Worked a bit more on address->url conversion.
[elpher.git] / elpher.el
index 56ab5e8..214f24f 100644 (file)
--- a/elpher.el
+++ b/elpher.el
@@ -4,10 +4,10 @@
 
 ;; Author: Tim Vaughan <tgvaughan@gmail.com>
 ;; Created: 11 April 2019
-;; Version: 1.2.0
+;; Version: 1.4.7
 ;; Keywords: comm gopher
 ;; Homepage: https://github.com/tgvaughan/elpher
-;; Package-Requires: ((emacs "25"))
+;; Package-Requires: ((emacs "26"))
 
 ;; This file is not part of GNU Emacs.
 
 
 ;;; Commentary:
 
-;; Elpher aims to provide a practical gopher client for GNU Emacs.
-;; It supports:
+;; Elpher aims to provide a practical and friendly gopher client
+;; for GNU Emacs.  It supports:
 
-;; - intuitive keyboard and mouse-driven interface,
-;; - caching of visited sites (both content and cursor position),
+;; - intuitive keyboard and mouse-driven browsing,
+;; - out-of-the-box compatibility with evil-mode,
+;; - clickable web and gopher links *in plain text*,
+;; - caching of visited sites,
 ;; - pleasant and configurable colouring of Gopher directories,
 ;; - direct visualisation of image files,
-;; - (m)enu key support, similar to Emacs' info browser,
-;; - clickable web and gopher links in plain text,
-;; - a simple bookmark management system.
-
-;; Visited pages are stored as a hierarchy rather than a linear history,
-;; meaning that navigation between these pages is quick and easy.
+;; - a simple bookmark management system,
+;; - connections using TLS encryption.
 
 ;; To launch Elpher, simply use 'M-x elpher'.  This will open a start
 ;; page containing information on key bindings and suggested starting
 ;; points for your gopher exploration.
 
-;; Faces, caching and other options can be configured via
-;; the Elpher customization group in Applications.
+;; Full instructions can be found in the Elpher info manual.
+
+;; Elpher is under active development.  Any suggestions for
+;; improvements are welcome!
 
 ;;; Code:
 
 (provide 'elpher)
+
+;;; Dependencies
+;;
+
 (require 'seq)
 (require 'pp)
 (require 'shr)
+(require 'url-util)
+
 
 ;;; Global constants
 ;;
 
-(defconst elpher-version "1.2.0"
+(defconst elpher-version "1.4.7"
   "Current version of elpher.")
 
 (defconst elpher-margin-width 6
   "Width of left-hand margin used when rendering indicies.")
 
-(defconst elpher-start-index
-  (mapconcat
-   'identity
-   (list "i\tfake\tfake\t1"
-         "i     --------------------------------------------\tfake\tfake\t1"
-         "i                Elpher Gopher Client             \tfake\tfake\t1"
-         (format "i                   version %s\tfake\tfake\t1" elpher-version)
-         "i     --------------------------------------------\tfake\tfake\t1"
-         "i\tfake\tfake\t1"
-         "iUsage:\tfake\tfake\t1"
-         "i\tfake\tfake\t1"
-         "i - tab/shift-tab: next/prev item on current page\tfake\tfake\t1"
-         "i - RET/mouse-1: open item under cursor\tfake\tfake\t1"
-         "i - m: select an item on current page by name (autocompletes)\tfake\tfake\t1"
-         "i - u: return to parent\tfake\tfake\t1"
-         "i - O: visit the root menu of the current server\tfake\tfake\t1"
-         "i - g: go to a particular menu or item\tfake\tfake\t1"
-         "i - i/I: info on item under cursor or current page\tfake\tfake\t1"
-         "i - c/C: copy URL representation of item under cursor or current page\tfake\tfake\t1"
-         "i - a/A: bookmark the item under cursor or current page\tfake\tfake\t1"
-         "i - x/X: remove bookmark for item under cursor or current page\tfake\tfake\t1"
-         "i - B: visit the bookmarks page\tfake\tfake\t1"
-         "i - r: redraw current page (using cached contents if available)\tfake\tfake\t1"
-         "i - R: reload current page (regenerates cache)\tfake\tfake\t1"
-         "i - d: download directory entry under cursor\tfake\tfake\t1"
-         "i - w: display the raw server response for the current page\tfake\tfake\t1"
-         "i\tfake\tfake\t1"
-         "iWhere to start exploring Gopherspace:\tfake\tfake\t1"
-         "i\tfake\tfake\t1"
-         "1Floodgap Systems Gopher Server\t/\tgopher.floodgap.com\t70"
-         "i\tfake\tfake\t1"
-         "iAlternatively, select the following item and enter some\tfake\tfake\t1"
-         "isearch terms:\tfake\tfake\t1"
-         "i\tfake\tfake\t1"
-         "7Veronica-2 Gopher Search Engine\t/v2/vs\tgopher.floodgap.com\t70"
-         ".\r\n")
-   "\r\n")
-  "Source for elpher start page.")
-
-(defconst elpher-type-map
-  '((?0 elpher-get-text-node "T" elpher-text)
-    (?1 elpher-get-index-node "/" elpher-index)
-    (?4 elpher-get-node-download "B" elpher-binary)
-    (?5 elpher-get-node-download "B" elpher-binary)
-    (?7 elpher-get-search-node "?" elpher-search)
-    (?8 elpher-get-telnet-node "?" elpher-telnet)
-    (?9 elpher-get-node-download "B" elpher-binary)
-    (?g elpher-get-image-node "im" elpher-image)
-    (?p elpher-get-image-node "im" elpher-image)
-    (?I elpher-get-image-node "im" elpher-image)
-    (?d elpher-get-node-download "d" elpher-binary)
-    (?h elpher-get-url-node "W" elpher-url)
-    (bookmarks elpher-get-bookmarks-node "#" elpher-index)
-    (start elpher-get-start-node "#" elpher-index))
+(defconst elpher-transport-map
+  '(("gopher" elpher-get-gopher-selector)
+    ("gophers" elpher-get-gopher-selector)
+    ("gemini" elpher-get-gemini-selector)))
+
+(defconst elpher-gopher-type-map
+  '((?0 elpher-display-text "txt" elpher-text)
+    (?1 elpher-display-gophermap "/" elpher-index)
+    (?4 nil "bin" elpher-binary)
+    (?5 nil "bin" elpher-binary)
+    (?7 elpher-display-search-node "?" elpher-search)
+    (?8 elpher-display-telnet-node "tel" elpher-telnet)
+    (?9 nil "bin" elpher-binary)
+    (?g elpher-display-image-node "img" elpher-image)
+    (?p elpher-display-image-node "img" elpher-image)
+    (?I elpher-display-image-node "img" elpher-image)
+    (?d nil "doc" elpher-binary)
+    (?P nil "doc" elpher-binary)
+    (?s nil "snd" elpher-binary)
+    (?h elpher-display-node-html "htm" elpher-html))
   "Association list from types to getters, margin codes and index faces.")
 
