Migrating to stack-based history.

[elpher.git] / elpher.el

diff --git a/elpher.el b/elpher.el
index 2c338a3..95c3057 100644 (file)
--- a/elpher.el
+++ b/elpher.el
@@ -4,9 +4,9 @@
 
 ;; Author: Tim Vaughan <tgvaughan@gmail.com>
 ;; Created: 11 April 2019
 
 ;; Author: Tim Vaughan <tgvaughan@gmail.com>
 ;; Created: 11 April 2019

-;; Version: 2.0.3
+;; Version: 2.4.4

 ;; Keywords: comm gopher
 ;; Keywords: comm gopher

-;; Homepage: https://github.com/tgvaughan/elpher
+;; Homepage: http://thelambdalab.xyz/elpher

 ;; Package-Requires: ((emacs "26"))
 
 ;; This file is not part of GNU Emacs.
 ;; Package-Requires: ((emacs "26"))
 
 ;; This file is not part of GNU Emacs.


@@ -37,7 +37,7 @@
 ;; - direct visualisation of image files,
 ;; - a simple bookmark management system,
 ;; - connections using TLS encryption,
 ;; - direct visualisation of image files,
 ;; - a simple bookmark management system,
 ;; - connections using TLS encryption,

-;; - basic support for the fledgling Gemini protocol.
+;; - support for the fledgling Gemini protocol.

 
 ;; To launch Elpher, simply use 'M-x elpher'.  This will open a start
 ;; page containing information on key bindings and suggested starting
 
 ;; To launch Elpher, simply use 'M-x elpher'.  This will open a start
 ;; page containing information on key bindings and suggested starting


@@ -46,7 +46,8 @@
 ;; Full instructions can be found in the Elpher info manual.
 
 ;; Elpher is under active development.  Any suggestions for
 ;; Full instructions can be found in the Elpher info manual.
 
 ;; Elpher is under active development.  Any suggestions for

-;; improvements are welcome!
+;; improvements are welcome, and can be made on the official
+;; project page, gopher://thelambdalab.xyz/1/projects/elpher/.

 
 ;;; Code:
 
 
 ;;; Code:
 


@@ -60,12 +61,13 @@
 (require 'shr)
 (require 'url-util)
 (require 'subr-x)
 (require 'shr)
 (require 'url-util)
 (require 'subr-x)

+(require 'dns)

 
 
 ;;; Global constants
 ;;
 
 
 
 ;;; Global constants
 ;;
 

-(defconst elpher-version "2.0.3"
+(defconst elpher-version "2.4.4"

   "Current version of elpher.")
 
 (defconst elpher-margin-width 6
   "Current version of elpher.")
 
 (defconst elpher-margin-width 6


@@ -88,7 +90,7 @@
     (gemini elpher-get-gemini-node elpher-render-gemini "gem" elpher-gemini)
     (telnet elpher-get-telnet-node nil "tel" elpher-telnet)
     (other-url elpher-get-other-url-node nil "url" elpher-other-url)
     (gemini elpher-get-gemini-node elpher-render-gemini "gem" elpher-gemini)
     (telnet elpher-get-telnet-node nil "tel" elpher-telnet)
     (other-url elpher-get-other-url-node nil "url" elpher-other-url)

-    ((special bookmarks) elpher-get-bookmarks-node nil)
+    ((special bookmarks) elpher-get-bookmarks-node nil "/" elpher-index)

     ((special start) elpher-get-start-node nil))
   "Association list from types to getters, renderers, margin codes and index faces.")
 
     ((special start) elpher-get-start-node nil))
   "Association list from types to getters, renderers, margin codes and index faces.")
 


@@ -161,7 +163,7 @@
 Otherwise, use the system browser via the BROWSE-URL function."
   :type '(boolean))
 
 Otherwise, use the system browser via the BROWSE-URL function."
   :type '(boolean))
 

-(defcustom elpher-buttonify-urls-in-directories nil
+(defcustom elpher-buttonify-urls-in-directories t

   "If non-nil, turns URLs matched in directories into clickable buttons."
   :type '(boolean))
 
   "If non-nil, turns URLs matched in directories into clickable buttons."
   :type '(boolean))
 


@@ -175,6 +177,9 @@ 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))
 
 allows switching from an encrypted channel back to plain text without user input."
   :type '(boolean))
 

+(defcustom elpher-connection-timeout 5
+  "Specifies the number of seconds to wait for a network connection to time out."
+  :type '(integer))

 
 ;;; Model
 ;;
 
 ;;; Model
 ;;


@@ -191,13 +196,14 @@ allows switching from an encrypted channel back to plain text without user input
   (let ((data (match-data))) ; Prevent parsing clobbering match data
     (unwind-protect
         (let ((url (url-generic-parse-url url-string)))
   (let ((data (match-data))) ; Prevent parsing clobbering match data
     (unwind-protect
         (let ((url (url-generic-parse-url url-string)))

-          (setf (url-fullness url) t)
-          (setf (url-filename url)
-                (url-unhex-string (url-filename url)))
-          (unless (url-type url)
-            (setf (url-type url) "gopher"))
-          (when (or (equal "gopher" (url-type url))
-                    (equal "gophers" (url-type url)))
+          (unless (and (not (url-fullness url)) (url-type url))
+            (setf (url-fullness url) t)
+            (setf (url-filename url)
+                  (url-unhex-string (url-filename url)))
+            (unless (url-type url)
+              (setf (url-type url) "gopher"))
+            (when (or (equal "gopher" (url-type url))
+                      (equal "gophers" (url-type url)))

               ;; Gopher defaults
               (unless (url-host url)
                 (setf (url-host url) (url-filename url))
               ;; Gopher defaults
               (unless (url-host url)
                 (setf (url-host url) (url-filename url))


