prng_cmds/init_rng() question/patch

[Jon Peatfield]

Since I've had no replies suggesting that it either is safe to move
the init_rng() call (to after we lose privelage) or any other sensible
way to achieve what I was trying to do (have a standalone ssh client
which needs no support files in fixed places), I may as well post my
patch in case anyone can spot any structural problems with it or
suggest better ways to do some bits.  I've tested that it works on a
small set of patforms (Tru64, Solaris-2.6, irix6.5, Linux (with
/dev/random disabled for testing).

--cut-here--
*** entropy.c.orig	Sun Mar 11 14:46:41 2001
--- entropy.c	Sun Mar 11 15:25:40 2001
***************
*** 641,646 ****
--- 641,671 ----
  	RAND_add(&seed, sizeof(seed), 0.0);
  }
  
+ /* include the "string" of commands we generated elsewhere 2001-03-10 JSP */
+ #include "ssh_prng_cmds.string"
+ 
+ char *index (const char *s, int c);
+
+ /* Hack function */
+ char *my_getline(char *s, int len, FILE *f, char **str)
+ {
+   char *ptr;
+   if (f) { /* Call fgets like original one did */
+     return (fgets(s, len, f));
+   }
+   
+   ptr = index(*str, '\n');
+   if (ptr) {
+     int n = ptr - *str;
+     if (n > len) n = len;
+     strncpy(s, *str, n);
+     debug("read builtin cmd: %.100s", s);
+     *str = ptr+1;
+     return s;    /* return what we copied */
+   } else {
+     return NULL; /* EOF */
+   }
+ }
  
  /*
   * entropy command initialisation functions
***************
*** 658,667 ****
  	int cur_cmd = 0;
  	double est;
  	entropy_source_t *entcmd;
  
  	f = fopen(cmdfilename, "r");
  	if (!f) {
! 		fatal("couldn't read entropy commands file %.100s: %.100s",
  		    cmdfilename, strerror(errno));
  	}
  
--- 681,691 ----
  	int cur_cmd = 0;
  	double est;
  	entropy_source_t *entcmd;
+ 	char *cmds_ptr=builtin_prng_cmds;
  
  	f = fopen(cmdfilename, "r");
  	if (!f) {
! 	        verbose("WARNING: couldn't read entropy commands file %.100s: %.100s",
  		    cmdfilename, strerror(errno));
  	}
  
***************
*** 670,676 ****
  
  	/* Read in file */
  	linenum = 0;
! 	while (fgets(line, sizeof(line), f)) {
  		int arg;
  		char *argv;
  
--- 694,700 ----
  
  	/* Read in file */
  	linenum = 0;
! 	while (my_getline(line, sizeof(line), f, &cmds_ptr)) {
  		int arg;
  		char *argv;
  
*** Makefile.in.orig	Sun Mar 11 15:26:17 2001
--- Makefile.in	Sun Mar 11 15:35:13 2001
***************
*** 76,88 ****
  
  manpages: $(MANPAGES)
  
! $(LIBSSH_OBJS): config.h
  $(SSHOBJS): config.h
  $(SSHDOBJS): config.h
  
  .c.o:
  	$(CC) $(CFLAGS) $(CPPFLAGS) -c $<
  
  LIBCOMPAT=openbsd-compat/libopenbsd-compat.a
  $(LIBCOMPAT): config.h
  	(cd openbsd-compat; $(MAKE))
--- 76,95 ----
  
  manpages: $(MANPAGES)
  
! $(LIBSSH_OBJS): config.h ssh_prng_cmds.string
  $(SSHOBJS): config.h
  $(SSHDOBJS): config.h
  
  .c.o:
  	$(CC) $(CFLAGS) $(CPPFLAGS) -c $<
  
+ ssh_prng_cmds.string:
+ 	if [ -f ssh_prng_cmds ]; then \
+ 		$(PERL) $(srcdir)/mkstring < ssh_prng_cmds > $@; \
+ 	else \
+ 		touch $@; \
+ 	fi;
+ 
  LIBCOMPAT=openbsd-compat/libopenbsd-compat.a
  $(LIBCOMPAT): config.h
  	(cd openbsd-compat; $(MAKE))
***************
*** 132,138 ****
  
  distclean: clean
  	(cd openbsd-compat; $(MAKE) distclean)
! 	rm -f Makefile config.h config.status ssh_prng_cmds *~
  
  mrproper: distclean
  
--- 139,145 ----
  
  distclean: clean
  	(cd openbsd-compat; $(MAKE) distclean)
! 	rm -f Makefile config.h config.status ssh_prng_cmds ssh_prng_cmds.string *~
  
  mrproper: distclean
  
*** mkstring.orig	Sun Mar 11 15:38:59 2001
--- mkstring	Sun Mar 11 15:39:43 2001
***************
*** 0 ****
--- 1,10 ----
+ #! /usr/bin/perl
+ #
+ # Is there a *standard* way to do this?  2001-03-10 JSP
+ print "static char *builtin_prng_cmds = \"";
+ while (<>) {
+     next if /^(\#|\s*$)/;
+     s/"/\\"/g;
+     chop; print "$_\\n";
+ }
+ print "\";\n";
--cut-here--

Of course I don't expect it to be included in any future release, but
at least I may get some feedback about the code :-)

-- 
Jon Peatfield,  DAMTP,  Computer Officer,   University of Cambridge
Telephone: +44 1223  3 37852    Mail: J.S.Peatfield at damtp.cam.ac.uk