+(defconst elpher-mime-type-map
+  '(("text/gemini" elpher-display-node-text)
+    ("text/html" elpher-display-node-html)
+    ("text/*" elpher-display-node-text)
+    ("image/*" elpher-display-image-node)))
 
 ;;; Customization group
 ;;
@@ -184,66 +161,91 @@ Otherwise, use the system browser via the BROWSE-URL function."
   "If non-nil, turns URLs matched in directories into clickable buttons."
   :type '(boolean))
 
-(defcustom elpher-cache-images nil
-  "If non-nil, cache images in memory in the same way as other content."
-  :type '(boolean))
-
 (defcustom elpher-use-header t
   "If non-nil, display current node information in buffer header."
   :type '(boolean))
 
+(defcustom elpher-auto-disengage-TLS nil
+  "If non-nil, automatically disengage TLS following an unsuccessful connection.
+While enabling this may seem convenient, it is also potentially dangerous as it
+allows switching from an encrypted channel back to plain text without user input."
+  :type '(boolean))
+
+
 ;;; Model
 ;;
 
 ;; Address
 
-(defun elpher-make-address (type &optional selector host port)
-  "Create an address of a gopher object with TYPE, SELECTOR, HOST and PORT.
-Although selector host and port are optional, they are only omitted for
-special address types, such as 'start for the start page."
-  (list type selector host port))
-
-(defun elpher-address-type (address)
-  "Retrieve type from ADDRESS."
-  (elt address 0))
-
-(defun elpher-address-selector (address)
-  "Retrieve selector from ADDRESS."
-  (elt address 1))
-
-(defun elpher-address-host (address)
-  "Retrieve host from ADDRESS."
-  (elt address 2))
-
-(defun elpher-address-port (address)
-  "Retrieve port from ADDRESS."
-  (elt address 3))
-
-(defun elpher-address-special-p (address)
-  "Return non-nil if ADDRESS is special (e.g. start page, bookmarks page)."
-  (not (elpher-address-host address)))
+(defun elpher-url-from-string (url-string)
+  "Create a URL object corresponding to the given URL-STRING."
+  (let ((url (url-generic-parse-url url-string)))
+    (if (and (url-type url)
+             (url-host url))
+        (setf (url-filename url) (url-unhex-string (url-filename url)))
+      (error "Malformed URL" url))))
+
+(defun elpher-url-to-url-string (url)
+  "Get string representation of URL."
+  (url-encode-url (url-recreate url)))
+
+(defun elpher-url-gopher-p (url)
+  "Return non-nil if URL object specifies a gopher address."
+  (let ((protocol (url-type url)))
+    (if (or (string-equal protocol "gopher")
+            (string-equal protocol "gophers")))))
+
+(defun elpher-gopher-url-selector-type (url)
+  "Retrieve selector type from URL object."
+  (let ((filename (url-filename url)))
+    (if (> (length filename) 0)
+        (string-to-char filename)
+      ?1)))
+
+(defun elpher-gopher-url-selector (url)
+  "Retrieve selector from URL object."
+  (let ((filename (url-filename url)))
+    (if (> (length filename) 0)
+        (substring filename 1)
+      "")))
+
+(defun elpher-url-host (url)
+  "Retrieve host from URL object."
+  (url-host url))
+
+(defun elpher-url-port (url)
+  "Retrieve port from URL object."
+  (url-port url))
+
+(defun elpher-url-use-tls-p (url)
+  "Return non-nil if URL is marked as needing TLS."
+  (string-equal (url-type address) "gophers"))
+
+(defun elpher-url-special-p (url)
+  "Return non-nil if URL object is special (e.g. start page, bookmarks page)."
+  (symbolp url))
 
 ;; Node
 
-(defun elpher-make-node (display-string address &optional parent)
-  "Create a node in the gopher page hierarchy.
+(defun elpher-make-node (display-string url &optional parent)
+  "Create a node in the page hierarchy.
 