@@ -205,6 +211,10 @@ allows switching from an encrypted channel back to plain text without user input
               (when (or (equal (url-filename url) "")
                         (equal (url-filename url) "/"))
                 (setf (url-filename url) "/1")))
               (when (or (equal (url-filename url) "")
                         (equal (url-filename url) "/"))
                 (setf (url-filename url) "/1")))

+            (when (equal "gemini" (url-type url))
+              ;; Gemini defaults
+              (if (equal (url-filename url) "")
+                  (setf (url-filename url) "/"))))

           url)
       (set-match-data data))))
 
           url)
       (set-match-data data))))
 


@@ -277,8 +287,11 @@ For gopher addresses this is a combination of the selector type and selector."
   (url-host address))
 
 (defun elpher-address-port (address)
   (url-host address))
 
 (defun elpher-address-port (address)

-  "Retrieve port from ADDRESS object."
-  (url-port address))
+  "Retrieve port from ADDRESS object.
+If no address is defined, returns 0.  (This is for compatibility with the URL library.)"
+  (if (symbolp address)
+      0
+    (url-port address)))

 
 (defun elpher-address-special-p (address)
   "Return non-nil if ADDRESS object is special (e.g. start page, bookmarks page)."
 
 (defun elpher-address-special-p (address)
   "Return non-nil if ADDRESS object is special (e.g. start page, bookmarks page)."


@@ -295,36 +308,8 @@ For gopher addresses this is a combination of the selector type and selector."
       ""
     (substring (url-filename address) 2)))
 
       ""
     (substring (url-filename address) 2)))
 

-;; Node
-
-(defun elpher-make-node (display-string address &optional parent)
-  "Create a node in the page hierarchy.
-
-DISPLAY-STRING records the display string used for the page.
-
-ADDRESS specifies the address 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))
+;; Page

 
 

-(defun elpher-node-display-string (node)
-  "Retrieve the display string of NODE."
-  (elt node 0))
-
-(defun elpher-node-address (node)
-  "Retrieve the ADDRESS object of NODE."
-  (elt node 1))
-
-(defun elpher-node-parent (node)
-  "Retrieve the parent node of NODE."
-  (elt node 2))
-
-(defun elpher-set-node-parent (node parent)
-  "Set the parent node of NODE to be PARENT."
-  (setcar (cdr (cdr node)) parent))

 
 ;; Cache
 
 
 ;; Cache
 


@@ -347,24 +332,31 @@ initially."
   "Set the cursor position cache for ADDRESS to POS."
   (puthash address pos elpher-pos-cache))
 
   "Set the cursor position cache for ADDRESS to POS."
   (puthash address pos elpher-pos-cache))
 

-;; Node graph traversal
+;; Page
+
+(defun elpher-make-page (address display-string)
+  (list address display-string))

 
 

-(defvar elpher-current-node nil)
+(defun elpher-page-address (page)
+  (elt page 0))

 
 

-(defun elpher-visit-node (node &optional renderer preserve-parent)
-  "Visit NODE using its own renderer or RENDERER, if non-nil.
-Additionally, set the parent of NODE to `elpher-current-node',
-unless PRESERVE-PARENT is non-nil."
+(defun elpher-page-display-string (page)
+  (elt page 1))
+
+
+(defvar elpher-current-page nil)
+(defvar elpher-history nil)
+
+(defun elpher-visit-page (page &optional renderer no-history)
+  "Visit PAGE using its own renderer or RENDERER, if non-nil.
+Additionally, push PAGE onto the stack of previously-visited pages,
+unless NO-HISTORY is non-nil."

   (elpher-save-pos)
   (elpher-process-cleanup)
   (elpher-save-pos)
   (elpher-process-cleanup)

-  (unless preserve-parent
-    (if (and (elpher-node-parent elpher-current-node)
-             (equal (elpher-node-address elpher-current-node)
-                    (elpher-node-address 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)
-  (let* ((address (elpher-node-address node))
+  (unless no-history
+    (push page elpher-history))
+  (setq elpher-current-page page)
+  (let* ((address (elpher-page-address node))

          (type (elpher-address-type address))
          (type-record (cdr (assoc type elpher-type-map))))
     (if type-record
          (type (elpher-address-type address))
          (type-record (cdr (assoc type elpher-type-map))))
     (if type-record


@@ -372,7 +364,7 @@ unless PRESERVE-PARENT is non-nil."
                  (if renderer
                      renderer
                    (cadr type-record)))
                  (if renderer
                      renderer
                    (cadr type-record)))

-      (elpher-visit-parent-node)
+      (elpher-visit-previous-page)

       (pcase type
         (`(gopher ,type-char)
          (error "Unsupported gopher selector type '%c' for '%s'"
       (pcase type
         (`(gopher ,type-char)
          (error "Unsupported gopher selector type '%c' for '%s'"


@@ -381,13 +373,13 @@ unless PRESERVE-PARENT is non-nil."
          (error "Unsupported address type '%S' for '%s'"
                 other (elpher-address-to-url address)))))))
 
          (error "Unsupported address type '%S' for '%s'"
                 other (elpher-address-to-url address)))))))
 

-(defun elpher-visit-parent-node ()
+(defun elpher-visit-previous-page ()

   "Visit the parent of the current 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 nil t))))
+  (let ((previous-page (pop elpher-history)))
+    (when previous-page
+      (elpher-visit-node previous-page nil t))))

       
       

-(defun elpher-reload-current-node ()
+(defun elpher-reload-current-page ()

   "Reload the current node, discarding any existing cached content."
   (elpher-cache-content (elpher-node-address elpher-current-node) nil)
   (elpher-visit-node elpher-current-node))
   "Reload the current node, discarding any existing cached content."
   (elpher-cache-content (elpher-node-address elpher-current-node) nil)
   (elpher-visit-node elpher-current-node))


@@ -411,7 +403,16 @@ unless PRESERVE-PARENT is non-nil."
 (defun elpher-update-header ()
   "If `elpher-use-header' is true, display current node info in window header."
   (if elpher-use-header
 (defun elpher-update-header ()
   "If `elpher-use-header' is true, display current node info in window header."
   (if elpher-use-header

-      (setq header-line-format (elpher-node-display-string elpher-current-node))))
+      (let* ((display-string (elpher-node-display-string elpher-current-node))
+             (address (elpher-node-address elpher-current-node))
+             (tls-string (if (and (not (elpher-address-special-p address))
+                                  (member (elpher-address-protocol address)
+                                          '("gophers" "gemini")))
+                             " [TLS encryption]"
+                           ""))
+             (header (concat display-string
+                             (propertize tls-string 'face 'bold))))
+        (setq header-line-format header))))

 
 (defmacro elpher-with-clean-buffer (&rest args)
   "Evaluate ARGS with a clean *elpher* buffer as current."
 
