(import (chicken tcp) (chicken port) (chicken io) (chicken string) (chicken pathname) (chicken file posix) (chicken time posix) (chicken condition) (chicken process) (chicken process-context) srfi-1 srfi-13 matchable) ;;; Global constants (define gopher-index-file-name "index") (define burrow-version "1.0.0") (define burrow-footer (conc "\n" "--------------------------------------------------\n" "Served by Burrow Gopher Server v" burrow-version "\n" "Powered by Chicken Scheme!")) ;;; 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) (define (run-server config) (print "Gopher server listening on port " (config-port config) " ...") (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) remote-ip 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))) ;;; Selector type inference (define (has-suffix? selector . suffixes) (if (null? suffixes) #f (if (string-suffix? (car suffixes) selector) #t (apply has-suffix? selector (cdr suffixes))))) (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 "?") 7) (else 9)))) ;;; Selector retrieval (define (serve-selector raw-selector remote-ip config) (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 remote-ip config)) ((0) (serve-text-file selector config)) ((7) (serve-query selector arguments remote-ip config)) (else (serve-binary-file selector config))))) (define (serve-directory selector remote-ip config) (let ((file-name (make-pathname (list (config-root-dir config) selector) gopher-index-file-name))) (if (regular-file? file-name) (begin (with-input-from-file file-name (lambda () (let loop ((c (peek-char))) (if (eof-object? c) 'done (begin (if (eq? c #\,) (begin (read-char) (serve-record (read) selector remote-ip config) (read-line)) (serve-info-records (read-line))) (loop (peek-char))))))) (if (config-display-footer config) (serve-info-records burrow-footer))) (error "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)))) (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 (lambda () (let loop ((b (read-byte))) (if (eof-object? b) 'done (begin (write-byte b) (loop (read-byte))))))) (error "File not found." file-name)))) (define (serve-query selector arguments remote-ip config) (let ((file-name (make-pathname (config-root-dir config) (conc (string-chomp selector "?") ".scm")))) (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)) (list (car arguments) remote-ip))))))) (error "Invalid query.")))) ;;; Index rendering (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 (('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 "\tfake\t80\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-selecto-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))) (serve-info-records (string-chomp (read-string #f in-port) "\n")))))) (define (serve-expression expression dir-selector config) (with-selector-dir dir-selector config (lambda () (serve-info-records (conc (eval expression)))))) ;;; Utility methods (define (with-current-working-directory directory thunk) (let ((old-wd (current-directory)) (result 'none)) (change-directory directory) (set! result (thunk)) (change-directory old-wd) result)) (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] gopher-root-dir server-hostname [server-port]\n" "\n" "The -n option tells the server to not display a directory footer.")) (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")) (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)))) (print 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))))))) ;; (main) (define (test) (run-server (make-config "gopher-root" "localhost" 70 #t))) ;; (test)