httphandler.h File Reference

Detailed Description

The httphandler will attempt to connect() to a http server and HTTP 'GET' a url, then regex match against each line in HTTP header and content. This is useful to poll web servers to see if they are up and if up, scan headers for certain codes (e.g., "404 Not Found"), scan content for application error messages (e.g., "Error"), etc. Using the triptime: option events with the round trip time will be generated.

You may have multiple regex's, each generating its own events. This avoids connecting for each regex, rather it is is read one time for all. You may optionally specify a subsitution string that behaves similar to 'sed' to customize the generated events.

If you supply a substitution string, rather than copying the original complete matching string, the substitution string is used, replacing all occurances of the special charcters \[0-9] with the associated substring matches. Note: \0 matches the whole expression, while \1,\2 through \9 are substring matches 1, 2 through 9. For example, say you are watching a web server, you might want a special message if you start getting file not found responses. The regex is:

"HTTP/.* 404"
and the substitution is:
"my.website.com/ returned file not found! Call Fred at 555.555.5555 and yell at him"

Regex's are POSIX 1003.2 "extended" form.

NOTE: If you are NOT measuring triptime, then the httphandler will check the Last-Modified: timestamp via a HEAD request before doing the GET and applying the regex matching. If the file has not been modified since the last handler, then noregex matching will be done.

Wire keywords (standard handler keywords documented in Wire )

url: URL (host:[port]) (port is optional defaults to 80)
connect: event (optional)
noconnect: event (optional)
service: event (optional)
noservice: event (optional)
triptime: event (optional)
match: match-event nomatch-event regexp subst send match-event if regex matches, else send nomatch-event, if either match-event or nomatch-event are empty strings they are ignored (optional)
mirror: update-event filename keep filename up to date with the contents of url, send update-event on change (optional)
timeout: int units == seconds

You my have multiple match: lines. Matches are applied in the order they are declared.

Example:

set noconnect create event { name: "noconnect"  priority: 1 }
set four-oh-four create event { name: "file not found"  priority: 1 }
set oracle-error create event { name: "oracle error"  priority: 1 }

create handler http { 
 url: http://webserver.mydomain.com
 noconnect: $noconnect
 match: $four-oh-four "" "HTTP/.* 404" "webserver home page is missing!"
 match: $oracle-error "" "ORA-[0-9][0-9][0-9][0-9][0-9][0-9]" ""
 timeout: 5
 cycletime: 60
}

Events generated:

Event Name	Type	Description
connect	AW_EVENT_TYPE_STRING	Was able to connect, send string of "url"
noconnect	AW_EVENT_TYPE_STRING	Was NOT able to connect, send string of "url"
service	AW_EVENT_TYPE_STRING	Found valid HTTP header, send string of "url"
noservice	AW_EVENT_TYPE_STRING	Did NOT find valid HTTP header, send string of "url"
match	AW_EVENT_TYPE_STRING	Regex match in line of HTTP header or body, send string of matching line or substitution
nomatch	AW_EVENT_TYPE_STRING	No regex match in any line of HTTP header or body, send string of "url"
triptime	AW_EVENT_TYPE_INT32	Estimated round trip time in usec

#include "regexmatch.h"
#include "sysnet.h"
#include "monitor.h"
#include "wire.h"

Go to the source code of this file.

Data Structures

struct aw_httphandler_cevents_t

Events generated for connect(). More...

struct aw_httphandler_mirror_t

Holds events_sig, filename, and fd for mirroring the file that we GET. More...

struct aw_httphandler_regex_t

Specifies a regex and associated events. More...

struct aw_httphandler_revents_t

Events generated for regex matching. More...

struct aw_httphandler_state_t

State of handler during probing. More...

struct aw_httphandler_t

Handler object. More...

struct aw_httphandler_watcher_t

Compiled regex, associated events and state. More...

Defines

#define AW_HTTPHANDLER_LASTMODIFIED_BUFFER_SIZE   64

#define AW_HTTPHANDLER_READ_BUFFER_SIZE   4096

Enumerations

enum aw_httphandler_state_cd_t {
  AW_HTTPHANDLER_IDLE, AW_HTTPHANDLER_WAIT_HEAD_CONNECT, AW_HTTPHANDLER_WAIT_HEAD_WRITE, AW_HTTPHANDLER_WAIT_HEAD_READ,
  AW_HTTPHANDLER_WAIT_GET_CONNECT, AW_HTTPHANDLER_WAIT_GET_WRITE, AW_HTTPHANDLER_WAIT_GET_READ, AW_HTTPHANDLER_DONE
}

The state codes for each state on handler, nominal path is straight thru. More...