 (defmacro elpher-with-clean-buffer (&rest args)
   "Evaluate ARGS with a clean *elpher* buffer as current."


@@ -448,11 +449,12 @@ away CRs and any terminating period."
 ;;
 
 (defun elpher-network-error (address error)
 ;;
 
 (defun elpher-network-error (address error)

-  "Display ERROR message following unsuccessful negotiation with ADDRESS."
+  "Display ERROR message following unsuccessful negotiation with ADDRESS.
+ERROR can be either an error object or a string."

   (elpher-with-clean-buffer
    (insert (propertize "\n---- ERROR -----\n\n" 'face 'error)
            "When attempting to retrieve " (elpher-address-to-url address) ":\n"
   (elpher-with-clean-buffer
    (insert (propertize "\n---- ERROR -----\n\n" 'face 'error)
            "When attempting to retrieve " (elpher-address-to-url address) ":\n"

-           (error-message-string error) ".\n"
+           (if (stringp error) error (error-message-string error)) "\n"

            (propertize "\n----------------\n\n" 'face 'error)
            "Press 'u' to return to the previous page.")))
 
            (propertize "\n----------------\n\n" 'face 'error)
            "Press 'u' to return to the previous page.")))
 


@@ -460,66 +462,88 @@ away CRs and any terminating period."
 ;;; Gopher selector retrieval
 ;;
 
 ;;; Gopher selector retrieval
 ;;
 

+(defvar elpher-network-timer nil
+  "Timer used for network connections.")
+

 (defun elpher-process-cleanup ()
 (defun elpher-process-cleanup ()

-  "Immediately shut down any extant elpher process."
+  "Immediately shut down any extant elpher process and timers."

   (let ((p (get-process "elpher-process")))
   (let ((p (get-process "elpher-process")))

-    (if p (delete-process p))))
+    (if p (delete-process p)))
+  (if (timerp elpher-network-timer)
+      (cancel-timer elpher-network-timer)))

 
 (defvar elpher-use-tls nil
   "If non-nil, use TLS to communicate with gopher servers.")
 
 
 (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 &optional propagate-error)
-  "Retrieve selector specified by ADDRESS, then execute AFTER.
-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 "")
+(defun elpher-get-selector (address renderer &optional force-ipv4)
+  "Retrieve selector specified by ADDRESS, then render it using RENDERER.
+If FORCE-IPV4 is non-nil, explicitly look up and use IPv4 address corresponding
+to ADDRESS."

   (when (equal (elpher-address-protocol address) "gophers")
   (when (equal (elpher-address-protocol address) "gophers")

-      (if (gnutls-available-p)
-          (when (not elpher-use-tls)
-            (setq elpher-use-tls t)
-            (message "Engaging TLS gopher mode."))
-        (error "Cannot retrieve TLS gopher selector: GnuTLS not available")))
-  (condition-case the-error
+    (if (gnutls-available-p)
+        (when (not elpher-use-tls)
+          (setq elpher-use-tls t)
+          (message "Engaging TLS gopher mode."))
+      (error "Cannot retrieve TLS gopher selector: GnuTLS not available")))
+  (unless (< (elpher-address-port address) 65536)
+    (error "Cannot retrieve gopher selector: port number > 65536"))
+  (condition-case nil

       (let* ((kill-buffer-query-functions nil)
       (let* ((kill-buffer-query-functions nil)

+             (port (elpher-address-port address))
+             (host (elpher-address-host address))
+             (selector-string "")

              (proc (open-network-stream "elpher-process"
              (proc (open-network-stream "elpher-process"

-                                       nil
-                                       (elpher-address-host address)
-                                       (if (> (elpher-address-port address) 0)
-                                           (elpher-address-port address)
-                                         70)
-                                       :type (if elpher-use-tls 'tls 'plain))))
+                                        nil
+                                        (if force-ipv4 (dns-query host) host)
+                                        (if (> port 0) port 70)
+                                        :type (if elpher-use-tls 'tls 'plain)
+                                        :nowait t))
+             (timer (run-at-time elpher-connection-timeout
+                                 nil
+                                 (lambda ()
+                                   (pcase (process-status proc)
+                                     ('failed
+                                      (if (and (not (equal (elpher-address-protocol address)
+                                                           "gophers"))
+                                               elpher-use-tls
+                                               (or elpher-auto-disengage-TLS
+                                                   (yes-or-no-p "Could not establish encrypted connection.  Disable TLS mode?")))
+                                          (progn
+                                            (message "Disabling TLS mode.")
+                                            (setq elpher-use-tls nil)
+                                            (elpher-get-selector address renderer))
+                                        (elpher-network-error address "Could not establish encrypted connection")))
+                                     ('connect
+                                      (elpher-process-cleanup)
+                                      (unless force-ipv4
+                                        (message "Connection timed out. Retrying with IPv4 address.")
+                                        (elpher-get-selector address renderer t))))))))
+        (setq elpher-network-timer timer)

