request-response.lisp

(in-package :wookie)

(define-condition response-error (wookie-error)
  ((response :initarg :response :reader response-error-response :initform nil))
  (:report (lambda (c s) (format s "Response error: ~a" (response-error-response c))))
  (:documentation "Describes a response error"))

(define-condition response-already-sent (response-error) ()
  (:report (lambda (c s) (format s "Response already sent: ~a" (response-error-response c))))
  (:documentation "Triggered when a response is attempted more than once."))

(defclass request ()
  ((socket :accessor request-socket :initarg :socket :initform nil)
   (method :accessor request-method :initarg :method :initform :get)
   (resource :accessor request-resource :initarg :resource :initform "/")
   (headers :accessor request-headers :initarg :headers :initform nil)
   (uri :accessor request-uri :initarg :url :initform nil)
   (data :accessor request-data :initarg :data :initform nil)
   (plugin-data :accessor request-plugin-data :initarg :plugin-data :initform nil)
   (body-callback :accessor request-body-callback :initarg :body-callback :initform nil)
   (http :accessor request-http :initarg :http :initform nil)
   (error-handlers :accessor request-error-handlers :initarg :error-handlers :initform nil)
   (error-precedence :accessor request-error-precedence :initarg :error-precedence :initform nil))
  (:documentation "A class describing a request, passed to every route."))

(defclass response ()
  ((headers :accessor response-headers :initarg :headers :initform nil)
   (request :accessor response-request :initarg :request :initform nil)
   (finishedp :accessor response-finished-p :initarg :finishedp :initform nil)
   (chunk-stream :accessor response-chunk-stream :initarg :chunk-stream :initform nil))
  (:documentation "A class holding information about a response to the client."))

(defgeneric get-socket (request/response)
  (:documentation
    "Grabs the current socket for the request/response given."))

(defmethod get-socket ((request request))
  (request-socket request))

(defmethod get-socket ((response response))
  (get-socket (response-request response)))

(defmacro with-chunking (request (chunk-data last-chunk-p) &body body)
  "Set up a listener for chunked data in a chunk-enabled router. This macro
   takes a request object, the names of the chunk-data/finishedp arguments
   for the body, and the body form.

   Chunk-data is a byte-array of data received as decoded chunked data comes in
   from the client, and last-chunk-p is a boolean indicating whether the last
   chunk from the request is being sent in."
  `(setf (request-body-callback ,request)
         (lambda (,chunk-data ,last-chunk-p)
           (wlog :debug "(chunk) Got chunk (~a) ~a~%"
                             ,last-chunk-p
                             (babel:octets-to-string ,chunk-data))
           ,@body)))

(defun add-default-headers (headers)
  "Add a number of default headers to a headers plist. If one of the default
   headers is already present, do NOT overwrite it. This allows the app to set
   its own headers that can override the defaults."
  (flet ((prepend-header-if-not-exists (key val)
           (unless (getf headers key)
             (setf headers (append (list key val) headers)))))
    (prepend-header-if-not-exists :date
                                  (local-time:format-timestring
                                    nil
                                    (local-time:now)
                                    :format local-time:+rfc-1123-format+))
    (prepend-header-if-not-exists :server
                                  (if *hide-version*
                                      "Wookie"
                                      (format nil "Wookie (~a)"
                                              (asdf:component-version
                                                (asdf:find-system :wookie))))))
  headers)

(defun send-response (response &key (status 200) headers body (close nil close-specified-p))
  "Send a response to an incoming request. Takes :status, :headers, and :body
   keyword arguments, which together form an entire response.

   If :close is T, close the client connection after the response has been
   sent fully. However, send-response does its best to read the request headers
   and determine whether or not the connection should be closed. Unless you have
   a reason to specify :close, it may be best to leave it blank."
  (wlog :debug "(response) Send response ~a (status ~a) (close ~a) (headers ~s) (body-length ~a)~%"
                    response status close
                    headers (length body))
  ;; make sure we haven't already responded to this request
  (when (response-finished-p response)
    (error (make-instance 'response-already-sent :response response)))

  (let* ((request (response-request response))
         (socket (request-socket request)))

    (when (as:socket-closed-p socket)
      (error 'as:socket-closed
             :code -1
             :msg "Trying to operate on a closed socket"
             :socket socket))
  
