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|
(* Feel free to use this example code in any way
you see fit (Public Domain) *)
// Original example: https://gnunet.org/svn/libmicrohttpd/doc/examples/sessions.c
program sessions;
{$mode objfpc}{$H+}
uses
SysUtils, BaseUnix, cmem, cutils, libmicrohttpd;
const
(**
* Invalid method page.
*)
METHOD_ERROR = '<html><head><title>Illegal request</title></head><body>Go away.</body></html>';
(**
* Invalid URL page.
*)
NOT_FOUND_ERROR = '<html><head><title>Not found</title></head><body>Go away.</body></html>';
(**
* Front page. (/)
*)
MAIN_PAGE = '<html><head><title>Welcome</title></head><body><form action="/2" method="post">What is your name? <input type="text" name="v1" value="%s" /><input type="submit" value="Next" /></body></html>';
(**
* Second page. (/2)
*)
SECOND_PAGE = '<html><head><title>Tell me more</title></head><body><a href="/">previous</a> <form action="/S" method="post">%s, what is your job? <input type="text" name="v2" value="%s" /><input type="submit" value="Next" /></body></html>';
(**
* Second page (/S)
*)
SUBMIT_PAGE = '<html><head><title>Ready to submit?</title></head><body><form action="/F" method="post"><a href="/2">previous </a> <input type="hidden" name="DONE" value="yes" /><input type="submit" value="Submit" /></body></html>';
(**
* Last page.
*)
LAST_PAGE = '<html><head><title>Thank you</title></head><body>Thank you.</body></html>';
(**
* Name of our cookie.
*)
COOKIE_NAME = 'session';
type
(**
* State we keep for each user/session/browser.
*)
PSession = ^TSession;
TSession = packed record
(**
* We keep all sessions in a linked list.
*)
next: PSession;
(**
* Unique ID for this session.
*)
sid: array[0..33] of Char;
(**
* Reference counter giving the number of connections
* currently using this session.
*)
rc: cint;
(**
* Time when this session was last active.
*)
start: time_t;
(**
* String submitted via form.
*)
value_1: array[0..64] of Char;
(**
* Another value submitted via form.
*)
value_2: array[0..64] of Char;
end;
(**
* Data kept per request.
*)
TRequest = packed record
(**
* Associated session.
*)
session: PSession;
(**
* Post processor handling form data (IF this is
* a POST request).
*)
pp: PMHD_PostProcessor;
(**
* URL to serve in response to this POST (if this request
* was a 'POST')
*)
post_url: pcchar;
end;
PRequest = ^TRequest;
var
(**
* Linked list of all active sessions. Yes, O(n) but a
* hash table would be overkill for a simple example...
*)
_sessions: PSession;
(**
* Return the session handle for this connection, or
* create one if this is a new user.
*)
function get_session(connection: PMHD_Connection): PSession;
var
ret: PSession;
cookie: pcchar;
begin
cookie := MHD_lookup_connection_value(connection, MHD_COOKIE_KIND, COOKIE_NAME);
if cookie <> nil then
begin
(* find existing session *)
ret := _sessions;
while nil <> ret do
begin
if StrComp(cookie, ret^.sid) = 0 then
Break;
ret := ret^.next;
end;
if nil <> ret then
begin
Inc(ret^.rc);
Exit(ret);
end;
end;
(* create fresh session *)
ret := CAlloc(1, SizeOf(TSession));
if nil = ret then
begin
WriteLn(stderr, 'calloc error: ', strerror(errno^));
Exit(nil);
end;
(* not a super-secure way to generate a random session ID,
but should do for a simple example... *)
snprintf(ret^.sid, SizeOf(ret^.sid), '%X%X%X%X', Cardinal(rand),
Cardinal(rand), Cardinal(rand), Cardinal(rand));
Inc(ret^.rc);
ret^.start := FpTime;
ret^.next := _sessions;
_sessions := ret;
Result := ret;
end;
(**
* Type of handler that generates a reply.
*
* @param cls content for the page (handler-specific)
* @param mime mime type to use
* @param session session information
* @param connection connection to process
* @param MHD_YES on success, MHD_NO on failure
*)
type
TPageHandler = function(cls: Pointer; mime: Pcchar; session: PSession;
connection: PMHD_Connection): LongInt; cdecl;
(**
* Entry we generate for each page served.
*)
{ TPage }
TPage = packed record
(**
* Acceptable URL for this page.
*)
url: Pcchar;
(**
* Mime type to set for the page.
*)
mime: Pcchar;
(**
* Handler to call to generate response.
