Mercurial > core / lisp/lib/net/proto/http.lisp

 ;;; lib/net/proto/http.lisp --- HTTP Support
 
 ;; based on https://github.com/fukamachi/fast-http
 
 ;; see also: https://github.com/orthecreedence/http-parse
 
 ;;; Commentary:
 
 ;; Fukamachi has implemented the current state-of-the-art HTTP libraries
 ;; (fast-http, dexador, etc). For the time being we'll be using these with
 ;; minimal changes. At some point in the future it would be ideal to
 ;; re-implement this in a sans-io style.
 
 ;;; Code:
 (in-package :net/proto/http)
 
 ;;; utils
 (defmacro casev (keyform &body clauses)
   (once-only (keyform)
     (flet ((get-val (val)
              (cond
                ((eq val 'otherwise) val)
                ((symbolp val) (symbol-value val))
                ((constantp val) val)
                (T (error "CASEV can be used only with variables or constants")))))
       `(case ,keyform
          ,@(loop for (val . clause) in clauses
                  if (eq val 'otherwise)
                    collect `(otherwise ,@clause)
                  else if (listp val)
                    collect `((,@(mapcar #'get-val val)) ,@clause)
                  else
                    collect `(,(get-val val) ,@clause))))))
 
 (defmacro casev= (keyform &body clauses)
   (once-only (keyform)
     (flet ((get-val (val)
              (cond
                ((eq val 'otherwise) val)
                ((symbolp val) (symbol-value val))
                ((constantp val) val)
                (T (error "CASEV can be used only with variables or constants")))))
       `(cond
          ,@(loop for (val . clause) in clauses
                  if (eq val 'otherwise)
                    collect `(T ,@clause)
                  else if (listp val)
                         collect `((or ,@(mapcar (lambda (val)
                                                   `(= ,keyform ,(get-val val)))
                                                 val))
                                   ,@clause)
                  else
                    collect `((= ,keyform ,(get-val val)) ,@clause))))))
 
 (defmacro case-byte (byte &body cases)
   `(casev= ,byte
      ,@(loop for (val . form) in cases
              if (eq val 'otherwise)
                collect `(,val ,@form)
              else if (listp val)
                collect `(,(mapcar #'char-code val) ,@form)
              else
                collect `(,(char-code val) ,@form))))
 
 (defmacro tagcase (keyform &body blocks)
   (let ((end (gensym "END")))
     `(tagbody
         (case ,keyform
           ,@(loop for (tag . body) in blocks
                   if (eq tag 'otherwise)
                     collect `(otherwise ,@body (go ,end))
                   else
                     collect `(,tag (go ,(if (listp tag) (car tag) tag)))))
         (go ,end)
         ,@(loop for (tag . body) in blocks
                 if (listp tag)
                   append tag
                 else
                   collect tag
                 collect `(progn ,@body
                                 (go ,end)))
       ,end)))
 
 (defmacro tagcasev (keyform &body blocks)
   (let ((end (gensym "END")))
     `(tagbody
         (casev ,keyform
           ,@(loop for (tag . body) in blocks
                   if (eq tag 'otherwise)
                     collect `(otherwise ,@body (go ,end))
                   else
                     collect `(,tag (go ,(if (listp tag) (car tag) tag)))))
         (go ,end)
         ,@(loop for (tag . body) in blocks
                 if (listp tag)
                   append tag
                 else if (not (eq tag 'otherwise))
                        collect tag
                 collect `(progn ,@body
                                 (go ,end)))
       ,end)))
 
 (defmacro tagcasev= (keyform &body blocks)
   (let ((end (gensym "END")))
     `(tagbody
         (casev= ,keyform
           ,@(loop for (tag . body) in blocks
                   if (eq tag 'otherwise)
                     collect `(otherwise ,@body (go ,end))
                   else
                     collect `(,tag (go ,(if (listp tag) (car tag) tag)))))
         (go ,end)
         ,@(loop for (tag . body) in blocks
                 if (listp tag)
                   append tag
                 else if (not (eq tag 'otherwise))
                        collect tag
                 collect `(progn ,@body
                                 (go ,end)))
       ,end)))
 
 (defun make-collector ()
   (let ((none '#:none))
     (declare (dynamic-extent none))
     (with-collectors (buffer)
       (return-from make-collector
         (lambda (&optional (data none))
           (unless (eq data none)
             (buffer data))
           buffer)))))
 
 (declaim (inline %whitespacep))
 (defun %whitespacep (char)
   (declare (type character char)
            (optimize (speed 3) (safety 0)))
   (or (char= char #\Space)
       (char= char #\Tab)))
 
 (declaim (inline position-not-whitespace))
 (defun position-not-whitespace (string &key from-end)
   (declare (type #+ecl string #-ecl simple-string string)
            (optimize (speed 3) (safety 0)))
   (let* ((len (length string))
          (start (if from-end (1- len) 0))
          (end (if from-end 0 (1- len)))
          (step-fn (if from-end #'1- #'1+)))
     (declare (type integer len start end))
     (do ((i start (funcall step-fn i)))
         ((= i end) i)
       (declare (type integer i))
       (unless (%whitespacep (aref string i))
         (return-from position-not-whitespace i)))))
 
 (declaim (inline number-string-p))
 (defun number-string-p (string)
   (declare (type simple-string string)
            (optimize (speed 3) (safety 2)))
   ;; empty string
   (when (zerop (length string))
     (return-from number-string-p nil))
   (let ((end (position-not-whitespace string :from-end t))
         (dot-read-p nil))
     ;; spaces string
     (when (null end)
       (return-from number-string-p nil))
     (locally (declare (type integer end)
                       (optimize (safety 0)))
       (incf end)
       (do ((i (the integer (or (position-not-whitespace string) 0)) (1+ i)))
           ((= i end) T)
         (declare (type integer i))
         (let ((char (aref string i)))
           (declare (type character char))
           (cond
             ((alpha-char-p char)
              (return-from number-string-p nil))
             ((digit-char-p char))
             ((char= char #\.)
              (when dot-read-p
                (return-from number-string-p nil))
              (setq dot-read-p t))
             (T (return-from number-string-p nil))))))))
 
 ;;; fast-http
 (defun make-parser (http &key first-line-callback header-callback body-callback finish-callback (head-request nil))
   (declare (type http http))
   (let (callbacks
 
         (parse-fn (etypecase http
                     (http-request #'parse-request)
                     (http-response #'parse-response)))
 
         (headers nil)
 
         (header-value-buffer nil)
         parsing-header-field
         data-buffer
 
         header-complete-p
         completedp)
     (flet ((collect-prev-header-value ()
              (when header-value-buffer
                (let ((header-value
                        (locally (declare (optimize (speed 3) (safety 0)))
                          (coerce-to-string
                           (the (or octet-concatenated-xsubseqs octet-xsubseq) header-value-buffer)))))
 
