xref: /csrg-svn/usr.sbin/sendmail/src/READ_ME (revision 64272)

# Copyright (c) 1983 Eric P. Allman
# Copyright (c) 1988 The Regents of the University of California.
# All rights reserved.
#
# %sccs.include.redist.sh%
#
#	@(#)READ_ME	8.15 (Berkeley) 08/15/93
#

This directory contains the source files for sendmail.

For detailed instructions, please read the document ../doc/op.me:

	eqn ../doc/op.me | pic | ditroff -me

The Makefile is for the new (4.4BSD) Berkeley make, available from
ftp.uu.net in the directory /systems/unix/bsd-sources/usr.bin/make.
It has assumptions about the 4.4 file system layout built in.  There
is also a Makefile.dist which is much less clever, but works on the
old traditional make.  You can use this using:

	make -f Makefile.dist

There are a bunch of other Makefiles for other systems -- these are
the ones that I use, they have "Berkeley quirks" in them, and I don't
guarantee that they will work unmodified in your environment.  However,
they are all designed for the old make and can be used to help you get
started.  They have names like "Makefile.HPUX".  Many of them include
-I/usr/sww/include/db and -L/usr/sww/lib -- this is Berkeley's
location for the new database libraries, described below.

There is also a shell script (makesendmail) that tries to be clever
about using object subdirectories.  It's pretty straightforward, and
may help if you share a source tree among different architectures.


+----------------------+
| DATABASE DEFINITIONS |
+----------------------+

There are several database formats that can be used for the alias files
and for general maps.  When used for alias files they interact in an
attempt to be back compatible.

The three options are NEWDB (the new Berkeley DB package), NDBM (the
older DBM implementation -- the very old V7 implementation is no
longer supported), and NIS (Network Information Services).  Used alone
these just include the support they indicate.

If NEWDB and NDBM are defined (but not NIS), then sendmail will read
NDBM format alias files, but the next time a newaliases is run the
format will be converted to NEWDB; that format will be used forever
more.  This is intended as a transition feature.  [Note however that
the NEWDB library also catches and maps NDBM calls; you will have to
back out this feature to get this to work.  See ``Quirks'' section
below for details.]

If all three are defined, sendmail operates as described above, and also
looks for the file /var/yp/Makefile.  If it exists, newaliases will
build BOTH the NEWDB and NDBM format alias files.  However, it will
only use the NEWDB file; the NDBM format file is used only by the
NIS subsystem.

If NDBM and NIS are defined (regardless of the definition of NEWDB
or the existance of /var/yp/Makefile), sendmail adds the special
tokens "YP_LAST_MODIFIED" and "YP_MASTER_NAME", both of which are
required if the NDBM file is to be used as an NIS map.

All of -DNEWDB, -DNDBM, and -DNIS are normally defined in the DBMDEF
line in the Makefile.


+---------------+
| COMPILE FLAGS |
+---------------+

Whereever possible, I try to make sendmail pull in the correct
compilation options needed to compile on various environments based on
automatically defined symbols.  Some machines don't seem to have useful
symbols availble, requiring the following compilation flags in the
Makefile:

SOLARIS		Define this if you are running Solaris 2.0 or higher.
NeXT		Define this if you are on a NeXT box.  (This one may
		be pre-defined for you.)  There are other hacks you
		have to make -- see below.
_AIX3		Define this if you are IBM AIX 3.x.
RISCOS		Define this if you are running RISC/os from MIPS.

If you are a system that sendmail has already been ported to, you
probably won't have to touch these.  But if you are porting, you may
have to tweak the following compilation flags in conf.h in order to
get it to compile and link properly:

