summaryrefslogtreecommitdiff
path: root/src/sysdeps
diff options
context:
space:
mode:
authorLaurent Bercot <ska-skaware@skarnet.org>2016-10-14 17:07:56 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2016-10-14 17:07:56 +0000
commita1933bd1847951b959016f59ee744d1b18a00142 (patch)
tree42392f2df048defd712fa12d290bf84a7a77df6d /src/sysdeps
parenteaf9404b22bba7be5092672144b867380c602beb (diff)
downloadskalibs-a1933bd1847951b959016f59ee744d1b18a00142.tar.xz
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.
Diffstat (limited to 'src/sysdeps')
-rw-r--r--src/sysdeps/tryarc4random.c11
-rw-r--r--src/sysdeps/trydevrandom.c54
-rw-r--r--src/sysdeps/trygetrandom.c22
3 files changed, 33 insertions, 54 deletions
diff --git a/src/sysdeps/tryarc4random.c b/src/sysdeps/tryarc4random.c
new file mode 100644
index 0000000..b2f596a
--- /dev/null
+++ b/src/sysdeps/tryarc4random.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#include <stdlib.h>
+
+int main (void)
+{
+ return arc4random_uniform(1) ;
+}
diff --git a/src/sysdeps/trydevrandom.c b/src/sysdeps/trydevrandom.c
deleted file mode 100644
index 395d008..0000000
--- a/src/sysdeps/trydevrandom.c
+++ /dev/null
@@ -1,54 +0,0 @@
-/* ISC license. */
-
-#include <unistd.h>
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
-
-static int fd_read (int fd, char *buf, unsigned int len)
-{
- register int r ;
- do r = read(fd, buf, len) ;
- while ((r == -1) && (errno == EINTR)) ;
- return r ;
-}
-
-static unsigned int allread (int fd, register char *buf, register unsigned int len)
-{
- register unsigned int written = 0 ;
- while (len)
- {
- register int w = fd_read(fd, buf, len) ;
- if (!w) errno = EPIPE ;
- if (w <= 0) break ;
- written += w ;
- buf += w ;
- len -= w ;
- }
- return written ;
-}
-
-static int byte_diff (char *s, unsigned int n, char *t)
-{
- for (;;)
- {
- if (!n) return 0 ;
- if (*s != *t) break ;
- ++s ; ++t ; --n ;
- }
- return ((int)(unsigned int)(unsigned char) *s)
- - ((int)(unsigned int)(unsigned char) *t);
-}
-
-int main ()
-{
- char a[64] ;
- char b[64] ;
- int fd = open("/dev/random", O_RDONLY) ;
- if ((fd == -1) || (allread(fd, a, 64) < 64) ) return 111 ;
- close(fd) ;
- fd = open("/dev/random", O_RDONLY) ;
- if ((fd == -1) || (allread(fd, b, 64) < 64) ) return 111 ;
- close(fd) ;
- return !byte_diff(a, 64, b) ;
-}
diff --git a/src/sysdeps/trygetrandom.c b/src/sysdeps/trygetrandom.c
new file mode 100644
index 0000000..67a623d
--- /dev/null
+++ b/src/sysdeps/trygetrandom.c
@@ -0,0 +1,22 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <sys/types.h>
+#include <sys/syscall.h>
+
+static int getrandom (void *buf, size_t buflen, unsigned int flags)
+{
+ return syscall(SYS_getrandom, buf, buflen, flags) ;
+}
+
+int main (void)
+{
+ char buf[4] ;
+ return getrandom(buf, 4, 0) ;
+}