Clean up and modernize librandom.

 Correct random number generation has historically been
suprisingly painful to achieve. There was no standard,
every system behaved in a subtly different way, and there
were a few userland initiatives to get decent randomness,
all incompatible of course.
 The situation is a bit better now, we're heading towards
some standardization. The arc4random() series of functions
is a good API, and available on a lot of systems -
unfortunately not Linux, but on Linux the new getrandom()
makes using /dev/random obsolete.

 So I removed the old crap in librandom, dropped EGD support,
dropped dynamic backend selection, made a single API series
(random_* instead of goodrandom_* and badrandom_*), added
an arc4random backend and a getrandom backend, and defaulted
to /dev/urandom backed up by SURF in the worst case. This
should be much smaller and logical. However, it's a major
API break, so the skarnet.org stack will be changed to
adapt.

1 files changed, 66 insertions, 0 deletions

diff --git a/src/librandom/random_string.c b/src/librandom/random_string.c
new file mode 100644
index 0000000..c87c8c2
--- /dev/null
+++ b/src/librandom/random_string.c
@@ -0,0 +1,66 @@
+/* ISC license. */
+
+#include <skalibs/sysdeps.h>
+
+#ifdef SKALIBS_HASARC4RANDOM
+
+#include <stdlib.h>
+#include <skalibs/random.h>
+
+void random_string (char *s, unsigned int n)
+{
+  arc4random_buf(s, n) ;
+}
+
+#else
+#ifdef SKALIBS_HASGETRANDOM
+
+#include <skalibs/nonposix.h>
+#include <sys/types.h>
+#include <sys/syscall.h>
+#include <skalibs/random.h>
+
+static int getrandom (void *buf, size_t buflen, unsigned int flags)
+{
+  return syscall(SYS_getrandom, buf, buflen, flags) ;
+}
+
+void random_string (char *s, unsigned int n)
+{
+  while (n)
+  {
+    register int r = getrandom(s, n, 0) ;
+    if (r >= 0)
+    {
+      s += r ;
+      n -= r ;
+    }
+  }
+}
+
+#else
+#ifdef SKALIBS_HASDEVURANDOM
+
+#include <skalibs/allreadwrite.h>
+#include <skalibs/random.h>
+#include "random-internal.h"
+
+void random_string (char *s, unsigned int n)
+{
+  unsigned int r = allread(random_fd, s, n) ;
+  if (r < n) surf(&surf_here, s+r, n-r) ;
+}
+
+#else /* default */
+
+#include <skalibs/random.h>
+#include "random-internal.h"
+
+void random_string (char *s, unsigned int n)
+{
+  surf(&surf_here, s, n) ;
+}
+
+#endif
+#endif
+#endif