Add separate randombytes module

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "randombytes"]
+	path = randombytes
+	url = https://github.com/dsprenkels/randombytes.git

Makefile

@@ -1,13 +1,18 @@
 CFLAGS = -Wall -g -O2
-SRCS = hazmat.c randombytes.c serialize.c sss.c keccak.c tweetnacl.c
-OBJS := ${SRCS:.c=.o}
+SRCS = hazmat.c serialize.c sss.c keccak.c tweetnacl.c
+OBJS = ${SRCS:.c=.o}
+LDFLAGS = -L./randombytes
+LDLIBS = -lrandombytes
 
 all: libsss.a
 
-libsss.a: $(OBJS)
+libsss.a: randombytes/librandombytes.a $(OBJS)
 	$(AR) -rcs libsss.a $^
 
-%.out: %.o
+randombytes/librandombytes.a:
+	$(MAKE) -C randombytes librandombytes.a
+
+%.out: %.o randombytes/librandombytes.a
 	$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS)
 	valgrind -q --leak-check=full --error-exitcode=1 ./$@
 
@@ -20,4 +25,5 @@ test: test_hazmat.out test_serialize.out test_sss.out
 
 .PHONY: clean
 clean:
+	$(MAKE) -C randombytes $@
 	$(RM) *.o *.gch *.a *.out

hazmat.c

@@ -1,5 +1,4 @@
 #include "hazmat.h"
-#include "randombytes.h"
 #include <assert.h>
 #include <string.h>
 

randombytes.c

@@ -1,20 +0,0 @@
-#include "randombytes.h"
-#include <assert.h>
-
-#ifdef __linux__
-# define _GNU_SOURCE
-# include <sys/syscall.h>
-#endif
-
-
-void randombytes(const void *buf, const size_t n)
-{
-	int tmp;
-#ifdef __linux__
-	tmp = syscall(SYS_getrandom, buf, n, 0);
-#else
-# warning "randombytes(...) is not supported on this platform. Using INSECURE dummy version."
-	memset(buf, 42, n);
-#endif /* __linux__ */
-	assert(tmp == n); /* Failure indicates a bug in the code */
-}

randombytes.h

@@ -1,14 +0,0 @@
-#ifndef sss_RANDOMBYTES_H
-#define sss_RANDOMBYTES_H
-
-#include <sys/syscall.h>
-#include <unistd.h>
-
-
-/*
- * Write `n` bytes of high quality random bytes to `buf`
- */
-void randombytes(const void *buf, size_t n);
-
-
-#endif /* sss_RANDOMBYTES_H */

sss.c

@@ -1,4 +1,4 @@
-#include "randombytes.h"
+#include "randombytes/randombytes.h"
 #include "sss.h"
 #include "tweetnacl.h"
 #include <assert.h>