From 96e026c1815f123e5a60ee106cb802fc841faa6c Mon Sep 17 00:00:00 2001 From: root Date: Thu, 29 Apr 2021 00:02:41 +0000 Subject: Fix filter-related bug Apparently, an Apache filter can be invoked more than once for a single request, depending on the size of the contents [1]. Luckily, though, a filter can save state in the ctx field [1,2]. The solution isn't perfect, as it can't handle arbitrary long heads, but they're very unlikely. [1] https://httpd.apache.org/docs/2.4/developer/output-filters.html#invocation [2] https://perl.apache.org/docs/2.0/user/handlers/filters.html#Introducing_Filters --- lib/Apache/Inject.pm | 16 ++++++++++++++++ lib/Apache/Inject/Filter.pm | 32 +++++++++++++++++++++++--------- 2 files changed, 39 insertions(+), 9 deletions(-) (limited to 'lib/Apache') diff --git a/lib/Apache/Inject.pm b/lib/Apache/Inject.pm index 1d6f49b..68e003e 100644 --- a/lib/Apache/Inject.pm +++ b/lib/Apache/Inject.pm @@ -182,6 +182,10 @@ intelligently and forwards their combined contents. =head1 CAVEATS +=over + +=item * + Apache::Inject::Filter uses a regular expression to determine the proper location of the injected header. It supports all valid HTML. However, it does not parse embedded CSS and JavaScript, which means @@ -204,10 +208,22 @@ This specific type of document, however, is I unlikely. In this case, an ad-hoc solution is simpler, more efficient and more maintainable than a general one. +=item * + +Because of how Apache filters work, Inject may fail to find the end +of the EheadE if the EheadE is very long (in my +experience over 7000 characters). If this happens, it will decline +the request, and the contents will be served as though Inject had +not been enabled. + +=item * + On FreeBSD, you may need to enable the accf_http kernel module in order for the tests to work. Note that Apache::Inject works fine without the module; it is only the tests that require it. +=back + =head1 DIAGNOSTICS Apache::Inject and Apache::Inject::Filter log all errors and diff --git a/lib/Apache/Inject/Filter.pm b/lib/Apache/Inject/Filter.pm index f87cdc1..67511e2 100644 --- a/lib/Apache/Inject/Filter.pm +++ b/lib/Apache/Inject/Filter.pm @@ -49,15 +49,29 @@ sub handler : FilterRequestHandler { return DECLINED; } - my ($buf, $content); - $content .= $buf while $f->read($buf); - return DECLINED if not $content =~ /$doc/; - - $f->print($+{head}) if $+{head}; - inject($f, "InjectHead"); - $f->print($+{body}) if $+{body}; - inject($f, "InjectFoot"); - $f->print($+{rest}) if $+{rest}; + # First pass + if (not $f->ctx) { + my ($buf, $content); + $content .= $buf while $f->read($buf); + if (not $content =~ /$doc/) { + $f->r->warn('Inject: Cannot find ( too long?)'); + return DECLINED; + } + + $f->print($+{head}) if $+{head}; + inject($f, "InjectHead"); + $f->print($+{body}) if $+{body}; + inject($f, "InjectFoot"); + $f->print($+{rest}) if $+{rest}; + + $f->ctx(1); + } + + # Any subsequent pass + else { + my $buf; + $f->print($buf) while $f->read($buf); + } return OK; } -- cgit v1.2.3