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init: split out some of whatsxmpp's component code

- whatsxmpp contains a bunch of code that's useful for building XMPP
  components in general. Why not factor this out into something more
- Eventually, we'll make whatsxmpp depend on this library...
eta 2 years ago
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.gitignore vendored

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(in-package :sxcl)
(defvar *xmpp-debug-io* (make-broadcast-stream))
(defvar *xmpp-debug-out* (make-synonym-stream '*xmpp-debug-io*))
(defclass xmpp-component (event-emitter)
:initarg :socket
:accessor component-socket)
:initform (bt:make-recursive-lock "component socket lock")
:accessor component-socket-lock)
:initform (bt:make-recursive-lock "component data lock")
:accessor component-data-lock)
:initarg :sink
:accessor component-sink)
:initarg :name
:reader component-name)
:initform nil
:accessor component-stream-id)
:initarg :shared-secret
:reader component-shared-secret)
:initform (make-hash-table)
:accessor component-handlers)
:initform (make-hash-table :test 'equal)
:accessor component-promises)))
(defmacro with-component-data-lock ((comp) &body body)
`(bt:with-recursive-lock-held ((component-data-lock ,comp))
(defclass xmpp-source (cxml:broadcast-handler)
:initarg :component
:accessor source-component)
:initform 0
:accessor source-depth)))
(defun make-xmpp-source (comp)
(let ((ret (cxml:make-broadcast-handler)))
(change-class ret 'xmpp-source
:component comp)
(defmethod sax:start-document ((s xmpp-source))
(declare (ignore s))
(format *xmpp-debug-out* "~&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 *xmpp-debug-out* "~&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 *xmpp-debug-out* "~&XMPP --> ")
(setf handlers (list (cxml:make-character-stream-sink *xmpp-debug-out*) 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 *xmpp-debug-out*)
(setf handlers nil)
(emit :raw-stanza comp stanza)))))
(defclass xmpp-sink (cxml:broadcast-handler)
:initform t
:accessor sink-open)))
(defmethod sax:start-document ((s xmpp-sink))
(declare (ignore s))
(format *xmpp-debug-out* "~&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 *xmpp-debug-out*))
(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 *xmpp-debug-out*)
(cxml:make-octet-stream-sink socket))))
(change-class ret 'xmpp-sink)
(defmacro with-dom-xml-output (&body body)
`(cxml:with-xml-output (cxml-dom:make-dom-builder)
(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?
;; ### Part II: The Fucking Stream Strikes Back ###
;; ...and, after another hour of debugging, I found out you have to specify the `name'
;; arg, otherwise it breaks -- but ONLY randomly and once you decide to deploy it
;; in production, of course.
(let ((source (make-xmpp-source comp))
(fucking-stream (cxml:make-xstream (component-socket comp)
:name (cxml::make-stream-name ; AAAARGH
:entity-name "main document"
:entity-kind :main
:uri nil)
:name "XMPP server stream"
:initial-speed 1)))
(cxml:parse fucking-stream source
:recode t)))
(defmacro with-component-xml-output ((comp) &body body)
(let ((ret-sym (gensym)))
`(with-accessors ((lock component-socket-lock) (socket component-socket) (sink component-sink))
(with-component-data-lock (,comp)
(bt:with-recursive-lock-held (lock)
(let ((,ret-sym nil))
(cxml:with-xml-output sink
(setf ,ret-sym ,@body))
(force-output socket)
(defun write-stream-header (comp)
(with-component-xml-output (comp)
(cxml:with-namespace ("stream" "")
(cxml:with-element "stream:stream"
(cxml:attribute "xmlns" +component-ns+)
(cxml:attribute "to" (component-name comp))))))
(defun component-stream-started (comp)
(with-component-xml-output (comp)
(cxml:with-element "handshake"
(cxml:attribute "xmlns" +component-ns+)
(cxml:text (string-downcase (sha1-hex (concatenate 'string (component-stream-id comp) (component-shared-secret comp))))))))
(defun register-component-iq-handler (comp handler-name func)
"Register FUNC to be called for the HANDLER-NAME IQ handler on COMP."
(with-component-data-lock (comp)
(setf (gethash handler-name (component-handlers comp)) func)))
(defun call-component-iq-handler (comp handler &rest args)
"Calls the IQ handler identified by the symbol HANDLER on COMP, with the provided ARGS."
