X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=elpher.git;a=blobdiff_plain;f=elpher.texi;h=7229c9998324678055f736173601e4a6b4696628;hp=5fb4882f908366b24253a5bc3d18bd803c3846fb;hb=refs%2Fheads%2Fpatch_multiple_buffers2;hpb=71b4b025b5c0450405aae3d342428cfd624ace01 diff --git a/elpher.texi b/elpher.texi index 5fb4882..7229c99 100644 --- a/elpher.texi +++ b/elpher.texi @@ -1,13 +1,17 @@ \input texinfo @c -*-texinfo-*- -@c %**start of header + @setfilename elpher.info -@settitle Elpher Manual v1.0.0 -@c %**end of header +@settitle Elpher Manual v2.10.0 + +@dircategory Emacs +@direntry +* Elpher: (elpher). A gopher and gemini client for Emacs. +@end direntry @copying -This manual documents Elpher, a gopher client for Emacs. +This manual documents Elpher, a gopher and gemini client for Emacs. -Copyright @copyright{} 2019 Tim Vaughan +Copyright @copyright{} 2019, 2020 Tim Vaughan @quotation The source and documentation of Elpher is free software. You can @@ -23,7 +27,7 @@ the file COPYING in the same directory as this file for more details. @end copying @titlepage -@title Elpher Gopher Client Manual +@title Elpher Gopher and Gemini Client Manual @author Tim Vaughan @page @@ -40,26 +44,49 @@ the file COPYING in the same directory as this file for more details. @insertcopying @end ifnottex +@macro keycmd{key,cmd} +@item \key\ (@code{\cmd\}) +@findex \cmd\ +@end macro + @menu * Introduction:: Elpher Overview: what's this all about? +* Installation:: Installing Elpher +* Quick Start:: Get up and running quickly * Navigation:: Fundamentals of Elpher navigation * Bookmarks:: How to record and visit bookmarks -* Character encodings:: How Elpher handles different character encodings +* Gopher character encodings:: How Elpher selects encodings for gopher pages +* Encrypted gopher connections:: How and when TLS is enabled for gopher +* Gemini support:: Support for the Gemini protocol +* Finger support:: Support for the Finger protocol * Customization:: How to customize various aspects of Elpher -* Hacking:: Contributing changes to Elpher -* Index:: +* Command Index:: + +@detailmenu + --- The Detailed Node Listing --- + +Navigation + +* Within-page navigation:: Moving about within a page +* Between-page navigation:: Commands for moving between pages +* History and Caching:: Explanation of how Elpher represents history + +@end detailmenu @end menu -@node Introduction, Navigation, Top, Top +@node Introduction, Installation, Top, Top @chapter Introduction -Elpher aims to be a capable and practical gopher client for Emacs. Its -focus is on easy keyboard-driven navigation based on sensible default -bindings (with out-of-the-box support for Evil). It is intended to be -robust and behave in non-surprising ways at all times. Additionally, -Elpher provides the following bells and whistles: +Elpher aims to be a capable and practical gopher and gemini client for +Emacs. Its focus is on easy keyboard-driven navigation based on +sensible default bindings (with out-of-the-box support for Evil). It is +intended to be robust and behave in non-surprising ways at all times. +Additionally, Elpher provides the following bells and whistles: @itemize +@item +followable web and gopher links in plain text, + @item an easily navigable history, sporting caching of visited pages (both content and cursor position), @@ -68,27 +95,104 @@ content and cursor position), auto-completing menu item navigation, @item -followable web and gopher links in plain text, +direct visualization of image files where supported (no writing to +disk), @item -direct visualization of image files where supported (no writing to -disk), and +a bookmark management system, + +@item +basic support for the new ``heavier than gopher, lighter than the web'' Gemini protocol, @item -a simple bookmark management system. +support for the Finger protocol. + @end itemize Elpher is still under active development. Although we try very hard to ensure that releases are bug-free, this cannot be guaranteed. However, this also means that any usability features that you feel are missing -can likely by incoroporated quickly, so please get in touch if you +can likely by incorporated quickly, so please get in touch if you have some ideas. -@node Navigation, Bookmarks, Introduction, Top -@chapter Navigation +@node Installation, Quick Start, Introduction, Top +@chapter Installation + +Elpher is available from the MELPA package repository. If you have +never installed packages from this repository before, you'll need +to follow the instructions at @url{https://melpa.org/#/getting-started}. + +@noindent To install