Apache 模組 mod_ext_filter

範例

從其他類型的回應產生 HTML

# mod_ext_filter directive to define a filter
# to HTML-ize text/c files using the external
# program /usr/bin/enscript, with the type of
# the result set to text/html
ExtFilterDefine c-to-html mode=output \
    intype=text/c outtype=text/html \
    cmd="/usr/bin/enscript --color -w html -Ec -o -"

<Directory "/export/home/trawick/apacheinst/htdocs/c">
    # core directive to cause the new filter to
    # be run on output
    SetOutputFilter c-to-html
    
    # mod_mime directive to set the type of .c
    # files to text/c
    AddType text/c .c
</Directory>

實作內容編碼過濾器

注意: 這個 gzip 範例僅供說明用途。如需實用的實作方式，請參考 mod_deflate。

# mod_ext_filter directive to define the external filter
ExtFilterDefine gzip mode=output cmd=/bin/gzip

<Location "/gzipped">
    
    # core directive to cause the gzip filter to be
    # run on output
    SetOutputFilter gzip
    
    # mod_headers directive to add
    # "Content-Encoding: gzip" header field
    Header set Content-Encoding gzip
</Location>

讓伺服器慢下來

# mod_ext_filter directive to define a filter
# which runs everything through cat; cat doesn't
# modify anything; it just introduces extra pathlength
# and consumes more resources
ExtFilterDefine slowdown mode=output cmd=/bin/cat \
    preservescontentlength

<Location "/">
    # core directive to cause the slowdown filter to
    # be run several times on output
    #
    SetOutputFilter slowdown;slowdown;slowdown
</Location>

使用 sed 取代回應中的文字

# mod_ext_filter directive to define a filter which
# replaces text in the response
#
ExtFilterDefine fixtext mode=output intype=text/html \
    cmd="/bin/sed s/verdana/arial/g"

<Location "/">
    # core directive to cause the fixtext filter to
    # be run on output
    SetOutputFilter fixtext
</Location>

追蹤其他過濾器

# Trace the data read and written by mod_deflate
# for a particular client (IP 192.168.1.31)
# experiencing compression problems.
# This filter will trace what goes into mod_deflate.
ExtFilterDefine tracebefore \
    cmd="/bin/tracefilter.pl /tmp/tracebefore" \
    EnableEnv=trace_this_client

# This filter will trace what goes after mod_deflate.
# Note that without the ftype parameter, the default
# filter type of AP_FTYPE_RESOURCE would cause the
# filter to be placed *before* mod_deflate in the filter
# chain.  Giving it a numeric value slightly higher than
# AP_FTYPE_CONTENT_SET will ensure that it is placed
# after mod_deflate.
ExtFilterDefine traceafter \
    cmd="/bin/tracefilter.pl /tmp/traceafter" \
    EnableEnv=trace_this_client ftype=21

<Directory "/usr/local/docs">
    SetEnvIf Remote_Addr 192.168.1.31 trace_this_client
    SetOutputFilter tracebefore;deflate;traceafter
</Directory>

#!/usr/local/bin/perl -w
use strict;

open(SAVE, ">$ARGV[0]")
    or die "can't open $ARGV[0]: $?";

while (<STDIN>) {
    print SAVE $_;
    print $_;
}

close(SAVE);