*)
handler: TPageHandler;
(**
* Extra argument to handler.
*)
handler_cls: Pcchar;
end;
(**
* Add header to response to set a session cookie.
*
* @param session session to use
* @param response response to modify
*)
procedure add_session_cookie(session: PSession; response: PMHD_Response);
var
cstr: array[0..256] of Char;
begin
snprintf(cstr, SizeOf(cstr), '%s=%s', COOKIE_NAME, session^.sid);
if MHD_NO =
MHD_add_response_header(response, MHD_HTTP_HEADER_SET_COOKIE, cstr) then
WriteLn(stderr, 'Failed to set session cookie header!');
end;
(**
* Handler that returns a simple static HTTP page that
* is passed in via 'cls'.
*
* @param cls a 'const char *' with the HTML webpage to return
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*)
function serve_simple_form(cls: Pointer; mime: Pcchar; session: PSession;
connection: PMHD_Connection): cint; cdecl;
var
ret: cint;
form: Pcchar;
response: PMHD_Response;
begin
form := cls;
(* return static form *)
response := MHD_create_response_from_buffer(Length(form), Pointer(form),
MHD_RESPMEM_PERSISTENT);
add_session_cookie(session, response);
MHD_add_response_header(response, MHD_HTTP_HEADER_CONTENT_ENCODING, mime);
ret := MHD_queue_response(connection, MHD_HTTP_OK, response);
MHD_destroy_response(response);
Result := ret;
end;
(**
* Handler that adds the 'v1' value to the given HTML code.
*
* @param cls a 'const char *' with the HTML webpage to return
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*)
function fill_v1_form(cls: Pointer; mime: Pcchar; session: PSession;
connection: PMHD_Connection): cint; cdecl;
var
ret: cint;
form: Pcchar;
reply: Pcchar;
response: PMHD_Response;
begin
form := cls;
if asprintf(@reply, form, session^.value_1) = -1 then
(* oops *)
Exit(MHD_NO);
(* return static form *)
response := MHD_create_response_from_buffer(Length(reply), Pointer(reply),
MHD_RESPMEM_MUST_FREE);
add_session_cookie(session, response);
MHD_add_response_header(response, MHD_HTTP_HEADER_CONTENT_ENCODING, mime);
ret := MHD_queue_response(connection, MHD_HTTP_OK, response);
MHD_destroy_response(response);
Result := ret;
end;
(**
* Handler that adds the 'v1' and 'v2' values to the given HTML code.
*
* @param cls a 'const char *' with the HTML webpage to return
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*)
function fill_v1_v2_form(cls: Pointer; mime: Pcchar; session: PSession;
connection: PMHD_Connection): cint; cdecl;
var
ret: cint;
form: Pcchar;
reply: Pcchar;
response: PMHD_Response;
begin
form := cls;
if asprintf(@reply, form, session^.value_1, session^.value_2) = -1 then
(* oops *)
Exit(MHD_NO);
(* return static form *)
response := MHD_create_response_from_buffer(Length(reply), Pointer(reply),
MHD_RESPMEM_MUST_FREE);
add_session_cookie(session, response);
MHD_add_response_header(response, MHD_HTTP_HEADER_CONTENT_ENCODING, mime);
ret := MHD_queue_response(connection, MHD_HTTP_OK, response);
MHD_destroy_response(response);
Result := ret;
end;
(**
* Handler used to generate a 404 reply.
*
* @param cls a 'const char *' with the HTML webpage to return
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*)
function not_found_page(cls: Pointer; mime: Pcchar; session: PSession;
connection: PMHD_Connection): cint; cdecl;
var
ret: cint;
response: PMHD_Response;
begin
(* unsupported HTTP method *)
response := MHD_create_response_from_buffer(Length(NOT_FOUND_ERROR),
Pcchar(NOT_FOUND_ERROR), MHD_RESPMEM_PERSISTENT);
ret := MHD_queue_response(connection, MHD_HTTP_NOT_FOUND, response);
MHD_add_response_header(response, MHD_HTTP_HEADER_CONTENT_ENCODING, mime);
MHD_destroy_response(response);
Result := ret;
end;
const
(**
* List of all pages served by this HTTP server.
*)
pages: array[0..4] of TPage = (
(url: '/'; mime: 'text/html'; handler: @fill_v1_form; handler_cls: MAIN_PAGE),
(url: '/2'; mime: 'text/html'; handler: @fill_v1_v2_form; handler_cls: SECOND_PAGE),
(url: '/S'; mime: 'text/html'; handler: @serve_simple_form; handler_cls: SUBMIT_PAGE),
(url: '/F'; mime: 'text/html'; handler: @serve_simple_form; handler_cls: LAST_PAGE),
(url: nil; mime: nil; handler: @not_found_page; handler_cls: nil) (* 404 *)
);
(**
* Iterator over key-value pairs where the value
* maybe made available in increments and/or may
* not be zero-terminated. Used for processing
* POST data.
