CS(8) CS(8)
NAME
cs, csquery - connection server
SYNOPSYS
ndb/cs [ -f database ] [ -v ] [ -x net ]
ndb/csquery [ -x net ] [ -s server ] [ address ... ]
DESCRIPTION
Cs spawns a process that serves a single file /net/cs, in
the current name space, answering requests by client pro-
cesses to translate symbolic network and service names into
instructions for connecting to the given service. It is
normally accessed indirectly by calls to sys-dial(2).
The network data is taken from the network database files,
described in ndb(6). By default, it is /lib/ndb/local but
the -f option can specify a different one.
Each write to /net/cs makes a query, expressed in one of two
forms. The first form is a network address of the same form
as the addr parameter to dial: network!netaddr!service where
service and network are optional for some networks. The
write returns an error if the address cannot be translated.
Otherwise, the file offset should be reset to 0 using sys-
seek(2) and each subsequent read will return either end-of-
file (if there are no further translations), or a single
line containing a translation of the form:
/net/proto/clone address!port
The first field is the name of the clone file for a network
protocol or interface. To make a connection or announce a
service, open that file, and write the text in the second
field preceded by connect or announce as required. (All
this activity is normally encapsulated in a call to sys-
dial(2)). Cs produces a translation for each network and for
each network address on which a symbolic netaddr is found.
When announcing a service, netaddr can be * to represent any
local interface, and the resulting recipes read from /net/cs
will not include an address! part.
Cs interprets a netaddr of the form $server specially: it
looks for an attribute server in the database in the entry
for the current host, then in the entry for each network
that contains it (if specified), and finally in a site-wide
entry labelled with the attribute infernosite. If found,
the value of the attribute replaces the netaddr before fur-
ther translation.
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CS(8) CS(8)
In the second form of query, the text written contains
space-separated attribute/value pairs following an initial
`!':
! attr1=val1 [ attr2=val2 ... ]
Cs looks for an ndb(6) entry that contains attribute/value
pairs matching those in the query. Any value but val1 may
be `*', to signify that the entry must contain the given
attribute but with any value. As before, the write returns
an error if no entry matches. Otherwise, each subsequent
read returns the whole of the next matching entry, in ndb(6)
form.
The file /net/cs persists until it is removed or unmounted
from /net, or the cs process is killed (see kill(1)). The -v
option causes cs to print each translation request and
results (if any) on standard error. The -x option gives an
alternative mount point for cs, when there is more than one
network stack (see ip(3)). It causes it cs to serve net/cs
instead of /net/cs.
Cs is normally started once, after dns(8) if used, but
before most other applications including the various listen-
ers described in svc(8). If another instance of cs(8) is
started on the same mount point, the file it serves replaces
the earlier one if permissions allow. (On Plan 9, Plan 9's
native connection service will be used by default if
Inferno's cs is not started.)
Csquery queries the given server (default: /net/cs) for a
translation of each address and prints the results, one per
line. If no address is given, csquery prompts for
address(es) to translate which it reads from the standard
input, printing the results of each translation on the stan-
dard output. The -x option gives an alternative mount point
for cs, when there is more than one network stack (see
ip(3)).
Cs(8) uses services(6) to map protocol and service names to
Internet port numbers. Finally, if all else fails, it
applies the built-in srv(2), if available. Consequently,
entries in services(6) and dns(6) take precedence over the
host's system-wide configuration. (This is helpful for
adding symbolic names for Inferno services without requiring
administrative privileges on the host system.)
EXAMPLE
Check the translation of the symbolic name $signer:
ndb/csquery
> net!$signer!inflogin
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CS(8) CS(8)
/net/tcp/clone 200.1.1.67!6673
FILES
#scs* service directory
/net/cs connection service
/net/dns domain name service
/lib/ndb/local map from symbolic service names to servers
SOURCE
/appl/cmd/ndb/cs.b
/appl/cmd/ndb/csquery.b
SEE ALSO
sys-dial(2), db(6), dns(8)
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