                  (if (string= parsing-header-field "set-cookie")
                      (push header-value (gethash "set-cookie" headers))
                      (multiple-value-bind (previous-value existp)
                          (gethash (the simple-string parsing-header-field) headers)
                        (setf (gethash (the simple-string parsing-header-field) headers)
                              (if existp
                                  (if (simple-string-p previous-value)
                                      (concatenate 'string (the simple-string previous-value) ", " header-value)
                                      (format nil "~A, ~A" previous-value header-value))
                                  header-value))))))))
       (setq callbacks
             (make-callbacks
              :message-begin (lambda (http)
                               (declare (ignore http))
                               (setq headers (make-hash-table :test 'equal)
                                     header-complete-p nil
                                     completedp nil))
              :url (lambda (http data start end)
                     (declare (type simple-byte-vector data)
                              (type pointer start end))
                     (setf (http-resource http)
                           (ascii-octets-to-string data :start start :end end)))
              :status (lambda (http data start end)
                        (declare (type simple-byte-vector data)
                                 (type pointer start end))
                        (setf (http-status-text http)
                              (ascii-octets-to-string data :start start :end end)))
              :first-line (and first-line-callback
                               (lambda (http)
                                 (declare (ignore http))
                                 (funcall (the function first-line-callback))))
              :header-field (lambda (http data start end)
                              (declare (ignore http)
                                       (type simple-byte-vector data)
                                       (type pointer start end))
                              (collect-prev-header-value)
                              (setq header-value-buffer (make-concatenated-xsubseqs))
                              (setq parsing-header-field
                                    (ascii-octets-to-lower-string data :start start :end end)))
              :header-value (lambda (http data start end)
                              (declare (ignore http)
                                       (type simple-byte-vector data)
                                       (type pointer start end))
                              (xnconcf header-value-buffer
                                       (xsubseq (subseq (the octet-vector data) start end) 0)))
              :headers-complete (lambda (http)
                                  (collect-prev-header-value)
                                  (setq header-value-buffer nil)
                                  (when (gethash "set-cookie" headers)
                                    (setf (gethash "set-cookie" headers)
                                          (nreverse (gethash "set-cookie" headers))))
                                  (setf (http-headers http) headers)
                                  (when header-callback
                                    (funcall (the function header-callback) headers))
                                  (when (and (not (http-chunked-p http))
                                             (not (numberp (http-content-length http))))
                                    (setq completedp t))
                                  (setq header-complete-p t))
              :body (and body-callback
                         (lambda (http data start end)
                           (declare (ignore http)
                                    (type simple-byte-vector data)
                                    (type pointer start end))
                           (funcall (the function body-callback)
                                    data start end)))
              :message-complete (lambda (http)
                                  (declare (ignore http))
                                  (collect-prev-header-value)
                                  (when finish-callback
                                    (funcall (the function finish-callback)))
                                  (setq completedp t)))))
 
     (lambda (data &key (start 0) end)
       (declare (optimize (speed 3) (safety 2)))
       (cond
         ((eql data :eof)
          (setq completedp t)
          (when finish-callback
            (funcall (the function finish-callback))))
         (T
          (locally (declare (type simple-byte-vector data)
                            (type pointer start))
            (check-type end (or null pointer))
            (when data-buffer
              (setq data
                    (coerce 'list
                     (xnconc (xsubseq data-buffer 0)
                             (xsubseq (the simple-byte-vector data) start (or end (length data))))))
              (setq data-buffer nil
                    start 0
                    end nil))
            (setf (http-mark http) start)
            (handler-case
                (funcall parse-fn http callbacks (the simple-byte-vector data) :start start :end end :head-request head-request)
              (eof ()
                (setq data-buffer
                      (subseq data (http-mark http) (or end (length data)))))))))
       (values http header-complete-p completedp))))
 
 (defun find-boundary (content-type)
   (declare (type string content-type))
   (let ((parsing-boundary nil))
     (parse-header-value-parameters content-type
                                    :header-value-callback
                                    (lambda (data start end)
                                      (unless (string= data "multipart/form-data"
                                                       :start1 start :end1 end)
                                        (return-from find-boundary nil)))
                                    :header-parameter-key-callback
                                    (lambda (data start end)
                                      (when (string= data "boundary"
                                                     :start1 start :end1 end)
                                        (setq parsing-boundary t)))
                                    :header-parameter-value-callback
                                    (lambda (data start end)
                                      (when parsing-boundary
                                        (return-from find-boundary (subseq data start end)))))))
 
 ;;; byte-vector
 (defconstant +cr+ (char-code #\Return))
 (defconstant +lf+ (char-code #\Newline))
 (defconstant +space+ (char-code #\Space))
 (defconstant +tab+ (char-code #\Tab))
 (defconstant +page+ (char-code #\Page))
 (defconstant +dash+ #.(char-code #\-))
 
 (define-constant +crlf+
   (make-array 2 :element-type '(unsigned-byte 8)
                 :initial-contents (list +cr+ +lf+))
   :test 'equalp)
 
 (deftype simple-byte-vector (&optional (len '*))
   `(simple-array (unsigned-byte 8) (,len)))
 
 (declaim (inline digit-byte-char-p
                  digit-byte-char-to-integer
                  alpha-byte-char-p
                  alpha-byte-char-to-lower-char
                  alphanumeric-byte-char-p
                  mark-byte-char-p))
 
 (defun digit-byte-char-p (byte)
   (declare (type (unsigned-byte 8) byte)
            (optimize (speed 3) (safety 0)))
   (<= #.(char-code #\0) byte #.(char-code #\9)))
 
 (declaim (ftype (function ((unsigned-byte 8)) fixnum) digit-byte-char-to-integer))
 (defun digit-byte-char-to-integer (byte)
   (declare (type (unsigned-byte 8) byte)
            (optimize (speed 3) (safety 0)))
   (the fixnum (- byte #.(char-code #\0))))
 
 (defun alpha-byte-char-p (byte)
   (declare (type (unsigned-byte 8) byte)
            (optimize (speed 3) (safety 0)))
   (or (<= #.(char-code #\A) byte #.(char-code #\Z))
       (<= #.(char-code #\a) byte #.(char-code #\z))))
 
 (defun alpha-byte-char-to-lower-char (byte)
   (declare (type (unsigned-byte 8) byte)
            (optimize (speed 3) (safety 0)))
   (the character
        (cond
          ((<= #.(char-code #\A) byte #.(char-code #\Z))
           (code-char (+ byte #x20)))
          (T #+nil(<= #.(char-code #\a) byte #.(char-code #\z))
             (code-char byte)))))
 
 (defun alphanumeric-byte-char-p (byte)
   (declare (type (unsigned-byte 8) byte))
   (or (alpha-byte-char-p byte)
       (digit-byte-char-p byte)))
 
 (defun mark-byte-char-p (byte)
   (declare (type (unsigned-byte 8) byte)
            (optimize (speed 3) (safety 0)))
   (or (= byte #.(char-code #\-))
       (= byte #.(char-code #\_))
       (= byte #.(char-code #\.))
       (= byte #.(char-code #\!))
       (= byte #.(char-code #\~))
       (= byte #.(char-code #\*))
       (= byte #.(char-code #\'))
       (= byte #.(char-code #\())
       (= byte #.(char-code #\)))))
 
 (declaim (ftype (function ((unsigned-byte 8)) (unsigned-byte 8)) byte-to-ascii-lower)
          (inline byte-to-ascii-lower))
 (defun byte-to-ascii-lower (x)
   (declare (type (unsigned-byte 8) x)
            (optimize (speed 3) (safety 0)))
   (if (<= #.(char-code #\A) x #.(char-code #\Z))
       (- x #.(- (char-code #\A) (char-code #\a)))
       x))
 
 (declaim (inline ascii-octets-to-string))
 (defun ascii-octets-to-string (octets &key (start 0) (end (length octets)))
   (declare (type simple-byte-vector octets)
            (type (unsigned-byte 64) start end)
            (optimize (speed 3) (safety 0)))
   (let* ((len (the (unsigned-byte 64) (- end start)))
          (string (make-string len :element-type 'character)))
     (declare (type (unsigned-byte 64) len)
              (type simple-string string))
     (do ((i 0 (1+ i))
          (j start (1+ j)))
         ((= j end) string)
       (setf (aref string i)
             (code-char (aref octets j))))))
 
 (declaim (inline ascii-octets-to-lower-string))
 (defun ascii-octets-to-lower-string (octets &key (start 0) (end (length octets)))
   (declare (type simple-byte-vector octets)
            (type (unsigned-byte 64) start end)
            (optimize (speed 3) (safety 0)))
   (let* ((len (the (unsigned-byte 64) (- end start)))
          (string (make-string len :element-type 'character)))
     (declare (type (unsigned-byte 64) len)
              (type simple-string string))
     (do ((i 0 (1+ i))
          (j start (1+ j)))
         ((= j end) string)
       (setf (aref string i)
             (code-char (byte-to-ascii-lower (aref octets j)))))))
 
 (defun append-byte-vectors (vec1 vec2)
   (declare (type simple-byte-vector vec1 vec2)
            (optimize (speed 3) (safety 0)))
   (let* ((vec1-len (length vec1))
          (vec2-len (length vec2))
          (result (make-array (+ vec1-len vec2-len)
                              :element-type '(unsigned-byte 8))))
     (declare (type simple-byte-vector result))
     (replace result vec1 :start1 0)
     (replace result vec2 :start1 vec1-len)
     result))
 