*
* @param cls user-specified closure
* @param kind type of the value
* @param key 0-terminated key for the value
* @param filename name of the uploaded file, NULL if not known
* @param content_type mime-type of the data, NULL if not known
* @param transfer_encoding encoding of the data, NULL if not known
* @param data pointer to size bytes of data at the
* specified offset
* @param off offset of data in the overall value
* @param size number of bytes in data available
* @return MHD_YES to continue iterating,
* MHD_NO to abort the iteration
*)
function post_iterator(cls: Pointer; kind: MHD_ValueKind; key: Pcchar;
filename: Pcchar; content_type: Pcchar; transfer_encoding: Pcchar;
data: Pcchar; off: cuint64; size: size_t): cint; cdecl;
var
request: PRequest;
session: PSession;
begin
request := cls;
session := request^.session;
if StrComp('DONE', key) = 0 then
begin
WriteLn(stdout, Format('Session `%s'' submitted `%s'', `%s''', [
session^.sid, session^.value_1, session^.value_2]));
Exit(MHD_YES);
end;
if StrComp('v1', key) = 0 then
begin
if (size + off) > SizeOf(session^.value_1) then
size := SizeOf(session^.value_1) - off;
Move(data^, session^.value_1[off], size);
if (size + off) < SizeOf(session^.value_1) then
session^.value_1[size + off] := #0;
Exit(MHD_YES);
end;
if StrComp('v2', key) = 0 then
begin
if (size + off) > SizeOf(session^.value_2) then
size := SizeOf(session^.value_2) - off;
Move(data^, session^.value_2[off], size);
if (size + off) < SizeOf(session^.value_2) then
session^.value_2[size + off] := #0;
Exit(MHD_YES);
end;
WriteLn(stderr, Format('Unsupported form value `%s''', [key]));
Result := MHD_YES;
end;
(**
* Main MHD callback for handling requests.
*
*
* @param cls argument given together with the function
* pointer when the handler was registered with MHD
* @param connection handle to connection which is being processed
* @param url the requested url
* @param method the HTTP method used ("GET", "PUT", etc.)
* @param version the HTTP version string (i.e. "HTTP/1.1")
* @param upload_data the data being uploaded (excluding HEADERS,
* for a POST that fits into memory and that is encoded
* with a supported encoding, the POST data will NOT be
* given in upload_data and is instead available as
* part of MHD_get_connection_values; very large POST
* data *will* be made available incrementally in
* upload_data)
* @param upload_data_size set initially to the size of the
* upload_data provided; the method must update this
* value to the number of bytes NOT processed;
* @param ptr pointer that the callback can set to some
* address and that will be preserved by MHD for future
* calls for this request; since the access handler may
* be called many times (i.e., for a PUT/POST operation
* with plenty of upload data) this allows the application
* to easily associate some request-specific state.
* If necessary, this state can be cleaned up in the
* global "MHD_RequestCompleted" callback (which
* can be set with the MHD_OPTION_NOTIFY_COMPLETED).
* Initially, <tt>*con_cls</tt> will be NULL.