         (set-process-coding-system proc 'binary)
         (set-process-filter proc
                             (lambda (_proc string)
         (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-gopher-address-selector address) "\n")))
+                              (cancel-timer timer)
+                              (setq selector-string
+                                    (concat selector-string string))))
+        (set-process-sentinel proc
+                              (lambda (_proc event)
+                                (condition-case the-error
+                                    (cond
+                                     ((string-prefix-p "deleted" event))
+                                     ((string-prefix-p "open" event)
+                                      (let ((inhibit-eol-conversion t))
+                                        (process-send-string
+                                         proc
+                                         (concat (elpher-gopher-address-selector address)
+                                                 "\r\n"))))
+                                     (t
+                                      (cancel-timer timer)
+                                      (funcall renderer selector-string)
+                                      (elpher-restore-pos)))
+                                  (error
+                                   (elpher-network-error address the-error))))))

     (error
     (error

-     (if (and (consp the-error)
-              (eq (car the-error) 'gnutls-error)
-              (not (equal (elpher-address-protocol address) "gophers"))
-              (or elpher-auto-disengage-TLS
-                  (yes-or-no-p "Could not establish encrypted connection.  Disable TLS mode? ")))
-         (progn
-           (message "Disengaging TLS gopher 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-address-to-url address) ".\n"
-                  (propertize "\n----------------\n\n" 'face 'error)
-                  "Press 'u' to return to the previous page.")))))))
+     (error "Error initiating connection to server"))))

 
 (defun elpher-get-gopher-node (renderer)
   "Getter function for gopher nodes.
 
 (defun elpher-get-gopher-node (renderer)
   "Getter function for gopher nodes.


@@ -533,11 +557,10 @@ once they are retrieved from the gopher server."
          (elpher-restore-pos))
       (elpher-with-clean-buffer
        (insert "LOADING... (use 'u' to cancel)"))
          (elpher-restore-pos))
       (elpher-with-clean-buffer
        (insert "LOADING... (use 'u' to cancel)"))

-      (elpher-get-selector address
-                           (lambda (_proc event)
-                             (unless (string-prefix-p "deleted" event)
-                               (funcall renderer elpher-selector-string)
-                               (elpher-restore-pos)))))))
+      (condition-case the-error
+          (elpher-get-selector address renderer)
+        (error
+         (elpher-network-error address the-error))))))

 
 ;; Index rendering
 
 
 ;; Index rendering
 


@@ -575,7 +598,9 @@ once they are retrieved from the gopher server."
 (defun elpher-node-button-help (node)
   "Return a string containing the help text for a button corresponding to NODE."
   (let ((address (elpher-node-address node)))
 (defun elpher-node-button-help (node)
   "Return a string containing the help text for a button corresponding to NODE."
   (let ((address (elpher-node-address node)))

-    (format "mouse-1, RET: open '%s'" (elpher-address-to-url address))))
+    (format "mouse-1, RET: open '%s'" (if (elpher-address-special-p address)
+                                          address
+                                        (elpher-address-to-url address)))))

 
 (defun elpher-insert-index-record (display-string &optional address)
   "Function to insert an index record into the current buffer.
 
 (defun elpher-insert-index-record (display-string &optional address)
   "Function to insert an index record into the current buffer.


@@ -598,11 +623,11 @@ If ADDRESS is not supplied or nil the record is rendered as an
       (pcase type
         ((or '(gopher ?i) 'nil) ;; Information
          (elpher-insert-margin)
       (pcase type
         ((or '(gopher ?i) 'nil) ;; Information
          (elpher-insert-margin)

-         (insert (propertize
-                  (if elpher-buttonify-urls-in-directories
-                      (elpher-buttonify-urls display-string)
-                    display-string)
-                  'face 'elpher-info)))
+         (let ((propertized-display-string
+                (propertize display-string 'face 'elpher-info)))
+           (insert (if elpher-buttonify-urls-in-directories
+                       (elpher-buttonify-urls propertized-display-string)
+                     propertized-display-string))))

         (`(gopher ,selector-type) ;; Unknown
          (elpher-insert-margin (concat (char-to-string selector-type) "?"))
          (insert (propertize display-string
         (`(gopher ,selector-type) ;; Unknown
          (elpher-insert-margin (concat (char-to-string selector-type) "?"))
          (insert (propertize display-string


@@ -626,7 +651,7 @@ If ADDRESS is not supplied or nil the record is rendered as an
 ;; Text rendering
 
 (defconst elpher-url-regex
 ;; Text rendering
 
 (defconst elpher-url-regex

-  "\\([a-zA-Z]+\\)://\\([a-zA-Z0-9.\-]+\\|\[[a-zA-Z0-9:]+\]\\)\\(?3::[0-9]+\\)?\\(?4:/[^<> \r\n\t(),]*\\)?"
+  "\\([a-zA-Z]+\\)://\\([a-zA-Z0-9.\-]*[a-zA-Z0-9\-]\\|\[[a-zA-Z0-9:]+\]\\)\\(:[0-9]+\\)?\\(/\\([0-9a-zA-Z\-_~?/@|:.%#]*[0-9a-zA-Z\-_~?/@|#]\\)?\\)?"

   "Regexp used to locate and buttniofy URLs in text files loaded by elpher.")
 
 (defun elpher-buttonify-urls (string)
   "Regexp used to locate and buttniofy URLs in text files loaded by elpher.")
 
 (defun elpher-buttonify-urls (string)


@@ -635,14 +660,15 @@ If ADDRESS is not supplied or nil the record is rendered as an
     (insert string)
     (goto-char (point-min))
     (while (re-search-forward elpher-url-regex nil t)
     (insert string)
     (goto-char (point-min))
     (while (re-search-forward elpher-url-regex nil t)

-      (let ((node (elpher-make-node (match-string 0)
+      (let ((node (elpher-make-node (substring-no-properties (match-string 0))

                                     (elpher-address-from-url (match-string 0)))))
           (make-text-button (match-beginning 0)
                             (match-end 0)
                             'elpher-node  node
                             'action #'elpher-click-link
                             'follow-link t
                                     (elpher-address-from-url (match-string 0)))))
           (make-text-button (match-beginning 0)
                             (match-end 0)
                             'elpher-node  node
                             'action #'elpher-click-link
                             'follow-link t

-                            'help-echo (elpher-node-button-help node))))
+                            'help-echo (elpher-node-button-help node)
+                            'face 'button)))

     (buffer-string)))
 
 (defun elpher-render-text (data &optional _mime-type-string)
     (buffer-string)))
 
 (defun elpher-render-text (data &optional _mime-type-string)


@@ -696,21 +722,19 @@ The response is rendered using the rendering function RENDERER."
 