(destructuring-bind (&key id to from &allow-other-keys) args
(with-component-data-lock (comp)
(let ((func (gethash handler (component-handlers comp))))
(unless func
(error 'stanza-error
:defined-condition "feature-not-implemented"
:text (format nil "No handler for ~A registered" handler)
:type "cancel"))
(let ((result (apply func comp args)))
(lambda (result-forms)
(eval `(with-component-xml-output (,comp)
(cxml:with-element "iq"
(cxml:attribute "type" "result")
(cxml:attribute "id" ,id)
(cxml:attribute "from" ,to)
(cxml:attribute "to" ,from)
(stanza-error (e)
(send-stanza-error comp
:stanza-type "iq"
:id id :to from :from to :e e))
(t (e)
(send-stanza-error comp
:stanza-type "iq"
:id id
:to from
:from to
:e (make-condition 'stanza-error
:defined-condition "internal-server-error"
:text (format nil "~A" e)
:type "cancel"))
(warn "IQ handler for ~A failed: ~A" handler e))))))
(defun handle-iq-get (comp id from stanza)
"Handles an IQ-get STANZA for component COMP."
(let* ((children (child-elements stanza))
(first-child (if (> (length children) 0)
(elt children 0)
(return-from handle-iq-get)))
(tag-name (dom:tag-name first-child))
(to (dom:get-attribute stanza "to"))
(xmlns (dom:get-attribute first-child "xmlns"))
((and (equal xmlns +disco-info-ns+) (equal tag-name "query"))
((and (equal xmlns +disco-items-ns+) (equal tag-name "query"))
((and (equal xmlns +vcard-temp-ns+) (equal tag-name "vCard"))
(call-component-iq-handler comp handler-type
:to to
:id id
:from from
:stanza stanza)))
(defun handle-iq-response (comp stanza)
"Handles an IQ response STANZA for component COMP."
(with-component-data-lock (comp)
(let ((type (dom:get-attribute stanza "type"))
(id (dom:get-attribute stanza "id"))
(from (dom:get-attribute stanza "from")))
(if (equal type "get")
(handle-iq-get comp id from stanza)
((promise (gethash id (component-promises comp))))
(if promise
(format t "~&IQ ~A from ~A for ~A~%" type from id)
((equal type "result") (finish promise (child-elements stanza)))
((equal type "error") (signal-error promise (extract-stanza-error stanza)))
(t (warn "Invalid IQ stanza type: ~A" type)))
(setf promise nil))
(warn "Unsolicited IQ stanza from ~A of type ~A, ID ~A" from type id)))))))
(defun handle-presence (comp stanza)
"Handles a presence STANZA for component COMP."
(let* ((type (dom:get-attribute stanza "type"))
(from (dom:get-attribute stanza "from"))
(to (dom:get-attribute stanza "to"))
((equal type "subscribe") :presence-subscribe)
((equal type "probe") :presence-probe)
((equal type "unavailable") :presence-unavailable)
(t :presence))))
(emit event-name comp :from from :to to :type type :stanza stanza)))
(defun handle-message (comp stanza)
"Handles a message STANZA for component COMP."
(let* ((from (dom:get-attribute stanza "from"))
(to (dom:get-attribute stanza "to"))
(id (dom:get-attribute stanza "id"))
(children (child-elements stanza))
(body (get-node-named children "body"))
(marker (get-node-with-xmlns children +chat-markers-ns+))
(chat-state (get-node-with-xmlns children +chat-states-ns+)))
(let* ((child-nodes (dom:child-nodes body))
(text (if (> (length child-nodes) 0)
(dom:node-value (elt child-nodes 0))
(emit :text-message comp :from from :to to :body text :id id :stanza stanza)))
(let ((marker-type (dom:tag-name marker))
(msgid (dom:get-attribute marker "id")))
(emit :message-marker comp :from from :to to :type marker-type :marker-id msgid :id id :stanza stanza)))
(let ((state-type (dom:tag-name chat-state)))
(emit :chat-state comp :from from :to to :type state-type :id id :stanza stanza)))
(emit :message comp :from from :to to :id id :stanza stanza)))))
(defun handle-connection-complete (comp)
(format *debug-io* "Connection complete! \\o/")
(emit :connected comp))
(defun component-stanza (comp stanza)
"Handles a STANZA received by component COMP."
(let* ((stanza (dom:document-element stanza))
(tag-name (dom:tag-name stanza)))
((equal tag-name "stream:error") (handle-stream-error comp stanza))
((equal tag-name "handshake") (handle-connection-complete comp))
((equal tag-name "iq") (handle-iq-response comp stanza))
((equal tag-name "presence") (handle-presence comp stanza))
((equal tag-name "message") (handle-message comp stanza))
(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)