 DISPLAY-STRING records the display string used for the page.
 
-ADDRESS specifies the address of the gopher page.
+URL specifies the url object of the page.
 
 The optional PARENT specifies the parent node in the hierarchy.
 This is set every time the node is visited, so while it forms
 an important part of the node data there is no need to set it
 initially."
-  (list display-string address parent))
+  (list display-string url parent))
 
 (defun elpher-node-display-string (node)
   "Retrieve the display string of NODE."
   (elt node 0))
 
-(defun elpher-node-address (node)
-  "Retrieve the address of NODE."
+(defun elpher-node-url (node)
+  "Retrieve the URL object of NODE."
   (elt node 1))
 
 (defun elpher-node-parent (node)
@@ -259,44 +261,56 @@ initially."
 (defvar elpher-content-cache (make-hash-table :test 'equal))
 (defvar elpher-pos-cache (make-hash-table :test 'equal))
 
-(defun elpher-get-cached-content (address)
-  "Retrieve the cached content for ADDRESS, or nil if none exists."
-  (gethash address elpher-content-cache))
+(defun elpher-get-cached-content (url)
+  "Retrieve the cached content for URL, or nil if none exists."
+  (gethash url elpher-content-cache))
 
-(defun elpher-cache-content (address content)
-  "Set the content cache for ADDRESS to CONTENT."
-  (puthash address content elpher-content-cache))
+(defun elpher-cache-content (url content)
+  "Set the content cache for URL to CONTENT."
+  (puthash url content elpher-content-cache))
 
-(defun elpher-get-cached-pos (address)
-  "Retrieve the cached cursor position for ADDRESS, or nil if none exists."
-  (gethash address elpher-pos-cache))
+(defun elpher-get-cached-pos (url)
+  "Retrieve the cached cursor position for URL, or nil if none exists."
+  (gethash url elpher-pos-cache))
 
-(defun elpher-cache-pos (address pos)
-  "Set the cursor position cache for ADDRESS to POS."
-  (puthash address pos elpher-pos-cache))
+(defun elpher-cache-pos (url pos)
+  "Set the cursor position cache for URL to POS."
+  (puthash url pos elpher-pos-cache))
 
 ;; Node graph traversal
 
 (defvar elpher-current-node nil)
 
-(defun elpher-visit-node (node &optional getter)
-  "Visit NODE using its own getter or GETTER, if non-nil."
+(defun elpher-visit-node (node &optional getter preserve-parent)
+  "Visit NODE using its own getter or GETTER, if non-nil.
+Additionally, set the parent of NODE to `elpher-current-node',
+unless PRESERVE-PARENT is non-nil."
   (elpher-save-pos)
   (elpher-process-cleanup)
-  (unless (eq node (elpher-node-parent elpher-current-node))
-      (elpher-set-node-parent node elpher-current-node))
+  (unless preserve-parent
+    (if (and (elpher-node-parent elpher-current-node)
+             (equal (elpher-node-url elpher-current-node)
+                    (elpher-node-url node)))
+        (elpher-set-node-parent node (elpher-node-parent elpher-current-node))
+      (elpher-set-node-parent node elpher-current-node)))
   (setq elpher-current-node node)
   (if getter
       (funcall getter)
-    (let* ((address (elpher-node-address node))
-           (type (elpher-address-type address)))
-      (funcall (car (alist-get type elpher-type-map))))))
+    ;; The business below needs updating: mapping from url->getter is different
+    ;; and more complex.
+    (let* ((url (elpher-node-url node))
+           (type (elpher-address-type address))
+           (type-record (alist-get type elpher-type-map)))
+      (if type-record
+          (funcall (car type-record))
+        (elpher-visit-parent-node)
+        (error "Unsupported gopher selector type '%c'" type)))))
 
 (defun elpher-visit-parent-node ()
   "Visit the parent of the current node."
   (let ((parent-node (elpher-node-parent elpher-current-node)))
     (when parent-node
-      (elpher-visit-node parent-node))))
+      (elpher-visit-node parent-node nil t))))
       
 (defun elpher-reload-current-node ()
   "Reload the current node, discarding any existing cached content."
@@ -334,14 +348,28 @@ initially."
                 args)))
 
 
-;;; Index rendering
+;;; Text Processing
 ;;
 