 ;;; multipart-parser
 (defstruct (ll-multipart-parser (:constructor make-ll-multipart-parser
                                   (&key boundary
                                    &aux (header-parser
                                          (let ((parser (make-http)))
                                            (setf (http-state parser) +state-headers+)
                                            parser)))))
   (state 0 :type fixnum)
   (header-parser)
   boundary
   body-mark
   body-buffer
   boundary-mark
   boundary-buffer)
 
 #.`(eval-when (:compile-toplevel :load-toplevel :execute)
      ,@(loop for i from 0
              for state in '(parsing-delimiter-dash-start
                             parsing-delimiter-dash
                             parsing-delimiter
                             parsing-delimiter-end
                             parsing-delimiter-almost-done
                             parsing-delimiter-done
                             header-field-start
                             body-start
                             looking-for-delimiter
                             maybe-delimiter-start
                             maybe-delimiter-first-dash
                             maybe-delimiter-second-dash
                             body-almost-done
                             body-done)
              collect `(defconstant ,(format-symbol t "+~A+" state) ,i)))
 
 (defun http-multipart-parse (parser callbacks data &key (start 0) end)
   (declare (type simple-byte-vector data))
   (let* ((end (or end (length data)))
          (boundary (map '(simple-array (unsigned-byte 8) (*)) #'char-code (ll-multipart-parser-boundary parser)))
          (boundary-length (length boundary))
          (header-parser (ll-multipart-parser-header-parser parser)))
     (declare (type simple-byte-vector boundary))
     (when (= start end)
       (return-from http-multipart-parse start))
 
     (macrolet ((with-body-cb (callback &body body)
                  `(handler-case (when-let ((,callback (callbacks-body callbacks)))
                                   ,@body)
                     (error (e)
                       (error 'cb-body :error e))))
                (call-body-cb (&optional (end '(ll-multipart-parser-boundary-mark parser)))
                  (let ((g-end (gensym "END")))
                    `(with-body-cb callback
                       (when (ll-multipart-parser-body-buffer parser)
                         (funcall callback parser
                                  (ll-multipart-parser-body-buffer parser)
                                  0 (length (ll-multipart-parser-body-buffer parser)))
                         (setf (ll-multipart-parser-body-buffer parser) nil))
                       (when-let ((,g-end ,end))
                         (funcall callback parser data
                                  (ll-multipart-parser-body-mark parser)
                                  ,g-end)))))
                (flush-boundary-buffer ()
                  `(with-body-cb callback
                     (when (ll-multipart-parser-boundary-buffer parser)
                       (funcall callback parser
                                (ll-multipart-parser-boundary-buffer parser)
                                0 (length (ll-multipart-parser-boundary-buffer parser)))
                       (setf (ll-multipart-parser-boundary-buffer parser) nil)))))
       (let* ((p start)
              (byte (aref data p)))
         #+http-debug
         (log:debug (code-char byte))
         (tagbody
            (macrolet ((go-state (tag &optional (advance 1))
                           `(progn
                              ,(case advance
                                 (0 ())
                                 (1 '(incf p))
                                 (otherwise `(incf p ,advance)))
                              (setf (ll-multipart-parser-state parser) ,tag)
                              #+http-debug
                              (log:debug ,(princ-to-string tag))
                              ,@(and (not (eql advance 0))
                                     `((when (= p end)
                                         (go exit-loop))
                                       (setq byte (aref data p))
                                       #+http-debug
                                       (log:debug (code-char byte))))
                              (go ,tag))))
              (tagcasev (ll-multipart-parser-state parser)
                (+parsing-delimiter-dash-start+
                 (unless (= byte +dash+)
                   (go-state +header-field-start+ 0))
                 (go-state +parsing-delimiter-dash+))
 
                (+parsing-delimiter-dash+
                 (unless (= byte +dash+)
                   (error 'invalid-multipart-body))
                 (go-state +parsing-delimiter+))
 
                (+parsing-delimiter+
                 (let ((end2 (+ p boundary-length)))
                   (cond
                     ((ll-multipart-parser-boundary-buffer parser)
                      (when (< (+ end (length (ll-multipart-parser-boundary-buffer parser)) -3) end2)
                        (setf (ll-multipart-parser-boundary-buffer parser)
                              (concatenate 'simple-byte-vector
                                           (ll-multipart-parser-boundary-buffer parser)
                                           data))
                        (go exit-loop))
                      (let ((data2 (make-array boundary-length :element-type '(unsigned-byte 8)))
                            (boundary-buffer-length (length (ll-multipart-parser-boundary-buffer parser))))
                        (replace data2 (ll-multipart-parser-boundary-buffer parser)
                                 :start2 2)
                        (replace data2 data
                                 :start1 (- boundary-buffer-length 2))
                        (unless (search boundary data2)
                          ;; Still in the body
                          (when (ll-multipart-parser-body-mark parser)
                            (call-body-cb nil)
                            (flush-boundary-buffer)
                            (go-state +looking-for-delimiter+))
                          (error 'invalid-boundary))
                        (go-state +parsing-delimiter-end+ (- boundary-length boundary-buffer-length -2))))
                     ((< (1- end) end2)
                      ;; EOF
                      (setf (ll-multipart-parser-boundary-buffer parser)
                            (if (ll-multipart-parser-boundary-buffer parser)
                                (concatenate 'simple-byte-vector
                                             (ll-multipart-parser-boundary-buffer parser)
                                             (subseq data (max 0 (- p 2))))
                                (subseq data (max 0 (- p 2)))))
                      (go exit-loop))
                     (T
                      (unless (search boundary data :start2 p :end2 end2)
                        ;; Still in the body
                        (when (ll-multipart-parser-body-mark parser)
                          (go-state +looking-for-delimiter+))
                        (error 'invalid-boundary))
                      (go-state +parsing-delimiter-end+ boundary-length)))))
 
                (+parsing-delimiter-end+
                 (casev byte
                   (+cr+ (go-state +parsing-delimiter-almost-done+))
                   (+lf+ (go-state +parsing-delimiter-almost-done+ 0))
                   (+dash+ (go-state +body-almost-done+))
                   (otherwise
                    ;; Still in the body
                    (when (ll-multipart-parser-body-mark parser)
                      (call-body-cb nil)
                      (flush-boundary-buffer)
                      (go-state +looking-for-delimiter+))
                    (error 'invalid-boundary))))
 
                (+parsing-delimiter-almost-done+
                 (unless (= byte +lf+)
                   (error 'invalid-boundary))
                 (when (ll-multipart-parser-body-mark parser)
                   ;; got a part
                   (when (ll-multipart-parser-boundary-mark parser)
                     (call-body-cb))
                   (when-let ((callback (callbacks-message-complete callbacks)))
                     (handler-case (funcall callback parser)
                       (error (e)
                         (error 'cb-message-complete :error e)))))
                 (go-state +parsing-delimiter-done+))
 
                (+parsing-delimiter-done+
                 (when-let ((callback (callbacks-message-begin callbacks)))
                   (handler-case (funcall callback parser)
                     (error (e)
                       (error 'cb-message-begin :error e))))
                 (setf (ll-multipart-parser-body-mark parser) p)
                 (go-state +header-field-start+ 0))
 
                (+header-field-start+
                 (let ((next (parse-headers header-parser callbacks data p end)))
                   (setq p (1- next)) ;; XXX
                   ;; parsing headers done
                   (when (= (http-state header-parser) +state-body+)
                     (when-let ((callback (callbacks-headers-complete callbacks)))
                       (handler-case (funcall callback parser)
                         (error (e)
                           (error 'cb-headers-complete :error e))))
                     (setf (http-state header-parser) +state-headers+))
                   (go-state +body-start+ 0)))
 
                (+body-start+
                 (setf (ll-multipart-parser-body-mark parser) (1+ p))
                 (go-state +looking-for-delimiter+))
 
