WEBFS(4)                                                 WEBFS(4)

     NAME
          webfs - world wide web file system

     SYNOPSIS
          webfs [ -c cookiefile ] [ -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.

          Webfs presents a three-level file system suggestive of the
          network protocol hierarchies ip(3) and ether(3).

          The top level contains three files: ctl, cookies, and clone.

          The ctl file is used to maintain parameters global to the
          instance of webfs. Reading the ctl file yields the current
          values of the parameters.  Writing strings of the form
          ``attr value'' sets a particular attribute.  Attributes are:

          chatty9p
               The chatty9p flag used by the 9P library, discussed in
               9p(2). 0 is no debugging, 1 prints 9P message traces on
               standard error, and values above 1 present more debug-
               ging, at the whim of the library.  The default for this
               and the following debug flags is 0.

          fsdebug
               This variable is the level of debugging output about
               the file system module.

          cookiedebug
               This variable is the level of debugging output about
               the cookie module.

          urldebug
               This variable is the level of debugging output about
               URL parsing.

          acceptcookies
               This flag controls whether to accept cookies presented
               by remote web servers.  (Cookies are described below,
               in the discussion of the cookies file.)  The values on
               and off are synonymous with 1 and 0.  The default is
               on.

          sendcookies
               This flag controls whether to present stored cookies to

     WEBFS(4)                                                 WEBFS(4)

               remote web servers.  The default is on.

          redirectlimit
               Web servers can respond to a request with a message
               redirecting to another page.  Webfs makes no effort to
               determine whether it is in an infinite redirect loop.
               Instead, it gives up after this many redirects.  The
               default is 10.

          useragent
               Webfs sends the value of this attribute in its
               User-Agent: header in its HTTP requests.  The default
               is ``webfs/2.0 (plan 9).''

          The top-level directory also contains numbered directories
          corresponding to connections, which may be used to fetch a
          single URL.  To allocate 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 connection is assumed
          closed once all files in its directory have been closed, and
          is then will be reallocated.

          Each connection has its own private set of acceptcookies,
          sendcookies, redirectlimit, and useragent variables, ini-
          tialized to the defaults set in the root's ctl file.  The
          per-connection ctl file allows editing the variables for
          this particular connection.

          Each connection also has a URL string variable url associ-
          ated 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 string variable sets the URL
          against which relative URLs are interpreted.  Once the URL
          has been set, its pieces can be retrieved via individual
          files in the parsed directory.  Webfs parses the following
          URL syntaxes; names in italics are the names of files in the
          parsed directory.

               scheme:schemedata
               http://host/path[?query][#fragment]
               ftp://[user[:password]@]host/path[;type=ftptype]
               file:path

          If there is associated data to be posted with the request,
          it can be written to postbody.  Finally, opening body initi-
          ates the request.  The resulting data may be read from body
          as it arrives.  After the request has been executed, the
          MIME content type may be read from the contenttype file.

          The top-level cookies file contains the internal set of HTTP
          cookies, which are used by HTTP servers to associate
          requests with persistent state such as user profiles.  It

     WEBFS(4)                                                 WEBFS(4)

          may be edited as an ordinary text file.  Multiple instances
          of webfs and webcookies(4) share cookies by keeping their
          internal set consistent with the cookiefile (default
          $home/lib/webcookies), which has the same format.

          These files contain one line per cookie; each cookie com-
          prises some number of attr=value pairs.  Cookie attributes
          are:

          name=name
               The name of the cookie on the remote server.

          value=value
               The value associated with that name on the remote
               server.  The actual data included when a cookie is sent
               back to the server is ``name=value'' (where, confus-
               ingly, name and value are the values associated with
               the name and value attributes.

          domain=domain
               If domain is an IP address, the cookie can only be used
               for URLs with host equal to that IP address.  Other-
               wise, domain must be a pattern beginning with a dot,
               and the cookie can only be used for URLs with a host
               having domain as a suffix.  For example, a cookie with
               domain=.bell-labs.com may be used on hosts www.bell-
               labs.com and www.research.bell-labs.com (but not
               www.not-bell-labs.com).

          path=path
               The cookie can only be used for URLs with a path begin-
               ning with path.

          version=version
               The version of the HTTP cookie specification, specified
               by the server.

          comment=comment
               A comment, specified by the server.

          expire=expire
               The cookie expires at time expire, which is a decimal
               number of seconds since the epoch.

          secure=1
               The cookie may only be used over secure (https) connec-
               tions.  Secure connections are currently unimplemented.

          explicitdomain=1
               The domain associated with this cookie was set by the
               server (rather than inferred from a URL).

     WEBFS(4)                                                 WEBFS(4)

          explicitpath=1
               The path associated with this cookie was set by the
               server (rather than inferred from a URL).

          netscapestyle=1
               The server presented the cookie in ``Netscape style,''
               which does not conform to the cookie standard, RFC2109.
               It is assumed that when presenting the cookie to the
               server, it must be sent back in Netscape style as well.

     EXAMPLE
          /sys/src/cmd/webfs/webget.c is a simple client.

     SOURCE
          /sys/src/cmd/webfs

     SEE ALSO
          hget(1), webcookies(4)

     BUGS
          It's not clear what the relationship between hget,
          webcookies and webfs should be.