Elpher, enter the following: + +@example +@kbd{M-x package-install @key{RET} elpher @key{RET}} +@end example + +@noindent To uninstall, use + +@example +@kbd{M-x package-delete @key{RET} elpher @key{RET}}. +@end example +While not recommended, it is also possible to install Elpher directly by +downloading the file @file{elpher.el} from +@url{gopher://thelambdalab.xyz/1/projects/elpher/}, adding it to a directory in +your @code{load-path}, and then adding + +@example +(require 'elpher) +@end example + +@noindent to your Emacs initialization file. + +@node Quick Start, Navigation, Installation, Top +@chapter Quick Start + +Before diving into the minutiae of the different commands available, +we will quickly describe how to get up and running with Elpher. + +Once installed, you can launch Elpher using + +@example +@kbd{M-x elpher @key{RET}} +@end example + +@noindent This will switch to the *Elpher* buffer and display a start +page, with information on each of the default keyboard bindings. + +From here you can move point between links (which may be menu items or +inline URLs in text files) by using @key{TAB} and @kbd{S-@key{TAB}}, +as in Info. You can also jump directly to a menu item using @key{m}, or +use the standard Emacs or Evil motion and search commands to find your +way around. To open a link, press @key{RET}. (Where a mouse is +available, Clicking on a link with the mouse cursor has the same +effect.) + +To return to the page you just followed the link from, press @key{u}. + +Elpher caches (for the duration of an Emacs session) both page contents +and the position of point on each of the pages (gopher menus, gemini +pages, query results, or text pages) you visit, restoring these when you +next visit the same page. Thus, pressing @key{u} displays the previous +page in exactly the same state as when you left, meaning that you can +quickly and visually explore the different documents in a menu without +having to wait for anything to reload. + +Of course, sometimes you'll @emph{want} to reload the current page +rather than stick with the cached version. To do this use @key{R}. +(This is particularly useful for search query results, where this +allows you to perform a different search.) + +That's more-or-less it. Elpher supports a number of other features, such +as bookmarking, support for different coding schemes and TLS encryption, +and a variety of customization options, all of which are explained in +the rest of this document. However the emphasis is on keeping the basic +navigation experience as intuitive and responsive as possible. + +@node Navigation, Bookmarks, Quick Start, Top +@chapter Navigation Throughout this manual, we use the word ``page'' to refer to any -visualization of a response from a gopher server, be it a +visualization of a response from a gopher or gemini server, be it a menu/directory, query result, text file or image. We use Elpher's navigation interface is inspired by the Emacs Info mode. @@ -100,7 +204,8 @@ coupled with caching of pages and cursor position. @menu * Within-page navigation:: Moving about within a page -* Between-page navigation:: Concepts and commands for moving between pages +* Between-page navigation:: Commands for moving between pages +* History and Caching:: Explanation of how Elpher represents history @end menu @@ -115,13 +220,13 @@ In addition, the following commands are provided for quickly moving between links and menu items. @table @asis -@item @kbd{tab} (@code{elpher-next-link}) +@keycmd{@key{TAB}, elpher-next-link} Move to the next link or menu item in the file. -@item @kbd{}/@kbd{} (@code{elpher-prev-link}) +@keycmd{@kbd{Shift-@key{TAB}}/@key{backtab}, @code{elpher-prev-link}} Move to the previous link or menu item in the file. -@item @kbd{m} (@code{elpher-jump}) +@keycmd{@key{m}, elpher-jump} Jump directly to a link within a file by specifying its display string or link text. (Unlike the previous two commands, this immediately opens the selected link. @@ -131,37 +236,50 @@ The following commands can be used to retrieve information about the current page, or the address of the link at point: @table @asis -@item @kbd{i} (@code{elpher-info-link}) +@keycmd{@key{i}, elpher-info-link} Display host, port and selector information for the link at point. -@item @kbd{I} (@code{elpher-info-current}) +@keycmd{@key{I}, elpher-info-current} Display host, port and selector information for the current page. -@item @kbd{c} (@code{elpher-copy-link-url}) +@keycmd{@key{c}, elpher-copy-link-url} Add URL representing address of link at point to the kill-ring and the system clipboard (if available). -@item @kbd{C} (@code{elpher-copy-current-url}) +@keycmd{@key{C}, elpher-copy-current-url} Add URL representing address of the current page to the kill-ring and the system clipboard (if available). -@end table +@keycmd{@key{d}, elpher-download} +Download link at point and save the result as a file. The minibuffer +will prompt for the name of the file to write, with the default name being +the display string (if available) associated with the link. + +@keycmd{@key{D}, elpher-download-current} +This is similar to @code{elpher-download}, but instead applies to the +current page rather than a link. + +@keycmd{@key{.