                (+looking-for-delimiter+
                 (setf (ll-multipart-parser-boundary-mark parser) nil)
                 (casev byte
                   (+cr+ (setf (ll-multipart-parser-boundary-mark parser) p)
                         (go-state +maybe-delimiter-start+))
                   (otherwise (go-state +looking-for-delimiter+))))
 
                (+maybe-delimiter-start+
                 (unless (= byte +lf+)
                   (go-state +looking-for-delimiter+ 0))
                 (go-state +maybe-delimiter-first-dash+))
 
                (+maybe-delimiter-first-dash+
                 (if (= byte +dash+)
                     (go-state +maybe-delimiter-second-dash+)
                     (if (= byte +cr+)
                         (progn
                           (setf (ll-multipart-parser-boundary-mark parser) p)
                           (go-state +maybe-delimiter-start+))
                         (go-state +looking-for-delimiter+))))
 
                (+maybe-delimiter-second-dash+
                 (if (= byte +dash+)
                     (go-state +parsing-delimiter+)
                     (go-state +looking-for-delimiter+)))
 
                (+body-almost-done+
                 (casev byte
                   (+dash+ (go-state +body-done+ 0))
                   (otherwise (error 'invalid-multipart-body))))
 
                (+body-done+
                 (when (ll-multipart-parser-body-mark parser)
                   ;; got a part
                   (setf (ll-multipart-parser-body-buffer parser) nil)
                   (call-body-cb)
                   (when-let ((callback (callbacks-message-complete callbacks)))
                     (handler-case (funcall callback parser)
                       (error (e)
                         (error 'cb-message-complete :error e))))
                   (setf (ll-multipart-parser-body-mark parser) nil))
                 (go exit-loop))))
          exit-loop)
         (when (ll-multipart-parser-body-mark parser)
           (when (<= +looking-for-delimiter+
                     (ll-multipart-parser-state parser)
                     +maybe-delimiter-second-dash+)
             (call-body-cb (or (ll-multipart-parser-boundary-mark parser) p)))
           ;; buffer the last part
           (when (ll-multipart-parser-boundary-mark parser)
             (setf (ll-multipart-parser-body-buffer parser)
                   (if (ll-multipart-parser-body-buffer parser)
                       (concatenate 'simple-byte-vector
                                    (ll-multipart-parser-body-buffer parser)
                                    (subseq data (ll-multipart-parser-boundary-mark parser)))
                       (subseq data (ll-multipart-parser-boundary-mark parser)))))
 
           (setf (ll-multipart-parser-body-mark parser) 0
                 (ll-multipart-parser-boundary-mark parser) nil))
         p))))
 
 (defun make-multipart-parser (content-type callback)
   (check-type content-type string)
   (let ((boundary (find-boundary content-type)))
     (unless boundary
       (return-from make-multipart-parser nil))
 
     (let ((parser (make-ll-multipart-parser :boundary boundary))
           (headers (make-hash-table :test 'equal))
           parsing-content-disposition
           parsing-header-field
           field-meta
           header-value-buffer
           (body-buffer (make-smart-buffer))
           callbacks)
       (flet ((collect-prev-header-value ()
                (when header-value-buffer
                  (let ((header-value
                          (babel:octets-to-string
                           header-value-buffer)))
                    (when parsing-content-disposition
                      (setq field-meta
                            (let (parsing-key
                                  (field-meta (make-hash-table :test 'equal)))
                              (parse-header-value-parameters header-value
                                                             :header-parameter-key-callback
                                                             (lambda (data start end)
                                                               (setq parsing-key
                                                                     (string-downcase (subseq data start end))))
                                                             :header-parameter-value-callback
                                                             (lambda (data start end)
                                                               (setf (gethash parsing-key field-meta)
                                                                     (subseq data start end))))
                              field-meta)))
                    (setf (gethash parsing-header-field headers)
                          header-value)))))
         (setq callbacks
               (make-callbacks
                :header-field (lambda (parser data start end)
                                (declare (ignore parser))
                                (collect-prev-header-value)
                                (setq header-value-buffer (make-concatenated-xsubseqs))
 
                                (let ((header-name
                                        (ascii-octets-to-lower-string data :start start :end end)))
                                  (setq parsing-content-disposition
                                        (string= header-name "content-disposition"))
                                  (setq parsing-header-field header-name)))
                :header-value (lambda (parser data start end)
                                (declare (ignore parser))
                                (xnconcf header-value-buffer
                                         (subseq (subseq data start end) 0)))
                :headers-complete (lambda (parser)
                                    (declare (ignore parser))
                                    (collect-prev-header-value))
                :message-complete (lambda (parser)
                                    (declare (ignore parser))
                                    (funcall callback
                                             (gethash "name" field-meta)
                                             headers
                                             field-meta
                                             body-buffer)
                                    (setq headers (make-hash-table :test 'equal)
                                          body-buffer (vector)
                                          header-value-buffer nil))
                :body (lambda (parser data start end)
                        (declare (ignore parser))
                        (write-sequence data body-buffer start end)))))
       (lambda (data)
         (http-multipart-parse parser callbacks data)
         (= (ll-multipart-parser-state parser) +body-done+)))))
 
 ;;; http
 ;;
 ;; Types
 
 (deftype status-code () '(integer 0 10000))
 
 ;;
 ;; States
 
 (defconstant +state-first-line+ 0)
 (defconstant +state-headers+ 1)
 (defconstant +state-chunk-size+ 2)
 (defconstant +state-body+ 3)
 (defconstant +state-chunk-body-end-crlf+ 4)
 (defconstant +state-trailing-headers+ 5)
 
 (defstruct (http (:conc-name :http-))
   (method nil :type symbol)
   (major-version 0 :type fixnum)
   (minor-version 9 :type fixnum)
   (status 0 :type status-code)
   (content-length nil :type (or null integer))
   (chunked-p nil :type boolean)
   (upgrade-p nil :type boolean)
 
   headers
 
   ;; private
   (header-read 0 :type fixnum)
   (mark -1 :type fixnum)
   (state +state-first-line+ :type fixnum))
 
 (defun http-version (http)
   (float
    (+ (http-major-version http)
       (/ (http-minor-version http) 10))))
 
 (defstruct (http-request (:include http)
                          (:conc-name :http-))
   resource)
 
 (defstruct (http-response (:include http)
                           (:conc-name :http-))
   status-text)
 
 ;;; Errors
 (define-condition http-error (net-error)
   (description)
   (:report
    (lambda (condition stream)
      (format stream "~A: ~A" (type-of condition) (slot-value condition 'description)))))
 
 
 ;;
 ;; Callback-related errors
 
 (define-condition callback-error (http-error)
   ((error :initarg :error
           :initform nil))
   (:report (lambda (condition stream)
              (with-slots (description error) condition
                (format stream "Callback Error: ~A~:[~;~:*~%  ~A~]"
                        description
                        error)))))
 
 (define-condition cb-message-begin (callback-error)
   ((description :initform "the message-begin callback failed")))
 (define-condition cb-url (callback-error)
   ((description :initform "the url callback failed")))
 (define-condition cb-first-line (callback-error)
   ((description :initform "the first line callback failed")))
 (define-condition cb-header-field (callback-error)
   ((description :initform "the header-field callback failed")))
 (define-condition cb-header-value (callback-error)
   ((description :initform "the header-value callback failed")))
 (define-condition cb-headers-complete (callback-error)
   ((description :initform "the headers-complete callback failed")))
 (define-condition cb-body (callback-error)
   ((description :initform "the body callback failed")))
 (define-condition cb-message-complete (callback-error)
   ((description :initform "the message-complete callback failed")))
 (define-condition cb-status (callback-error)
   ((description :initform "the status callback failed")))
 
 
 ;;
 ;; Parsing-related errors
 
 (define-condition parsing-error (http-error) ())
 
