--- /dev/null
+;;; Scratchy gopher server
+;;
+;; Requires Chicken 5.0.0.
+;;
+
+;;; Imports
+
+(import (chicken tcp)
+ (chicken port)
+ (chicken io)
+ (chicken string)
+ (chicken pathname)
+ (chicken file)
+ (chicken time posix)
+ (chicken condition)
+ (chicken process)
+ (chicken process-context)
+ (chicken process-context posix)
+ srfi-1 srfi-13 matchable)
+
+;;; Global constants
+
+(define scratchy-version "1.0.0")
+
+(define scratchy-footer
+ (conc "\n"
+ "--------------------------------------------------\n"
+ "This gopher hole was dug using Scratchy v" scratchy-version ".\n"
+ "Powered by Chicken Scheme!"))
+
+(define gopher-index-filename "index")
+
+;;; Server loop
+
+;; We don't yet use worker threads here to handle requests,
+;; the server just blocks until the first request is finished.
+;; While we should fix this, it's actually probably okay, as
+;; we genuinely don't expect a huge flood of gopher traffic. :-(
+
+(define-record config
+ root-dir host port display-footer user group)
+
+(define (run-server config)
+ (set-buffering-mode! (current-output-port) #:line)
+ (let ((listener (tcp-listen (config-port config))))
+ (print "Gopher server listening on port " (config-port config) " ...")
+ (drop-privs config)
+ (server-loop listener config))
+ (tcp-close listener))
+
+(define (drop-privs config)
+ (let ((uid (config-user config))
+ (gid (config-group config)))
+ (if (not (null? gid)) ; Group first, since only root can switch groups.
+ (set! (current-group-id) gid))
+ (if (not (null? uid))
+ (set! (current-user-id) uid))))
+
+(define (server-loop listener config)
+ (let-values (((in-port out-port) (tcp-accept listener)))
+ (let* ((line (read-line in-port))
+ (selector (string-trim-both line)))
+ (let-values (((local-ip remote-ip) (tcp-addresses in-port)))
+ (print "Accepted connection from " remote-ip
+ " on " (seconds->string))
+ (condition-case
+ (begin
+ (with-output-to-port out-port
+ (lambda ()
+ (serve-selector (if (= (string-length selector) 0)
+ "/"
+ selector)
+ config)))
+ (print "... served selector '" selector "'. Closing connection."))
+ (o (exn)
+ (print-error-message o out-port)
+ (print-error-message o)
+ (print "Error while attempting to serve selector " selector ".")))))
+ (close-input-port in-port)
+ (close-output-port out-port))
+ (server-loop listener config))
+
+;;; Selector type inference
+
+(define (true-for-one? predicate values)
+ (if (null? values)
+ #f
+ (if (predicate (car values))
+ #t
+ (true-for-one? predicate (cdr values)))))
+
+(define (has-suffix? selector . suffixes)
+ (true-for-one? (lambda (suffix)
+ (string-suffix? suffix selector))
+ suffixes))
+
+(define (has-prefix? selector . prefixes)
+ (true-for-one? (lambda (prefix)
+ (string-prefix? prefix selector))
+ prefixes))
+
+(define (infer-selector-type selector)
+ (let ((l (string-downcase selector)))
+ (cond
+ ((or (= (string-length l) 0)
+ (string-suffix? "/" l)) 1)
+ ((has-suffix? l ".txt" ".org" ".md") 0)
+ ((has-suffix? l ".png" ".jpg" ".gif" ".bmp" ".tif" ".tga") 'I)
+ ((has-suffix? l "?" "%3f") 7)
+ ((has-prefix? l "url:" "/url:") 'h)
+ (else 9))))
+
+
+;;; Selector retrieval
+
+(define (serve-selector raw-selector config)
+ (let* ((selector-list (string-split raw-selector "\t"))
+ (selector (car selector-list))
+ (arguments (cdr selector-list)))
+ (if (string-contains selector "|")
+ (let ((l (string-split selector "|")))
+ (serve-script (car l) (cdr l) config))
+ (case (infer-selector-type selector)
+ ((1) (serve-directory-file selector config))
+ ((7) (let ((l (string-split selector "?")))