}, elpher-view-raw} +This displays the raw server response for the current page. While not +useful for general browsing, it is useful for debugging incorrect rendering +or out-of-spec server responses. +@end table -@node Between-page navigation, , Within-page navigation, Navigation +@node Between-page navigation, History and Caching, Within-page navigation, Navigation @section Between-page navigation Moving to a different page can be accomplished in several ways, described by the following command: @table @asis -@item @kbd{RET}, @kbd{mouse-1} (@code{elpher-follow-link}) +@keycmd{@key{RET}\, @kbd{mouse-1}, elpher-follow-link} Follow the menu item or link at point (or selected with the mouse). Exactly what is meant by ``follow'' depends on the kind of item selected: @itemize @item -For text or menu type items or links, the curent page text is replaced +For text or menu type items or links, the current page text is replaced by the text of this item. Unless the customization variable @code{elpher-use-header} (@pxref{Customization}) is @code{nil}, the display string of the link is displayed in the buffer header. @@ -176,37 +294,361 @@ items. @item Following links to binary files (and image files on unsupported systems) causes Elpher to prompt for a filename in which to save the content. + +@item +Following links of type `h' with a selector having the `URL:' prefix, or +unsuported URLs in text files, will result in Elpher using an external +programme to open the URL. This will be either the default system browser +or, if the @code{elpher-open-urls-with-eww} customization variable is non-nil, +Emacs' own EWW browser. (See @pxref{Customization}.) + @end itemize -Once a text, menu or query response page is retrieved, its contents are +Once a text, menu or query response page has been displayed, its contents are cached for the duration of the Emacs session. -@item @kbd{d} (@code{elpher-download}) +@keycmd{@key{g}, elpher-go} +Open a particular page by specifying either its full URL or just entering +a gopher host name. (The protocol defaults to gopher, so gemini links must include the @code{gemini://} prefix. + +If a unsupported protocol is used in the URL the result will be the same +as following a URL link of the same type from a link in a page. + +@keycmd{@key{o}, elpher-go-current} +Prompts for a URL similar to @code{elpher-go}, but initialized to the URL +of the current page. This allows you to easily try other selectors for the +same server. -@item @kbd{g} (@code{elpher-go}) +Remember however, that the Gopher RFC 1436 provides @emph{no} guarantees about the +structure of selectors. -@item @kbd{O} (@code{elpher-root-dir}) +@keycmd{@key{O}, elpher-root-dir} +Open the root page (empty selector) on the current host. -@item @kbd{u} (@code{elpher-back}) +@keycmd{@key{u}\, @kbd{mouse-3}, elpher-back} Return to the previous page, where ``previous'' means the page where the page which was displayed immediately before the current page. @end table -@node Bookmarks, Character encodings, Navigation, Top + +@node History and Caching, , Between-page navigation, Navigation +@section History and Caching + +The history and caching strategy in Elpher is extremely simple, but +may be confusing without a good mental model of how it works. That +is what this section attempts to provide. + +Essentially, @strong{every} time you navigate to a new page, either +by clicking or pressing @key{RET} on a link, using @key{g} to jump +to a new page by its address, or using @key{O} to open the root selector, +the following two things occur: + +@enumerate +@item +the cursor position and content for the original page are recorded in an +in-memory cache, and + +@item +the original page is set as the ``parent'' of the new page. +@end enumerate + +The only way to return to pages in this history is by using @key{u}, +which returns to the previous of the current page. @footnote{The +addition of the new page to the history happens even if the new page is +one that has been seen before. This is mostly the desired behaviour. +However, opening an explicit ``back'' link provided by a gopher menu or +gemini page will also add a new entry to the history. Unless you +haven't yet visited that menu, it's therefore better to use @key{u} to +go back in this case.