+(defvar elpher-user-coding-system nil
+  "User-specified coding system to use for decoding text responses.")
+
+(defun elpher-decode (string)
+  "Decode STRING using autodetected or user-specified coding system."
+  (decode-coding-string string
+                        (if elpher-user-coding-system
+                            elpher-user-coding-system
+                          (detect-coding-string string t))))
+
 (defun elpher-preprocess-text-response (string)
-  "Clear away CRs and terminating period from STRING."
-  (replace-regexp-in-string "\n\.\n$" "\n"
-                            (replace-regexp-in-string "\r" ""
-                                                      string)))
+  "Preprocess text selector response contained in STRING.
+This involes decoding the character representation, and clearing
+away CRs and any terminating period."
+  (elpher-decode (replace-regexp-in-string "\n\.\n$" "\n"
+                                           (replace-regexp-in-string "\r" "" string))))
+
+;;; Index rendering
+;;
 
 (defun elpher-insert-index (string)
   "Insert the index corresponding to STRING into the current buffer."
@@ -357,8 +385,9 @@ initially."
                (host (elt fields 2))
                (port (if (elt fields 3)
                          (string-to-number (elt fields 3))
-                       nil)))
-          (elpher-insert-index-record display-string type selector host port))))))
+                       nil))
+               (address (elpher-make-address type selector host port)))
+          (elpher-insert-index-record display-string address))))))
 
 (defun elpher-insert-margin (&optional type-name)
   "Insert index margin, optionally containing the TYPE-NAME, into the current buffer."
@@ -383,12 +412,12 @@ initially."
               (elpher-address-host address)
               (elpher-address-port address)))))
 
-(defun elpher-insert-index-record (display-string type selector host port)
+
+(defun elpher-insert-index-record (display-string address)
   "Function to insert an index record into the current buffer.
-The contents of the record are dictated by TYPE, DISPLAY-STRING, SELECTOR, HOST
-and PORT."
-  (let ((address (elpher-make-address type selector host port))
-        (type-map-entry (alist-get type elpher-type-map)))
+The contents of the record are dictated by DISPLAY-STRING and ADDRESS."
+  (let* ((type (elpher-address-type address))
+         (type-map-entry (alist-get type elpher-type-map)))
     (if type-map-entry
         (let* ((margin-code (elt type-map-entry 1))
                (face (elt type-map-entry 2))
@@ -428,29 +457,59 @@ and PORT."
   (let ((p (get-process "elpher-process")))
     (if p (delete-process p))))
 
+(defvar elpher-use-tls nil
+  "If non-nil, use TLS to communicate with gopher servers.")
+
 (defvar elpher-selector-string)
 
-(defun elpher-get-selector (address after)
+(defun elpher-get-selector (address after &optional propagate-error)
   "Retrieve selector specified by ADDRESS, then execute AFTER.
-The result is stored as a string in the variable ‘elpher-selector-string’."
+The result is stored as a string in the variable ‘elpher-selector-string’.
+
+Usually errors result in an error page being displayed.  This is only
+appropriate if the selector is to be directly viewed.  If PROPAGATE-ERROR
+is non-nil, this message is not displayed.  Instead, the error propagates
+up to the calling function."
   (setq elpher-selector-string "")
-  (condition-case nil
-      (progn
-        (make-network-process :name "elpher-process"
-                              :host (elpher-address-host address)
-                              :service (elpher-address-port address)
-                              :filter (lambda (proc string)
-                                        (setq elpher-selector-string
-                                              (concat elpher-selector-string string)))
-                              :sentinel after)
-        (process-send-string "elpher-process"
+  (when (elpher-address-use-tls-p address)
+      (if (gnutls-available-p)
+          (when (not elpher-use-tls)
+            (setq elpher-use-tls t)
+            (message "Engaging TLS mode."))
+        (error "Cannot retrieve TLS selector: GnuTLS not available")))
+  (condition-case the-error
+      (let* ((kill-buffer-query-functions nil)
+             (proc (open-network-stream "elpher-process"
+                                       nil
+                                       (elpher-address-host address)
+                                       (elpher-address-port address)
+                                       :type (if elpher-use-tls 'tls 'plain))))
+        (set-process-coding-system proc 'binary)
+        (set-process-filter proc
+                            (lambda (proc string)
+                              (setq elpher-selector-string
+                                    (concat elpher-selector-string string))))
+        (set-process-sentinel proc after)
+        (process-send-string proc
                              (concat (elpher-address-selector address) "\n")))
     (error
-     (elpher-with-clean-buffer
-      (insert (propertize "\n---- ERROR -----\n\n" 'face 'error)
-              "Failed to connect to " (elpher-get-address-url address) ".\n"
-              (propertize "\n----------------\n\n" 'face 'error)
-              "Press 'u' to return to the previous page.")))))
+     (if (and (consp the-error)
+              (eq (car the-error) 'gnutls-error)
+              (not (elpher-address-use-tls-p address))
+              (or elpher-auto-disengage-TLS
+                  (yes-or-no-p "Could not establish encrypted connection.  Disable TLS mode? ")))
+         (progn
+           (message "Disengaging TLS mode.")
+           (setq elpher-use-tls nil)
+           (elpher-get-selector address after))
+       (elpher-process-cleanup)
+       (if propagate-error
+           (error the-error)
+         (elpher-with-clean-buffer
+          (insert (propertize "\n---- ERROR -----\n\n" 'face 'error)
+                  "Failed to connect to " (elpher-get-address-url address) ".\n"
+                  (propertize "\n----------------\n\n" 'face 'error)
+                  "Press 'u' to return to the previous page.")))))))
 