+ (serve-script (car l) arguments config)))
+ ((0) (serve-text-file selector config))
+ ((h) (serve-url selector config))
+ (else (serve-binary-file selector config))))))
+
+(define (legal-filename? filename config)
+ (and (string-prefix? (config-root-dir config)
+ (normalize-pathname filename))
+ (file-exists? filename)
+ (not (directory-exists? filename))
+ (file-readable? filename)))
+
+(define (legal-script-filename? filename config)
+ (and (legal-filename? filename config)
+ (string-suffix? ".scm" filename)
+ (file-executable? filename)))
+
+(define (serve-directory-file selector config)
+ (let ((filename (make-pathname (list (config-root-dir config) selector)
+ gopher-index-filename)))
+ (if (legal-filename? filename config)
+ (begin
+ (with-input-from-file filename
+ (lambda ()
+ (let loop ((c (peek-char)))
+ (if (eof-object? c)
+ 'done
+ (begin
+ (if (eq? c #\,)
+ (begin
+ (read-char)
+ (serve-record (read) selector config)
+ (read-line))
+ (serve-info-records (read-line)))
+ (loop (peek-char)))))))
+ (if (config-display-footer config)
+ (serve-info-records scratchy-footer))
+ (print ".\r"))
+ (error "No legal index file not found."))))
+
+(define (serve-text-file selector config)
+ (let ((filename (make-pathname (config-root-dir config) selector)))
+ (if (legal-filename? filename config)
+ (begin
+ (with-input-from-file filename
+ (lambda ()
+ (for-each
+ (lambda (line)
+ (print line "\r"))
+ (read-lines))))
+ (print ".\r"))
+ (error "File not found." filename))))
+
+(define (serve-binary-file selector config)
+ (let ((filename (make-pathname (config-root-dir config) selector)))
+ (if (legal-filename? filename config)
+ (with-input-from-file filename
+ (lambda ()
+ (let loop ((b (read-byte)))
+ (if (eof-object? b)
+ 'done
+ (begin
+ (write-byte b)
+ (loop (read-byte)))))))
+ (error "File not found." filename))))
+
+(define (serve-url selector config)
+ (let ((url (substring selector 4)))
+ (print
+ "<html><head><title>Redirection</title>"
+ "<meta http-equiv=\"refresh\" content=\"10; URL='" url "'\" />"
+ "</head><body>"
+ "<p>If you are seeing this page, your gopher browser does not "
+ "properly support URL directory entries or cannot follow such "
+ "links.</p>"
+ "<p>If you are viewing this page using a web browser, you should "
+ "be redirected shortly. Otherwise, you can manually open the "
+ "the follwing url:\n"
+ "\n"
+ "<a href=\"" url "\">" url "</a>\n"
+ "</body></html>")))
+
+(define (serve-script selector arguments config)
+ (let ((filename (make-pathname (config-root-dir config) selector)))
+ (if (legal-script-filename? filename config)
+ (let* ((sexp (with-input-from-file filename read))
+ (script-result (with-selector-dir
+ selector config
+ (lambda ()
+ (apply (eval sexp) arguments)))))
+ (when (pair? script-result)
+ (serve-records script-result
+ (pathname-directory selector) config)
+ (print ".\r")))
+ (error "No legal index script not found." filename))))
+
+
+;;; Index rendering
+
+(define (serve-records records dir-selector config)
+ (for-each
+ (lambda (record)
+ (serve-record record dir-selector config))
+ records))
+
+(define (serve-info-records string)
+ (for-each
+ (lambda (line)
+ (print* "i")
+ (for-each (lambda (char)
+ (print* (if (eq? char #\tab)
+ " "
+ char)))
+ (string->list line))
+ (print "\tfake\tfake\t1\r"))
+ (string-split string "\n" #t)))
+
+(define (serve-record record dir-selector config)
+ (match record
+ ((? string?) (serve-info-records record))
+ (('shell command) (serve-shell-command command dir-selector config))
+ (('eval expression) (serve-expression expression dir-selector config))
+ (('url display-string url)
+ (print #\h display-string "\tURL:" url
+ "\t" (config-host config)
+ "\t" (config-port config) "\r"))
+ ((type display-string selector host port)
+ (print type display-string "\t" selector "\t" host "\t" port "\r"))
+ ((type display-string selector host)
+ (serve-record (list type display-string selector host 70)
+ dir-selector config))
+ ((type display-string selector)
+ (serve-record (list type display-string
+ (make-pathname dir-selector selector)
+ (config-host config) (config-port config))
+ dir-selector config))
+ ((display-string selector)
+ (serve-record (list (infer-selector-type selector) display-string selector)
+ dir-selector config))
+ ((selector)
+ (serve-record (list (infer-selector-type selector) selector)
+ dir-selector config))
+ (else (error "Unknown record type."))))