 (define-condition invalid-eof-state (parsing-error)
   ((description :initform "stream ended at an unexpected time")))
 (define-condition header-overflow (parsing-error)
   ((description :initform "too many header bytes seen; overflow detected")))
 (define-condition closed-connection (parsing-error)
   ((description :initform "data received after completed connection: close message")))
 (define-condition invalid-version (parsing-error)
   ((description :initform "invalid HTTP version")))
 (define-condition invalid-status (parsing-error)
   ((description :initform "invalid HTTP status code")
    (status-code :initarg :status-code
                 :initform nil))
   (:report (lambda (condition stream)
              (with-slots (description status-code) condition
                (format stream "~A: ~A~:[~;~:* (Code=~A)~]"
                        (type-of condition)
                        description
                        status-code)))))
 (define-condition invalid-method (parsing-error)
   ((description :initform "invalid HTTP method")))
 (define-condition invalid-url (parsing-error)
   ((description :initform "invalid URL")))
 (define-condition invalid-host (parsing-error)
   ((description :initform "invalid host")))
 (define-condition invalid-port (parsing-error)
   ((description :initform "invalid port")))
 (define-condition invalid-path (parsing-error)
   ((description :initform "invalid path")))
 (define-condition invalid-query-string (parsing-error)
   ((description :initform "invalid query string")))
 (define-condition invalid-fragment (parsing-error)
   ((description :initform "invalid fragment")))
 (define-condition lf-expected (parsing-error)
   ((description :initform "LF character expected")))
 (define-condition invalid-header-token (parsing-error)
   ((description :initform "invalid character in header")))
 (define-condition invalid-content-length (parsing-error)
   ((description :initform "invalid character in content-length header")))
 (define-condition invalid-chunk-size (parsing-error)
   ((description :initform "invalid character in chunk size header")))
 (define-condition invalid-constant (parsing-error)
   ((description :initform "invalid constant string")))
 
 (define-condition invalid-internal-state (parsing-error)
   ((description :initform "encountered unexpected internal state")
    (code :initarg :code))
   (:report
    (lambda (condition stream)
      (format stream "~A: ~A (Code=~A)"
              (type-of condition)
              (slot-value condition 'description)
              (slot-value condition 'code)))))
 (define-condition strict-error (parsing-error)
   ((description :initform "strict mode assertion failed")
    (form :initarg :form))
   (:report
    (lambda (condition stream)
      (format stream "~A: ~A~%  ~A"
              (type-of condition)
              (slot-value condition 'description)
              (slot-value condition 'form)))))
 (define-condition paused-error (parsing-error)
   ((description :initform "parser is paused")))
 (define-condition unknown-error (parsing-error)
   ((description :initform "an unknown error occured")))
 
 
 ;;
 ;; Multipart parsing
 
 (define-condition multipart-parsing-error (http-error) ())
 
 (define-condition invalid-multipart-body (multipart-parsing-error)
   ((description :initform "invalid multipart body")))
 (define-condition invalid-boundary (multipart-parsing-error)
   ((description :initform "invalid boundary")))
 
 
 ;;
 ;; Header value parsing
 
 (define-condition header-value-parsing-error (multipart-parsing-error) ())
 
 (define-condition invalid-header-value (header-value-parsing-error)
   ((description :initform "invalid header value")))
 (define-condition invalid-parameter-key (header-value-parsing-error)
   ((description :initform "invalid parameter key")))
 (define-condition invalid-parameter-value (header-value-parsing-error)
   ((description :initform "invalid parameter value")))
 
 ;;; parser
 ;;
 ;; Variables
 
 (declaim (type fixnum +max-header-line+))
 (defconstant +max-header-line+ 1024
   "Maximum number of header lines allowed.
 
 This restriction is for protecting users' application
 against denial-of-service attacks where the attacker feeds
 us a never-ending header that the application keeps buffering.")
 
 
 ;;
 ;; Types
 
 (deftype pointer () 'integer)
 
 
 ;;
 ;; Callbacks
 
 (defstruct callbacks
   (message-begin nil :type (or null function))     ;; 1 arg
   (url nil :type (or null function))
   (first-line nil :type (or null function))
   (status nil :type (or null function))
   (header-field nil :type (or null function))
   (header-value nil :type (or null function))
   (headers-complete nil :type (or null function))  ;; 1 arg
   (body nil :type (or null function))
   (message-complete nil :type (or null function)))
 
 (defmacro callback-data (name http callbacks data start end)
   (with-gensyms (callback e)
     `(when-let ((,callback (,(format-symbol t "~A-~A" :callbacks name) ,callbacks)))
        (handler-bind ((error
                         (lambda (,e)
                           (unless (typep ,e 'http-error)
                             (error ',(format-symbol t "~A-~A" :cb name)
                                    :error ,e)
                             (abort ,e)))))
          (funcall ,callback ,http ,data ,start ,end)))))
 
 (defmacro callback-notify (name http callbacks)
   (with-gensyms (callback e)
     `(when-let ((,callback (,(format-symbol t "~A-~A" :callbacks name) ,callbacks)))
        (handler-bind ((error
                         (lambda (,e)
                           (unless (typep ,e 'http-error)
                             (error ',(format-symbol t "~A-~A" :cb name)
                                    :error ,e)
                             (abort ,e)))))
          (funcall ,callback ,http)))))
 
 
 ;;
 ;; Parser utilities
 
 (define-condition eof () ())
 
 (define-condition expect-failed (parsing-error)
   ((description :initform "expect failed")))
 
 
 ;;
 ;; Tokens
 
 (declaim (type (simple-array character (128)) +tokens+))
 (define-constant +tokens+
     (make-array 128
                 :element-type 'character
                 :initial-contents
                 '( #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul
                    #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul
                    #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul
                    #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul
                    #\Nul   #\!   #\Nul   #\#    #\$    #\%    #\&    #\'
                    #\Nul  #\Nul   #\*    #\+   #\Nul    #\-   #\.   #\Nul
                    #\0    #\1    #\2    #\3    #\4    #\5    #\6    #\7
                    #\8    #\9   #\Nul  #\Nul  #\Nul  #\Nul  #\Nul  #\Nul
                    #\Nul   #\a    #\b    #\c    #\d    #\e    #\f    #\g
                    #\h    #\i    #\j    #\k    #\l    #\m    #\n    #\o
                    #\p    #\q    #\r    #\s    #\t    #\u    #\v    #\w
                    #\x    #\y    #\z   #\Nul  #\Nul  #\Nul   #\^    #\_
                    #\`    #\a    #\b    #\c    #\d    #\e    #\f    #\g
                    #\h    #\i    #\j    #\k    #\l    #\m    #\n    #\o
                    #\p    #\q    #\r    #\s    #\t    #\u    #\v    #\w
                    #\x    #\y    #\z   #\Nul   #\|   #\Nul   #\~   #\Nul ))
     :test 'equalp)
 
 (declaim (type (simple-array fixnum (128)) +unhex+))
 (define-constant +unhex+
     (make-array 128 :element-type 'fixnum :initial-contents
                 '(-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
                   -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
                   -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
                   0  1  2  3  4  5  6  7  8  9 -1 -1 -1 -1 -1 -1
                   -1 10 11 12 13 14 15 -1 -1 -1 -1 -1 -1 -1 -1 -1
                   -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
                   -1 10 11 12 13 14 15 -1 -1 -1 -1 -1 -1 -1 -1 -1
                   -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1))
     :test 'equalp)
 
 (defun unhex-byte (byte)
   (aref +unhex+ byte))
 
 ;;
 ;; Main
 
 (defun parse-method (data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (with-octets-parsing (data :start start :end end)
     (return-from parse-method
       (values
        (prog1
            (match-case
             ("CONNECT"     :CONNECT)
             ("COPY"        :COPY)
             ("CHECKOUT"    :CHECKOUT)
             ("DELETE"      :DELETE)
             ("GET"         :GET)
             ("HEAD"        :HEAD)
             ("LOCK"        :LOCK)
             ("MKCOL"       :MKCOL)
             ("MKCALENDAR"  :MKCALENDAR)
             ("MKACTIVITY"  :MKACTIVITY)
             ("MOVE"        :MOVE)
             ("MERGE"       :MERGE)
             ("M-SEARCH"    :M-SEARCH)
             ("NOTIFY"      :NOTIFY)
             ("OPTIONS"     :OPTIONS)
             ("POST"        :POST)
             ("PROPFIND"    :PROPFIND)
             ("PROPPATCH"   :PROPPATCH)
             ("PUT"         :PUT)
             ("PURGE"       :PURGE)
             ("PATCH"       :PATCH)
             ("REPORT"      :REPORT)
             ("SEARCH"      :SEARCH)
             ("SUBSCRIBE"   :SUBSCRIBE)
             ("TRACE"       :TRACE)
             ("UNLOCK"      :UNLOCK)
             ("UNSUBSCRIBE" :UNSUBSCRIBE)
             (otherwise (error 'invalid-method)))
          (unless (= (current) +space+)
            (error 'invalid-method)))
        (pos))))
   (error 'eof))
 