} + +One aspect that may seem peculiar is that Elpher lacks a corresponding ``next'' or +``forward'' command. However, since Elpher caches the position of point, +this will be automatically positioned on the link that was most recently followed +from a given page. This means that, at least for links followed from menus +and text files, the inverse of @key{u} is actually just @key{RET}. + + +@node Bookmarks, Gopher character encodings, Navigation, Top @chapter Bookmarks -@node Character encodings, Customization, Bookmarks, Top -@chapter Character encodings +Elpher has a very simple link bookmarking system involving the +following commands: + +@table @asis +@keycmd{@key{a}, elpher-bookmark-link} +Add a bookmark for the link at point. The minibuffer will prompt for +a name for the bookmark, which defaults to the display string. + +@keycmd{@key{A}, elpher-bookmark-current} +Add a bookmark for the current page. The minibuffer will prompt for +a name for the bookmark, defaulting to the display string associated +with the link that was followed to reach the current page. + +@keycmd{@key{x}, elpher-unbookmark-link} +Immediately remove the bookmark (if one exists) to the link at point. + +@keycmd{@key{X}, elpher-unbookmark-current} +Immediately remove the bookmark (if one exists) to the current page. + +@keycmd{@key{B}, elpher-bookmarks} +Open a page displaying all current bookmarks. Note that this bookmark +page is added to the history just as if you had opened it using a link. +Thus to return to the previous page, use @kbd{u}. This also means +that you can peruse the various bookmarks by visiting them in turn, +using @kbd{u} to return to the bookmark page (where the position of point +is cached), then moving to another bookmarked link and so on. +@end table + +Bookmarks are stored as a s-exp in the file @file{elpher-bookmarks} +in the user emacs directory (usually @file{~/.emacs.d/}). +Any command which modifies the list of bookmarks immediately updates +this file. + +@node Gopher character encodings, Encrypted gopher connections, Bookmarks, Top +@chapter Gopher character encodings + +Responses Elpher retrieves from servers are initially read as pure +binary data. When the data is intended to be interpreted as textual (as +determined by the type parameter of the gopher menu item or the gopher +URL), this data needs to be @emph{decoded} into a sequence of +characters. To do this properly requires knowledge of the encoding +system used by whoever authored the document. + +Unfortunately gopher lacks a systematic way of acquiring this necessary +information. Thus, the details of the coding system must be either inferred from the binary data, +or must be specified by the user. + +By default, Elpher applies Emacs' built-in character encoding detection +system to the full (undecoded) response data and uses this to attempt to +convert it into a character string. +(See @pxref{Recognize coding, Recognizing coding systems, ,emacs}.) While +this approach can be okay, it is important to realize that its inference +algorithm is extremely primitive and depends heavily on assumptions based +on the language settings of your emacs system. + +The alternative is to explicitly set the coding system used for decoding +using the following command: + +@table @asis +@keycmd{@key{S},elpher-set-coding-system} +Causes a elpher to prompt for a coding system to use for decoding +future gopher text. The @key{TAB} key can be used at this prompt to display a +list of alternatives (which is extensive) and to auto-complete. An empty +response will cause Elpher to return to its default auto-detection +behaviour. +@end table + +Note that changing the coding system only affects newly loaded text. +Thus, if text has already been decoded using an incorrect system, you +will need to select the correct coding and then reload the text using +@key{R}. + + +@node Encrypted gopher connections, Gemini support, Gopher character encodings, Top +@chapter Encrypted gopher connections + +While RFC 1436 does not broach the topic of encryption at all, several +modern gopher servers can serve content over encrypted connections, +and a common choice for this is TLS. + +Elpher can retrieve selectors using Emacs' built-in TLS support which +uses the GnuTLS library. (It is possible to build emacs without +GnuTLS, in