Fix ipfw invalid mbuf handling.

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.Dd $Mdocdate: March 18 2017 $
.Dt MAN.CGI 8
.Os
.Sh NAME
.Nm man.cgi
.Nd CGI program to search and display manual pages
.Sh DESCRIPTION
The
.Nm
CGI program searches for manual pages on a WWW server
and displays them to HTTP clients,
providing functionality equivalent to the
.Xr man 1
and
.Xr apropos 1
utilities.
It can use multiple manual trees in parallel.
.Ss HTML search interface
At the top of each generated HTML page,
.Nm
displays a search form containing these elements:
.Bl -enum
.It
An input box for search queries, expecting
either a name of a manual page or an
.Ar expression
using the syntax described in the
.Xr apropos 1
manual; filling this in is required for each search.
.Pp
The expression is broken into words at whitespace.
Whitespace characters and backslashes can be escaped
by prepending a backslash.
The effect of prepending a backslash to another character is undefined;
in the current implementation, it has no effect.
.It
A
.Xr man 1
submit button.
The string in the input box is interpreted as the name of a manual page.
.It
An
.Xr apropos 1
submit button.
The string in the input box is interpreted as a search
.Ar expression .
.It
A dropdown menu to optionally select a manual section.
If one is provided, it has the same effect as the
.Xr man 1
and
.Xr apropos 1
.Fl s
option.
Otherwise, pages from all sections are shown.
.It
A dropdown menu to optionally select an architecture.
If one is provided, it has the same effect as the
.Xr man 1
and
.Xr apropos 1
.Fl S
option.
By default, pages for all architectures are shown.
.It
A dropdown menu to select a manual tree.
If the configuration file
.Pa /var/www/man/manpath.conf
contains only one manpath, the dropdown menu is not shown.
By default, the first manpath given in the file is used.
.El
.Ss Program output
The
.Nm
program generates five kinds of output pages:
.Bl -tag -width Ds
.It The index page.
This is returned when calling
.Nm
without
.Ev PATH_INFO
and without a
.Ev QUERY_STRING .
It serves as a starting point for using the program
and shows the search form only.
.It A list page.
Lists are returned when searches match more than one manual page.
The first column shows the names and section numbers of manuals
as clickable links.
The second column shows the one-line descriptions of the manuals.
.It A manual page.
This output format is used when a search matches exactly one
manual page, or when a link on a list page or an
.Ic \&Xr
link on another manual page is followed.
.It A no-result page.
This is shown when a search request returns no results -
eiher because it violates the query syntax, or because
the search does not match any manual pages.
.It \&An error page.
This cannot happen by merely clicking the
.Dq Search
button, but only by manually entering an invalid URI.
It does not show the search form, but only an error message
and a link back to the index page.
.El
.Ss Setup
For each manual tree, create one first-level subdirectory below
.Pa /var/www/man .
The name of one of these directories is called a
.Dq manpath
in the context of
.Nm .
Create a single ASCII text file
.Pa /var/www/man/manpath.conf
containing the names of these directories, one per line.
The directory given first is used as the default manpath.
.Pp
Inside each of these directories, use the same directory and file
structure as found below
.Pa /usr/share/man ,
that is, second-level subdirectories
.Pa /var/www/man/*/man1 , /var/www/man/*/man2
etc. containing source
.Xr mdoc 7
and
.Xr man 7
manuals with file name extensions matching the section numbers,
second-level subdirectories
.Pa /var/www/man/*/cat1 , /var/www/man/*/cat2
etc. containing preformatted manuals with the file name extension
.Sq 0 ,
and optional third-level subdirectories for architectures.
Use
.Xr makewhatis 8
to create a
.Xr mandoc.db 5
database inside each manpath.
.Pp
Configure your web server to execute CGI programs located in
.Pa /cgi-bin .
When using
.Ox
.Xr httpd 8 ,
the
.Xr slowcgi 8
proxy daemon is needed to translate FastCGI requests to plain old CGI.
.Pp
To compile
.Nm ,
first copy
.Pa cgi.h.example
to
.Pa cgi.h
and edit it according to your needs.
It contains the following compile-time definitions:
.Bl -tag -width Ds
.It Ev COMPAT_OLDURI
Only useful for running on www.openbsd.org to deal with old URIs containing
.Qq "manpath=OpenBSD "
where the blank character has to be translated to a hyphen.
When compiling for other sites, this definition can be deleted.
.It Dv CSS_DIR
An optional file system path to the directory containing the file
.Pa mandoc.css ,
to be specified relative to the server's document root,
and to be specified without a trailing slash.
When empty, the CSS file is assumed to be in the document root.
Otherwise, a leading slash is needed.
This is used in generated HTML code.
.It Dv CUSTOMIZE_TITLE
An ASCII string to be used for the HTML <TITLE> element.
.It Dv MAN_DIR
A file system path to the
.Nm
data directory relative to the web server
.Xr chroot 2
directory, to be specified with a leading slash and without a trailing slash.
It needs to have at least one component; the root directory cannot be used
for this purpose.
The files
.Pa manpath.conf ,
.Pa header.html ,
and
.Pa footer.html
are looked up in this directory.
It is also prepended to the manpath when opening
.Xr mandoc.db 5
and manual page files.
.It Dv SCRIPT_NAME
The initial component of URIs, to be specified without leading
and trailing slashes.