 ;; Index retrieval
 
@@ -478,7 +537,7 @@ The result is stored as a string in the variable ‘elpher-selector-string’."
 ;; Text retrieval
 
 (defconst elpher-url-regex
-  "\\([a-zA-Z]+\\)://\\([a-zA-Z0-9.\-]+\\)\\(?3::[0-9]+\\)?\\(?4:/[^ \r\n\t(),]*\\)?"
+  "\\([a-zA-Z]+\\)://\\([a-zA-Z0-9.\-]+\\|\[[a-zA-Z0-9:]+\]\\)\\(?3::[0-9]+\\)?\\(?4:/[^ \r\n\t(),]*\\)?"
   "Regexp used to locate and buttinofy URLs in text files loaded by elpher.")
 
 (defun elpher-make-node-from-matched-url (&optional string)
@@ -488,8 +547,12 @@ If STRING is non-nil, this is given as an argument to all `match-string'
 calls, as is necessary if the match is performed by `string-match'."
   (let ((url (match-string 0 string))
         (protocol (downcase (match-string 1 string))))
-    (if (string= protocol "gopher")
-        (let* ((host (match-string 2 string))
+    (if (or (string= protocol "gopher")
+            (string= protocol "gophers"))
+        (let* ((bare-host (match-string 2 string))
+               (host (if (string-prefix-p "[" bare-host)
+                         (substring bare-host 1 (- (length bare-host) 1))
+                       bare-host))
                (port (if (> (length (match-string 3 string))  1)
                          (string-to-number (substring (match-string 3 string) 1))
                        70))
@@ -497,10 +560,13 @@ calls, as is necessary if the match is performed by `string-match'."
                (type (if (> (length type-and-selector) 1)
                          (elt type-and-selector 1)
                        ?1))
-               (selector (if (> (length type-and-selector) 1)
-                             (substring type-and-selector 2)
-                           ""))
-               (address (elpher-make-address type selector host port)))
+               (selector (decode-coding-string
+                          (url-unhex-string
+                           (if (> (length type-and-selector) 1)
+                               (substring type-and-selector 2)
+                             "")) 'utf-8))
+               (use-tls (string= protocol "gophers"))
+               (address (elpher-make-address type selector host port use-tls)))
           (elpher-make-node url address))
       (let* ((host (match-string 2 string))
              (port (if (> (length (match-string 3 string)) 1)
@@ -554,33 +620,21 @@ calls, as is necessary if the match is performed by `string-match'."
 
 (defun elpher-get-image-node ()
   "Getter which retrieves the current node contents as an image to view."
-  (let* ((address (elpher-node-address elpher-current-node))
-         (content (elpher-get-cached-content address)))
-    (if content
+  (let* ((address (elpher-node-address elpher-current-node)))
+    (if (display-images-p)
         (progn
           (elpher-with-clean-buffer
-           (insert-image content)
-           (elpher-restore-pos)))
-      (if (display-images-p)
-          (progn
-            (elpher-with-clean-buffer
-             (insert "LOADING IMAGE... (use 'u' to cancel)"))
-            (elpher-get-selector address
-                                 (lambda (proc event)
-                                   (unless (string-prefix-p "deleted" event)
-                                     (let ((image (create-image
-                                                   (encode-coding-string
-                                                    elpher-selector-string
-                                                    'no-conversion)
-                                                   nil t)))
-                                       (elpher-with-clean-buffer
-                                        (insert-image image)
-                                        (elpher-restore-pos))
-                                       (if elpher-cache-images
-                                           (elpher-cache-content
-                                            (elpher-node-address elpher-current-node)
-                                            image)))))))
-        (elpher-get-node-download)))))
+           (insert "LOADING IMAGE... (use 'u' to cancel)"))
+          (elpher-get-selector address
+                               (lambda (proc event)
+                                 (unless (string-prefix-p "deleted" event)
+                                   (let ((image (create-image
+                                                 elpher-selector-string
+                                                 nil t)))
+                                     (elpher-with-clean-buffer
+                                      (insert-image image)
+                                      (elpher-restore-pos)))))))
+      (elpher-get-node-download))))
 
 ;; Search retrieval
 
@@ -624,17 +678,12 @@ calls, as is necessary if the match is performed by `string-match'."
   (let ((address (elpher-node-address elpher-current-node)))
     (elpher-with-clean-buffer
      (insert "LOADING RAW SERVER RESPONSE... (use 'u' to cancel)"))
-    (if address
-        (elpher-get-selector address
-                              (lambda (proc event)
-                                (unless (string-prefix-p "deleted" event)
-                                  (elpher-with-clean-buffer
-                                   (insert elpher-selector-string)
-                                   (goto-char (point-min))))))
-      (progn
-        (elpher-with-clean-buffer
-         (insert elpher-start-index))
-        (goto-char (point-min)))))
+    (elpher-get-selector address
+                         (lambda (proc event)
+                           (unless (string-prefix-p "deleted" event)
+                             (elpher-with-clean-buffer
+                              (insert elpher-selector-string)
+                              (goto-char (point-min)))))))
   (message "Displaying raw server response.  Reload or redraw to return to standard view."))
  
