implement

unix v7是最后一个广泛发布的研究型UNIX版本

.I Type
is an upper case letter,
(
.I C
-\ copy command file,
.I D
-\ data file,
.I X
-\ execute file);
.IP
.I System-name
is the remote system;
.IP
.I Grade
is a character;
.IP
.I Number
is a four digit, padded sequence number.
.LP
The file
.IP "" 12
C.res45n0031
.LP
would be a
.I "work file"
for a file transfer between the local
machine and the ``res45'' machine.
.LP
The scan for work is done by looking through the
spool directory for
.I "work files"
(files with prefix ``C.'').
A list is made of all systems to be called.
.I Uucico
will then call each system and process all
.I "work files" .
.SH
Call Remote System
.LP
The call is made using information from several
files which reside in the uucp program directory.
At the start of the call process, a lock is
set to forbid multiple conversations 
between the same two systems.
.LP
The system name is found in the
.I L.sys
file.
The information contained for each system is;
.RS
.IP [1]
system name,
.IP [2]
times to call the system
(days-of-week and times-of-day),
.IP [3]
device or device type to be used for call,
.IP [4]
line speed,
.IP [5]
phone number if field [3] is
.I ACU
or the device name (same as field [3])
if not
.I ACU,
.IP [6]
login information (multiple fields),
.RE
.LP
The time field is checked against the present time to see
if the call should be made.
.LP
The
.I
phone number
.R
may contain abbreviations (e.g. mh, py, boston) which get translated into dial
sequences using the
.I L-dialcodes
file.
.LP
The
.I L-devices
file is scanned using fields [3] and [4] from the
.I L.sys
file to find an available device for the call.
The program will try all devices which satisfy
[3] and [4] until the call is made, or no more
devices can be tried.
If a device is successfully opened, a lock file
is created so that another copy of
.I uucico
will not try to use it.
If the call is complete, the
.I
login information
.R
(field [6] of
.I L.sys )
is used to login.
.LP
The conversation between the two
.I uucico
programs begins with a handshake started by the called,
.I SLAVE ,
system.
The
.I SLAVE
sends a message to let the
.I MASTER
know it is ready to receive the system
identification and conversation sequence number.
The response from the
.I MASTER
is
verified by the
.I SLAVE
and if acceptable, protocol selection begins.
The
.I SLAVE
can also reply with a ``call-back required''
message in which case, the current conversation
is terminated.
.SH
Line Protocol Selection
.LP
The remote system sends a message
.IP "" 12
P\fIproto-list\fR
.LP
where proto-list is a string of characters, each
representing a line protocol.
.LP
The calling program checks the proto-list
for a letter corresponding to an available line
protocol and returns a
.I use-protocol
message.
The
.I use-protocol
message is
.IP "" 12
U\fIcode\fR
.LP
where code is either a one character
protocol letter or
.I N
which means there is no common protocol.
.SH
Work Processing
.LP
The initial roles (
.I MASTER
or
.I SLAVE
) for the work processing are
the mode in which each program starts.
(The 
.I MASTER
has been specified by the ``\-r1'' uucico option.)
The
.I MASTER
program does a work search similar to the
one used in the ``Scan For Work'' section.
.LP
There are five messages used during the
work processing, each specified by the first
character of the message.
They are;
.IP "" 12
.RS
.IP S 3
send a file,
.IP R
receive a file,
.IP C
copy complete,
.IP X
execute a
.I uucp
command,
.IP H
hangup.
.RE
.LP
The
.I MASTER
will send
.I R ,
.I S
or
.I X
messages until all work from the spool directory is
complete, at which point an
.I H
message will be sent.
The
.I SLAVE
will reply with
\fISY\fR, \fISN\fR, \fIRY\fR, \fIRN\fR, \fIHY\fR, \fIHN\fR,
\fIXY\fR, \fIXN\fr,
corresponding to
.I yes
or
.I no
for each request.
