Renamed programme.

[scratchy.git] / gopher-server.scm

diff --git a/gopher-server.scm b/gopher-server.scm
new file mode 100644 (file)
index 0000000..f047bdc
--- /dev/null
+++ b/gopher-server.scm
@@ -0,0 +1,166 @@
+(import (chicken tcp)
+        (chicken port)
+        (chicken io)
+        (chicken string)
+        (chicken pathname)
+        (chicken file posix)
+        (chicken time posix)
+        (chicken condition)
+        (chicken process-context)
+        srfi-13)
+
+(define gopher-index-file-name "index")
+
+;;; Server loop
+;; We don't actually use worker threads here to handle requests,
+;; the server just blocks until the first request is finished.
+
+(define (run-server gopher-root gopher-server-hostname gopher-server-port)
+  (print "Gopher server listening on port " gopher-server-port " ...")
+  (let ((listener (tcp-listen gopher-server-port)))
+    (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-file 
+                     (if (= (string-length selector) 0)
+                         "1/"
+                         selector)
+                     gopher-root
+                     gopher-server-hostname
+                     gopher-server-port)))
+                (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)))
+
+
+;;; Item retrieval
+
+(define (serve-file selector gopher-root server-host server-port)
+  (let ((type (with-input-from-string (substring selector 0 1) read))
+        (path (substring selector 1)))
+    (case type
+      ((1) (serve-index-file path gopher-root server-host server-port))
+      ((0) (serve-text-file path gopher-root))
+      ((9 g I) (serve-binary-file path gopher-root))
+      (else (error "Unhandled file type:" type)))))
+
+(define (serve-index-file path gopher-root server-host server-port)
+  (let ((file-name (make-pathname (list gopher-root path) gopher-index-file-name)))
+    (if (regular-file? file-name)
+        (with-input-from-file file-name
+          (lambda ()
+            (render-index (read)
+                          path
+                          server-host
+                          server-port)))
+        (error "Index file not found."))))
+  
+(define (serve-text-file path gopher-root)
+  (let ((file-name (make-pathname gopher-root path)))
+    (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 path gopher-root)
+  (let ((file-name (make-pathname gopher-root path)))
+    (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))))
+
+
+;;; Index rendering
+
+(define entry-type car)
+
+(define entry-name cadr)
+
+(define (has-selector? entry) (>= (length entry) 3))
+
+(define (entry-selector entry) (list-ref entry 2))
+
+(define (has-host? entry) (>= (length entry) 4))
+
+(define (entry-host entry) (list-ref entry 3))
+
+(define (has-port? entry) (>= (length entry) 5))
+
+(define (entry-port entry) (list-ref entry 4))
+
+(define (render-entry entry default-selector default-host default-port selector-prefix)
+  (let ((name-string (entry-name entry)))
+    (for-each
+     (lambda (name-string-line)
+       (print* (entry-type entry) name-string-line)
+       (print* "\t" (if (has-selector? entry)
+                        (if (has-host? entry)
+                            (entry-selector entry)
+                            (conc (entry-type entry)
+                                  (make-pathname selector-prefix (entry-selector entry))))
+                        default-selector))
+       (print* "\t" (if (has-host? entry)
+                        (entry-host entry)
+                        default-host))
+       (print* "\t" (if (has-port? entry)
+                        (entry-port entry)
+                        default-port))
+       (print* "\r\n"))
+     (string-split name-string "\n" #t))))
+
+(define (render-index index selector-prefix this-host this-port)
+  (for-each
+   (lambda (entry)
+     (if (eq? (entry-type entry) 'i)
+         (render-entry entry "fake.selector" "fake.host" 1 selector-prefix)
+         (render-entry entry "" this-host this-port selector-prefix)))
+   index)
+  (print "."))
+
+
+;;; main
+
+(define (main)
+  (let ((progname (car (argv)))
+        (args (cdr (argv))))
+    (if (or (< (length args) 2)
+            (equal? (car args) "-h")
+            (equal? (car args) "--help"))
+        (print "Usage:\n"
+               progname " -h/--help\n"
+               progname " gopher-root-dir server-hostname server-port")
+        (let ((root (car args))
+              (hostname (cadr args))
+              (port (if (= (length args) 3) (string->number (caddr args)) 70)))
+          (if port
+              (run-server root hostname port)
+              (error "Invalid port argument." port))))))
+
+(main)
+
+;; (define (test)
+  ;; (run-server "gopher-root" "localhost" 70))