* @return MHS_YES if the connection was handled successfully,
* MHS_NO if the socket must be closed due to a serios
* error while handling the request
*)
function create_response(cls: Pointer; connection: PMHD_Connection;
url: Pcchar; method: Pcchar; version: Pcchar; upload_data: Pcchar;
upload_data_size: Psize_t; ptr: PPointer): cint; cdecl;
var
response: PMHD_Response;
request: PRequest;
session: PSession;
ret: cint;
i: Cardinal;
begin
request := ptr^;
if nil = request then
begin
request := CAlloc(1, SizeOf(TRequest));
if nil = request then
begin
WriteLn(stderr, 'calloc error: ', strerror(errno^));
Exit(MHD_NO);
end;
ptr^ := request;
if StrComp(method, MHD_HTTP_METHOD_POST) = 0 then
begin
request^.pp := MHD_create_post_processor(connection, 1024,
@post_iterator, request);
if nil = request^.pp then
begin
WriteLn(stderr, Format('Failed to setup post processor for `%s''',
[url]));
Exit(MHD_NO); (* internal error *)
end;
end;
Exit(MHD_YES);
end;
if nil = request^.session then
begin
request^.session := get_session(connection);
if nil = request^.session then
begin
WriteLn(stderr, Format('Failed to setup session for `%s''', [url]));
Exit(MHD_NO); (* internal error *)
end;
end;
session := request^.session;
session^.start := FpTime;
if StrComp(method, MHD_HTTP_METHOD_POST) = 0 then
begin
(* evaluate POST data *)
MHD_post_process(request^.pp, upload_data, upload_data_size^);
if upload_data_size^ <> 0 then
begin
upload_data_size^ := 0;
Exit(MHD_YES);
end;
(* done with POST data, serve response *)
MHD_destroy_post_processor(request^.pp);
request^.pp := nil;
method := MHD_HTTP_METHOD_GET; (* fake 'GET' *)
if nil <> request^.post_url then
url := request^.post_url;
end;
if (StrComp(method, MHD_HTTP_METHOD_GET) = 0) or
(StrComp(method, MHD_HTTP_METHOD_HEAD) = 0) then
begin
(* find out which page to serve *)
i := 0;
while (pages[i].url <> nil) and (StrComp(pages[i].url, url) <> 0) do
Inc(i);
ret := pages[i].handler(pages[i].handler_cls, pages[i].mime, session,
connection);
if ret <> MHD_YES then
WriteLn(stderr, Format('Failed to create page for `%s''', [url]));
Exit(ret);
end;
(* unsupported HTTP method *)
response := MHD_create_response_from_buffer(Length(METHOD_ERROR),
Pcchar(METHOD_ERROR), MHD_RESPMEM_PERSISTENT);
ret := MHD_queue_response(connection, MHD_HTTP_NOT_ACCEPTABLE, response);
MHD_destroy_response(response);
Result := ret;
end;
(**
* Callback called upon completion of a request.
* Decrements session reference counter.
*
* @param cls not used
* @param connection connection that completed
* @param con_cls session handle
* @param toe status code
*)
procedure request_completed_callback(cls: Pointer; connection: PMHD_Connection;
con_cls: PPointer; toe: MHD_RequestTerminationCode);
var
request: PRequest;
begin
request := con_cls^;
if nil = request then
Exit;
if nil <> request^.session then
Dec(request^.session^.rc);
if nil <> request^.pp then
MHD_destroy_post_processor(request^.pp);
Free(request);
end;
(**
* Clean up handles of sessions that have been idle for
* too long.
*)
procedure expire_sessions;
var
pos: PSession;
prev: PSession;
next: PSession;
now: time_t;
begin
now := FpTime;
prev := nil;
pos := _sessions;
while nil <> pos do
begin
next := pos^.next;
if (now - pos^.start) > (60 * 60) then
begin
(* expire sessions after 1h *)
if nil = prev then
_sessions := pos^.next
else
prev^.next := next;
Free(pos);
end
else
prev := pos;
pos := next;
end;
end;
(**
* Call with the port number as the only argument.
* Never terminates (other than by signals, such as CTRL-C).
*)
var
d: PMHD_Daemon;
tv: timeval;
tvp: ptimeval;
rs: TFDSet;
ws: TFDSet;
es: TFDSet;
max: cint;
mhd_timeout: MHD_UNSIGNED_LONG_LONG;
begin
if argc <> 2 then
begin
WriteLn(argv[0], ' PORT');
Halt(1);
end;
(* initialize PRNG *)
Randomize;
d := MHD_start_daemon(MHD_USE_DEBUG, StrToInt(argv[1]), nil, nil,
@create_response, nil, MHD_OPTION_CONNECTION_TIMEOUT, cuint(15),
MHD_OPTION_NOTIFY_COMPLETED, @request_completed_callback, nil, MHD_OPTION_END);
if nil = d then
Halt(1);
while True do
begin
expire_sessions;
max := 0;
fpFD_ZERO(rs);
fpFD_ZERO(ws);
fpFD_ZERO(es);
if MHD_YES <> MHD_get_fdset(d, @rs, @ws, @es, @max) then
Break; (* fatal internal error *)
if MHD_get_timeout(d, @mhd_timeout) = MHD_YES then
begin
tv.tv_sec := mhd_timeout div 1000;
tv.tv_usec := (mhd_timeout - (tv.tv_sec * 1000)) * 1000;
tvp := @tv;
end
else
tvp := nil;
if -1 = fpSelect(max + 1, @rs, @ws, @es, tvp) then
begin
if (ESysEINTR <> errno^) then
WriteLn(stderr, 'Aborting due to error during select: ', strerror(errno^));
Break;
end;
MHD_run(d);
end;
MHD_stop_daemon(d);
end.
|