 ;; File export retrieval
@@ -654,13 +703,17 @@ calls, as is necessary if the match is performed by `string-match'."
                                        "gopher.file"))))
       (message "Downloading...")
       (setq elpher-download-filename filename)
-      (elpher-get-selector address
-                            (lambda (proc event)
-                              (let ((coding-system-for-write 'binary))
-                                (with-temp-file elpher-download-filename
-                                  (insert elpher-selector-string)
-                                  (message (format "Download complate, saved to file %s."
-                                                   elpher-download-filename)))))))))
+      (condition-case the-error
+          (elpher-get-selector address
+                               (lambda (proc event)
+                                 (let ((coding-system-for-write 'binary))
+                                   (with-temp-file elpher-download-filename
+                                     (insert elpher-selector-string)
+                                     (message (format "Download complate, saved to file %s."
+                                                      elpher-download-filename)))))
+                               t)
+        (error
+         (error "Error downloading %s" elpher-download-filename))))))
 
 ;; URL retrieval
 
@@ -716,7 +769,53 @@ calls, as is necessary if the match is performed by `string-match'."
 (defun elpher-get-start-node ()
   "Getter which displays the start page."
   (elpher-with-clean-buffer
-   (elpher-insert-index elpher-start-index)
+   (insert "     --------------------------------------------\n"
+           "                Elpher Gopher Client             \n"
+           "                   version " elpher-version "\n"
+           "     --------------------------------------------\n"
+           "\n"
+           "Default bindings:\n"
+           "\n"
+           " - TAB/Shift-TAB: next/prev item on current page\n"
+           " - RET/mouse-1: open item under cursor\n"
+           " - m: select an item on current page by name (autocompletes)\n"
+           " - u: return to previous page\n"
+           " - o/O: visit different selector or the root menu of the current server\n"
+           " - g: go to a particular gopher address\n"
+           " - i/I: info on item under cursor or current page\n"
+           " - c/C: copy URL representation of item under cursor or current page\n"
+           " - a/A: bookmark the item under cursor or current page\n"
+           " - x/X: remove bookmark for item under cursor or current page\n"
+           " - B: visit the bookmarks page\n"
+           " - r: redraw current page (using cached contents if available)\n"
+           " - R: reload current page (regenerates cache)\n"
+           " - T: toggle TLS mode\n"
+           " - d/D: download item under cursor or current page\n"
+           " - .: display the raw server response for the current page\n"
+           " - S: set an explicit character coding system (default is to autodetect)\n"
+           "\n"
+           "Start your exploration of gopher space:\n")
+   (elpher-insert-index-record "Floodgap Systems Gopher Server"
+                               (elpher-make-address ?1 "" "gopher.floodgap.com" 70))
+   (insert "\n"
+           "Alternatively, select the following item and enter some search terms:\n")
+   (elpher-insert-index-record "Veronica-2 Gopher Search Engine"
+                               (elpher-make-address ?7 "/v2/vs" "gopher.floodgap.com" 70))
+   (insert "\n"
+           "** Refer to the ")
+   (let ((help-string "RET,mouse-1: Open Elpher info manual (if available)"))
+     (insert-text-button "Elpher info manual"
+                         'face 'link
+                         'action (lambda (button)
+                                   (interactive)
+                                   (info "(elpher)"))
+                         'follow-link t
+                         'help-echo help-string))
+   (insert " for the full documentation. **\n")
+   (insert (propertize
+            (concat "  (This should be available if you have installed Elpher using\n"
+                    "   MELPA. Otherwise you will have to install the manual yourself.)")
+            'face 'shadow))
    (elpher-restore-pos)))
 
 ;; Bookmarks page node retrieval
@@ -730,11 +829,7 @@ calls, as is necessary if the match is performed by `string-match'."
          (dolist (bookmark bookmarks)
            (let ((display-string (elpher-bookmark-display-string bookmark))
                  (address (elpher-bookmark-address bookmark)))
-             (elpher-insert-index-record display-string
-                                         (elpher-address-type address)
-                                         (elpher-address-selector address)
-                                         (elpher-address-host address)
-                                         (elpher-address-port address))))
+             (elpher-insert-index-record display-string address)))
        (insert "No bookmarks found.\n")))
    (insert "\n-----------------------\n\n"
            "- u: return to previous page\n"
@@ -802,6 +897,7 @@ If ADDRESS is already bookmarked, update the label only."
                    (not (equal (elpher-bookmark-address bookmark) address)))
                  (elpher-load-bookmarks))))
 
+
 ;;; Interactive procedures
 ;;
 
@@ -839,20 +935,44 @@ host, selector and port."
     (switch-to-buffer "*elpher*")
     (elpher-visit-node node)))
 
-(defun  elpher-redraw ()
+(defun elpher-go-current ()
+  "Go to a particular site read from the minibuffer, initialized with the current URL."
+  (interactive)
+  (let ((address (elpher-node-address elpher-current-node)))
+    (if (elpher-address-special-p address)
+        (error "Command not valid for this page")
+      (let ((url (read-string "URL: " (elpher-get-address-url address))))
+        (if (string-match elpher-url-regex url)
+            (let ((new-node (elpher-make-node-from-matched-url url)))
+              (unless (equal (elpher-node-address new-node) address)
+                (elpher-visit-node new-node)))
+          (error "Could not parse URL %s" url))))))
+
+(defun elpher-redraw ()
   "Redraw current page."
   (interactive)
   (if elpher-current-node
       (elpher-visit-node elpher-current-node)
     (message "No current site.")))
 
