body of a HTTP message.

Definition at line 123 of file request_parser.h.

◆ HTTP_METHOD_ST

const int isc::http::HttpRequestParser::HTTP_METHOD_ST = SM_DERIVED_STATE_MIN + 2

static

Parsing HTTP method, e.g. GET, POST etc.

Definition at line 65 of file request_parser.h.

◆ HTTP_URI_ST

const int isc::http::HttpRequestParser::HTTP_URI_ST = SM_DERIVED_STATE_MIN + 3

static

Parsing URI.

Definition at line 68 of file request_parser.h.

◆ HTTP_VERSION_H_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_H_ST = SM_DERIVED_STATE_MIN + 4

static

Parsing letter "H" of "HTTP".

Definition at line 71 of file request_parser.h.

◆ HTTP_VERSION_MAJOR_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_MAJOR_ST = SM_DERIVED_STATE_MIN + 10

static

Parsing major HTTP version number.

Definition at line 89 of file request_parser.h.

◆ HTTP_VERSION_MAJOR_START_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_MAJOR_START_ST = SM_DERIVED_STATE_MIN + 9

static

Starting to parse major HTTP version number.

Definition at line 86 of file request_parser.h.

◆ HTTP_VERSION_MINOR_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_MINOR_ST = SM_DERIVED_STATE_MIN + 12

static

Parsing minor HTTP version number.

Definition at line 95 of file request_parser.h.

◆ HTTP_VERSION_MINOR_START_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_MINOR_START_ST = SM_DERIVED_STATE_MIN + 11

static

Starting to parse minor HTTP version number.

Definition at line 92 of file request_parser.h.

◆ HTTP_VERSION_P_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_P_ST = SM_DERIVED_STATE_MIN + 7

static

Parsing letter "P" in "HTTP".

Definition at line 80 of file request_parser.h.

◆ HTTP_VERSION_SLASH_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_SLASH_ST = SM_DERIVED_STATE_MIN + 8

static

Parsing slash character in "HTTP/Y.X".

Definition at line 83 of file request_parser.h.

◆ HTTP_VERSION_T1_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_T1_ST = SM_DERIVED_STATE_MIN + 5

static

Parsing first occurrence of "T" in "HTTP".

Definition at line 74 of file request_parser.h.

◆ HTTP_VERSION_T2_ST

const int isc::http::HttpRequestParser::HTTP_VERSION_T2_ST = SM_DERIVED_STATE_MIN + 6

static

Parsing second occurrence of "T" in "HTTP".

Definition at line 77 of file request_parser.h.

◆ RECEIVE_START_ST

const int isc::http::HttpRequestParser::RECEIVE_START_ST = SM_DERIVED_STATE_MIN + 1

static

State indicating a beginning of parsing.

Definition at line 62 of file request_parser.h.

Referenced by initModel().

◆ SPACE_BEFORE_HEADER_VALUE_ST

const int isc::http::HttpRequestParser::SPACE_BEFORE_HEADER_VALUE_ST = SM_DERIVED_STATE_MIN + 17

static

Parsing space before header value.

Definition at line 111 of file request_parser.h.

The documentation for this class was generated from the following files:

States supported by the HttpRequestParser.

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ HttpRequestParser()

Member Function Documentation

◆ initModel()

Member Data Documentation

◆ EXPECTING_NEW_LINE1_ST

◆ EXPECTING_NEW_LINE2_ST

◆ EXPECTING_NEW_LINE3_ST

◆ HEADER_LINE_START_ST

◆ HEADER_LWS_ST

◆ HEADER_NAME_ST

◆ HEADER_VALUE_ST

◆ HTTP_BODY_ST

◆ HTTP_METHOD_ST

◆ HTTP_URI_ST

◆ HTTP_VERSION_H_ST

◆ HTTP_VERSION_MAJOR_ST

◆ HTTP_VERSION_MAJOR_START_ST

◆ HTTP_VERSION_MINOR_ST

◆ HTTP_VERSION_MINOR_START_ST

◆ HTTP_VERSION_P_ST

◆ HTTP_VERSION_SLASH_ST

◆ HTTP_VERSION_T1_ST

◆ HTTP_VERSION_T2_ST

◆ RECEIVE_START_ST

◆ SPACE_BEFORE_HEADER_VALUE_ST