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It's some somewhat functional XMPP component stuff!

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eta 2020-04-01 17:47:01 +01:00
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(defpackage :whatsxmpp
(:use :cl :usocket :event-emitter))
(in-package :whatsxmpp)
(defvar *last-stanza*)
(defparameter +streams-ns+ "urn:ietf:params:xml:ns:xmpp-streams")
(defparameter +component-ns+ "jabber:component:accept")
(defclass xmpp-component (event-emitter)
((socket
:initarg :socket
:accessor component-socket)
(socket-lock
:initform (bt:make-recursive-lock)
:accessor component-socket-lock)
(data-lock
:initform (bt:make-recursive-lock)
:accessor component-data-lock)
(sink
:initarg :sink
:accessor component-sink)
(name
:initarg :name
:reader component-name)
(stream-id
:initform nil
:accessor component-stream-id)
(shared-secret
:initarg :shared-secret
:reader component-shared-secret)))
(defmacro with-component-data-lock (comp &body body)
`(bt:with-recursive-lock-held ((component-data-lock ,comp))
,@body))
(defmethod sax:start-document ((s start-ignoring-sink))
(declare (ignore s)))
(defclass xmpp-source (cxml:broadcast-handler)
((component
:initarg :component
:accessor source-component)
(depth
:initform 0
:accessor source-depth)))
(defun make-xmpp-source (comp)
(let ((ret (cxml:make-broadcast-handler)))
(change-class ret 'xmpp-source
:component comp)
ret))
(defmethod sax:start-document ((s xmpp-source))
(declare (ignore s))
(format *debug-io* "~&XMPP --> [document started]~%"))
(defmethod sax:start-element ((s xmpp-source) namespace-uri local-name qname attributes)
(with-accessors ((depth source-depth) (comp source-component) (handlers cxml:broadcast-handler-handlers)) s
(incf depth)
(when (and (eql depth 1) (equal qname "stream:stream"))
(flet ((local-name-is-id (attr)
(equal (sax:attribute-local-name attr) "id")))
(let ((stream-id-attr (find-if #'local-name-is-id attributes)))
(when (not stream-id-attr)
(error "Server didn't send a stream ID"))
(format *debug-io* "~&XMPP --> [stream started, ID ~A]~%" (sax:attribute-value stream-id-attr))
(with-component-data-lock comp
(setf (component-stream-id comp) (sax:attribute-value stream-id-attr))
(emit :stream-started comp))
(return-from sax:start-element))))
(when (eql depth 2)
(let ((dom-builder (cxml-dom:make-dom-builder)))
(format *debug-io* "~&XMPP --> ")
(setf handlers (list (cxml:make-character-stream-sink *debug-io*) dom-builder))
(sax:start-document dom-builder)))
(call-next-method s namespace-uri local-name qname attributes)))
(defmethod sax:end-element :before ((s xmpp-source) namespace-uri local-name qname)
(when (equal qname "stream:stream")
(error "Server closed the stream")))
(defmethod sax:end-element :after ((s xmpp-source) namespace-uri local-name qname)
(with-accessors ((depth source-depth) (comp source-component) (handlers cxml:broadcast-handler-handlers)) s
(decf depth)
(when (eql depth 1)
(let* ((debug-sink (first handlers))
(dom-builder (second handlers))
(stanza (sax:end-document dom-builder)))
(sax:end-document debug-sink)
(terpri *debug-io*)
(setf handlers nil)
(emit :raw-stanza comp stanza)))))
(defclass xmpp-sink (cxml:broadcast-handler)
((sink-open
:initform t
:accessor sink-open)))
(defmethod sax:start-document ((s xmpp-sink))
(declare (ignore s))
(format *debug-io* "~&XMPP <-- "))
(defmethod sax:end-element ((s xmpp-sink) namespace-uri local-name qname)
(if (and (sink-open s) (equal local-name "stream"))
;; The <stream:stream> element gets opened at the start of the connection
;; and closing it represents ending the connection. We therefore don't
;; want to close it...
;; Instead, send some empty characters to get the sinks to write the last ">"
;; bit of the opening tag.
