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 processes to translate sym‐
bolic network and service names into instructions for connecting to the
given service. It is normally accessed indirectly by calls to 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 param‐
eter 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 contain‐
ing 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
dial(2).) Cs produces a translation for each network and for each net‐
work 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.
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 match‐
ing 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 listeners 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
standard output. The -x option gives an alternative mount point for
cs, when there is more than one network stack (see ip(3)).
Cs uses ndb(6) to map protocol and service names to Internet port num‐
bers. When running hosted, if entries are not in ndb(6), cs applies
the built-in srv(2), if available, to have the host system try the
translation. Consequently, entries in ndb(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
/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 ALSOdial(2), ndb(6), dns(8)CS(8)
