400 Bad Request when sending a http request with Common Lisp usocket

Question

I'm using the following code to grab the url http://brandonhsiao.com/essays.html:

(defparameter *new-line* '(#\Return #\Newline))

(defun read-url (host port path)
  (let ((sock (usocket:socket-connect host port)))
    (format (usocket:socket-stream sock) "~A"
            (concatenate 'string
                         "GET " path " HTTP/1.1" *new-line*
                         "Connection: close" *new-line* *new-line*))
    (force-output (usocket:socket-stream sock))
    (do ((line
           (read-line (usocket:socket-stream sock) nil)
           (read-line (usocket:socket-stream sock) nil))
         (all ""))
      ((not line) all)
      (setf all (concatenate 'string all line *new-line*)))))

(print (read-url "brandonhsiao.com" 80 "/essays.html"))

This gives me a 400 Bad Request error, but when I visit http://brandonhsiao.com/essays.html with Firefox, everything is fine. What am I doing wrong?

Answer 1

It looks like I needed to include the host.

(defparameter *new-line* '(#\Return #\Newline))

(defun read-url (host port path)
  (let ((sock (usocket:socket-connect host port)))
    (format (usocket:socket-stream sock) "~A"
            (concatenate 'string
                         "GET " path " HTTP/1.1" *new-line*
                         "Host: " host *new-line* *new-line*))
    (force-output (usocket:socket-stream sock))
    (do ((line
           (read-line (usocket:socket-stream sock) nil)
           (read-line (usocket:socket-stream sock) nil))
         (all ""))
      ((not line) all)
      (setf all (concatenate 'string all line " ")))))