HTTPD(8) 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 pri-
vate 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. Persis-
tent connections are supported for HTTP/1.1 or later
clients; all connections close after a magic command is exe-
cuted. The Content-type (default application/octet-stream)
and Content-encoding (default binary) of a file are deter-
mined by looking for suffixes of the file name in
/sys/lib/mimetype.
Redirection
Each requested URI is looked up in a redirection table, read
from /sys/lib/httpd.rewrite. Fields are separated by spaces
and tabs. Anything 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 redirection 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;
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otherwise it is a prefix match. The first field is a lit-
eral 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 fol-
lowing 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 ref-
erences to an old subtree to a single error page.
Httpd handles replacements prefixed with `@' internally,
treating the request as if it were for the replacement
(without the @) but not informing the client of the rewrit-
ten 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
connections. 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 direc-
tory 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 separated 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 exe-
cutes the file /bin/ip/httpd/server to finish servicing the
request. All the auxiliaries take the same arguments.
Method and version are those received 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 connec-
tion. 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 request 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
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HTTPD(8) HTTPD(8)
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 entries 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 assumed 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 list-
ing of `.' and `..'). If webls.allowed exists but
webls.denied does not, any directory to be listed must be
described by a regular expression in webls.allowed. Simi-
larly, if webls.denied exists but webls.allowed does not,
any directory to be listed must not be described by a regu-
lar 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
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HTTPD(8) HTTPD(8)
/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; over-
rides 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)
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