             (elpher-with-clean-buffer
              (insert "LOADING RESULTS... (use 'u' to cancel)"))
 
             (elpher-with-clean-buffer
              (insert "LOADING RESULTS... (use 'u' to cancel)"))

-            (elpher-get-selector search-address
-                                 (lambda (_proc event)
-                                   (unless (string-prefix-p "deleted" event)
-                                     (funcall renderer elpher-selector-string)
-                                     (elpher-restore-pos)))))
+            (elpher-get-selector search-address renderer))

         (if aborted
             (elpher-visit-parent-node))))))
  
 ;; Raw server response rendering
 
         (if aborted
             (elpher-visit-parent-node))))))
  
 ;; Raw server response rendering
 

-(defun elpher-render-raw (data &optional _mime-type-string)
-  "Display raw DATA in buffer.  MIME-TYPE-STRING is unused."
+(defun elpher-render-raw (data &optional mime-type-string)
+  "Display raw DATA in buffer.  MIME-TYPE-STRING is also displayed if provided."

   (if (not data)
       nil
     (elpher-with-clean-buffer
   (if (not data)
       nil
     (elpher-with-clean-buffer

+     (when mime-type-string
+       (insert "MIME type specified by server: '" mime-type-string "'\n"))

      (insert data)
      (goto-char (point-min)))
     (message "Displaying raw server response.  Reload or redraw to return to standard view.")))
      (insert data)
      (goto-char (point-min)))
     (message "Displaying raw server response.  Reload or redraw to return to standard view.")))


@@ -749,79 +773,123 @@ The response is rendered using the rendering function RENDERER."
 
 ;; Gemini node retrieval
 
 
 ;; Gemini node retrieval
 

-(defvar elpher-gemini-response)
+(defvar elpher-gemini-redirect-chain)

 
 

-(defun elpher-get-gemini-response (address after)
-  "Retrieve gemini ADDRESS, then execute AFTER.
-The response is stored in the variable ‘elpher-gemini-response’."
-  (setq elpher-gemini-response "")
+(defun elpher-get-gemini-response (address renderer &optional force-ipv4)
+  "Retrieve gemini ADDRESS, then render using RENDERER.
+If FORCE-IPV4 is non-nil, explicitly look up and use IPv4 address corresponding
+to ADDRESS."

   (if (not (gnutls-available-p))
   (if (not (gnutls-available-p))

