4.8 HTTP and CGI

(require 'http) or (require 'cgi)

Function: http:header alist ¶

Returns a string containing lines for each element of alist; the car of which is followed by ‘: ’, then the cdr.

Function: http:content alist body … ¶

Returns the concatenation of strings body with the (http:header alist) and the ‘Content-Length’ prepended.

Variable: *http:byline* ¶

String appearing at the bottom of error pages.

Function: http:error-page status-code reason-phrase html-string … ¶

status-code and reason-phrase should be an integer and string as specified in RFC 2068. The returned page (string) will show the status-code and reason-phrase and any additional html-strings …; with *http:byline* or SLIB’s default at the bottom.

Function: http:forwarding-page title dly uri html-string … ¶

The string or symbol title is the page title. dly is a non-negative integer. The html-strings … are typically used to explain to the user why this page is being forwarded.

http:forwarding-page returns an HTML string for a page which automatically forwards to uri after dly seconds. The returned page (string) contains any html-strings … followed by a manual link to uri, in case the browser does not forward automatically.

Function: http:serve-query serve-proc input-port output-port ¶

reads the URI and query-string from input-port. If the query is a valid ‘"POST"’ or ‘"GET"’ query, then http:serve-query calls serve-proc with three arguments, the request-line, query-string, and header-alist. Otherwise, http:serve-query calls serve-proc with the request-line, #f, and header-alist.

If serve-proc returns a string, it is sent to output-port. If serve-proc returns a list whose first element is an integer, then an error page with the status integer which is the first element of the list and strings from the list. If serve-proc returns a list whose first element isn’t an number, then an error page with the status code 500 and strings from the list. If serve-proc returns #f, then a ‘Bad Request’ (400) page is sent to output-port.

Otherwise, http:serve-query replies (to output-port) with appropriate HTML describing the problem.

This example services HTTP queries from port-number:

(define socket (make-stream-socket AF_INET 0))
(and (socket:bind socket port-number) ; AF_INET INADDR_ANY
     (socket:listen socket 10)        ; Queue up to 10 requests.
     (dynamic-wind
         (lambda () #f)
         (lambda ()
           (do ((port (socket:accept socket) (socket:accept socket)))
               (#f)
             (let ((iport (duplicate-port port "r"))
                   (oport (duplicate-port port "w")))
               (http:serve-query build:serve iport oport)
               (close-port iport)
               (close-port oport))
             (close-port port)))
         (lambda () (close-port socket))))

Function: cgi:serve-query serve-proc ¶

reads the URI and query-string from (current-input-port). If the query is a valid ‘"POST"’ or ‘"GET"’ query, then cgi:serve-query calls serve-proc with three arguments, the request-line, query-string, and header-alist. Otherwise, cgi:serve-query calls serve-proc with the request-line, #f, and header-alist.

If serve-proc returns a string, it is sent to (current-ouput-port). If serve-proc returns a list whose first element is an integer, then an error page with the status integer which is the first element of the list and strings from the list. If serve-proc returns a list whose first element isn’t an number, then an error page with the status code 500 and strings from the list. If serve-proc returns #f, then a ‘Bad Request’ (400) page is sent to (current-ouput-port).

Otherwise, cgi:serve-query replies (to (current-output-port)) with appropriate HTML describing the problem.

Function: make-query-alist-command-server rdb command-table ¶

Function: make-query-alist-command-server rdb command-table #t ¶

Returns a procedure of one argument. When that procedure is called with a query-alist (as returned by uri:decode-query, the value of the ‘*command*’ association will be the command invoked in command-table. If ‘*command*’ is not in the query-alist then the value of ‘*suggest*’ is tried. If neither name is in the query-alist, then the literal value ‘*default*’ is tried in command-table.

If optional third argument is non-false, then the command is called with just the parameter-list; otherwise, command is called with the arguments described in its table.