+;;; Burrower gopher server
+;;
+;; Requires Chicken 5.0.0.
+;;
+
;;; Imports
-;; Chicken 5
(import (chicken tcp)
(chicken port)
(chicken io)
(chicken string)
(chicken pathname)
- (chicken file posix)
+ (chicken file)
(chicken time posix)
(chicken condition)
(chicken process)
(chicken process-context)
+ (chicken process-context posix)
srfi-1 srfi-13 matchable)
-;; Chicken 4
-;; (use srfi-1 srfi-13 tcp posix matchable)
-
;;; Global constants
-(define gopher-index-file-name "index")
-
(define burrower-version "1.0.0")
(define burrower-footer
(conc "\n"
"--------------------------------------------------\n"
- "This gopher hole was dug using Burrower v" burrower-version "\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,
;; 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)
+(define-record config
+ root-dir host port display-footer user group)
(define (run-server config)
- (print "Gopher server listening on port " (config-port config) " ...")
+ (set-buffering-mode! (current-output-port) #:line)
(let ((listener (tcp-listen (config-port config))))
- (let server-loop ()
- (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))
- (tcp-close listener)))
-
+ (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 (infer-selector-type selector)
(let ((l (string-downcase selector)))
(cond
- ((or (= (string-length l) 0) (string-suffix? "/" l)) 1)
+ ((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 "?.scm") 7)
+ ((has-suffix? l "?" "%3f") 7)
((has-prefix? l "url:" "/url:") 'h)
(else 9))))
(let* ((selector-list (string-split raw-selector "\t"))
(selector (car selector-list))
(arguments (cdr selector-list)))
- (case (infer-selector-type selector)
- ((1) (serve-directory selector config))
- ((0) (serve-text-file selector config))
- ((7) (serve-query selector arguments config))
- ((h) (serve-url selector config))
- (else (serve-binary-file selector config)))))
-
-(define (serve-directory selector config)
- (let ((file-name (make-pathname (list (config-root-dir config) selector)
- gopher-index-file-name)))
- (if (regular-file? file-name)
+ (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 file-name
+ (with-input-from-file filename
(lambda ()
(let loop ((c (peek-char)))
(if (eof-object? c)
(serve-info-records (read-line)))
(loop (peek-char)))))))
(if (config-display-footer config)
- (serve-info-records burrower-footer)))
- (error "Index file not found."))))
+ (serve-info-records burrower-footer))
+ (print ".\r"))
+ (error "No legal index file not found."))))
(define (serve-text-file selector config)
- (let ((file-name (make-pathname (config-root-dir config) selector)))
- (if (regular-file? file-name)
- (with-input-from-file file-name
- (lambda ()
- (for-each
- (lambda (line)
- (print line "\r"))
- (read-lines))))
- (error "File not found." file-name))))
+ (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 ((file-name (make-pathname (config-root-dir config) selector)))
- (if (regular-file? file-name)
- (with-input-from-file file-name
+ (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)
(begin
(write-byte b)
(loop (read-byte)))))))
- (error "File not found." file-name))))
-
-(define (serve-query selector arguments config)
- (let ((file-name (make-pathname (config-root-dir config) selector)))
- (if (and (regular-file? file-name)
- (= (length arguments) 1))
- (with-input-from-file file-name
- (lambda ()
- (serve-info-records
- (with-selector-dir
- selector config
- (lambda ()
- (apply (eval (read)) arguments))))))
- (error "Invalid query." selector arguments))))
-
+ (error "File not found." filename))))
(define (serve-url selector config)
(let ((url (substring selector 4)))
(print
- "If you are seeing this page, your gopher browser does not\r\n"
- "properly support URL directory entries or cannot follow such\r\n"
- "links. To view the link you requested, use a web browser to\r\n"
- "open the follwing url:\r\n"
- "\r\n"
- url "\r\n")))
+ "<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)
(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)
(serve-record (list (infer-selector-type selector) display-string selector)
dir-selector config))
((selector)
- (serve-record (list (infer-selecto-type selector) selector)
+ (serve-record (list (infer-selector-type selector) selector)
dir-selector config))
(else (error "Unknown record type."))))
(let ((string (read-string #f in-port)))
(if (and (not (eof-object? string))
(> (string-length string) 0))
- (serve-info-records (string-chomp string "\n"))))))))
+ (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-info-records (conc (eval expression))))))
+ (serve-records (eval expression) dir-selector config))))
;;; Utility methods
(make-pathname (config-root-dir config)
(pathname-directory selector)) thunk))
-;;; main
+
+;;; Main
(define (print-usage progname)
(print "Usage:\n"
progname " -h/--help\n"
- progname " [-n/--no-footer] gopher-root-dir server-hostname [server-port]\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 -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)))
- (args (cdr (argv)))
- (config (make-config '() '() 70 #t)))
-
- (if (or (null? args)
- (equal? (car args) "-h")
- (equal? (car args) "--help"))
+ (config (make-config '() '() 70 #t '() '())))
+ (if (null? (cdr (argv)))
(print-usage progname)
- (begin
- (if (or (equal? (car args) "-n")
- (equal? (car args) "--no-footer"))
- (begin
- (config-display-footer-set! config #f)
- (set! args (cdr args))))
- (if (or (< (length args) 2)
- (> (length args) 3))
- (print-usage progname)
- (begin
- (config-root-dir-set! config (car args))
- (config-host-set! config (cadr args))
- (if (= (length args) 3)
- (config-port-set! config (string->number (caddr args))))
- (run-server config)))))))
+ (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)))
+;; (run-server (make-config "gopher-root" "localhost" 70 #t '() '())))
;; (test)
The Lambda Lab / projects / scratchy.git / blobdiff