which case encryption is not supported.) + +To retrieve documents using TLS, Elpher's TLS mode must be enabled. +This can be directly toggled using @key{T}, but note that just as with +the character encoding, changing this mode only affects subsequent +connections. + +Alternatively, TLS mode is @emph{automatically} enabled whenever +gopher URLs starting with @code{gophers://} are followed. + +The mode is sticky, so it remains active until switched off. +It can also be automatically switched off when a TLS connection fails. +In this case Elpher will prompt for your confirmation to ensure that +you can't accidentally make a non-TLS connection. + +@node Gemini support, Finger support, Encrypted gopher connections, Top +@chapter Gemini support + +@uref{gopher://gemini.circumlunar.space, Gemini} +is a new protocol being developed by several members of +gopherspace. It aims to solve some of the long-standing technical +issues associated with gopher as a protocol, while keeping the major benefits. +For instance, it _requires_ encrypted connections, it does away with +the selector type, and allows servers to explicitly specify the +character coding scheme used for text documents. + +The latest versions of Elpher aim to provide seamless transitions between +gemini and gopher documents. Basically you should be able to open, +bookmark, download and otherwise interact with gemini pages in exactly +the same way as you do with other non-gemini pages. The only major +difference from your perspective as a user is that you should no longer +have to worry about manually toggling TLS on or off (for gemini it's +always on), and you should never have to manually set a character coding +scheme. + +The gemini protocol specification recommends a Trust on First Use (TOFU) +behaviour when validating gemini server TLS certificates. This is +because many gemini servers rely on self-signed certificates rather +than certificates signed by a CA. Sadly however, this TOFU behaviour is +far from straight-forward to configure using Emacs' existing Network +Security Manager. For this reason, elpher defaults to performing no +certificate verification by default. This behaviour can be easily +customized by setting the @code{elpher-gemini-TLS-cert-checks} +customization variable to non-nil. + +The gemini specification concerns both the protocol and a simple text +document format (mimetype text/gemini) which is like a mixture between +gophermap files and markdown-formatted files but simpler than both. +Elpher renders gemini responses which are provided in this format in +line with the rules in the spec. This includes wrapping long lines at +word boundaries. The specific column at which this text is wrapped is +defined by the customization variable +@code{elpher-gemini-max-fill-width}, which is set to 80 columns by +default. (This is slightly wider than Emacs' default fill width of 70 +columns due to the fact that there are a significant amount of older +gemini content which, against the advice of the current spec, hard wraps +at <80 columns. The larger default allows this to still look okay, +while still keeping content without hard wraps looking pleasant.) + +The text/gemini format also possesses a section header syntax similar to +markdown. Elpher allows different header levels to be drawn with +different, customizable, faces. By default, on graphically-capable +emacs systems, these faces are given different heights to distinguish +among levels. On terminal systems, the level is indicated by the +number of preceding # symbols. + +I should emphasize however that, while it is definitely functional, +Elpher's gemini support is still experimental, and various aspects will +change as the protocol develops further. + +@section Client Certificates for Gemini + +Gemini makes explicit use of the client certificate mechanism that TLS +provides for allowing clients to authenticate themselves with servers. +The Gemini specification suggests two distinct classes of client +certificates: short-lived certificates used to identify you for a single +session, and more permanent certificates used to identify you over a +longer time period. + +When Elpher receives a request for a client certificate from a server, +it will present you with the option to create and use a single-use +``throwaway'' certificate, or to use a ``persistent'' +certificate (optionally creating it or installing pre-existing key and +certificate files). + +Certificate creation in Elpher requires an installation of OpenSSL, and +---in particular---that Elpher be able to run the @command{openssl} command-line +utility. By default, Elpher assumes that the @command{openssl} is on the +system path, but the precise location can be set by customizing the +@code{elpher-openssl-command} variable. + +Each generated certificate results in the creation of a .key file and +a .crt file. In the case of a throwaway certificate, these files are +stored in the temporary directory indicated by the Emacs variable +@code{temporary-file-directory} and are deleted when ``forgotten'' +(as described below). + +In the case of persistent certificates, these files are stored in the +folder defined by the Elpher variable +@code{elpher-certificate-directory}, and are never deleted by Elpher. +(Of course you can delete them yourself whenever you like.) +The base name of the files (i.e. sans extension) is what Elpher uses +to identify the certificate. + +Using throwaway certificates is as simple as pressing the @key{t} +key at the prompt which appears following a certificate request from +a server. There is nothing more to do. + +Using a persistent certificate requires instead selecting @key{p} from the same +menu. This will result in Elpher asking you for the name identifying +the certificate. This entry autocompletes to the list of known certificate +names, so you can use @key{TAB} to display the list. + +In the case that you choose a name that does not belong to the list of +known certificates, Elpher will offer to create one for you or to +``install'' one from existing key and certificate files. +Pressing the @key{n} key will cause Elpher to begin the process of +creating a new persistent certificate, using some additional +details for which you will be prompted. +Alternatively, pressing the @key{i} key will cause Elpher to ask for the +locations of edisting key and certificate files to add to +@code{elpher-certificate-directory} under the chosen name. + +Once a certificate is selected, it will be used for all subsequent TLS +transactions to the host for which the certificate was created. +It is immediately ``forgotten'' when a TLS connection to another host +is attempted, or the following command is issued: + +@table @asis +@keycmd{@key{F},elpher-forget-certificate} +Causes Elpher to immediately forget any currently-loaded client certificate. +@end table + +In either case, ``forgetting'' means that the details of the key and +certificate file pair are erased from memory. Furthermore, in the case +of throw-away certificates, the corresponding files are deleted. + + +@node Finger support, Customization, Gemini support, Top +@chapter Finger support + +Incidentally, Elpher has native support for querying finger servers. +Of course, one could argue that this functionality is more easily +provided by one's local telnet client. However finger URLs do appear +on occasion in gopherspace, and it's nice to be able to open them +in place. + +Elpher interprets @code{finger://} URLs as follows: + +@itemize + +@item +The host is determined by the host name portion of the URL. -@node Customization, Hacking, Character encodings, Top +@item +In the case that the @emph{file name} portion of the URL is non-empty (besides +the leading slash), this is interpreted as the user to finger. + +@item +Otherwise, the @emph{user} portion of the URL is interpreted as the user to finger. + +@item +If no user is provided, the root directory of the finger server is requested. + +@end itemize + +Thus @code{finger://user@@hostname} and @code{finger://hostname/user} are both equivalent. + +(The precedence of the /user notation over the user@ notation reflects a +preference of the community.) + +@node Customization, Command Index, Finger support, Top @chapter Customization -@node Hacking, Index, Customization, Top -@chapter Hacking +Various parts of Elpher can be customized via the +variables belonging to the elpher customization group, accessible +using + +@example +@kbd{M-x customize-group elpher @key{RET}} +@end example + +@noindent This group contains a number of faces that can be modified to change +the appearance of Elpher, including one face per menu item type. + +The group also contains variables for customizing the behaviour of +Elpher. This includes how to open arbitrary (non-gopher) URLs, whether +to display buffer headers, how to deal with ANSI escape sequences in +text, the timeout to impose on network connections, and whether to +prompt for confirmation when switching away from TLS. + +See the customization group itself for details. -@node Index, , Hacking, Top -@unnumbered Index +@node Command Index, , Customization, Top +@unnumbered Command Index -@printindex cp +@printindex fn @bye