    ;; run the response hooks
    (do-run-hooks (socket) (run-hooks :response-started response request status headers body)
      (let* ((headers (append (response-headers response) headers))
             (body-enc (when body (babel:string-to-octets body :encoding :utf-8)))
             (headers (if (and body (not (getf headers :content-length)))
                          (append headers (list :content-length (length body-enc)))
                          headers))
             (status-text (lookup-status-text status)))
        ;; make writing a single HTTP line a bit less painful
        (flet ((write-http-line (format-str &rest format-args)
                 (as:write-socket-data
                   socket
                   (apply #'format
                          (append (list nil
                                        (concatenate 'string format-str "~c~c"))
                                  (append format-args (list #\return #\newline)))))))
          ;; write the status line
          (write-http-line "HTTP/1.1 ~a ~a" status status-text)
          (setf headers (add-default-headers headers))
          ;; write all the headers
          (map-plist headers
                     (lambda (header value)
                       (let ((header-name (camel-case header)))
                         (if (listp value)
                             (dolist (val value)
                               (write-http-line "~a: ~a" header-name val))
                             (write-http-line "~a: ~a" header-name value)))))
          ;; finalize headers (closing \r\n)
          (write-http-line "")
          ;; send body if specified
          (when body
            (as:write-socket-data socket body-enc)))

        ;; auto-select the best close method, but only if close wasn't specified
        (unless close-specified-p
          (let ((request-headers (request-headers request)))
            (cond
              ;; we're chunking, so don't close yet
              ((string= (getf request-headers :transfer-encoding) "chunked")
               (setf close nil))
              ;; we got Connection: keep-alive. so, keep-alive...
              ((string= (getf request-headers :connection) "keep-alive")
               (setf close nil))
              ;; we got a Connection: close and we're not chunking. close.
              ((string= (getf request-headers :connection) "close")
               (setf close t)))))

        ;; if we speficied we want to close, do it now
        (if close
            ;; close the socket once it's done writing
            (as:write-socket-data socket (as:bytes nil)
              :write-cb (lambda (socket)
                          (wlog :debug "(response) Close socket ~a~%" response)
                          (setf (as:socket-data socket) nil)
                          (as:close-socket socket)))
            ;; we sent a response, but aren't closing. reset the parser so that if
            ;; another request comes in on the same socket, WE'LL BE READY!!!!11one
            (progn
              (wlog :debug "(response) Reset parser: ~a~%" response)
              (setup-parser socket)))

        ;; mark the response as having been sent
        (setf (response-finished-p response) t)
        response))))

(defun start-response (response &key (status 200) headers)
  "Start a response to the client, but do not specify body content (or close the
   connection). Return a chunked (chunga) stream that can be used to send the
   body content bit by bit until finished by calling finish-response."
  (wlog :debug "(response) Start chunked response ~a (status ~a) (headers ~s)~%"
                    response status headers)
  ;; we need to add in our own transfer header, so remove all others
  (dolist (head-list (list headers (response-headers response)))
    (remf head-list :content-length)
    (remf head-list :transfer-encoding))
  (send-response response
                 :status status
                 :headers (append headers
                                  (list :transfer-encoding "chunked"))
                 :close nil)
  (let* ((request (response-request response))
         (async-stream (make-instance 'as:async-io-stream :socket (request-socket request)))
         (chunked-stream (chunga:make-chunked-stream async-stream)))
    (setf (chunga:chunked-stream-output-chunking-p chunked-stream) t
          (response-chunk-stream response) chunked-stream)
    chunked-stream))

(defun finish-response (response &key (close nil close-specified-p))
  "Given the stream passed back from start-response, finalize the response (send
   empty chunk) and close the connection, if specified."
  (wlog :debug "(response) Finish response (close ~a)~%" close)
  (let* ((chunked-stream (response-chunk-stream response))
         (request (response-request response))
         (socket (request-socket request)))
    ;; make sure the stream writes its final data
    (force-output chunked-stream)
    ;; auto-select the best close method, but only if close wasn't specified
    (unless close-specified-p
      (let ((request-headers (request-headers request)))
        (cond
          ;; we got Connection: keep-alive. so, keep-alive...
          ((string= (getf request-headers :connection) "keep-alive")
           (setf close nil))
          ;; we got a Connection: close so let's oblige the client
          ((string= (getf request-headers :connection) "close")
           (setf close t)))))

    ;; write empty chunk
    (as:write-socket-data socket (as:bytes #(48 13 10 13 10))   ; "0\r\n\r\n"
      :write-cb (lambda (socket)
                  (when close
                    (wlog :debug "(response) Finish, close socket~%")
                    (setf (as:socket-data socket) nil)
                    (as:close-socket socket)))))
  response)