+++ /dev/null
-;;; Burrower 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 burrower-version "1.0.0")
-
-(define burrower-footer
- (conc "\n"
- "--------------------------------------------------\n"
- "This gopher hole was dug using Burrower v" burrower-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 burrower-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