Functions

aw_httphandler_t * aw_create_httphandler (const byte_t *url, const aw_httphandler_cevents_t *cevents, const aw_timestamp_t timeout, u_int32_t nregexs, const aw_httphandler_regex_t *regexs, const byte_t *mirror_filename, const aw_event_sig_t *mirror_updated, int32_t(*regevent)(aw_handler_t *h, aw_address_t *eventid, u_int32_t index), int32_t(*regmaskevent)(aw_handler_t *h, aw_address_t *eventid, u_int32_t index), const aw_alarm_sched_t *sched, aw_logger_t *logger)

Create a http handler.

void aw_free_httphandler (aw_httphandler_t *p)

Free handler and all associated resources.

aw_handler_t * aw_wire_httphandler (aw_wire_mkhandler_args_t *args)

Create a http handler using "wire". See header doc for keyword documentation.

Define Documentation

#define AW_HTTPHANDLER_LASTMODIFIED_BUFFER_SIZE 64

#define AW_HTTPHANDLER_READ_BUFFER_SIZE 4096

Enumeration Type Documentation

enum aw_httphandler_state_cd_t

The state codes for each state on handler, nominal path is straight thru.

Enumeration values:

AW_HTTPHANDLER_IDLE not doing anything

AW_HTTPHANDLER_WAIT_HEAD_CONNECT waiting on a connect()

AW_HTTPHANDLER_WAIT_HEAD_WRITE waiting on a write()

AW_HTTPHANDLER_WAIT_HEAD_READ waiting on a read()

AW_HTTPHANDLER_WAIT_GET_CONNECT waiting on a connect()

AW_HTTPHANDLER_WAIT_GET_WRITE waiting on a write()

AW_HTTPHANDLER_WAIT_GET_READ waiting on a read()

AW_HTTPHANDLER_DONE done

Function Documentation

aw_httphandler_t* aw_create_httphandler ( const byte_t * url,

const aw_httphandler_cevents_t * cevents,

const aw_timestamp_t timeout,

u_int32_t nregexs,

const aw_httphandler_regex_t * regexs,

const byte_t * mirror_filename,

const aw_event_sig_t * mirror_updated,

int32_t(* regevent)(aw_handler_t *h, aw_address_t *eventid, u_int32_t index),

int32_t(* regmaskevent)(aw_handler_t *h, aw_address_t *eventid, u_int32_t index),

const aw_alarm_sched_t * sched,

aw_logger_t * logger

)

Create a http handler.
aw_create_httphandler

Parameters:

url Url to GET

cevents Events to generate connect/noconnect

timeout Max time to connect()

nregexs How many regex strings

regexs Array of regex strings/events

mirror_filename If not NULL, put contents of GET into file

mirror_updated Event to generate when mirror is updated, may be NULL

regevent Function pointer for event registration

regmaskevent Function pointer for event mask registration

sched Run schedule

logger Logger object

Returns:
Handler object

void aw_free_httphandler ( aw_httphandler_t * p )

Free handler and all associated resources.
aw_free_httphandler

Parameters:

p The handler

aw_handler_t* aw_wire_httphandler ( aw_wire_mkhandler_args_t * args )

Create a http handler using "wire". See header doc for keyword documentation.
aw_wire_httphandler


Data Structures
struct	aw_httphandler_cevents_t
	Events generated for connect(). More...
struct	aw_httphandler_mirror_t
	Holds events_sig, filename, and fd for mirroring the file that we GET. More...
struct	aw_httphandler_regex_t
	Specifies a regex and associated events. More...
struct	aw_httphandler_revents_t
	Events generated for regex matching. More...
struct	aw_httphandler_state_t
	State of handler during probing. More...
struct	aw_httphandler_t
	Handler object. More...
struct	aw_httphandler_watcher_t
	Compiled regex, associated events and state. More...
Defines
#define	AW_HTTPHANDLER_LASTMODIFIED_BUFFER_SIZE 64
#define	AW_HTTPHANDLER_READ_BUFFER_SIZE 4096
Enumerations
enum	aw_httphandler_state_cd_t { AW_HTTPHANDLER_IDLE, AW_HTTPHANDLER_WAIT_HEAD_CONNECT, AW_HTTPHANDLER_WAIT_HEAD_WRITE, AW_HTTPHANDLER_WAIT_HEAD_READ, AW_HTTPHANDLER_WAIT_GET_CONNECT, AW_HTTPHANDLER_WAIT_GET_WRITE, AW_HTTPHANDLER_WAIT_GET_READ, AW_HTTPHANDLER_DONE }
	The state codes for each state on handler, nominal path is straight thru. More...
Functions
aw_httphandler_t *	aw_create_httphandler (const byte_t url, const aw_httphandler_cevents_t cevents, const aw_timestamp_t timeout, u_int32_t nregexs, const aw_httphandler_regex_t regexs, const byte_t mirror_filename, const aw_event_sig_t mirror_updated, int32_t(regevent)(aw_handler_t h, aw_address_t eventid, u_int32_t index), int32_t(regmaskevent)(aw_handler_t h, aw_address_t eventid, u_int32_t index), const aw_alarm_sched_t sched, aw_logger_t *logger)
	Create a http handler.
void	aw_free_httphandler (aw_httphandler_t *p)
	Free handler and all associated resources.
aw_handler_t *	aw_wire_httphandler (aw_wire_mkhandler_args_t *args)
	Create a http handler using "wire". See header doc for keyword documentation.