 (defun parse-url (data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (flet ((url-char-byte-p (byte)
            (or (<= (char-code #\!) byte (char-code #\~))
                (<= 128 byte))))
     (with-octets-parsing (data :start start :end end)
       (skip-while url-char-byte-p)
       (return-from parse-url (pos)))
     (error 'eof)))
 
 (defun parse-http-version (data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (let (major minor)
     (with-octets-parsing (data :start start :end end)
       (or (match? "HTTP/")
           (return-from parse-http-version (values nil nil (pos))))
       (if (digit-byte-char-p (current))
           (setq major (digit-byte-char-to-integer (current)))
           (return-from parse-http-version (values nil nil (pos))))
       (advance)
       (or (skip? #\.) (return-from parse-http-version (values nil nil (pos))))
       (if (digit-byte-char-p (current))
           (setq minor (digit-byte-char-to-integer (current)))
           (return-from parse-http-version (values nil nil (pos))))
       (advance)
       (return-from parse-http-version
         (values major minor (pos))))
     (error 'eof)))
 
 (defun parse-status-code (http callbacks data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (or (with-octets-parsing (data :start start :end end)
         (if (digit-byte-char-p (current))
             (setf (http-status http) (digit-byte-char-to-integer (current)))
             (error 'invalid-status))
         (loop
           (advance)
           (cond
             ((digit-byte-char-p (current))
              (setf (http-status http)
                    (+ (the fixnum (* 10 (http-status http)))
                       (digit-byte-char-to-integer (current))))
              (when (< 999 (http-status http))
                (error 'invalid-status :status-code (http-status http))))
             ((= (current) +space+)
              ;; Reading the status text
              (advance)
              (let ((status-text-start (pos)))
                (skip* (not #\Return))
                (advance)
                (skip #\Newline)
                (callback-data :status http callbacks data status-text-start (- (pos) 1)))
              (return))
             ((= (current) +cr+)
              ;; No status text
              (advance)
              (skip #\Newline)
              (return))
             (T (error 'invalid-status))))
         (pos))
       (error 'eof)))
 
 (defun parse-header-field-and-value (http callbacks data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (or
    (with-octets-parsing (data :start start :end end)
      (let ((field-start (pos))
            field-end)
        (macrolet ((skip-until-value-start-and (&body body)
                     `(progn
                        ;; skip #\: and leading spaces
                        (skip #\:)
                        (skip* #\Space #\Tab)
                        (cond
                          ((= (current) +cr+)
                           ;; continue to the next line
                           (advance)
                           (skip #\Newline)
                           (cond
                             ((or (= (current) +space+)
                                  (= (current) +tab+))
                              (skip* #\Space #\Tab)
                              (if (= (current) +cr+)
                                  ;; empty body
                                  (progn
                                    (advance)
                                    (skip #\Newline)
                                    (callback-data :header-field http callbacks data field-start field-end)
                                    (callback-data :header-value http callbacks data (pos) (pos)))
                                  (progn ,@body)))
                             ;; empty body
                             (t
                              (callback-data :header-field http callbacks data field-start field-end)
                              (callback-data :header-value http callbacks data (pos) (pos)))))
                          (t ,@body))))
                   (handle-otherwise ()
                     `(progn
                        ;; skip until field end
                        (do ((char (aref +tokens+ (current))
                                   (aref +tokens+ (current))))
                            ((= (current) (char-code #\:)))
                          (declare (type character char))
                          (when (char= char #\Nul)
                            (error 'invalid-header-token))
                          (advance))
 
                        (setq field-end (pos))
                        (skip-until-value-start-and
                         (advance-to*
                          (parse-header-value http callbacks data (pos) end field-start field-end)))))
                   (expect-field-end (&body body)
                     `(if (= (current) #.(char-code #\:))
                          (progn
                            (setq field-end (pos))
                            ,@body)
                          (handle-otherwise))))
          (match-i-case
           ("content-length"
            (expect-field-end
             (skip-until-value-start-and
              (multiple-value-bind (value-start value-end next content-length)
                  (parse-header-value-content-length data (pos) end)
                (declare (type pointer next))
                (setf (http-content-length http) content-length)
                (advance-to* next)
                (callback-data :header-field http callbacks data field-start field-end)
                (callback-data :header-value http callbacks data value-start value-end)))))
           ("transfer-encoding"
            (expect-field-end
             (skip-until-value-start-and
              (multiple-value-bind (value-start value-end next chunkedp)
                  (parse-header-value-transfer-encoding data (pos) end)
                (declare (type pointer next))
                (setf (http-chunked-p http) chunkedp)
                (advance-to* next)
                (callback-data :header-field http callbacks data field-start field-end)
                (callback-data :header-value http callbacks data value-start value-end)))))
           ("upgrade"
            (expect-field-end
             (skip-until-value-start-and
              (setf (http-upgrade-p http) T)
              (let ((value-start (pos)))
                (skip* (not #\Return))
                (advance)
                (skip #\Newline)
                (callback-data :header-field http callbacks data field-start field-end)
                (callback-data :header-value http callbacks data value-start (- (pos) 2))))))
           (otherwise (handle-otherwise)))))
      (pos))
    (error 'eof)))
 
 (defun parse-header-value (http callbacks data start end &optional field-start field-end)
   (or (with-octets-parsing (data :start start :end end)
         (skip* (not #\Return))
         (advance)
         (skip #\Newline)
         (when field-start
           (callback-data :header-field http callbacks data field-start field-end))
         (callback-data :header-value http callbacks data start (- (pos) 2))
         (pos))
       (error 'eof)))
 
 (defun parse-header-value-transfer-encoding (data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (with-octets-parsing (data :start start :end end)
     (match-i-case
      ("chunked"
       (if (= (current) +cr+)
           (progn
             (advance)
             (skip #\Newline)
             (return-from parse-header-value-transfer-encoding
               (values start (- (pos) 2) (pos) t)))
           (progn
             (skip+ (not #\Return))
             (advance)
             (skip #\Newline)
             (return-from parse-header-value-transfer-encoding
               (values start (- (pos) 2) (pos) nil)))))
      (otherwise
       (skip* (not #\Return))
       (advance)
       (skip #\Newline)
       (return-from parse-header-value-transfer-encoding
         (values start (- (pos) 2) (pos) nil)))))
   (error 'eof))
 
 (defun parse-header-value-content-length (data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (let ((content-length 0))
     (declare (type integer content-length))
     (with-octets-parsing (data :start start :end end)
       (if (digit-byte-char-p (current))
           (setq content-length (digit-byte-char-to-integer (current)))
           (error 'invalid-content-length))
       (loop
         (advance)
         (cond
           ((digit-byte-char-p (current))
            (setq content-length
                  (+ (* 10 content-length)
                     (digit-byte-char-to-integer (current)))))
           ((= (current) +cr+)
            (advance)
            (skip #\Newline)
            (return-from parse-header-value-content-length
              (values start (- (pos) 2) (pos) content-length)))
           ((= (current) +space+)
            ;; Discard spaces
            )
           (t (error 'invalid-content-length)))))
     (error 'eof)))
 
 (defun parse-header-line (http callbacks data start end)
   (declare (type simple-byte-vector data)
            (type pointer start end))
   (when (<= end start)
     (error 'eof))
   (let ((current (aref data start)))
     (declare (type (unsigned-byte 8) current))
     (cond
       ((or (= current +tab+)
            (= current +space+))
        (parse-header-value http callbacks data start end))
       ((/= current +cr+)
        (parse-header-field-and-value http callbacks data start end))
       (t
        (incf start)
        (when (= start end)
          (error 'eof))
        (setq current (aref data start))
        (unless (= current +lf+)
          (error 'expect-failed))
        (values (1+ start) t)))))
 