It can be empty.
.El
.Pp
After editing
.Pa cgi.h ,
run
.Pp
.Dl make man.cgi
.Pp
and copy the resulting binary to the proper location,
for example using the command:
.Pp
.Dl make installcgi
.Pp
In addition to that, make sure the default manpath contains the files
.Pa man1/apropos.1
and
.Pa man8/man.cgi.8 ,
or the documentation links at the bottom of the index page will not work.
.Ss URI interface
.Nm
uniform resource identifiers are not needed for interactive use,
but can be useful for deep linking.
They consist of:
.Bl -enum
.It
The
.Cm http://
protocol specifier.
.It
The host name.
.It
The
.Dv SCRIPT_NAME ,
preceded by a slash unless empty.
.It
To show a single page, a slash, the manpath, another slash,
and the name of the requested file, for example
.Pa /OpenBSD-current/man1/mandoc.1 .
This can be abbreviated according to the following syntax:
.Sm off
.Op / Ar manpath
.Op / Cm man Ar sec
.Op / Ar arch
.Pf / Ar name Op \&. Ar sec
.Sm on
.It
For searches, a query string starting with a question mark
and consisting of
.Ar key Ns = Ns Ar value
pairs, separated by ampersands, for example
.Pa ?manpath=OpenBSD-current&query=mandoc .
Supported keys are
.Cm manpath ,
.Cm query ,
.Cm sec ,
.Cm arch ,
corresponding to
.Xr apropos 1
.Fl M ,
.Ar expression ,
.Fl s ,
.Fl S ,
respectively, and
.Cm apropos ,
which is a boolean parameter to select or deselect the
.Xr apropos 1
query mode.
For backward compatibility with the traditional
.Nm ,
.Cm sektion
is supported as an alias for
.Cm sec .
.El
.Ss Restricted character set
For security reasons, in particular to prevent cross site scripting
attacks, some strings used by
.Nm
can only contain the following characters:
.Pp
.Bl -dash -compact -offset indent
.It
lower case and upper case ASCII letters
.It
the ten decimal digits
.It
the dash
.Pq Sq -
.It
the dot
.Pq Sq \&.
.It
the slash
.Pq Sq /
.It
the underscore
.Pq Sq _
.El
.Pp
In particular, this applies to all manpaths and architecture names.
.Sh ENVIRONMENT
The web server may pass the following CGI variables to
.Nm :
.Bl -tag -width Ds
.It Ev SCRIPT_NAME
The initial part of the URI passed from the client to the server,
starting after the server's host name and ending before
.Ev PATH_INFO .
This is ignored by
.Nm .
When constructing URIs for links and redirections, the
.Dv SCRIPT_NAME
preprocessor constant is used instead.
.It Ev PATH_INFO
The final part of the URI path passed from the client to the server,
starting after the
.Ev SCRIPT_NAME
and ending before the
.Ev QUERY_STRING .
It is used by the
.Cm show
page to acquire the manpath and filename it needs.
.It Ev QUERY_STRING
The HTTP query string passed from the client to the server.
It is the final part of the URI, after the question mark.
It is used by the
.Cm search
page to acquire the named parameters it needs.
.El
.Sh FILES
.Bl -tag -width Ds
.It Pa /var/www
Default web server
.Xr chroot 2
directory.
All the following paths are specified relative to this directory.
.It Pa /cgi-bin/man.cgi
The usual file system path to the
.Nm
program inside the web server
.Xr chroot 2
directory.
A different name can be chosen, but in any case, it needs to be configured in
.Xr httpd.conf 5 .
.It Pa /htdocs
The file system path to the server document root directory
relative to the server
.Xr chroot 2
directory.
This is part of the web server configuration and not specific to
.Nm .
.It Pa /htdocs/mandoc.css
A style sheet for
.Xr mandoc 1
HTML styling, referenced from each generated HTML page.
.It Pa /man
Default
.Nm
data directory containing all the manual trees.
Can be overridden by
.Dv MAN_DIR .
.It Pa /man/manpath.conf
The list of available manpaths, one per line.
If any of the lines in this file contains a slash
.Pq Sq /
or any character not contained in the
.Sx Restricted character set ,
.Nm
reports an internal server error and exits without doing anything.
.It Pa /man/header.html
An optional file containing static HTML code to be inserted right
after opening the <BODY> element.
.It Pa /man/footer.html
An optional file containing static HTML code to be inserted right
before closing the <BODY> element.
.It Pa /man/OpenBSD-current/man1/mandoc.1
An example
.Xr mdoc 7
source file located below the
.Dq OpenBSD-current
manpath.
.El
.Sh COMPATIBILITY
The
.Nm
CGI program is call-compatible with queries from the traditional
.Pa man.cgi
script by Wolfram Schneider.
However, the output may not be quite the same.
.Sh SEE ALSO
.Xr apropos 1 ,
.Xr mandoc.db 5 ,
.Xr makewhatis 8 ,
.Xr slowcgi 8
.Sh HISTORY
A version of
.Nm
based on
.Xr mandoc 1
first appeared in mdocml-1.12.1 (March 2012).
The current
.Xr mandoc.db 5
database format first appeared in
.Ox 6.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm
program was written by
.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv
and is maintained by
.An Ingo Schwarze Aq Mt schwarze@openbsd.org ,
who also designed and implemented the database format.