-(defun  elpher-reload ()
+(defun elpher-reload ()
   "Reload current page."
   (interactive)
   (if elpher-current-node
       (elpher-reload-current-node)
     (message "No current site.")))
 
+(defun elpher-toggle-tls ()
+  "Toggle TLS encryption mode."
+  (interactive)
+  (setq elpher-use-tls (not elpher-use-tls))
+  (if elpher-use-tls
+      (if (gnutls-available-p)
+          (message "TLS mode enabled.  (Will not affect current page until reload.)")
+        (setq elpher-use-tls nil)
+        (error "Cannot enable TLS mode: GnuTLS not available"))
+    (message "TLS mode disabled.  (Will not affect current page until reload.)")))
+
 (defun elpher-view-raw ()
   "View raw server response for current page."
   (interactive)
@@ -882,6 +1002,18 @@ host, selector and port."
                                #'elpher-get-node-download)))
       (error "No link selected"))))
 
+(defun elpher-download-current ()
+  "Download the current page."
+  (interactive)
+  (if (elpher-address-special-p (elpher-node-address elpher-current-node))
+      (error "Cannot download this page")
+    (elpher-visit-node (elpher-make-node
+                        (elpher-node-display-string elpher-current-node)
+                        (elpher-node-address elpher-current-node)
+                        elpher-current-node)
+                       #'elpher-get-node-download
+                       t)))
+
 (defun elpher-build-link-map ()
   "Build alist mapping link names to destination nodes in current buffer."
   (let ((link-map nil)
@@ -935,12 +1067,14 @@ host, selector and port."
 (defun elpher-bookmark-current ()
   "Bookmark the current node."
   (interactive)
-  (unless (elpher-bookmarks-current-p)
-      (let ((address (elpher-node-address elpher-current-node))
-            (display-string (read-string "Bookmark display string: "
-                                         (elpher-node-display-string elpher-current-node))))
-        (elpher-add-address-bookmark address display-string)
-        (message "Bookmark added."))))
+  (let ((address (elpher-node-address elpher-current-node))
+        (display-string (elpher-node-display-string elpher-current-node)))
+    (if (not (elpher-address-special-p address))
+        (let ((bookmark-display-string (read-string "Bookmark display string: "
+                                                    display-string)))
+          (elpher-add-address-bookmark address bookmark-display-string)
+          (message "Bookmark added."))
+      (error "Cannot bookmark %s" display-string))))
 
 (defun elpher-bookmark-link ()
   "Bookmark the link at point."
@@ -949,19 +1083,23 @@ host, selector and port."
     (if button
         (let* ((node (button-get button 'elpher-node))
                (address (elpher-node-address node))
-               (display-string (read-string "Bookmark display string: "
-                                            (elpher-node-display-string node))))
-          (elpher-add-address-bookmark address display-string)
-          (elpher-reload-bookmarks)
-          (message "Bookmark added."))
+               (display-string (elpher-node-display-string node)))
+          (if (not (elpher-address-special-p address))
+              (let ((bookmark-display-string (read-string "Bookmark display string: "
+                                                          display-string)))
+                (elpher-add-address-bookmark address bookmark-display-string)
+                (elpher-reload-bookmarks)
+                (message "Bookmark added."))
+            (error "Cannot bookmark %s" display-string)))
       (error "No link selected"))))
 
 (defun elpher-unbookmark-current ()
   "Remove bookmark for the current node."
   (interactive)
-  (unless (elpher-bookmarks-current-p)
-    (elpher-remove-address-bookmark (elpher-node-address elpher-current-node))
-    (message "Bookmark removed.")))
+  (let ((address (elpher-node-address elpher-current-node)))
+    (unless (elpher-address-special-p address)
+      (elpher-remove-address-bookmark address)
+      (message "Bookmark removed."))))
 