SYSTEM5		Adjust for System V.
SYS5SIGNALS	Use System V signal semantics -- the signal handler
		is automatically dropped when the signal is caught.
		If this is not set, use POSIX/BSD semantics, where the
		signal handler stays in force until an exec or an
		explicit delete.  Implied by SYSTEM5.
HASFLOCK	Set this if you prefer to use the flock(2) system call
		rather than using fcntl-based locking.  Fcntl locking
		has some semantic gotchas, but many vendor systems
		also interface it to lockd(8) to do NFS-style locking.
		For this reason, this should not be set unless you
		don't have an alternative.
HASUNAME	Set if you have the "uname" system call.  Implied by
		SYSTEM5.
HASUNSETENV	Define this if your system library has the "unsetenv"
		subroutine.
HASSTATFS	Define this if you have the statfs(2) system call.  It's
		not a disaster to get this wrong -- but you do lose the
		queue free space code.
HASUSTAT	Define this if you have the ustat(2) system call.  It's
		not a disaster to get this wrong -- but you do lose the
		queue free space code.
HASSETSID	Define this if you have the setsid(2) system call.  This
		is implied if your system appears to be POSIX compliant.
HASINITGROUPS	Define this if you have the initgroups(3) routine.
HASSETVBUF	Define this if you have the setvbuf(3) library call.
		If you don't, setlinebuf will be used instead.  This
		defaults on if your compiler defines __STDC__.
HASSETREUID	Define this if you have setreuid(2) ***AND*** root can
		use setreuid to change to an arbitrary user.  This second
		condition is not satisfied on AIX 3.x.  You may find that
		your system has setresuid(2), (for example, on HP-UX) in
		which case you will also have to #define setreuid(r, e)
		to be the appropriate call.  Some systems (such as Solaris)
		have a compatibility routine that doesn't work properly.
		The important thing is that you have a call that will set
		the effective uid independently of the real or saved uid.
		Setting this improves the security somewhat, since
		sendmail doesn't have to read .forward and :include: files
		as root.
GIDSET_T	The type of entries in a gidset passed as the second
		argument to getgroups(2).  Historically this has been an
		int, so this is the default, but some systems (such as
		IRIX) pass it as a gid_t, which is an unsigned short.
		This will make a difference, so it is important to get
		this right!  However, it is only an issue if you have
		group sets.
SLEEP_T		The type returned by the system sleep() function.
		Defaults to "unsigned int".  Don't worry about this
		if you don't have compilation problems.
ARBPTR_T	The type of an arbitrary pointer -- defaults to "void *".
		If you are an very old compiler you may need to define
		this to be "char *".
LA_TYPE		The type of load average your kernel supports.  These
		can be LA_SUBR (4) if you have the getloadavg(3) routine,
		LA_FLOAT (3) if you read kmem and interpret the value
		as a floating point number, LA_INT (2) to interpret as
		an integer.  These last two have several other parameters
		that they try to divine: the name of your kernel, the name
		of the variable in the kernel to examine, the number of
		bits of precision in a fixed point load average, and so
		forth.  In desparation, use LA_ZERO -- it always returns
		the load average as "zero" (and does so on all architectures).
		The actual code is in conf.c -- it can be tweaked if you
		are brave.
ERRLIST_PREDEFINED
		If set, assumes that some header file defines sys_errlist.
		This may be needed if you get type conflicts on this
		variable -- otherwise don't worry about it.


+-----------------------+
| COMPILE-TIME FEATURES |
+-----------------------+

There are a bunch of features that you can decide to compile in, such
as selecting various database packages and special protocol support.
Several are assumed based on other compilation flags -- if you want to
"un-assume" something, you probably need to edit conf.h.  Compilation
flags that add support for special features include:

NDBM		Include support for "new" DBM library for aliases and maps.
		Normally defined in the Makefile.
NEWDB		Include support for Berkeley "db" package (hash & btree)
		for aliases and maps.  Normally defined in the Makefile.
NIS		Define this to get NIS (YP) support for aliases and maps.
		Normally defined in the Makefile.
USERDB		Include support for the User Information Database.  Implied
		by NEWDB in conf.h.
IDENTPROTO	Define this to get IDENT (RFC 1413) protocol support.
		This is assumed unless you are running on Ultrix or
		HP-UX, both of which have a problem in the UDP
		implementation.
MIME		Include support for MIME-encapsulated error messages.
FROZENCONFIG	Define this to get support for frozen configuration
		files.  Frozen configurations make sense if your I/O system
		is fast relative to your processor.  At this point this
		is NOT recommended.
LOG		Set this to get syslog(3) support.  Defined by default
		in conf.h.  You want this if at all possible.
NETINET		Set this to get TCP/IP support.  Defined by default
		in conf.h.  You probably want this.
NETISO		Define this to get ISO networking support.
SMTP		Define this to get the SMTP code.  Implied by NETINET
		or NETISO.
NAMED_BIND	Define this to get DNS (name daemon) support, including
		MX support.  The specs you must use this if you run
		SMTP.  Defined by default in conf.h.
QUEUE		Define this to get queueing code.  Implied by NETINET
		or NETISO; required by SMTP.  This gives you other good
		stuff -- it should be on.
DAEMON		Define this to get general network support.  Implied by
		NETINET or NETISO.  Defined by default in conf.h.  You
		almost certainly want it on.
MATCHGECOS	Permit fuzzy matching of user names against the full
		name (GECOS) field in the /etc/passwd file.  This should
		probably be on, since you can disable it from the config
		file if you want to.  Defined by default in conf.h.
SETPROCTITLE	Try to set the string printed by "ps" to something
		informative about what sendmail is doing.  Defined by
		default in conf.h.