 (defun parse-headers (http callbacks data start end)
   (declare (type http http)
            (type simple-byte-vector data)
            (type pointer start end))
   (or (with-octets-parsing (data :start start :end end)
         ;; empty headers
         (when (= (current) +cr+)
           (advance)
           (if (= (current) +lf+)
               (return-from parse-headers (1+ (pos)))
               (error 'expect-failed)))
 
         (advance-to* (parse-header-field-and-value http callbacks data start end))
 
         (setf (http-mark http) (pos))
         (loop
           (when (= +max-header-line+ (the fixnum (incf (http-header-read http))))
             (error 'header-overflow))
           (multiple-value-bind (next endp)
               (parse-header-line http callbacks data (pos) end)
             (advance-to* next)
             (when endp
               (return)))
           (setf (http-mark http) (pos)))
         (setf (http-mark http) (pos))
         (setf (http-state http) +state-body+)
 
         (pos))
       (error 'eof)))
 
 (defun read-body-data (http callbacks data start end)
   (declare (type http http)
            (type simple-byte-vector data)
            (type pointer start end))
   (let ((readable-count (the pointer (- end start))))
     (declare (dynamic-extent readable-count)
              (type pointer readable-count))
     (if (<= (http-content-length http) readable-count)
         (let ((body-end (+ start (http-content-length http))))
           (declare (dynamic-extent body-end))
           (setf (http-content-length http) 0)
           (callback-data :body http callbacks data start body-end)
           (setf (http-mark http) body-end)
           (values body-end t))
         ;; still needs to read
         (progn
           (decf (http-content-length http) readable-count)
           (callback-data :body http callbacks data start end)
           (setf (http-mark http) end)
           (values end nil)))))
 
 (defun http-message-needs-eof-p (http)
   (let ((status-code (http-status http)))
     (declare (type status-code status-code))
     (when (= status-code 0) ;; probably request
       (return-from http-message-needs-eof-p nil))
 
     (when (or (< 99 status-code 200) ;; 1xx e.g. Continue
               (= status-code 204)    ;; No Content
               (= status-code 304))   ;; Not Modified
       (return-from http-message-needs-eof-p nil))
 
     (when (or (http-chunked-p http)
               (http-content-length http))
       (return-from http-message-needs-eof-p nil))
     T))
 
 (defun parse-body (http callbacks data start end requestp)
   (declare (type http http)
            (type simple-byte-vector data)
            (type pointer start end))
   (macrolet ((message-complete ()
                `(progn
                   (callback-notify :message-complete http callbacks)
                   (setf (http-state http) +state-first-line+))))
     (case (http-content-length http)
       (0
        ;; Content-Length header given but zero: Content-Length: 0\r\n
        (message-complete)
        start)
       ('nil
        (if (or requestp
                (not (http-message-needs-eof-p http)))
            ;; Assume content-length 0 - read the next
            (progn
              (message-complete)
              ;; By returning "start", we'll continue
              ;; to parse the next request in case if
              ;; HTTP pipelining is used. Probably
              ;; we need some way to enable (or disable)
              ;; HTTP pipelining support.
              start)
            ;; read until EOF
            (progn
              (callback-data :body http callbacks data start end)
              (setf (http-mark http) end)
 	     (message-complete)
              end)))
       (otherwise
        ;; Content-Length header given and non-zero
        (multiple-value-bind (next completedp)
            (read-body-data http callbacks data start end)
          (when completedp
            (message-complete))
          next)))))
 
 (defun parse-chunked-body (http callbacks data start end)
   (declare (type http http)
            (type simple-byte-vector data)
            (type pointer start end))
 
   (when (= start end)
     (return-from parse-chunked-body start))
 
   (or (with-octets-parsing (data :start start :end end)
         (tagbody
            (cond
              ((= (http-state http) +state-chunk-size+)
               (go chunk-size))
              ((= (http-state http) +state-body+)
               (go body))
              ((= (http-state http) +state-chunk-body-end-crlf+)
               (go body-end-crlf))
              ((= (http-state http) +state-trailing-headers+)
               (go trailing-headers))
              (T (error 'invalid-internal-state :code (http-state http))))
 
          chunk-size
            (let ((unhex-val (unhex-byte (current))))
              (declare (type fixnum unhex-val)
                       (dynamic-extent unhex-val))
              (when (= unhex-val -1)
                (error 'invalid-chunk-size))
              (setf (http-content-length http) unhex-val)
 
              (loop
                (advance)
                (if (= (current) +cr+)
                    (progn
                      (advance)
                      (tagbody
                         (skip #\Newline)
                       :eof
                         (return)))
                    (progn
                      (setq unhex-val (unhex-byte (current)))
                      (cond
                        ((= unhex-val -1)
                         (cond
                           ((or (= (current) (char-code #\;))
                                (= (current) (char-code #\Space)))
                            (skip* (not #\Return))
                            (advance)
                            (tagbody
                               (skip #\Newline)
                             :eof
                               (return)))
                           (t (error 'invalid-chunk-size))))
                        (t (setf (http-content-length http)
                                 (+ (* 16 (http-content-length http)) unhex-val)))))))
              (setf (http-state http) +state-body+) 
              (if (eofp)
                  (return-from parse-chunked-body (pos))
                  (setf (http-mark http) (pos))))
 
          body
            (cond
              ((zerop (http-content-length http))
               ;; trailing headers
               (setf (http-state http) +state-trailing-headers+)
               (go trailing-headers))
              (T
               (multiple-value-bind (next completedp)
                   (read-body-data http callbacks data (pos) end)
                 (declare (type pointer next))
                 (unless completedp
                   (return-from parse-chunked-body (pos)))
                 (setf (http-state http) +state-chunk-body-end-crlf+)
                 (advance-to next))))
 
          body-end-crlf
            (skip #\Return)
            (tagbody
               (skip #\Newline)
             :eof
               (setf (http-state http) +state-chunk-size+)
               (when (eofp)
                 (return-from parse-chunked-body (pos))))
            (setf (http-mark http) (pos))
            (go chunk-size)
 
          trailing-headers
            (return-from parse-chunked-body
              (prog1 (parse-headers http callbacks data (pos) end)
                (callback-notify :message-complete http callbacks)))))
       (error 'eof)))
 
 (defun parse-request (http callbacks data &key (start 0) end (head-request nil))
   (declare (type http http)
            (type simple-byte-vector data)
 	   (ignorable head-request))
   (let ((end (or end (length data))))
     (declare (type pointer start end))
     (handler-bind ((match-failed
                      (lambda (c)
                        (declare (ignore c))
                        (error 'expect-failed))))
       (with-octets-parsing (data :start start :end end)
         (setf (http-mark http) start)
 
         (tagbody
            (let ((state (http-state http)))
              (declare (type fixnum state))
              (cond
                ((= +state-first-line+ state)
                 (go first-line))
                ((= +state-headers+ state)
                 (go headers))
                ((<= +state-chunk-size+ state +state-trailing-headers+)
                 (go body))
                (T (error 'invalid-internal-state :code state))))
 
          first-line
            ;; skip first empty line (some clients add CRLF after POST content)
            (when (= (current) +cr+)
              (advance)
              (tagbody
                 (skip #\Newline)
               :eof
                 (when (eofp)
                   (return-from parse-request (pos)))))
 
            (setf (http-mark http) (pos))
            (callback-notify :message-begin http callbacks)
 
            (multiple-value-bind (method next)
                (parse-method data (pos) end)
              (declare (type pointer next))
              (setf (http-method http) method)
              (advance-to* next))
            (skip* #\Space)
            (let ((url-start-mark (pos))
                  (url-end-mark (parse-url data (pos) end)))
              (declare (type pointer url-start-mark url-end-mark))
              (tagbody retry-url-parse
                 (advance-to* url-end-mark)
 
                 (skip* #\Space)
 