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(in-package :sxcl)
(defparameter +streams-ns+ "urn:ietf:params:xml:ns:xmpp-streams")
(defparameter +stanzas-ns+ "urn:ietf:params:xml:ns:xmpp-stanzas")
(defparameter +component-ns+ "jabber:component:accept")
(defparameter +disco-info-ns+ "")
(defparameter +disco-items-ns+ "")
(defparameter +muc-ns+ "")
(defparameter +file-upload-ns+ "urn:xmpp:http:upload:0")
(defparameter +oob-ns+ "jabber:x:oob")
(defparameter +chat-markers-ns+ "urn:xmpp:chat-markers:0")
(defparameter +delivery-delay-ns+ "urn:xmpp:delay")
(defparameter +vcard-temp-ns+ "vcard-temp")
(defparameter +vcard-avatar-ns+ "vcard-temp:x:update")
(defparameter +nick-ns+ "")
(defparameter +roster-exchange-ns+ "")
(defparameter +delivery-receipts-ns+ "urn:xmpp:receipts")
(defparameter +muc-invite-ns+ "jabber:x:conference")
(defparameter +muc-stable-id-ns+ "")
(defparameter +muc-user-ns+ "")
(defparameter +unique-stanzas-ns+ "urn:xmpp:sid:0")
(defparameter +chat-states-ns+ "")
(defparameter +hints-ns+ "urn:xmpp:hints")
(defparameter +entity-caps-ns+ "")


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(defpackage :sxcl
(:use :cl :event-emitter :blackbird :blackbird-base :usocket))


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(defsystem "sxcl"
:depends-on ("bordeaux-threads" "event-emitter" "blackbird" "cxml" "sha1" "uuid" "babel" "qbase64" "usocket")
:serial t
((:file "packages")
(:file "utils")
(:file "namespaces")
(:file "component")
(:file "xmpp")
(:file "xep-0030")
(:file "xep-0363")
(:file "xep-0115")))


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(in-package :sxcl)
(defun octets-to-lowercase-hex (buf)
"Formats BUF, a vector of octets, as a lowercase hex string and returns it."
(declare (type (vector (unsigned-byte 8)) buf))
(format nil "~(~{~2,'0X~}~)" (coerce buf 'list)))
(defun sha1-octets (buf)
"Returns the SHA1 of BUF, a vector of octets, in lowercase hex."
(octets-to-lowercase-hex (coerce (sha1:sha1-digest buf) '(vector (unsigned-byte 8)))))
(defun sha1-hex (str)
"Returns the SHA1 of STR, a string, in lowercase hex."
(sha1-octets (babel:string-to-octets str)))
(defun child-elements (node)
"Returns the child elements (excluding text nodes) of the CXML DOM node NODE."
(remove-if-not #'dom:element-p (dom:child-nodes node)))
(defmacro with-promise-from-thread (() &body forms)
"Return a promise that executes FORMS in a new thread, resolving the promise with the return value of (PROGN ,@FORMS) or rejecting it if an ERROR condition is thrown (with said condition)."
(let ((resolve (gensym))
(reject (gensym)))
`(with-promise (,resolve ,reject)
(lambda ()
(,resolve (progn ,@forms))
(error (e) (,reject e))))))))
(defun split-at (seq pos &optional (consume-value-at-pos-p t))
"Splits SEQ at POS, returning two values. If CONSUME-VALUE-AT-POS-P is truthy, throws away the element at POS."
(declare (type sequence seq) (type fixnum pos))
((> pos (length seq)) (error "Position is outside sequence."))
((eql pos (length seq)) (values seq nil))
(t (values (subseq seq 0 pos) (subseq seq (+ pos (if consume-value-at-pos-p 1 0)))))))


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(in-package :sxcl)
(defun get-disco-info (comp to &optional from)
"Send an XEP-0030 disco#info request. Returns a promise that resolves with a list of supported features."
(with-iq (comp to :from from)
(cxml:with-element "query"
(cxml:attribute "xmlns" +disco-info-ns+)))
(lambda (results)
(let ((query-node (get-node-named results "query"))
(features '()))
(unless query-node
(error "Malformed disco#info response: no <query/>"))
for node across (child-elements query-node)
do (let ((name (dom:tag-name node)))
(when (equal name "feature")
(setf features (cons (dom:get-attribute node "var") features)))))
(defun get-disco-items (comp to &optional from)
"Send an XEP-0030 disco#items request. Returns a promise that resolves with an alist, mapping JIDs to names."
(with-iq (comp to :from from)
(cxml:with-element "query"
(cxml:attribute "xmlns" +disco-items-ns+)))
(lambda (results)
(let ((query-node (get-node-named results "query"))
(items '()))
(unless query-node
(error "Malformed disco#items response: no <query/>"))
for node across (child-elements query-node)
do (let ((name (dom:tag-name node)))
(when (equal name "item")
(setf items (cons
(cons (dom:get-attribute node "jid") (dom:get-attribute node "name"))
(defmacro disco-identity (name type category)
`(cxml:with-element "identity"
,@(when name
`((cxml:attribute "name" ,name)))
(cxml:attribute "type" ,type)
(cxml:attribute "category" ,category)))
(defmacro disco-feature (feature)
`(cxml:with-element "feature"
(cxml:attribute "var" ,feature)))