+-------------------------------------+
| OPERATING SYSTEM AND COMPILE QUIRKS |
+-------------------------------------+

SunOS
	If you are compiling on SunOS and want to use frozen configuration
	files, you must use -Bstatic -- if you do not, frozen
	configuration files fail in bizarre ways and you will open up
	several security holes.

	You may have to use -lresolv on SunOS.

OSF/1
	If you are compiling on OSF/1 (DEC Alpha), you must use -lmld.

NeXT
	If you are compiling on NeXT, you will have to create an empty
	file "unistd.h" and create a file "dirent.h" containing:

		#include <sys/dir.h>
		#define dirent	direct

	(The Makefile.NeXT should try to do both of these for you.)

BSDI (BSD/386)
	I have reports that the "m4" from BSDI won't handle the config
	files properly.  I haven't had a chance to test this myself.

Both NEWDB and NDBM
	If you use both -DNDBM and -DNEWDB, you must delete the module
	ndbm.o from libdb.a and delete the file "ndbm.h" from the files
	that get installed (that is, use the OLD ndbm.h, not the new
	ndbm.h).  This compatibility module maps ndbm calls into DB
	calls, and breaks things rather badly.


+-----------------------------+
| DESCRIPTION OF SOURCE FILES |
+-----------------------------+

The following list describes the files in this directory:

Makefile	The makefile used here; this version only works with
		the new Berkeley make.
Makefile.dist	A trimmed down version of the makefile that works with
		the old make.
READ_ME		This file.
TRACEFLAGS	My own personal list of the trace flags -- not guaranteed
		to be particularly up to date.
alias.c		Does name aliasing in all forms.
arpadate.c	A subroutine which creates ARPANET standard dates.
clock.c		Routines to implement real-time oriented functions
		in sendmail -- e.g., timeouts.
collect.c	The routine that actually reads the mail into a temp
		file.  It also does a certain amount of parsing of
		the header, etc.
conf.c		The configuration file.  This contains information
		that is presumed to be quite static and non-
		controversial, or code compiled in for efficiency
		reasons.  Most of the configuration is in sendmail.cf.
conf.h		Configuration that must be known everywhere.
convtime.c	A routine to sanely process times.
daemon.c	Routines to implement daemon mode.  This version is
		specifically for Berkeley 4.1 IPC.
deliver.c	Routines to deliver mail.
domain.c	Routines that interface with DNS (the Domain Name
		System).
err.c		Routines to print error messages.
envelope.c	Routines to manipulate the envelope structure.
headers.c	Routines to process message headers.
macro.c		The macro expander.  This is used internally to
		insert information from the configuration file.
main.c		The main routine to sendmail.  This file also
		contains some miscellaneous routines.
map.c		Support for database maps.
mci.c		Routines that handle mail connection information caching.
parseaddr.c	The routines which do address parsing.
queue.c		Routines to implement message queueing.
readcf.c	The routine that reads the configuration file and
		translates it to internal form.
recipient.c	Routines that manipulate the recipient list.
savemail.c	Routines which save the letter on processing errors.
sendmail.h	Main header file for sendmail.
srvrsmtp.c	Routines to implement server SMTP.
stab.c		Routines to manage the symbol table.
stats.c		Routines to collect and post the statistics.
sysexits.c	List of error messages associated with error codes
		in sysexits.h.
trace.c		The trace package.  These routines allow setting and
		testing of trace flags with a high granularity.
udb.c		The user database interface module.
usersmtp.c	Routines to implement user SMTP.
util.c		Some general purpose routines used by sendmail.
version.c	The version number and information about this
		version of sendmail.  Theoretically, this gets
		modified on every change.

Eric Allman

(Version 8.15, last update 08/15/93 13:18:30)