-      (error "Cannot retrieve TLS selector: GnuTLS not available")
-    (let* ((kill-buffer-query-functions nil)
-           (proc (open-network-stream "elpher-process"
-                                      nil
-                                      (elpher-address-host address)
-                                      (if (> (elpher-address-port address) 0)
-                                          (elpher-address-port address)
-                                        1965)
-                                      :type 'tls)))
-      (set-process-coding-system proc 'binary)
-      (set-process-filter proc
-                          (lambda (_proc string)
-                            (setq elpher-gemini-response
-                                  (concat elpher-gemini-response string))))
-      (set-process-sentinel proc after)
-      (process-send-string proc
-                           (concat (elpher-address-to-url address) "\r\n")))))
-
-
-(defun elpher-process-gemini-response (renderer)
-  "Process the gemini response and pass the result to RENDERER.
-The response is assumed to be in the variable `elpher-gemini-response'."
-  (condition-case the-error
-      (let* ((response-header (car (split-string elpher-gemini-response "\r\n")))
-             (response-body (substring elpher-gemini-response
-                                       (+ (string-match "\r\n" elpher-gemini-response) 2)))
-             (response-code (car (split-string response-header)))
-             (response-meta (string-trim
-                             (substring response-header
-                                        (string-match "[ \t]+" response-header)))))
-        (pcase (elt response-code 0)
-          (?1 ; Input required
-           (elpher-with-clean-buffer
-            (insert "Gemini server is requesting input."))
-           (let* ((query-string (read-string (concat response-meta ": ")))
-                  (url (elpher-address-to-url (elpher-node-address elpher-current-node)))
-                  (query-address (elpher-address-from-url (concat url "?" query-string))))
-             (elpher-get-gemini-response query-address
-                                         (lambda (_proc event)
-                                           (unless (string-prefix-p "deleted" event)
-                                             (funcall #'elpher-process-gemini-response
-                                                      renderer)
-                                             (elpher-restore-pos))))))
-          (?2 ; Normal response
-           ;; (message response-header)
-           (funcall renderer response-body response-meta))
-          (?3 ; Redirect
-           (message "Following redirect to %s" response-meta)
-           (let ((redirect-address (elpher-address-from-gemini-url response-meta)))
-             (elpher-get-gemini-response redirect-address
-                                         (lambda (_proc event)
-                                           (unless (string-prefix-p "deleted" event)
-                                             (funcall #'elpher-process-gemini-response
-                                                      renderer)
-                                             (elpher-restore-pos))))))
-          (?4 ; Temporary failure
-           (error "Gemini server reports TEMPORARY FAILURE for this request"))
-          (?5 ; Permanent failure
-           (error "Gemini server reports PERMANENT FAILURE for this request"))
-          (?6 ; Client certificate required
-           (error "Gemini server requires client certificate (unsupported at this time)"))
-          (_other
-           (error "Gemini server responded with unknown response code %S"
-                  response-code))))
-    (error
-     (elpher-network-error (elpher-node-address elpher-current-node) the-error))))
+      (error "Cannot establish gemini connection: GnuTLS not available")
+    (unless (< (elpher-address-port address) 65536)
+      (error "Cannot establish gemini connection: port number > 65536"))
+    (condition-case nil
+        (let* ((kill-buffer-query-functions nil)
+               (port (elpher-address-port address))
+               (host (elpher-address-host address))
+               (response-string "")
+               (proc (open-network-stream "elpher-process"
+                                          nil
+                                          (if force-ipv4 (dns-query host) host)
+                                          (if (> port 0) port 1965)
+                                          :type 'tls
+                                          :nowait t))
+               (timer (run-at-time elpher-connection-timeout nil
+                                   (lambda ()
+                                     (elpher-process-cleanup)
+                                     (unless force-ipv4
+                                        ; Try again with IPv4
+                                       (message "Connection timed out.  Retrying with IPv4.")
+                                       (elpher-get-gemini-response address renderer t))))))
+          (setq elpher-network-timer timer)
+          (set-process-coding-system proc 'binary)
+          (set-process-filter proc
+                              (lambda (_proc string)
+                                (cancel-timer timer)
+                                (setq response-string
+                                      (concat response-string string))))
+          (set-process-sentinel proc
+                                (lambda (proc event)
+                                  (condition-case the-error
+                                      (cond
+                                       ((string-prefix-p "open" event)    ; request URL
+                                        (let ((inhibit-eol-conversion t))
+                                          (process-send-string
+                                           proc
+                                           (concat (elpher-address-to-url address)
+                                                   "\r\n"))))
+                                       ((string-prefix-p "deleted" event)) ; do nothing
+                                       ((and (string-empty-p response-string)
+                                             (not force-ipv4))
+                                        ; Try again with IPv4
+                                        (message "Connection failed. Retrying with IPv4.")
+                                        (cancel-timer timer)
+                                        (elpher-get-gemini-response address renderer t))
+                                       (t
+                                        (funcall #'elpher-process-gemini-response
+                                                 response-string
+                                                 renderer)
+                                        (elpher-restore-pos)))
+                                    (error
+                                           (elpher-network-error address the-error))))))
+      (error
+       (error "Error initiating connection to server")))))
+
+(defun elpher-parse-gemini-response (response)
+  "Parse the RESPONSE string and return a list of components.
+The list is of the form (code meta body).  A response of nil implies
+that the response was malformed."
+  (let ((header-end-idx (string-match "\r\n" response)))
+    (if header-end-idx
+        (let ((header (string-trim (substring response 0 header-end-idx)))
+              (body (substring response (+ header-end-idx 2))))
+          (if (>= (length header) 2)
+              (let ((code (substring header 0 2))
+                    (meta (string-trim (substring header 2))))
+                (list code meta body))
+            (error "Malformed response: No response status found in header %s" header)))
+      (error "Malformed response: No CRLF-delimited header found"))))
+
+(defun elpher-process-gemini-response (response-string renderer)
+  "Process the gemini response RESPONSE-STRING and pass the result to RENDERER."
+  (let ((response-components (elpher-parse-gemini-response response-string)))
+    (let ((response-code (elt response-components 0))
+          (response-meta (elt response-components 1))
+          (response-body (elt response-components 2)))
+      (pcase (elt response-code 0)
+        (?1 ; Input required
+         (elpher-with-clean-buffer
+          (insert "Gemini server is requesting input."))
+         (let* ((query-string (read-string (concat response-meta ": ")))
+                (url (elpher-address-to-url (elpher-node-address elpher-current-node)))
+                (query-address (elpher-address-from-url (concat url "?" query-string))))
+           (elpher-get-gemini-response query-address renderer)))
+        (?2 ; Normal response
+         (funcall renderer response-body response-meta))
+        (?3 ; Redirect
+         (message "Following redirect to %s" response-meta)
+         (if (>= (length elpher-gemini-redirect-chain) 5)
+             (error "More than 5 consecutive redirects followed"))
+         (let ((redirect-address (elpher-address-from-gemini-url response-meta)))
+           (if (member redirect-address elpher-gemini-redirect-chain)
+               (error "Redirect loop detected"))
+           (if (not (string= (elpher-address-protocol redirect-address)
+                             "gemini"))
+               (error "Server tried to automatically redirect to non-gemini URL: %s"
+                      response-meta))
+           (add-to-list 'elpher-gemini-redirect-chain redirect-address)
+           (elpher-get-gemini-response redirect-address renderer)))
+        (?4 ; Temporary failure
+         (error "Gemini server reports TEMPORARY FAILURE for this request: %s %s"
+                response-code response-meta))
+        (?5 ; Permanent failure
+         (error "Gemini server reports PERMANENT FAILURE for this request: %s %s"
+                response-code response-meta))
+        (?6 ; Client certificate required
+         (error "Gemini server requires client certificate (unsupported at this time)"))
+        (_other
+         (error "Gemini server response unknown: %s %s"
+                response-code response-meta))))))

 
 (defun elpher-get-gemini-node (renderer)
   "Getter which retrieves and renders a Gemini node and renders it using RENDERER."
 
 (defun elpher-get-gemini-node (renderer)
   "Getter which retrieves and renders a Gemini node and renders it using RENDERER."


