maradns reproducibility fixes and the merits of picking a random number

[Vagrant Cascadian <vagrant@reproducible-builds.org>]

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So, I've got a fix for the reproducibility issues for maradns... part of
the fixes are fairly obvious, setting a specific date and setting the
version to be, well, the version...

But there's one nervous-making issue this revealed; maradns embeds a
random number at build time ... allegedly for systems that don't have
/dev/urandom... see
maradns-3.5.0020/deadwood-3.5.0020/src/Makefile.ubuntu2004:

  # Since some systems may not have /dev/urandom (Windows, *cough* *cough*), we
  # keep a randomly generated prime around

So it's got some code to generate a random number at build time and
embed it in the binary. Now, if there's anything I know about good
practices about random numbers, this sort of thing is generally a very
large red flag! It also makes the package build differently every time!

So, Debian's maradns package just removes this embedding of a "random"
number, and I've basically adapted their patches to build reproducibly
on guix too... by basically embedding the same "random" number every
single build!

That said, hopefully it actually uses /dev/urandom and this is just a
fallback for when /dev/urandom is missing? Is that actually how this is
supposed to work? Is that actually how the code does work? If that's the
case, I think the following patch should work ok on Guix.

But I wanted some extra eyes on this before pushing...

live well,
  vagrant

p.s. Obviously, I picked the best random number.

From a2e10d39de37c363b25f06dbb275e2bf6d614b7c Mon Sep 17 00:00:00 2001
From: Vagrant Cascadian <vagrant@reproducible-builds.org>
Date: Sun, 5 Jun 2022 13:57:27 -0700
Subject: [PATCH 3/3] gnu: maradns: Build reproducibly.

* gnu/packages/patches/maradns-deadwood-do-not-embed-random-number.patch: New
  file.
* gnu/local.mk (dist_patch_DATA): Add patch.
* gnu/package/dns.scm (maradns)[source]: Add patch.
  [arguments]: Pass VERSION and COMPILED via makeflags.
---
 gnu/local.mk                                  |  1 +
 gnu/packages/dns.scm                          |  7 +++-
 ...-deadwood-do-not-embed-random-number.patch | 38 +++++++++++++++++++
 3 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/maradns-deadwood-do-not-embed-random-number.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 68b317b32a..ff1135e48e 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1471,6 +1471,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/lvm2-static-link.patch			\
   %D%/packages/patches/mailutils-variable-lookup.patch		\
   %D%/packages/patches/make-impure-dirs.patch			\
+  %D%/packages/patches/maradns-deadwood-do-not-embed-random-number.patch	\
   %D%/packages/patches/mariadb-link-libatomic.patch		\
   %D%/packages/patches/mars-install.patch			\
   %D%/packages/patches/mars-sfml-2.3.patch			\
diff --git a/gnu/packages/dns.scm b/gnu/packages/dns.scm
index fea255c930..39268ddfcf 100644
--- a/gnu/packages/dns.scm
+++ b/gnu/packages/dns.scm
@@ -1302,7 +1302,10 @@ (define-public maradns
                            (version-major+minor version) "/"
                            version "/maradns-" version ".tar.xz"))
        (sha256
-        (base32 "1qgabw6y2bwy6y88dikis62k789i0xh7iwxan8jmqpzvksqwjfgw"))))
+        (base32 "1qgabw6y2bwy6y88dikis62k789i0xh7iwxan8jmqpzvksqwjfgw"))
+       (patches
+        (search-patches
+         "maradns-deadwood-do-not-embed-random-number.patch"))))
     (build-system gnu-build-system)
     (arguments
      `(#:tests? #f                      ; need to be root to run tests
@@ -1310,6 +1313,8 @@ (define-public maradns
        (list
         ,(string-append "CC=" (cc-for-target))
         (string-append "PREFIX=" %output)
+        (string-append "COMPILED=" "2012-04-18")
+        (string-append "VERSION=" ,version)
         (string-append "RPM_BUILD_ROOT=" %output))
        #:phases
        (modify-phases %standard-phases
diff --git a/gnu/packages/patches/maradns-deadwood-do-not-embed-random-number.patch b/gnu/packages/patches/maradns-deadwood-do-not-embed-random-number.patch
new file mode 100644
index 0000000000..7e51e79259
--- /dev/null
+++ b/gnu/packages/patches/maradns-deadwood-do-not-embed-random-number.patch
@@ -0,0 +1,38 @@
+Adapted from https://sources.debian.org/src/maradns/2.0.13-1.4/debian/patches/deadwood_makefile.patch/
+
+diff --git a/deadwood-3.5.0020/src/Makefile.ubuntu2004 b/deadwood-3.5.0020/src/Makefile.ubuntu2004
+index 62868aa..2c8c094 100644
+--- a/deadwood-3.5.0020/src/Makefile.ubuntu2004
++++ b/deadwood-3.5.0020/src/Makefile.ubuntu2004
+@@ -29,13 +29,10 @@ all:	Deadwood version.h
+ #
+ 
+ clean:
+-	rm -f Test DwMain DwTcp *.exe *.o a.out RandomPrime writehash_test* \
+-		Deadwood foo* dw_cache DwHash DwCompress *stackdump \
+-		core ; \
+-		./make.version.h ; if [ -e /dev/urandom ] ; \
+-			then rm DwRandPrime.h  ; \
+-			cc RandomPrime.c ; ./a.out > DwRandPrime.h ; rm a.out \
+-		; fi 
++	rm -f Test DwMain DwTcp *.exe *.o a.out writehash_test* \
++		Deadwood foo* dw_cache DwHash DwCompress *stackdump core
++
++
+ 
+ version.h:	
+ 	./make.version.h
+@@ -67,11 +64,8 @@ DwSocket.o:	DwSocket.c DwStr.h DwSocket.h
+ DwSys.o:	DwSys.c DwStr.h version.h
+ 	$(CC) $(FLAGS) -Wall -c -o DwSys.o DwSys.c
+ 
+-RandomPrime:	RandomPrime.c
+-	$(CC) -O3 -o RandomPrime RandomPrime.c
+-
+-DwRandPrime.h: RandomPrime
+-	if [ -e /dev/urandom ] ; then ./RandomPrime > DwRandPrime.h ; fi
++DwRandPrime.h:
++	echo '#define MUL_CONSTANT 1238145941' > DwRandPrime.h
+ 
+ DwHash.o:	DwHash.c DwStr.h DwRandPrime.h DwHash.h
+ 	$(CC) $(FLAGS) -Wall -c -o DwHash.o DwHash.c
-- 
2.35.1


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