 (defun elpher-unbookmark-link ()
   "Remove bookmark for the link at point."
@@ -975,17 +1113,17 @@ host, selector and port."
       (error "No link selected"))))
 
 (defun elpher-bookmarks ()
-  "Visit bookmarks."
+  "Visit bookmarks page."
   (interactive)
   (switch-to-buffer "*elpher*")
   (elpher-visit-node
-   (elpher-make-node "Bookmarks" (elpher-make-address 'bookmarks))))
+   (elpher-make-node "Bookmarks Page" (elpher-make-address 'bookmarks))))
 
 (defun elpher-info-node (node)
   "Display information on NODE."
   (let ((display-string (elpher-node-display-string node))
         (address (elpher-node-address node)))
-    (if address
+    (if (not (elpher-address-special-p address))
         (message "`%s' on %s port %s"
                 (elpher-address-selector address)
                 (elpher-address-host address)
@@ -1005,25 +1143,14 @@ host, selector and port."
   (interactive)
   (elpher-info-node elpher-current-node))
 
-(defun elpher-get-address-url (address)
-  "Get URL representation of ADDRESS."
-  (concat "gopher://"
-          (elpher-address-host address)
-          (let ((port (elpher-address-port address)))
-            (if (equal port 70)
-                ""
-              (format ":%d" port)))
-          "/" (string (elpher-address-type address))
-          (elpher-address-selector address)))
-
 (defun elpher-copy-node-url (node)
   "Copy URL representation of address of NODE to `kill-ring'."
   (let ((address (elpher-node-address node)))
-    (if address
-        (let ((url (elpher-get-address-url address)))
-          (message url)
-          (kill-new url))
-      (error (format "Cannot represent %s as URL" (elpher-node-display-string node))))))
+    (if (elpher-address-special-p address)
+        (error (format "Cannot represent %s as URL" (elpher-node-display-string node)))
+      (let ((url (elpher-get-address-url address)))
+        (message "Copied \"%s\" to kill-ring/clipboard." url)
+        (kill-new url)))))
 
 (defun elpher-copy-link-url ()
   "Copy URL of item at point to `kill-ring'."
@@ -1038,6 +1165,16 @@ host, selector and port."
   (interactive)
   (elpher-copy-node-url elpher-current-node))
 
+(defun elpher-set-coding-system ()
+  "Specify an explicit character coding system."
+  (interactive)
+  (let ((system (read-coding-system "Set coding system to use (default is to autodetect): " nil)))
+    (setq elpher-user-coding-system system)
+    (if system
+        (message "Coding system fixed to %s. (Reload to see effect)." system)
+      (message "Coding system set to autodetect. (Reload to see effect)."))))
+
+
 ;;; Mode and keymap
 ;;
 
@@ -1048,10 +1185,13 @@ host, selector and port."
     (define-key map (kbd "u") 'elpher-back)
     (define-key map (kbd "O") 'elpher-root-dir)
     (define-key map (kbd "g") 'elpher-go)
+    (define-key map (kbd "o") 'elpher-go-current)
     (define-key map (kbd "r") 'elpher-redraw)
     (define-key map (kbd "R") 'elpher-reload)
-    (define-key map (kbd "w") 'elpher-view-raw)
+    (define-key map (kbd "T") 'elpher-toggle-tls)
+    (define-key map (kbd ".") 'elpher-view-raw)
     (define-key map (kbd "d") 'elpher-download)
+    (define-key map (kbd "D") 'elpher-download-current)
     (define-key map (kbd "m") 'elpher-jump)
     (define-key map (kbd "i") 'elpher-info-link)
     (define-key map (kbd "I") 'elpher-info-current)
@@ -1062,6 +1202,7 @@ host, selector and port."
     (define-key map (kbd "x") 'elpher-unbookmark-link)
     (define-key map (kbd "X") 'elpher-unbookmark-current)
     (define-key map (kbd "B") 'elpher-bookmarks)
+    (define-key map (kbd "S") 'elpher-set-coding-system)
     (when (fboundp 'evil-define-key)
       (evil-define-key 'motion map
         (kbd "TAB") 'elpher-next-link
@@ -1070,10 +1211,13 @@ host, selector and port."
         (kbd "u") 'elpher-back
         (kbd "O") 'elpher-root-dir
         (kbd "g") 'elpher-go
+        (kbd "o") 'elpher-go-current
         (kbd "r") 'elpher-redraw
         (kbd "R") 'elpher-reload
-        (kbd "w") 'elpher-view-raw
+        (kbd "T") 'elpher-toggle-tls
+        (kbd ".") 'elpher-view-raw
         (kbd "d") 'elpher-download
+        (kbd "D") 'elpher-download-current
         (kbd "m") 'elpher-jump
         (kbd "i") 'elpher-info-link
         (kbd "I") 'elpher-info-current
@@ -1083,16 +1227,22 @@ host, selector and port."
         (kbd "A") 'elpher-bookmark-current
         (kbd "x") 'elpher-unbookmark-link
         (kbd "X") 'elpher-unbookmark-current
-        (kbd "B") 'elpher-bookmarks))
+        (kbd "B") 'elpher-bookmarks
+        (kbd "S") 'elpher-set-coding-system))
     map)
   "Keymap for gopher client.")
 
 (define-derived-mode elpher-mode special-mode "elpher"
-  "Major mode for elpher, an elisp gopher client.")
+  "Major mode for elpher, an elisp gopher client.
+
+This mode is automatically enabled by the interactive
+functions which initialize the gopher client, namely
+`elpher', `elpher-go' and `elpher-bookmarks'.")
 
 (when (fboundp 'evil-set-initial-state)
   (evil-set-initial-state 'elpher-mode 'motion))
 
+
 ;;; Main start procedure
 ;;