miniserver.c File Reference

Small Framework to make MHD based server side develpment more bearable. More...

#include <microhttpd.h>
#include <jansson.h>
#include "proclister.h"
#include <fcntl.h>
#include <sys/stat.h>

Include dependency graph for miniserver.c:

Functions
int	ms_answer_to_connection (void *cls, struct MHD_Connection *connection, const char *url, const char *method, const char *version, const char *upload_data, size_t *upload_data_size, void **con_cls)
	Miniserver framework main request dispatcher. More...
static int	ms_on_client_connect (void *cls, const struct sockaddr *addr, socklen_t addrlen)
	MHD Client authorization handler (Hooked as 3rd param to MHD_start_daemon()). More...
void	ms_req_term_cb (void *cls, struct MHD_Connection *connection, void **con_cls, enum MHD_RequestTerminationCode toe)
	MHD Post request handler. More...
miniserver *	server_new (json_t *json)
	App: Instantiate server with basic settings (e.g. More...
void	server_run (miniserver *s)
	App: Start Running Server and accepting requests. More...
void	server_actions_load (miniserver *s, action *actarr, int cnt)
	App: Load actions from C Array of actions. More...
request *	req_new (miniserver *s, const char *url, const char *method)
	Allocate and initialize request. More...
void	req_free (request *req)
	Free request and its members. More...
response *	res_new (action *act)
void	res_free (response *res)
action *	action_find (miniserver *s, const char *url)
	Lookup an action (during dispatching). More...
void	res_set_str_cont (response *res, char *contstr)
	Set string content as content to respond with. More...
void	res_set_conttype (response *res, char *conttype)
struct MHD_Response *	req_trystatic (request *req, response *res)
	Try to resolve url to a static file and return response for it. More...

Detailed Description

Small Framework to make MHD based server side develpment more bearable.

miniserver * ms = server_new(NULL);
server_actions_load(ms, actarr, 3);
server_run(ms);

Notes on response content allocation

MHD has following enums to hint memory management strategy in microhttpd.h

• 0 - MHD_RESPMEM_PERSISTENT global/static, wont change (NOT stack). NOT to be free()d
• 1 - MHD_RESPMEM_MUST_FREE - heap allocated (e.g. by malloc()), should be free()d by MHD
• 2 - MHD_RESPMEM_MUST_COPY - transient/stack allocated (NON-heap). MHD will make a copy (and free copy)

  MHD Doc on run modes: "Thread modes and even loops"

These are extracted notes from documenation (See first flag param to MHD_start_daemon(flags, ...), see also enum MHD_FLAG). For list of flags in documenation "2 Constants". What is this: MHD_USE_SELECT_INTERNALLY

• external sockets polling (no threads) - DEFAULT (because simple /universal ?)
• internal polling ("one thread for all connections" - sounds ambiguous .. one of each or one for all) MHD_USE_INTERNAL_POLLING_THREAD=8
• polling in thread pool (... used to process all connections)
• thread-per-connection ( 1 thr for listen sockets and then 1 per accepted conn.) MHD_USE_THREAD_PER_CONNECTION=4 (Reqs: MHD_USE_INTERNAL_POLLING_THREAD.)

Earlier modes must be combined with event loop styles: select, poll and epoll (epoll and poll may not be available on some platforms). Are these: MHD_USE_SELECT_INTERNALLY, MHD_USE_POLL, MHD_USE_EPOLL

Forking to BG

• https://www.raspberrypi.org/forums/viewtopic.php?t=47210

  References

• /usr/include/microhttpd.h
• MHD official PDF Tutorial: https://www.gnu.org/software/libmicrohttpd/tutorial.pdf
• https://fossies.org/linux/libmicrohttpd/src/examples/demo.c Great examples, e.g: list_directory()
• Google: Libmicrohttpd example

Other web servers:

• Lwan
• http://siliconframework.org/docs/microhttpd.html (See: SQL REST, SQL CRUD, Websocketpp backend)
• https://www.reddit.com/r/cpp/comments/4o5zdm/a_good_c_or_c_honestly_so_long_as_it_works_http/

Function Documentation

action_find()

action* action_find	(	miniserver *	s,
		const char *	url
	)

Lookup an action (during dispatching).