@@ -834,12 +902,8 @@ The response is assumed to be in the variable `elpher-gemini-response'."
               (elpher-restore-pos))
           (elpher-with-clean-buffer
            (insert "LOADING GEMINI... (use 'u' to cancel)"))
               (elpher-restore-pos))
           (elpher-with-clean-buffer
            (insert "LOADING GEMINI... (use 'u' to cancel)"))

-          (elpher-get-gemini-response address
-                                      (lambda (_proc event)
-                                        (unless (string-prefix-p "deleted" event)
-                                          (funcall #'elpher-process-gemini-response
-                                                   renderer)
-                                          (elpher-restore-pos)))))
+          (setq elpher-gemini-redirect-chain nil)
+          (elpher-get-gemini-response address renderer))

       (error
        (elpher-network-error address the-error)))))
 
       (error
        (elpher-network-error address the-error)))))
 


@@ -859,17 +923,18 @@ The response is assumed to be in the variable `elpher-gemini-response'."
                                    (list (downcase (string-trim (car key-val)))
                                          (downcase (string-trim (cadr key-val))))))
                                (cdr mime-type-split))))
                                    (list (downcase (string-trim (car key-val)))
                                          (downcase (string-trim (cadr key-val))))))
                                (cdr mime-type-split))))

-      (if (and (equal "text/gemini" mime-type)
-               (not (assoc "charset" parameters)))
-          (setq parameters (cons (list "charset" "utf-8") parameters)))

       (when (string-prefix-p "text/" mime-type)
       (when (string-prefix-p "text/" mime-type)

-        (if (assoc "charset" parameters)
-            (setq body (decode-coding-string body
-                                             (intern (cadr (assoc "charset" parameters))))))
+        (setq body (decode-coding-string
+                    body
+                    (if (assoc "charset" parameters)
+                        (intern (cadr (assoc "charset" parameters)))
+                      'utf-8)))

         (setq body (replace-regexp-in-string "\r" "" body)))
       (pcase mime-type
         ((or "text/gemini" "")
          (elpher-render-gemini-map body parameters))
         (setq body (replace-regexp-in-string "\r" "" body)))
       (pcase mime-type
         ((or "text/gemini" "")
          (elpher-render-gemini-map body parameters))

+        ("text/html"
+         (elpher-render-html body))

         ((pred (string-prefix-p "text/"))
          (elpher-render-gemini-plain-text body parameters))
         ((pred (string-prefix-p "image/"))
         ((pred (string-prefix-p "text/"))
          (elpher-render-gemini-plain-text body parameters))
         ((pred (string-prefix-p "image/"))


@@ -889,12 +954,27 @@ The response is assumed to be in the variable `elpher-gemini-response'."
         (string-trim (substring rest (+ idx 1)))
       "")))
 
         (string-trim (substring rest (+ idx 1)))
       "")))
 

+(defun elpher-collapse-dot-sequences (filename)
+  "Collapse dot sequences in FILENAME.
+For instance, the filename /a/b/../c/./d will reduce to /a/c/d"
+  (let* ((path (split-string filename "/"))
+         (path-reversed-normalized
+          (seq-reduce (lambda (a b)
+                        (cond ((and a (equal b "..") (cdr a)))
+                              ((and (not a) (equal b "..")) a) ;leading .. are dropped
+                              ((equal b ".") a)
+                              (t (cons b a))))
+                      path nil)))
+    (string-join (reverse path-reversed-normalized) "/")))
+

 (defun elpher-address-from-gemini-url (url)
   "Extract address from URL with defaults as per gemini map files."
   (let ((address (url-generic-parse-url url)))
     (unless (and (url-type address) (not (url-fullness address))) ;avoid mangling mailto: urls
       (setf (url-fullness address) t)
 (defun elpher-address-from-gemini-url (url)
   "Extract address from URL with defaults as per gemini map files."
   (let ((address (url-generic-parse-url url)))
     (unless (and (url-type address) (not (url-fullness address))) ;avoid mangling mailto: urls
       (setf (url-fullness address) t)

-      (unless (url-host address) ;if there is an explicit host, filenames are explicit
+      (if (url-host address) ;if there is an explicit host, filenames are absolute
+          (if (string-empty-p (url-filename address))
+              (setf (url-filename address) "/")) ;ensure empty filename is marked as absolute

         (setf (url-host address) (url-host (elpher-node-address elpher-current-node)))
         (unless (string-prefix-p "/" (url-filename address)) ;deal with relative links
           (setf (url-filename address)
         (setf (url-host address) (url-host (elpher-node-address elpher-current-node)))
         (unless (string-prefix-p "/" (url-filename address)) ;deal with relative links
           (setf (url-filename address)


@@ -902,7 +982,10 @@ The response is assumed to be in the variable `elpher-gemini-response'."
                          (url-filename (elpher-node-address elpher-current-node)))
                         (url-filename address)))))
       (unless (url-type address)
                          (url-filename (elpher-node-address elpher-current-node)))
                         (url-filename address)))))
       (unless (url-type address)

-        (setf (url-type address) "gemini")))
+        (setf (url-type address) "gemini"))
+      (if (equal (url-type address) "gemini")
+          (setf (url-filename address)
+                (elpher-collapse-dot-sequences (url-filename address)))))

     address))
 
 (defun elpher-render-gemini-map (data _parameters)
     address))
 
 (defun elpher-render-gemini-map (data _parameters)


@@ -956,7 +1039,9 @@ The response is assumed to be in the variable `elpher-gemini-response'."
          (host (elpher-address-host address))
          (port (elpher-address-port address)))
     (elpher-visit-parent-node)
          (host (elpher-address-host address))
          (port (elpher-address-port address)))
     (elpher-visit-parent-node)

-    (telnet host port)))
+    (if (> port 0)
+        (telnet host port)
+      (telnet host))))

 
 ;; Start page node retrieval
 
 
 ;; Start page node retrieval
 


@@ -976,7 +1061,7 @@ The response is assumed to be in the variable `elpher-gemini-response'."
            " - 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"
            " - 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"
+           " - u/mouse-3: 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"
            " - d/D: download item under cursor or current page\n"
            " - o/O: visit different selector or the root menu of the current server\n"
            " - g: go to a particular gopher address\n"
            " - d/D: download item under cursor or current page\n"