                 (cond
                   ;; No HTTP version
                   ((= (current) +cr+)
                    (callback-data :url http callbacks data url-start-mark url-end-mark)
                    (advance)
                    (skip #\Newline))
                   (t (multiple-value-bind (major minor next)
                          (parse-http-version data (pos) end)
                        (declare (type pointer next))
                        (unless major
                          ;; Invalid HTTP version.
                          ;; Assuming it's also a part of URI.
                          (let ((new-url-end-mark (parse-url data next end)))
                            (when (= url-end-mark new-url-end-mark)
                              (error 'invalid-version))
                            (setq url-end-mark new-url-end-mark)
                            (go retry-url-parse)))
                        (callback-data :url http callbacks data url-start-mark url-end-mark)
                        (setf (http-major-version http) major
                              (http-minor-version http) minor)
                        (advance-to* next))
                      (skip #\Return)
                      (skip #\Newline)))))
 
            (setf (http-mark http) (pos))
            (setf (http-state http) +state-headers+)
            (callback-notify :first-line http callbacks)
 
          headers
            (advance-to* (parse-headers http callbacks data (pos) end))
 
            (callback-notify :headers-complete http callbacks)
            (setf (http-header-read http) 0)
 
            ;; Exit, the rest of the connect is in a different protocol.
            (when (http-upgrade-p http)
              (setf (http-state http) +state-first-line+)
              (callback-notify :message-complete http callbacks)
              (return-from parse-request (pos)))
 
            (setf (http-state http)
                  (if (http-chunked-p http)
                      +state-chunk-size+
                      +state-body+))
 
          body
            (if (http-chunked-p http)
                (advance-to* (parse-chunked-body http callbacks data (pos) end))
                (progn
                  (and (advance-to* (parse-body http callbacks data (pos) end t))
                       (go first-line))))
            (return-from parse-request (pos)))))
     (error 'eof)))
 
 (defun parse-response (http callbacks data &key (start 0) end (head-request nil))
   (declare (type http http)
            (type simple-byte-vector data))
   (let ((end (or end
                  (length data))))
     (declare (type pointer start end))
     (handler-bind ((match-failed
                      (lambda (c)
                        (declare (ignore c))
                        (error 'expect-failed))))
       (with-octets-parsing (data :start start :end end)
         (setf (http-mark http) start)
 
         (tagbody
            (let ((state (http-state http)))
              (declare (type fixnum state))
              (cond
                ((= +state-first-line+ state)
                 (go first-line))
                ((= +state-headers+ state)
                 (go headers))
                ((<= +state-chunk-size+ state +state-trailing-headers+)
                 (go body))
                (T (error 'invalid-internal-state :code state))))
 
          first-line
            (setf (http-mark http) (pos))
            (callback-notify :message-begin http callbacks)
 
            (multiple-value-bind (major minor next)
                (parse-http-version data (pos) end)
              (declare (type pointer next))
              (setf (http-major-version http) major
                    (http-minor-version http) minor)
              (advance-to* next))
 
            (cond
              ((= (current) +space+)
               (advance)
               (advance-to (parse-status-code http callbacks data (pos) end)))
              ((= (current) +cr+)
               (skip #\Newline))
              (T (error 'invalid-version)))
 
            (setf (http-mark http) (pos))
            (setf (http-state http) +state-headers+)
            (callback-notify :first-line http callbacks)
 
          headers
            (advance-to* (parse-headers http callbacks data (pos) end))
 
            (callback-notify :headers-complete http callbacks)
            (setf (http-header-read http) 0)
            (setf (http-state http)
                  (if (http-chunked-p http)
                      +state-chunk-size+
                      +state-body+))
 
 	   (when head-request
 	     (callback-notify :message-complete http callbacks)
 	     (setf (http-state http) +state-first-line+)
 	     (return-from parse-response (pos)))
 
          body
            (if (http-chunked-p http)
                (advance-to* (parse-chunked-body http callbacks data (pos) end))
                (progn
                  (advance-to* (parse-body http callbacks data (pos) end nil))
                  (unless (eofp)
                    (go first-line))))
            (return-from parse-response (pos)))))
     (error 'eof)))
 
 (defun parse-header-value-parameters (data &key
                                              header-value-callback
                                              header-parameter-key-callback
                                              header-parameter-value-callback)
   (declare (type simple-string data)
            (optimize (speed 3) (safety 2)))
 
   (let* ((header-name-mark 0)
          parameter-key-mark
          parameter-value-mark
          parsing-quoted-string-p
          (p 0)
          (end (length data))
          (char (aref data p)))
     (declare (type character char))
 
     (when (= end 0)
       (return-from parse-header-value-parameters 0))
 
     (macrolet ((go-state (state &optional (advance 1))
                    `(locally (declare (optimize (speed 3) (safety 0)))
                       (incf p ,advance)
                       (when (= p end)
                         (go eof))
                       (setq char (aref data p))
                       (go ,state))))
       (flet ((tokenp (char)
                (declare (optimize (speed 3) (safety 0)))
                (let ((byte (char-code char)))
                  (and (< byte 128)
                       (not (char= (the character (aref +tokens+ byte)) #\Nul))))))
         (tagbody
          parsing-header-value-start
            (case char
              ((#\Space #\Tab)
               (go-state parsing-header-value))
              (otherwise
               (unless (tokenp char)
                 (error 'invalid-header-value))
               (setq header-name-mark p)
               (go-state parsing-header-value 0)))
 
          parsing-header-value
            (case char
              (#\;
               (when header-value-callback
                 (funcall (the function header-value-callback)
                          data header-name-mark p))
               (setq header-name-mark nil)
               (go-state looking-for-parameter-key))
              (otherwise (go-state parsing-header-value)))
 
          looking-for-parameter-key
            (case char
              ((#\Space #\Tab #\; #\Newline #\Return)
               (go-state looking-for-parameter-key))
              (otherwise
               (unless (tokenp char)
                 (error 'invalid-parameter-key))
               (setq parameter-key-mark p)
               (go-state parsing-parameter-key)))
 
          parsing-parameter-key
            (case char
              (#\=
               (assert parameter-key-mark)
               (when header-parameter-key-callback
                 (funcall (the function header-parameter-key-callback)
                          data parameter-key-mark p))
               (setq parameter-key-mark nil)
               (go-state parsing-parameter-value-start))
              (otherwise
               (unless (tokenp char)
                 (error 'invalid-parameter-key))
               (go-state parsing-parameter-key)))
 
          parsing-parameter-value-start
            (case char
              (#\"
               ;; quoted-string
               (setq parameter-value-mark (1+ p))
               (setq parsing-quoted-string-p t)
               (go-state parsing-parameter-quoted-value))
              ((#.+space+ #.+tab+)
               (go-state parsing-parameter-value-start))
              (otherwise
               (setq parameter-value-mark p)
               (go-state parsing-parameter-value 0)))
 
          parsing-parameter-quoted-value
            (if (char= char #\")
                (progn
                  (assert parameter-value-mark)
                  (setq parsing-quoted-string-p nil)
                  (when header-parameter-value-callback
                    (funcall (the function header-parameter-value-callback)
                             data parameter-value-mark p))
                  (setq parameter-value-mark nil)
                  (go-state looking-for-parameter-key))
                (go-state parsing-parameter-quoted-value))
 
          parsing-parameter-value
            (case char
              (#\;
               (assert parameter-value-mark)
               (when header-parameter-value-callback
                 (funcall (the function header-parameter-value-callback)
                          data parameter-value-mark p))
               (setq parameter-value-mark nil)
               (go-state looking-for-parameter-key))
              (otherwise
               (go-state parsing-parameter-value)))
 
          eof
            (when header-name-mark
              (when header-value-callback
                (funcall (the function header-value-callback)
                         data header-name-mark p)))
            (when parameter-key-mark
              (error 'invalid-eof-state))
            (when parameter-value-mark
              (when parsing-quoted-string-p
                (error 'invalid-eof-state))
              (when header-parameter-value-callback
                (funcall (the function header-parameter-value-callback)
                         data parameter-value-mark p))))))
     p))