Apache HTTP Server 版本2.2
Apache HTTP Server 版本2.2
| 說明 | 使用外部程序作為過濾器 |
|---|---|
| 狀態(tài) | 擴(kuò)展(E) |
| 模塊名 | ext_filter_module |
| 源文件 | mod_ext_filter.c |
mod_ext_filter presents a simple and familiar
programming model for 過濾器. With
this module, a program which reads from stdin and writes to stdout
(i.e., a Unix-style filter command) can be a filter for
Apache. This filtering mechanism is much slower than using a
filter which is specially written for the Apache API and runs
inside of the Apache server process, but it does have the
following benefits:
Even when the performance characteristics are not suitable
for production use, mod_ext_filter can be used as
a prototype environment for filters.
# 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
# mod_ext_filter directive to set the debug
# level just high enough to see a log message
# per request showing the configuration in force
ExtFilterOptions DebugLevel=1
</Directory>
Note: this gzip example is just for the purposes of illustration.
Please refer to mod_deflate for a practical
implementation.
# 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_header directive to add
# "Content-Encoding: gzip" header field
Header set Content-Encoding gzip
</Location>
# 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>
# 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>
# 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);
| 說明 | Define an external filter |
|---|---|
| 語法 | ExtFilterDefine filtername parameters |
| 作用域 | server config |
| 狀態(tài) | 擴(kuò)展(E) |
| 模塊 | mod_ext_filter |
ExtFilterDefine directive defines the
characteristics of an external filter, including the program to
run and its arguments.
filtername specifies the name of the filter being
defined. This name can then be used in SetOutputFilter
directives. It must be unique among all registered filters.
At the present time, no error is reported by the
register-filter API, so a problem with duplicate names isn't
reported to the user.
Subsequent parameters can appear in any order and define the
external command to run and certain other characteristics. The
only required parameter is cmd=. These parameters
are:
cmd=cmdlinecmd= keyword allows you to specify the
external command to run. If there are arguments after the
program name, the command line should be surrounded in
quotation marks (例如，cmd="/bin/mypgm
arg1 arg2".) Normal shell quoting is
not necessary since the program is run directly, bypassing the shell.
Program arguments are blank-delimited. A backslash can be used to
escape blanks which should be part of a program argument. Any
backslashes which are part of the argument must be escaped with
backslash themselves. In addition to the standard CGI environment
variables, DOCUMENT_URI, DOCUMENT_PATH_INFO, and
QUERY_STRING_UNESCAPED will also be set for the program.mode=modemode=output (the default) for filters which
process the response. Use mode=input for filters
which process the request. mode=input is available
in Apache 2.1 and later.intype=imtintype= is
specified, the filter will be disabled for documents of other
types.outtype=imtPreservesContentLengthPreservesContentLength keyword specifies
that the filter preserves the content length. This is not the
default, as most filters change the content length. In the
event that the filter doesn't modify the length, this keyword
should be specified.ftype=filtertypedisableenv=envenableenv=env| 說明 | Configure mod_ext_filter options |
|---|---|
| 語法 | ExtFilterOptions option [option] ... |
| 默認(rèn)值 | ExtFilterOptions DebugLevel=0 NoLogStderr |
| 作用域 | directory |
| 狀態(tài) | 擴(kuò)展(E) |
| 模塊 | mod_ext_filter |
ExtFilterOptions directive specifies
special processing options for mod_ext_filter.
Option can be one of
DebugLevel=nDebugLevel keyword allows you to specify
the level of debug messages generated by
mod_ext_filter. By default, no debug messages
are generated. This is equivalent to
DebugLevel=0. With higher numbers, more debug
messages are generated, and server performance will be
degraded. The actual meanings of the numeric values are
described with the definitions of the DBGLVL_ constants
near the beginning of mod_ext_filter.c.
Note: The core directive LogLevel should be used to cause debug messages to
be stored in the Apache error log.
LogStderr | NoLogStderrLogStderr keyword specifies that
messages written to standard error by the external filter
program will be saved in the Apache error log.
NoLogStderr disables this feature.
ExtFilterOptions LogStderr DebugLevel=0
Messages written to the filter's standard error will be stored
in the Apache error log. No debug messages will be generated by
mod_ext_filter.