@@ -998,6 +1083,16 @@ The response is assumed to be in the variable `elpher-gemini-response'."
            "Alternatively, select the following item and enter some search terms:\n")
    (elpher-insert-index-record "Veronica-2 Gopher Search Engine"
                                (elpher-make-gopher-address ?7 "/v2/vs" "gopher.floodgap.com" 70))
            "Alternatively, select the following item and enter some search terms:\n")
    (elpher-insert-index-record "Veronica-2 Gopher Search Engine"
                                (elpher-make-gopher-address ?7 "/v2/vs" "gopher.floodgap.com" 70))

+   (insert "\n"
+           "This page contains your bookmarked sites (also visit with B):\n")
+   (elpher-insert-index-record "Your Bookmarks" 'bookmarks)
+   (insert "\n"
+           "For Elpher release news or to leave feedback, visit:\n")
+   (elpher-insert-index-record "The Elpher Project Page"
+                               (elpher-make-gopher-address ?1
+                                                           "/projects/elpher/"
+                                                           "thelambdalab.xyz"
+                                                           70))

    (insert "\n"
            "** Refer to the ")
    (let ((help-string "RET,mouse-1: Open Elpher info manual (if available)"))
    (insert "\n"
            "** Refer to the ")
    (let ((help-string "RET,mouse-1: Open Elpher info manual (if available)"))


@@ -1011,7 +1106,7 @@ The response is assumed to be in the variable `elpher-gemini-response'."
    (insert " for the full documentation. **\n")
    (insert (propertize
             (concat "  (This should be available if you have installed Elpher using\n"
    (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.)")
+                    "   MELPA. Otherwise you will have to install the manual yourself.)\n")

             'face 'shadow))
    (elpher-restore-pos)))
 
             'face 'shadow))
    (elpher-restore-pos)))
 


@@ -1031,12 +1126,23 @@ The response is assumed to be in the variable `elpher-gemini-response'."
                  (address (elpher-address-from-url (elpher-bookmark-url bookmark))))
              (elpher-insert-index-record display-string address)))
        (insert "No bookmarks found.\n")))
                  (address (elpher-address-from-url (elpher-bookmark-url bookmark))))
              (elpher-insert-index-record display-string address)))
        (insert "No bookmarks found.\n")))

-   (insert "\n-----------------------\n\n"
+   (insert "\n-----------------------\n"
+           "\n"

            "- u: return to previous page\n"
            "- x: delete selected bookmark\n"
            "- u: return to previous page\n"
            "- x: delete selected bookmark\n"

-           "- a: rename selected bookmark\n\n"
-           "Bookmarks are stored in the file "
-           (locate-user-emacs-file "elpher-bookmarks"))
+           "- a: rename selected bookmark\n"
+           "\n"
+           "Bookmarks are stored in the file ")
+   (let ((filename (locate-user-emacs-file "elpher-bookmarks"))
+         (help-string "RET,mouse-1: Open bookmarks file in new buffer for editing."))
+     (insert-text-button filename
+                         'face 'link
+                         'action (lambda (_)
+                                   (interactive)
+                                   (find-file filename))
+                         'follow-link t
+                         'help-echo help-string))
+   (insert "\n")

    (elpher-restore-pos)))
   
 
    (elpher-restore-pos)))
   
 


@@ -1161,7 +1267,7 @@ If ADDRESS is already bookmarked, update the label only."
     (message "No current site.")))
 
 (defun elpher-toggle-tls ()
     (message "No current site.")))
 
 (defun elpher-toggle-tls ()

-  "Toggle TLS encryption mode."
+  "Toggle TLS encryption mode for gopher."

   (interactive)
   (setq elpher-use-tls (not elpher-use-tls))
   (if elpher-use-tls
   (interactive)
   (setq elpher-use-tls (not elpher-use-tls))
   (if elpher-use-tls


@@ -1324,7 +1430,7 @@ If ADDRESS is already bookmarked, update the label only."
         (address (elpher-node-address node)))
     (if (elpher-address-special-p address)
         (message "Special page: %s" display-string)
         (address (elpher-node-address node)))
     (if (elpher-address-special-p address)
         (message "Special page: %s" display-string)

-      (message (elpher-address-to-url address)))))
+      (message "%s" (elpher-address-to-url address)))))

 
 (defun elpher-info-link ()
   "Display information on node corresponding to link at point."
 
 (defun elpher-info-link ()
   "Display information on node corresponding to link at point."


@@ -1379,6 +1485,7 @@ If ADDRESS is already bookmarked, update the label only."
     (define-key map (kbd "TAB") 'elpher-next-link)
     (define-key map (kbd "<backtab>") 'elpher-prev-link)
     (define-key map (kbd "u") 'elpher-back)
     (define-key map (kbd "TAB") 'elpher-next-link)
     (define-key map (kbd "<backtab>") 'elpher-prev-link)
     (define-key map (kbd "u") 'elpher-back)

+    (define-key map [mouse-3] '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 "O") 'elpher-root-dir)
     (define-key map (kbd "g") 'elpher-go)
     (define-key map (kbd "o") 'elpher-go-current)


@@ -1405,6 +1512,7 @@ If ADDRESS is already bookmarked, update the label only."
         (kbd "C-") 'elpher-follow-current-link
         (kbd "C-t") 'elpher-back
         (kbd "u") 'elpher-back
         (kbd "C-") 'elpher-follow-current-link
         (kbd "C-t") 'elpher-back
         (kbd "u") 'elpher-back

+        [mouse-3] 'elpher-back

         (kbd "g") 'elpher-go
         (kbd "o") 'elpher-go-current
         (kbd "r") 'elpher-redraw
         (kbd "g") 'elpher-go
         (kbd "o") 'elpher-go-current
         (kbd "r") 'elpher-redraw


@@ -1428,7 +1536,7 @@ If ADDRESS is already bookmarked, update the label only."
   "Keymap for gopher client.")
 
 (define-derived-mode elpher-mode special-mode "elpher"
   "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
 
 This mode is automatically enabled by the interactive
 functions which initialize the gopher client, namely