.LP
The send and receive replies are
based on permission to access the
requested file/directory using the
.I USERFILE
and read/write permissions of the file/directory.
After each file is copied into the spool directory
of the receiving system,
a copy-complete message is sent by the receiver of the file.
The message
.I CY
will be sent if the
file has successfully been moved from the
temporary spool file to the actual destination.
Otherwise, a
.I CN
message is sent.
(In the case of
.I CN ,
the transferred file will be in the spool
directory with a name beginning with ``TM'.)
The requests and results are logged on both systems.
.LP
The hangup response is determined by the
.I SLAVE
program by a work scan of the spool directory.
If work for the remote system exists in the
.I SLAVE's
spool directory, an
.I HN
message is sent and the programs switch roles.
If no work exists, an
.I HY
response is sent.
.SH
Conversation Termination
.LP
When a
.I HY
message is received by the
.I MASTER
it is echoed back to the
.I SLAVE
and the protocols are turned off.
Each program sends a final ``OO'' message to the
other.
The original
.I SLAVE
program will clean up and terminate.
The
.I MASTER
will proceed to call other systems
and process work as long as possible
or terminate if a
.I \-s
option was specified.
.LP
.NH
Uuxqt - Uucp Command Execution
.LP
The
.I uuxqt
program is used to execute
.I
execute files
.R
generated by
.I uux.
The
.I uuxqt
program may be started by either the
.I uucico
or
.I uux
programs.
The program scans the spool directory for
.I
execute files
.R
(prefix ``X.'').
Each one is checked to see if all the required files are available and
if so, the command line or send line is executed.
.LP
The
.I
execute file
.R
is described in the ``Uux''
section above.
.SH
Command Execution
.LP
The execution is accomplished by executing a
.I
sh \-c
.R
of the command line after appropriate
standard input and standard output have been opened.
If a standard output is specified, the program
will create a send command or copy the output
file as appropriate.
.NH
Uulog - Uucp Log Inquiry
.LP
The
.I uucp
programs create individual
log files for each program invocation.
Periodically,
.I uulog
may be executed to prepend these files to the
system logfile.
This method of logging was chosen to minimize file
locking of the logfile during program execution.
.LP
The
.I uulog
program merges the individual
log files and outputs specified log entries.
The output request is specified by the use of the
following options:
.RS
.IP \-s\fIsys\fR 9
Print entries where
.I sys
is the remote system name;
.IP \-u\fIuser\fR
Print entries for user
.I user.
.RE
.LP
The intersection of lines satisfying the two options is output.
A null
.I sys
or
.I user
means all system names or users respectively.
.NH
Uuclean - Uucp Spool Directory Cleanup
.LP
This program is typically started by the daemon, once a day.
Its function is to remove files from the spool directory which
are more than 3 days old.
These are usually files for work which can not be completed.
.LP
.LP
The options available are:
.RS
.IP \-d\fIdir\fR 10
The directory to be scanned is
.I dir .
.IP \-m
Send mail to the owner of each file being removed.
(Note that most files put into the spool directory
will be owned by the owner of the
uucp programs since the setuid bit will be set on these
programs.
The mail will therefore most often go to the owner
of the uucp programs.)
.IP \-n\fIhours\fR
Change the aging time from 72 hours to
.I hours
hours.
.IP \-p\fIpre\fR
Examine files with prefix
.I pre
for deletion.
(Up to 10 file prefixes may be specified.)
.IP \-x\fInum\fR
This is the level of debugging output desired.
.RE
.NH
Security
.LP
.LG
\fB
The uucp system, left unrestricted,
will let any outside user execute any commands
and copy in/out any file which is readable/writable
by the uucp login user.
It is up to the individual sites to be aware of this and
apply the protections that they feel are necessary.
\fR
.NL
.LP
There are several security features available aside from the
normal file mode protections.
These must be set up by the installer of the
.I uucp
system.
