\input texinfo @c -*-texinfo-*-
@setfilename elpher.info
-@settitle Elpher Manual v1.0.0
+@settitle Elpher Manual v2.10.0
@dircategory Emacs
@direntry
-* Elpher: (elpher). A gopher client for Emacs.
+* 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
@end copying
@titlepage
-@title Elpher Gopher Client Manual
+@title Elpher Gopher and Gemini Client Manual
@author Tim Vaughan
@page
* 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
-* Encrypted connections:: How and when TLS is enabled
+* 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
* 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, 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
@item
direct visualization of image files where supported (no writing to
-disk), and
+disk),
+
+@item
+a bookmark management system,
@item
-a simple bookmark management system.
+basic support for the new ``heavier than gopher, lighter than the web'' Gemini protocol,
+
+@item
+support for the Finger protocol.
+
@end itemize
Elpher is still under active development. Although we try very hard to
While not recommended, it is also possible to install Elpher directly by
downloading the file @file{elpher.el} from
-@url{https://github.com/tgvaughan/elpher}, adding it to a directory in
+@url{gopher://thelambdalab.xyz/1/projects/elpher/}, adding it to a directory in
your @code{load-path}, and then adding
@example
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, 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.
+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}.
@node Navigation, Bookmarks, Quick Start, Top
@chapter Navigation
-by
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.
This is similar to @code{elpher-download}, but instead applies to the
current page rather than a link.
-@keycmd{@key{w}, elpher-view-raw}
+@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.
@item
Following links of type `h' with a selector having the `URL:' prefix, or
-non-gopher URLs in text files, will result in Elpher using an external
+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}.)
cached for the duration of the Emacs session.
@keycmd{@key{g}, elpher-go}
-Open a particular page by specifying either its URL or directly entering
-a host, port and selector.
+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.
-Note that if a non-gopher protocol is used in the URL the result will be
-the same as following a URL link of the same type from a gopher menu.
+Remember however, that the Gopher RFC 1436 provides @emph{no} guarantees about the
+structure of selectors.
@keycmd{@key{O}, elpher-root-dir}
Open the root page (empty selector) on the current host.
-@keycmd{@key{u}, 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
@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 will also add a new entry to the history. Unless you
+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.}
and text files, the inverse of @key{u} is actually just @key{RET}.
-@node Bookmarks, Character encodings, Navigation, Top
+@node Bookmarks, Gopher character encodings, Navigation, Top
@chapter Bookmarks
Elpher has a very simple link bookmarking system involving the
Any command which modifies the list of bookmarks immediately updates
this file.
-@node Character encodings, Encrypted connections, Bookmarks, Top
-@chapter Character encodings
+@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
@table @asis
@keycmd{@key{S},elpher-set-coding-system}
Causes a elpher to prompt for a coding system to use for decoding
-future text. The @key{TAB} key can be used at this prompt to display a
+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.
@key{R}.
-@node Encrypted connections, Customization, Character encodings, Top
-@chapter Encrypted connections
+@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,
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.
+
+@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, Encrypted connections, Top
+@node Customization, Command Index, Finger support, Top
@chapter Customization
Various parts of Elpher can be customized via the
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, whether to look for naked URLs in
-gopher menus (as opposed to just plain text files), and whether
-to prompt for confirmation when switching away from TLS.
+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.
The Lambda Lab / projects / elpher.git / blobdiff