* [pmg-devel] [PATCH pmg-api 1/1] rulesystem: limit linelength of disclaimer to 998 bytes
@ 2021-11-22 19:50 Stoiko Ivanov
2021-11-23 6:16 ` Thomas Lamprecht
0 siblings, 1 reply; 2+ messages in thread
From: Stoiko Ivanov @ 2021-11-22 19:50 UTC (permalink / raw)
To: pmg-devel
As described in
http://www.postfix.org/postconf.5.html#smtp_line_length_limit
postfix splits lines which are longer by inserting <cr><lf><space> to
adhere with RFC 5322 (section 2.1.1):
https://datatracker.ietf.org/doc/html/rfc5322#section-2.1.1
If a longer line is part of the disclaimer pmg-smtp-filter adds it
without this modification, which breaks DKIM signatures (since the
body is modified by postfix after the body hash is computed)
reported in our community forum:
https://forum.proxmox.com/threads/dkim-body-has-been-altered-when-enabling-disclaimer-function.97919/
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
src/PMG/RuleDB/Disclaimer.pm | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/PMG/RuleDB/Disclaimer.pm b/src/PMG/RuleDB/Disclaimer.pm
index 1b1accf..1c81b03 100644
--- a/src/PMG/RuleDB/Disclaimer.pm
+++ b/src/PMG/RuleDB/Disclaimer.pm
@@ -84,6 +84,10 @@ sub save {
defined($self->{ogroup}) || die "undefined object attribute: ERROR";
defined($self->{value}) || die "undefined object attribute: ERROR";
+ if ($self->{value} =~ /^.{998,}$/m) {
+ die "too long line in disclaimer - breaks RFC 5322!\n";
+ }
+
if (defined ($self->{id})) {
# update
--
2.30.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [pmg-devel] [PATCH pmg-api 1/1] rulesystem: limit linelength of disclaimer to 998 bytes
2021-11-22 19:50 [pmg-devel] [PATCH pmg-api 1/1] rulesystem: limit linelength of disclaimer to 998 bytes Stoiko Ivanov
@ 2021-11-23 6:16 ` Thomas Lamprecht
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Lamprecht @ 2021-11-23 6:16 UTC (permalink / raw)
To: Stoiko Ivanov, pmg-devel
On 22.11.21 20:50, Stoiko Ivanov wrote:
> As described in
> http://www.postfix.org/postconf.5.html#smtp_line_length_limit
>
> postfix splits lines which are longer by inserting <cr><lf><space> to
> adhere with RFC 5322 (section 2.1.1):
> https://datatracker.ietf.org/doc/html/rfc5322#section-2.1.1
>
> If a longer line is part of the disclaimer pmg-smtp-filter adds it
> without this modification, which breaks DKIM signatures (since the
> body is modified by postfix after the body hash is computed)
>
> reported in our community forum:
> https://forum.proxmox.com/threads/dkim-body-has-been-altered-when-enabling-disclaimer-function.97919/
>
> Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
> ---
> src/PMG/RuleDB/Disclaimer.pm | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/src/PMG/RuleDB/Disclaimer.pm b/src/PMG/RuleDB/Disclaimer.pm
> index 1b1accf..1c81b03 100644
> --- a/src/PMG/RuleDB/Disclaimer.pm
> +++ b/src/PMG/RuleDB/Disclaimer.pm
> @@ -84,6 +84,10 @@ sub save {
> defined($self->{ogroup}) || die "undefined object attribute: ERROR";
> defined($self->{value}) || die "undefined object attribute: ERROR";
>
> + if ($self->{value} =~ /^.{998,}$/m) {
1. a comment that the regex match is used to avoid the fact that the `length` function is
working on characters (vs. bytes) only would be good, but..
2. regex isn't actually _that_ better, if one adds a `use utf8` it also matches chars and
not bytes here
Maybe go for the more explicit variant? I think the following should work (but with encodings
involved one is never sure..)
if (length(Encode::encode("UTF-8", $self->{value})) > 998)
> + die "too long line in disclaimer - breaks RFC 5322!\n";
> + }
> +
> if (defined ($self->{id})) {
> # update
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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