.IP - 3
The login for uucp does not get a standard shell.
Instead, the
.I uucico
program is started.
Therefore, the only work that can be done is through
.I uucico .
.IP -
A path check is done on file names that are to be sent
or received.
The
.I USERFILE
supplies the information for these checks.
The
.I USERFILE
can also be set up to require call-back
for certain login-ids.
(See the ``Files required for execution'' section
for the file description.)
.IP -
A conversation sequence count can be set up so
that the called system
can be more confident that the caller
is who he says he is.
.IP -
The
.I uuxqt
program comes with a list of commands that it
will execute.
A ``PATH'' shell statement is prepended to the command
line as specifed in the
.I uuxqt
program.
The installer may modify the list or remove the
restrictions as desired.
.IP -
The
.I L.sys
file should be owned by uucp and have mode 0400
to protect the phone numbers and login information
for remote sites.
(Programs uucp, uucico, uux, uuxqt should be also
owned by uucp and have the setuid bit set.)
.NH
Uucp Installation
.LP
There are several source modifications that may be required
before the system programs are compiled.
These relate to the directories used during compilation,
the directories used during execution,
and the local
.I
uucp system-name.
.R
.LP
The four directories are:
.RS
.IP lib 12
(/usr/src/cmd/uucp)
This directory contains the source files for generating the
.I uucp
system.
.IP program
(/usr/lib/uucp)
This is the directory used for the executable system programs and
the system files.
.IP spool
(/usr/spool/uucp)
This is the spool directory used during
.I uucp
execution.
.IP xqtdir
(/usr/spool/uucp/.XQTDIR)
This directory is used during execution of
.I "execute files" .
.RE
.LP
The names given in parentheses above are the default values
for the directories.
The italicized named
.I
lib, program, xqtdir,
.R
and
.I spool
will be used in the following text to represent the
appropriate directory names.
.LP
There are two files which may require modification,
the
.I makefile
file and the
.I uucp.h
file.
The following paragraphs describe the modifications.
The modes of
.I spool
and
.I xqtdir
should be made ``0777''.
.SH
Uucp.h modification
.LP
Change the
.I program
and the
.I spool
names from the default values to the directory
names to be used on the local system using
global edit commands.
.LP
Change the
.I define
value for
.I MYNAME
to be the local
.I uucp
system-name.
.SH
makefile modification
.LP
There are several
.I make
variable definitions which may need modification.
.RS
.IP INSDIR 10
This is the
.I program
directory
(e.g. INSDIR=/usr/lib/uucp).
This parameter is used if ``make cp'' is
used after the programs are compiled.
.IP IOCTL
This is required to be set if an appropriate
.I ioctl
interface subroutine does not exist in the standard
``C'' library;
the statement
``IOCTL=ioctl.o'' is required in this case.
.IP PKON
The statement ``PKON=pkon.o'' is required if the
packet driver is not in the kernel.
.RE
.SH
Compile the system
The command
.IP "" 12
make
.LP
will compile the entire system.
The command
.IP "" 12
make cp
.LP
will copy the commands to the
to the appropriate directories.
.LP
The programs
.I uucp ,
.I uux ,
and
.I uulog
should be put in ``/usr/bin''.
The programs
.I uuxqt ,
.I uucico ,
and
.I uuclean
should be put in the
.I program
directory.
.SH
Files required for execution
.LP
There are four files which are required for execution,
all of which should reside in the
.I program
directory.
The field separator for all files is a space unless otherwise
specified.
.SH
L-devices
.LP
This file contains entries for the call-unit devices and
hardwired connections which are to be used by
.I uucp.
The special device files are assumed to be in the
.I /dev
directory.
The format for each entry is
.IP "" 12
line\ \ call-unit\ \ speed
.LP
where;
.RS
.IP line 12
is the device for the line (e.g. cul0),
.IP call-unit
is the automatic call unit associated with
.I line