Migrating to stack-based history.
[elpher.git] / elpher.el
index 55161c3..95c3057 100644 (file)
--- a/elpher.el
+++ b/elpher.el
@@ -4,9 +4,9 @@
 
 ;; Author: Tim Vaughan <tgvaughan@gmail.com>
 ;; Created: 11 April 2019
-;; Version: 2.1.1
+;; Version: 2.4.4
 ;; 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.
@@ -37,7 +37,7 @@
 ;; - 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
@@ -46,7 +46,8 @@
 ;; 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:
 
 (require 'shr)
 (require 'url-util)
 (require 'subr-x)
+(require 'dns)
 
 
 ;;; Global constants
 ;;
 
-(defconst elpher-version "2.1.1"
+(defconst elpher-version "2.4.4"
   "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)
-    ((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.")
 
@@ -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))
 
+(defcustom elpher-connection-timeout 5
+  "Specifies the number of seconds to wait for a network connection to time out."
+  :type '(integer))
 
 ;;; Model
 ;;
@@ -282,15 +287,11 @@ For gopher addresses this is a combination of the selector type and selector."
   (url-host address))
 
 (defun elpher-address-port (address)
-  "Retrieve port from ADDRESS object."
+  "Retrieve port from ADDRESS object.
+If no address is defined, returns 0.  (This is for compatibility with the URL library.)"
   (if (symbolp address)
-      nil)
-  (or (> (url-port address) 0)
-      (and (or (equal (url-type address) "gopher")
-               (equal (url-type address) "gophers"))
-           70)
-      (and (equal (url-type address) "gemini")
-           1965)))
+      0
+    (url-port address)))
 
 (defun elpher-address-special-p (address)
   "Return non-nil if ADDRESS object is special (e.g. start page, bookmarks page)."
@@ -307,36 +308,8 @@ For gopher addresses this is a combination of the selector type and selector."
       ""
     (substring (url-filename address) 2)))
 
-;; Node
+;; Page
 
-(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))
-
-(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
 
@@ -359,24 +332,31 @@ initially."
   "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)
-  (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
@@ -384,7 +364,7 @@ unless PRESERVE-PARENT is non-nil."
                  (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'"
@@ -393,13 +373,13 @@ unless PRESERVE-PARENT is non-nil."
          (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."
-  (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))
@@ -423,7 +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
-      (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."
@@ -460,11 +449,12 @@ away CRs and any terminating period."
 ;;
 
 (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"
-           (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.")))
 
@@ -472,64 +462,88 @@ away CRs and any terminating period."
 ;;; Gopher selector retrieval
 ;;
 
+(defvar elpher-network-timer nil
+  "Timer used for network connections.")
+
 (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")))
-    (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-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")
-      (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)
+             (port (elpher-address-port address))
+             (host (elpher-address-host address))
+             (selector-string "")
              (proc (open-network-stream "elpher-process"
-                                       nil
-                                       (elpher-address-host address)
-                                       (elpher-address-port address)
-                                       :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)
-                              (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
-     (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.
@@ -543,11 +557,10 @@ once they are retrieved from the gopher server."
          (elpher-restore-pos))
       (elpher-with-clean-buffer
        (insert "LOADING... (use 'u' to cancel)"))
-      (elpher-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
 
@@ -585,7 +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)))
-    (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.
@@ -636,7 +651,7 @@ If ADDRESS is not supplied or nil the record is rendered as an
 ;; 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)
@@ -645,7 +660,7 @@ 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)
-      (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)
@@ -707,21 +722,19 @@ The response is rendered using the rendering function RENDERER."
 
             (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
 
-(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
+     (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.")))
@@ -760,77 +773,123 @@ The response is rendered using the rendering function RENDERER."
 
 ;; 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))
-      (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)
-                                      (elpher-address-port address)
-                                      :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."
@@ -843,12 +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-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)))))
 
@@ -868,17 +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))))
-      (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)
-        (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))
+        ("text/html"
+         (elpher-render-html body))
         ((pred (string-prefix-p "text/"))
          (elpher-render-gemini-plain-text body parameters))
         ((pred (string-prefix-p "image/"))
@@ -898,12 +954,27 @@ The response is assumed to be in the variable `elpher-gemini-response'."
         (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)
-      (unless (url-host address) ;if there is an explicit host, filenames are absolute
+      (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)
@@ -911,7 +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)
-        (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)
@@ -965,7 +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)
-    (telnet host port)))
+    (if (> port 0)
+        (telnet host port)
+      (telnet host))))
 
 ;; Start page node retrieval
 
@@ -985,7 +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"
-           " - 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"
@@ -1007,6 +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))
+   (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)"))
@@ -1020,7 +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"
-                    "   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)))
 
@@ -1040,12 +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")))
-   (insert "\n-----------------------\n\n"
+   (insert "\n-----------------------\n"
+           "\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)))
   
 
@@ -1170,7 +1267,7 @@ If ADDRESS is already bookmarked, update the label only."
     (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
@@ -1333,7 +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)
-      (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."