* [bug#41870] [PATCH 1/2] channels: Warn when pulling from a mirror.
2020-06-15 15:12 [bug#41870] [PATCH 0/2] Allow '.guix-channel' to advertise the primary URL Ludovic Courtès
@ 2020-06-15 15:20 ` Ludovic Courtès
2020-06-15 15:20 ` [bug#41870] [PATCH 2/2] .guix-channel: Add primary URL Ludovic Courtès
2020-06-17 17:33 ` bug#41870: [PATCH 0/2] Allow '.guix-channel' to advertise the " Ludovic Courtès
1 sibling, 1 reply; 4+ messages in thread
From: Ludovic Courtès @ 2020-06-15 15:20 UTC (permalink / raw)
To: 41870; +Cc: Ludovic Courtès
* guix/channels.scm (<channel-metadata>)[url]: New field.
(read-channel-metadata): Initialize it.
(read-channel-metadata-from-source): Likewise.
(channel-instance-primary-url): New procedure.
(latest-channel-instances): Compare CHANNEL's URL against it.
* doc/guix.texi (Channels)[Primary URL]: New subsection.
---
doc/guix.texi | 22 ++++++++++++++++++++++
guix/channels.scm | 29 +++++++++++++++++++++++++----
2 files changed, 47 insertions(+), 4 deletions(-)
diff --git a/doc/guix.texi b/doc/guix.texi
index 81a11c6756..16ef5bf42e 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4153,6 +4153,28 @@ add a meta-data file @file{.guix-channel} that contains:
(directory "guix"))
@end lisp
+@cindex primary URL, channels
+@subsection Primary URL
+
+Channel authors can indicate the primary URL of their channel's Git
+repository in the @file{.guix-channel} file, like so:
+
+@lisp
+(channel
+ (version 0)
+ (url "https://example.org/guix.git"))
+@end lisp
+
+This allows @command{guix pull} to determine whether it is pulling code
+from a mirror of the channel; when that is the case, it warns the user
+that the mirror might be stale and displays the primary URL. That way,
+users cannot be tricked into fetching code from a stale mirror that does
+not receive security updates.
+
+This feature only makes sense for authenticated repositories, such as
+the official @code{guix} channel, for which @command{guix pull} ensures
+the code it fetches is authentic.
+
@cindex news, for channels
@subsection Writing Channel News
diff --git a/guix/channels.scm b/guix/channels.scm
index 38ec68fec1..7e4d6e4c84 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -182,12 +182,13 @@ introduction, add it."
(checkout channel-instance-checkout))
(define-record-type <channel-metadata>
- (channel-metadata directory dependencies news-file keyring-reference)
+ (channel-metadata directory dependencies news-file keyring-reference url)
channel-metadata?
(directory channel-metadata-directory) ;string with leading slash
(dependencies channel-metadata-dependencies) ;list of <channel>
(news-file channel-metadata-news-file) ;string | #f
- (keyring-reference channel-metadata-keyring-reference)) ;string
+ (keyring-reference channel-metadata-keyring-reference) ;string
+ (url channel-metadata-url)) ;string | #f
(define %default-keyring-reference
;; Default value of the 'keyring-reference' field.
@@ -209,6 +210,7 @@ if valid metadata could not be read from PORT."
(let ((directory (and=> (assoc-ref properties 'directory) first))
(dependencies (or (assoc-ref properties 'dependencies) '()))
(news-file (and=> (assoc-ref properties 'news-file) first))
+ (url (and=> (assoc-ref properties 'url) first))
(keyring-reference
(or (and=> (assoc-ref properties 'keyring-reference) first)
%default-keyring-reference)))
@@ -229,7 +231,8 @@ if valid metadata could not be read from PORT."
(commit (get 'commit))))))
dependencies)
news-file
- keyring-reference)))
+ keyring-reference
+ url)))
((and ('channel ('version version) _ ...) sexp)
(raise (condition
(&message (message "unsupported '.guix-channel' version"))
@@ -253,7 +256,7 @@ doesn't exist."
read-channel-metadata))
(lambda args
(if (= ENOENT (system-error-errno args))
- (channel-metadata "/" '() #f %default-keyring-reference)
+ (channel-metadata "/" '() #f %default-keyring-reference #f)
(apply throw args)))))
(define (channel-instance-metadata instance)
@@ -463,6 +466,11 @@ been tampered with and is trying to force a roll-back, preventing you from
getting the latest updates. If you think this is not the case, explicitly
allow non-forward updates."))))))))))
+(define (channel-instance-primary-url instance)
+ "Return the primary URL advertised for INSTANCE, or #f if there is no such
+information."
+ (channel-metadata-url (channel-instance-metadata instance)))
+
(define* (latest-channel-instances store channels
#:key
(current-channels '())
@@ -518,6 +526,19 @@ depending on the policy it implements."
validate-pull
#:starting-commit
current)))
+ (when authenticate?
+ ;; CHANNEL is authenticated so we can trust the
+ ;; primary URL advertised in its metadata and warn
+ ;; about possibly stale mirrors.
+ (let ((primary-url (channel-instance-primary-url
+ instance)))
+ (unless (or (not primary-url)
+ (channel-commit channel)
+ (string=? primary-url (channel-url channel)))
+ (warning (G_ "pulled channel '~a' from a mirror \
+of ~a, which might be stale~%")
+ (channel-name channel)
+ primary-url))))
(let-values (((new-instances new-channels)
(loop (channel-instance-dependencies instance)
--
2.26.2
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