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;;;; XEP-0115: Entity Capabilities
(in-package :sxcl)
(defun format-disco-identity (name type category &optional (lang ""))
"Formats a disco#info identity into a verification string part."
(format nil "~A/~A/~A/~A" category type lang name))
(defun generate-entity-caps (disco-info-list)
"Using DISCO-INFO-LIST, a quoted list of calls to DISCO-IDENTITY and DISCO-FEATURE, generate and return an XEP-0115 verification string.
WARNING: You must pre-sort DISCO-INFO-LIST according to the rules in XEP-0115 § 5.1."
(let (identities features)
for call in disco-info-list
do (ecase (car call)
(disco-identity (push (cdr call) identities))
(disco-feature (push (cdr call) features))))
(ironclad:digest-sequence :sha1
(format nil "~{~A<~}~{~A<~}"
(mapcar (lambda (call)
;; intentionally take the same lambda lists,
;; we can just do this.
(apply #'format-disco-identity call))
;; NREVERSE because pushing things does it the wrong
;; way round (FIXME, inefficient)
(nreverse identities))
;; DISCO-FEATURE takes one argument (the feature name)
(mapcar #'car (nreverse features))))))))


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(in-package :sxcl)
(defun request-http-upload-slot (comp service-jid filename size mime-type)
"Requests an XEP-0363 HTTP Upload slot from the service at SERVICE-JID, aiming to upload the file with FILENAME, SIZE (in bytes) and MIME-TYPE. Returns a promise that resolves with a list of the form ((PUT-URL . ((HEADER-NAME . HEADER-VALUE) ...)) GET-URL)."
(declare (type xmpp-component comp) (type string service-jid filename mime-type) (type integer size))
(with-iq (comp service-jid)
(cxml:with-element "request"
(cxml:attribute "xmlns" +file-upload-ns+)
(cxml:attribute "filename" filename)
(cxml:attribute "size" (write-to-string size))
(cxml:attribute "content-type" mime-type)))
(lambda (results)
(let ((slot-node (get-node-named results "slot")))
(unless slot-node
(error "Malformed XEP-0363 response: no <slot/>"))
(let* ((children (child-elements slot-node))
(put-node (get-node-named children "put"))
(get-node (get-node-named children "get"))
(headers '()))
(unless (and put-node get-node)
(error "Malformed XEP-0363 response: PUT or GET nodes missing"))
for node across (child-elements put-node)
do (let ((name (dom:tag-name node)))
(when (equal name "header")
(setf headers (cons
(cons (dom:get-attribute node "name")
(dom:node-value (elt (child-elements node) 0)))
`((,(dom:get-attribute put-node "url") . ,headers) ,(dom:get-attribute get-node "url")))))))


