term% cat index.txt HTTPD(8) System Manager's Manual HTTPD(8)
NAME
httpd, save, imagemap, man2html, webls - HTTP server
SYNOPSIS
ip/httpd/httpd [-a srvaddr] [-c cert [-C certchain]] [-d domain] [-n
namespace] [-w webroot]
ip/httpd/save [-b inbuf] [-d domain] [-r remoteip] [-w webroot] [-N
netdir] method version uri [search]
ip/httpd/imagemap ...
ip/httpd/man2html ...
ip/httpd/webls ...
DESCRIPTION
Httpd serves the webroot directory of the file system described by
namespace (default /lib/namespace.httpd), using version 1.1 of the HTTP
protocol. It announces the service srvaddr (default tcp!*!http), and
listens for incoming calls. If an X.509 certificate is supplied with
the -c option, then the service is instead tcp!*!https. There should
already be a factotum holding the corresponding private key. If the
specified certificate has been signed by a certificate authority, the
-C option may be used to specify a file containing a chain of signed
certificates.
Httpd supports only the GET and HEAD methods of the HTTP protocol; some
magic programs support POST as well. Persistent connections are sup‐
ported for HTTP/1.1 or later clients; all connections close after a
magic command is executed. The Content-type (default applica‐
tion/octet-stream) and Content-encoding (default binary) of a file are
determined by looking for suffixes of the file name in /sys/lib/mime‐
type.
Redirection
Each requested URI is looked up in a redirection table, read from
/sys/lib/httpd.rewrite. Fields are separated by spaces and tabs. Any‐
thing following a is ignored. The first field of each line is a URI;
the second a replacement path. If a prefix of the URI matches a redi‐
rection path, the URI is rewritten using the corresponding replacement
path instead of the prefix, and a temporary redirect is sent to the
HTTP client. If the replacement path does not specify a server name,
and the request has no explicit host, then domain is the host name used
in the redirection. The prefix can either be a domain root like
http://system/ (which matches that URL only) or a path like /who/rob
(which matches that path no matter what the requested server), but not
both: http://system/who/rob will never match a request. If the first
field ends in a slash, this is an exact match; otherwise it is a prefix
match. The first field is a literal string, matched against each file
prefix of each URL. The most specific, i.e., longest, pattern wins,
and is applied once (there is no rescanning), except for the following
exceptions. Httpd matches only the prefix and not subordinate pages if
a replacement is prefixed with Httpd omits the unmatched part of the
original URI from the rewritten URI if the replacement is prefixed with
This permits many-to-one mappings; for example, to send all references
to an old subtree to a single error page.
Httpd handles replacements prefixed with internally, treating the re‐
quest as if it were for the replacement (without the @) but not inform‐
ing the client of the rewritten name. Replacement URLs prefixed with
generate a permanent redirection instead of a temporary one. Httpd
checks to see if this file has changed once every 50 new TCP connec‐
tions. HTTP 1.1 persistent connection implies many pages may come in
one browser connection, so to kick-start httpd, try
for(i in `{seq 50}) hget http://www.your-domain.com/ >/dev/null
Access Control
Before opening any file, httpd looks for a file in the same directory
called .httplogin. If the file exists, the directory is considered
locked and the client must specify a user name and password matching a
pair in the file. .httplogin contains a list of space or newline sepa‐
rated tokens, each possibly delimited by single quotes. The first is a
domain name presented to the HTTP client. The rest are pairs of user
name and password. Thus, there can be many user name/password pairs
valid for a directory.
Auxiliaries (magic)
If the requested URI begins with /magic/server/, httpd executes the
file /bin/ip/httpd/server to finish servicing the request. All the
auxiliaries take the same arguments. Method and version are those re‐
ceived on the first line of the request. Uri is the remaining portion
of the requested URI. Inbuf contains the rest of the bytes read by the
server, and netdir is the network directory for the connection. There
are routines for processing command arguments, parsing headers, etc. in
the httpd library, /sys/src/cmd/ip/httpd/libhttpd.a.$O. See httpd.h in
that directory and existing magic commands for more details.
Save writes a line to /usr/web/save/uri.data and returns the contents
of /usr/web/save/uri.html. Both files must be accessible for the re‐
quest to succeed. The saved line includes the current time and either
the search string from a HEAD or GET or the first line of the body from
a POST. It is used to record form submissions.
Imagemap processes an HTML imagemap query. It looks up the point
search in the image map file given by uri, and returns a redirection to
the appropriate page. The map file defaults to NCSA format. Any en‐
tries after a line starting with the word #cern are interpreted in CERN
format.
Man2html converts man(6) format manual pages into html. It includes
some abilities to search the manuals.
Webls produces directory listings on the fly, with output in the style
of ls(1). /sys/lib/webls.allowed and /sys/lib/webls.denied contain
regular expressions describing what parts of httpd's namespace may and
may not be listed, respectively. Webls.denied is first searched to see
if access is by default denied. If so webls.allowed is then searched
to see if access is explicitly allowed. Thus one can have very general
expressions in the denied list (like .*), yet still allow exceptions.
If webls.denied does not exist or is unreadable, all accesses are as‐
sumed to be denied unless explicitly allowed in webls.allowed.
Other sites will note that if neither webls.denied nor webls.allowed
exist, any portion of httpd's namespace can be listed (however, webls
will always endeavor to prevent listing of `.' and `..'). If webls.al‐
lowed exists but webls.denied does not, any directory to be listed must
be described by a regular expression in webls.allowed. Similarly, if
webls.denied exists but webls.allowed does not, any directory to be
listed must not be described by a regular expression in webls.denied.
If both exist, a directory is listable if either it doesn't appear in
webls.denied, or it appears in both webls.denied and webls.allowed. In
other words, webls.allowed overrides webls.denied. If a listing for a
directory is requested and access is denied, or another error occurs, a
simple error page is returned.
EXAMPLES
These are all examples of how to use httpd.rewrite.
A local redirection:
/netlib/c++/idioms/index.html.Z /netlib/c++/idioms/index.html
Redirection to another site:
/netlib/lapack/lawns =http://netlib.org/lapack/lawns
http://inferno.bell-labs.com =http://www.vitanuova.com
Root directory for virtual host:
http://www.ampl.com /cm/cs/what/ampl
FILES
/sys/lib/mimetype
content type description file
/lib/namespace.httpd
default namespace file for httpd
/sys/lib/httpd.rewrite
redirection file
/sys/lib/webls.allowed
regular expressions describing explicitly listable pathnames;
overrides webls.denied
/sys/lib/webls.denied
regular expressions describing explicitly unlistable pathnames
SOURCE
/sys/src/cmd/ip/httpd
SEE ALSO
newns in auth(2), listen(8), rsa(8)
HTTPD(8)