1 files changed, 146 insertions, 0 deletions
diff --git a/librecrypt_rng_.c b/librecrypt_rng_.c
new file mode 100644
index 0000000..8b9f138
--- /dev/null
+++ b/librecrypt_rng_.c
@@ -0,0 +1,146 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+
+ssize_t
+librecrypt_rng_(void *out, size_t n, void *user)
+{
+	static unsigned int seed = 0u;
+	unsigned char *buf = out;
+	int v, fd, saved_errno = errno;
+	unsigned int state;
+	size_t i, min, ret = 0u;
+	ssize_t r;
+	struct timespec ts;
+#if defined(__linux__) && defined(AT_RANDOM)
+	const unsigned char *at_random;
+	uintptr_t at_random_addr;
+#endif
+
+	(void) user;
+
+	if (!n)
+		return 0;
+
+	if (n > (size_t)SSIZE_MAX)
+		n = (size_t)SSIZE_MAX;
+
+#if defined(__linux__)
+	for (;;) {
+		r = getrandom(buf, n, 0u);
+		if (r < 0) {
+			if (errno != EINTR)
+				break;
+			saved_errno = EINTR;
+		} else if (r > 0) {
+			ret += (size_t)r;
+			buf = &buf[(size_t)r];
+			n -= (size_t)r;
+			if (!n)
+				goto out;
+		} else {
+			break;
+		}
+	}
+#endif
+
+	for (;;) {
+		min = n < 256u ? n : 256u;
+		if (getentropy(buf, min)) {
+			if (errno != EINTR)
+				break;
+			saved_errno = EINTR;
+		} else {
+			ret += min;
+			buf = &buf[min];
+			n -= min;
+			if (!n)
+				goto out;
+		}
+	}
+
+#ifndef O_CLOEXEC
+# define O_CLOEXEC 0
+#endif
+	fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
+	if (fd >= 0) {
+		for (;;) {
+			r = read(fd, buf, n);
+			if (r < 0) {
+				if (errno != EINTR) {
+					close(fd);
+					break;
+				}
+				saved_errno = EINTR;
+			} else if (r > 0) {
+				ret += (size_t)r;
+				buf = &buf[(size_t)r];
+				n -= (size_t)r;
+				if (!n) {
+					close(fd);
+					goto out;
+				}
+			} else {
+				close(fd);
+				break;
+			}
+		}
+	}
+
+	state = seed;
+	if (!state) {
+		state = (unsigned int)rand();
+		state ^= (unsigned int)time(NULL);
+		if (!clock_gettime(CLOCK_MONOTONIC, &ts)) {
+			state ^= (unsigned int)ts.tv_sec;
+			state ^= (unsigned int)ts.tv_nsec;
+		}
+#if defined(__linux__) && defined(AT_RANDOM)
+		at_random_addr = (uintptr_t)getauxval(AT_RANDOM);
+		if (at_random_addr) {
+			at_random = (const void *)at_random_addr;
+			for (i = 0u; i < 16u; i++)
+				state ^= (unsigned int)at_random[i] << (i % sizeof(unsigned int) * 8u);
+		}
+	}
+#endif
+	for (i = 0u; i < n; i++) {
+		v = rand_r(&state);
+		v = (int)((uintmax_t)v * 255u / (uintmax_t)RAND_MAX);
+		buf[i] = (unsigned char)v;
+	}
+	ret += n;
+	seed = state;
+
+out:
+	errno = saved_errno;
+	return (ssize_t)ret;
+}
+
+
+#else
+
+
+int
+main(void)
+{
+	/* TODO test failure cases */
+
+	unsigned char buf1[1024u];
+	unsigned char buf2[sizeof(buf1)];
+	ssize_t n1, n2;
+
+	SET_UP_ALARM();
+
+	n1 = librecrypt_rng_(buf1, sizeof(buf1), NULL);
+	n2 = librecrypt_rng_(buf2, sizeof(buf2), NULL);
+	EXPECT(n1 >= 128 && (size_t)n1 <= sizeof(buf1));
+	EXPECT(n2 >= 128 && (size_t)n2 <= sizeof(buf2));
+	EXPECT(memcmp(buf1, buf2, (size_t)(n1 < n2 ? n1 : n2)));
+
+	return 0;
+}
+
+
+#endif