term% cat index.txt WEBFS(4) Kernel Interfaces Manual WEBFS(4)
NAME
webfs - world wide web file system
SYNOPSIS
webfs [ -A useragent ] [ -T timeout ] [ -m mtpt ] [ -s service ]
DESCRIPTION
Webfs presents a file system interface to the parsing and retrieving of
URLs. Webfs mounts itself at mtpt (default /mnt/web), and, if service
is specified, will post a service file descriptor in /srv/service.
If the environment variable httpproxy is set, all HTTP request initi‐
ated by webfs will be made through that proxy url.
Webfs presents a three-level file system suggestive of the network pro‐
tocol hierarchies ip(3) and ether(3).
The top level contains the two files: ctl, and clone.
The top level ctl file is used to maintain parameters global to the in‐
stance of webfs. Reading the ctl file yields the current values of the
parameters. Writing strings of the form ``attr value'' sets a particu‐
lar attribute.
The following global parameters can be set:
useragent
Sets the HTTP user agent string.
timeout
Sets the request timeout in seconds.
flushauth url
Flushes any associated authentication information for resources
under url or all resources if no url was given.
preauth url realm
Preauthenticates all resources under url with the given realm
using HTTP Basic authentication. This will cause webfs to pre‐
emptively send the resulting authorization information not wait‐
ing for the server to respond with an HTTP 401 Unauthorized sta‐
tus.
The top-level directory also contains numbered directories correspond‐
ing to connections, which may be used to fetch a single URL. To allo‐
cate a connection, open the clone file and read a number n from it.
After opening, the clone file is equivalent to the file n/ctl. A con‐
nection is assumed closed once all files in its directory have been
closed, and is then will be reallocated.
Each connection has a URL attribute url associated with it. This URL
may be an absolute URL such as http://www.lucent.com/index.html or a
relative URL such as ../index.html. The baseurl attribute sets the URL
against which relative URLs are interpreted. Once the URL has been set
by writing to the ctl file of the connection, its pieces can be re‐
trieved via individual files in the parsed directory:
parsed/url
http://pete:secret@www.example.com:8000/cgi/search?q=kittens#re‐
sults
parsed/scheme
http
parsed/user
pete
parsed/pass
secret
parsed/host
www.example.com
parsed/port
8000
parsed/path
/cgi/search
parsed/query
q=kittens
parsed/fragment
results
If there is associated data to be posted with the request, it can be
written to postbody. Opening postbody or body initiates the request.
If the request fails, then opening the body or writing to postbody file
will fail and return a error string.
When the body file has been opened, response headers appear as files in
the connection directory. For example reading the contenttype file
yields the MIME content type of the body data. If the request was
redirected, the URL represented by the parsed directory will change to
the final destination.
The resulting data may be read from body as it arrives.
The following is a list of attributes that can be set to do a connec‐
tion prior initiating the request:
url,baseurl
See above.
useragent
Sets a custom useragent string to be used with the request.
contenttype
Sets the MIME content type of the postbody.
request
Usually, the HTTP method used is POST when postbody file is
opend first or GET otherwise. This can be overridden with the
request attribute so send arbitrary HTTP requests.
headers
Adds arbitrary HTTP headers to be send with the request.
EXAMPLE
/rc/bin/hget is a simple client.
SOURCE
/sys/src/cmd/webfs
SEE ALSO
webcookies(4), hget(1)
DIAGNOSTICS
For cookies to work, webcookies(4), should be running and mounted on
/mnt/webcookies otherwise cookies will be ignored.
HISTORY
Webfs first appeared in Plan 9 from Bell Labs. It was rewritten from
scratch for 9front (January, 2012).
WEBFS(4)