(sax:characters s "")
(call-next-method s namespace-uri local-name qname))
(terpri *debug-io*))
(defun close-xmpp-component (comp)
(bt:with-recursive-lock-held ((component-socket-lock comp))
(setf (sink-open (component-sink comp)) nil)
(write-sequence (babel:string-to-octets "</stream:stream>"
:encoding :utf-8)
(component-socket comp))
(force-output (component-socket comp))
(close (component-socket comp))))
(defun make-xmpp-sink (socket)
(let ((ret (cxml:make-broadcast-handler
(cxml:make-character-stream-sink *debug-io*)
(cxml:make-octet-stream-sink socket))))
(change-class ret 'xmpp-sink)
ret))
(defmacro with-dom-xml-output (&body body)
`(cxml:with-xml-output (cxml-dom:make-dom-builder)
,@body))
(defun component-listen-thread (comp)
"Listening thread for an XMPP component: constantly reads from the socket and emits new stanzas."
(format *debug-io* "Starting component listening thread~%")
;; ### Story time! ###
;; So I spent an hour debugging why this wasn't working.
;; And, long story short, if you just call CXML:PARSE with a stream
;; it gets converted into an 'xstream' inside CXML, which has a :SPEED
;; property. This :SPEED property controls how many bytes it tries to buffer
;; before actually doing the parsing and the goddamn default is 8192 (!!).
;; This obviously ain't gonna fly for our TCP socket, because the initial stream
;; start element is less than 8192 bytes. So we make our own stupid xstream
;; and specify the speed manually, and then it works.
;;
;; Wouldn't it be nice if people documented this sort of thing?
(let ((source (make-xmpp-source comp))
(fucking-stream (cxml:make-xstream (component-socket comp)
:speed 1 ; FFFFFFFFUUUUUUUU
:initial-speed 1)))
(cxml:parse fucking-stream source
:recode t)))
(defmacro with-component-xml-output (comp &rest body)
`(with-accessors ((lock component-socket-lock) (socket component-socket) (sink component-sink))
,comp
(bt:with-recursive-lock-held (lock)
(cxml:with-xml-output sink
,@body)
(force-output socket))))
(defun write-stream-header (comp)
(with-component-data-lock comp
(with-component-xml-output comp
(cxml:with-namespace ("stream" "http://etherx.jabber.org/streams")
(cxml:with-element "stream:stream"
(cxml:attribute "xmlns" +component-ns+)
(cxml:attribute "to" (component-name comp)))))))
(defun component-stream-started (comp)
(with-component-data-lock comp
(with-component-xml-output comp
(cxml:with-element "handshake"
(cxml:attribute "xmlns" +component-ns+)
(cxml:text (string-downcase (sha1:sha1-hex (concatenate 'string (component-stream-id comp) (component-shared-secret comp)))))))))
(defun handle-stream-error (comp stanza)
(flet ((is-error-node (node)
(equal (dom:namespace-uri node) +streams-ns+))
(is-text-node (node)
(equal (dom:tag-name node) "text")))
(let* ((children (dom:child-nodes stanza))
(error-node (find-if #'is-error-node children))
(error-text-node (find-if #'is-text-node children))
(error-name (dom:tag-name error-node))
(error-text (when error-text-node
(dom:node-value (elt (dom:child-nodes error-text-node) 0)))))
(warn "Stream error of type ~A encountered: ~A" error-name error-text)
(emit :stream-error comp error-name error-text stanza))))
(defun handle-connection-complete (comp)
(declare (ignore comp))
(format *debug-io* "Connection complete! \o/"))
(defun component-stanza (comp stanza)
(setf *last-stanza* stanza)
(let* ((stanza (dom:document-element stanza))
(tag-name (dom:tag-name stanza)))
(cond
((equal tag-name "stream:error") (handle-stream-error comp stanza))
((equal tag-name "handshake") (handle-connection-complete comp))
(t (emit :stanza comp stanza)))))
(defun make-component (server port shared-secret name)
"Make a new XMPP component, connecting to SERVER on PORT with SHARED-SECRET."
(let* ((socket (socket-stream
(socket-connect server port
:element-type '(unsigned-byte 8))))
(component (make-instance 'xmpp-component
:socket socket
:sink (make-xmpp-sink socket)
:name name
:shared-secret shared-secret)))
(bt:make-thread (lambda ()
(component-listen-thread component))
:name "XMPP component listen thread")
(on :stream-started component (lambda ()
(component-stream-started component)))
(on :raw-stanza component (lambda (stanza)
(component-stanza component stanza)))
(write-stream-header component)
component))