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(in-package :sxcl)
(defun make-message-uuid (comp)
(with-accessors ((promises component-promises)) comp
(let ((uuid (string-downcase (write-to-string (uuid:make-v4-uuid))))
(promise (make-promise)))
(setf (gethash uuid promises) promise)
(values uuid promise))))
(defmacro with-stanza ((comp stanza-name &key type from to id) &body body)
(alexandria:with-gensyms (uuid ret from-sym id-sym)
`(with-component-xml-output (,comp)
(let ((,from-sym (or ,from (component-name ,comp)))
(,id-sym ,id))
(multiple-value-bind (,uuid ,ret)
(if ,id-sym
(values ,id-sym ,id-sym)
(make-message-uuid ,comp))
(cxml:with-element ,stanza-name
(cxml:attribute "from" ,from-sym)
(cxml:attribute "id" ,uuid)
,(when to
`(cxml:attribute "to" ,to))
,(when type
`(cxml:attribute "type" ,type))
(defmacro with-iq ((comp to &key (type "get") from id) &body body)
"Send an IQ stanza (of type TYPE) on the COMP component, from the JID FROM (default: component name) to the JID TO, with BODY specifying further CXML commands to make up the body of the stanza. Returns a promise."
`(with-stanza (,comp "iq"
:type ,type
:to ,to
:from ,from
:id ,id)
(defmacro with-message ((comp to &key (type "chat") from id) &body body)
"Send a message stanza (of type TYPE) on the COMP component. Semantics the same as WITH-IQ, except for the fact that message stanzas don't normally prompt a response."
`(with-stanza (,comp "message"
:type ,type
:to ,to
:from ,from
:id ,id)
(defmacro with-presence ((comp to &key type from id) &body body)
"Send a presence stanza (of type TYPE) on the COMP component. Semantics the same as WITH-IQ, except for the fact that presence stanzas don't normally prompt a response."
`(with-stanza (,comp "presence"
:type ,type
:to ,to
:from ,from
:id ,id)
(defun get-node-named (nodes name)
"Finds the node with tag name NAME in NODES, returning NIL if none was found."
(flet ((is-the-node (node) (and (dom:element-p node) (equal (dom:tag-name node) name))))
(find-if #'is-the-node nodes)))
(defun get-node-with-xmlns (nodes xmlns)
"Finds the node with XML namespace XMLNS in NODES, returning NIL if none was found."
(flet ((is-the-node (node) (and (dom:element-p node) (equal (dom:get-attribute node "xmlns") xmlns))))
(find-if #'is-the-node nodes)))
(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 (child-elements 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))))
(define-condition stanza-error (error)
:initarg :defined-condition
:accessor stanza-error-condition)
:initarg :type
:accessor stanza-error-type)
:initarg :text
:initform nil
:accessor stanza-error-text)
:initarg :raw
:initform nil
:accessor stanza-error-raw))
(:report (lambda (err stream)
(with-slots (defined-condition type text) err
(format stream "~A (type ~A): ~A" defined-condition type text)))))
(defun extract-stanza-error (stanza)
"Extracts a STANZA-ERROR from the given STANZA, which must contain an <error/> element conforming to RFC 6120 § 8.3."
(flet ((is-error-condition-node (node)
(equal (dom:namespace-uri node) +stanzas-ns+))
(is-error-node (node)
(equal (dom:tag-name node) "error"))
(is-text-node (node)
(and (equal (dom:namespace-uri node) +stanzas-ns+) (equal (dom:tag-name node) "text"))))
(let* ((error-node (find-if #'is-error-node (child-elements stanza)))
(error-children (child-elements error-node))
(type (dom:get-attribute error-node "type"))
(condition-node (find-if #'is-error-condition-node error-children))
(condition-name (dom:tag-name condition-node))
(text-node (find-if #'is-text-node error-children))
(text (when text-node
(dom:node-value (elt (dom:child-nodes text-node) 0)))))
(make-condition 'stanza-error
:raw error-node
:defined-condition condition-name
:type type
:text text))))
(defun send-stanza-error (comp &key id to from e stanza-type)
"Send E (a STANZA-ERROR) as an error response to a stanza of type STANZA."
(with-component-xml-output (comp)
(cxml:with-element stanza-type
(cxml:attribute "type" "error")
(cxml:attribute "id" id)
(cxml:attribute "from" from)
(cxml:attribute "to" to)
(cxml:with-element "error"
(cxml:attribute "type" (stanza-error-type e))
(cxml:with-element (stanza-error-condition e)
(cxml:attribute "xmlns" +stanzas-ns+))
(when (stanza-error-text e)
(cxml:with-element "text"
(cxml:text (stanza-error-text e))))))))
(defun parse-jid (jid)
"Parse JID, returning the multiple values HOSTNAME, LOCALPART and RESOURCE."
(declare (type string jid))
(let ((at-pos (position #\@ jid))
(slash-pos (position #\/ jid)))
((and (not slash-pos) (not at-pos))
(values jid nil nil))
((and slash-pos (not at-pos))
(multiple-value-bind (hostname resource)
(split-at jid slash-pos)
(values hostname nil resource)))
((and (not slash-pos) at-pos)
(multiple-value-bind (localpart hostname)
(split-at jid at-pos)
(values hostname localpart nil)))
(multiple-value-bind (rest resource)
(split-at jid slash-pos)
(multiple-value-bind (localpart hostname)
(split-at rest at-pos)
(values hostname localpart resource)))))))
(defun strip-resource (jid)
"Strips a resource from JID, if there is one, returning the bare JID."
(let ((slash-pos (position #\/ jid)))
(if slash-pos
(split-at jid slash-pos)