Parameters

s	- Server
url	- URL by which action node should be looked up

Returns

Action node matched or NULL for no action matching passed URL.

References miniserver::actions, and action::url.

Referenced by main(), and ms_answer_to_connection().

ms_answer_to_connection()

int ms_answer_to_connection	(	void *	cls,
		struct MHD_Connection *	connection,
		const char *	url,
		const char *	method,
		const char *	version,
		const char *	upload_data,
		size_t *	upload_data_size,
		void **	con_cls
	)

Miniserver framework main request dispatcher.

Derives the action to dispatch based on the URL.

References action_find(), response::code, response::conn, response::cont, response::contlen, response::conttype, miniserver::debug, action::hdlr, response::json, response::memmode, MHD_add_response_header(), MHD_create_response_from_buffer(), MHD_destroy_response(), miniserver::port, req_new(), req_trystatic(), request::res, res_new(), res_set_conttype(), and res_set_str_cont().

Referenced by server_run().

ms_on_client_connect()

static int ms_on_client_connect ( void *  cls, const struct sockaddr *  addr, socklen_t  addrlen  )

static

MHD Client authorization handler (Hooked as 3rd param to MHD_start_daemon()).

Gets called twice per request ? No. But multiple requests can be batched to go through Access check first.

References MHD_YES.

Referenced by server_run().

ms_req_term_cb()

void ms_req_term_cb	(	void *	cls,
		struct MHD_Connection *	connection,
		void **	con_cls,
		enum MHD_RequestTerminationCode	toe
	)

MHD Post request handler.

• Release miniserver request req,res
• Mark con_cls as NULL

References req_free(), request::res, and res_free().

Referenced by server_run().

req_free()

void req_free

(

request *

req

)

Free request and its members.

References request::method, and request::url.

Referenced by ms_req_term_cb().

req_new()

request* req_new	(	miniserver *	s,
		const char *	url,
		const char *	method
	)

Allocate and initialize request.

References request::method, request::ms, and request::url.

Referenced by ms_answer_to_connection().

req_trystatic()

struct MHD_Response* req_trystatic	(	request *	req,
		response *	res
	)

Try to resolve url to a static file and return response for it.

Parameters

req	- Request with URL to test for static content
res	- Response to set possible http return codes to (in res->code)

Returns

MHD_Response (pointer) for static file or NULL

Todo:

: Check suffix and try to map to appropriate mime-type

References response::code, miniserver::docroot, MHD_create_response_from_fd(), request::ms, and request::url.

Referenced by ms_answer_to_connection().

res_free()

void res_free

(

response *

res

)

References response::conn, and response::conttype.

Referenced by ms_req_term_cb().

res_new()

response* res_new

(

action *

act

)

References response::code, action::conttype, and response::conttype.

Referenced by ms_answer_to_connection().

res_set_conttype()

void res_set_conttype	(	response *	res,
		char *	conttype
	)

References response::conttype.

Referenced by ms_answer_to_connection().

res_set_str_cont()

void res_set_str_cont	(	response *	res,
		char *	contstr
	)

Set string content as content to respond with.

Length is figured out from sting. Binary data not allowed with this methos.

Parameters

res	- Response (to which content is set)
contstr	- Content string.

References response::cont, and response::contlen.

Referenced by ms_answer_to_connection().

server_actions_load()

void server_actions_load	(	miniserver *	s,
		action *	actarr,
		int	cnt
	)

App: Load actions from C Array of actions.

Parameters

s	- Miniserver (to/for which actions will be loaded)
actarr	- Array of actions (not action pointers) to add
cnt	- Number of actions to add

Returns

none

References miniserver::actions, and action::url.

Referenced by main().

server_new()

miniserver* server_new

(

json_t *

json

)

App: Instantiate server with basic settings (e.g.

docroot, port).

• docroot
• port
• JSON indent/prettiness

References miniserver::debug, miniserver::docroot, docroot, miniserver::logfh, miniserver::logfname, miniserver::port, and miniserver::reqdebug.

Referenced by main().

server_run()

void server_run

(

miniserver *

s

)

App: Start Running Server and accepting requests.

Parameters

s

- Server

Returns

None

References ms_answer_to_connection(), ms_on_client_connect(), ms_req_term_cb(), and miniserver::port.

Referenced by main().