+
+(define (serve-shell-command command dir-selector config)
+ (with-selector-dir
+ dir-selector config
+ (lambda ()
+ (let-values (((in-port out-port id) (process command)))
+ (let ((string (read-string #f in-port)))
+ (if (and (not (eof-object? string))
+ (> (string-length string) 0))
+ (serve-info-records (string-chomp string "\n")))
+ (close-input-port in-port)
+ (close-output-port out-port))))))
+
+(define (serve-expression expression dir-selector config)
+ (with-selector-dir
+ dir-selector config
+ (lambda ()
+ (serve-records (eval expression) dir-selector config))))
+
+
+;;; Utility methods
+
+(define (with-current-working-directory directory thunk)
+ (let ((old-wd (current-directory))
+ (result 'none))
+ (condition-case
+ (begin
+ (change-directory directory)
+ (set! result (thunk))
+ (change-directory old-wd)
+ result)
+ (o (exn)
+ (change-directory old-wd)
+ (signal o)))))
+
+(define (with-selector-dir selector config thunk)
+ (with-current-working-directory
+ (make-pathname (config-root-dir config)
+ (pathname-directory selector)) thunk))
+
+
+;;; Main
+
+(define (print-usage progname)
+ (print "Usage:\n"
+ progname " -h/--help\n"
+ progname " [-n/--no-footer] [-u/--user UID] [-g/--group GID] root-dir hostname [port]\n"
+ "\n"
+ "The -n option tells the server to not display a directory footer."
+ "The -u and -g can be used to set the UID and GID of the process following"
+ "the creation of the TCP port listener (which often requires root)."))
+
+(define (main)
+ (let* ((progname (car (argv)))
+ (config (make-config '() '() 70 #t '() '())))
+ (if (null? (cdr (argv)))
+ (print-usage progname)
+ (let loop ((args (cdr (argv))))
+ (let ((this-arg (car args))
+ (rest-args (cdr args)))
+ (if (string-prefix? "-" this-arg)
+ (cond
+ ((or (equal? this-arg "-h")
+ (equal? this-arg "--help"))
+ (print-usage progname))
+ ((or (equal? this-arg "-n")
+ (equal? this-arg "--no-footer"))
+ (config-display-footer-set! config #f)
+ (loop rest-args))
+ ((or (equal? this-arg "-u")
+ (equal? this-arg "--user"))
+ (config-user-set! config (string->number (car rest-args)))
+ (loop (cdr rest-args)))
+ ((or (equal? this-arg "-g")
+ (equal? this-arg "--group"))
+ (config-group-set! config (string->number (car rest-args)))
+ (loop (cdr rest-args)))
+ (else
+ (print-usage progname)))
+ (begin
+ (config-root-dir-set! config (car args))
+ (config-host-set! config (cadr args))
+ (if (>= (length rest-args) 2)
+ (config-port-set! config (string->number (caddr args))))
+ (run-server config))))))))
+
+(main)
+
+;; (define (test)
+;; (run-server (make-config "gopher-root" "localhost" 70 #t '() '())))
+
+;; (test)
The Lambda Lab / projects / scratchy.git / blobdiff