merge of 9522146cb07d4576f161fc4567c2c2fbd6f61fbb

     and b11630c15bc4d0649dba51c3572cac6f44e0ab0e

--HG--
extra : convert_revision : e0686662cdbee8c0b06e72e6105a390ea4f4c007

1 files changed, 58 insertions, 3 deletions

diff --git a/random.c b/random.c
index c69f641..d58c8a8 100644
--- a/random.c
+++ b/random.c
@@ -25,14 +25,15 @@
 #include "includes.h"
 #include "buffer.h"
 #include "dbutil.h"
+#include "bignum.h"
 
-int donerandinit = 0;
+static int donerandinit = 0;
 
 /* this is used to generate unique output from the same hashpool */
-unsigned int counter = 0;
+static unsigned int counter = 0;
 #define MAX_COUNTER 1000000/* the max value for the counter, so it won't loop */
 
-unsigned char hashpool[SHA1_HASH_SIZE];
+static unsigned char hashpool[SHA1_HASH_SIZE];
 
 #define INIT_SEED_SIZE 32 /* 256 bits */
 
@@ -50,6 +51,7 @@ static void readrand(unsigned char* buf, unsigned int buflen);
 
 static void readrand(unsigned char* buf, unsigned int buflen) {
 
+	static int already_blocked = 0;
 	int readfd;
 	unsigned int readpos;
 	int readlen;
@@ -92,6 +94,24 @@ static void readrand(unsigned char* buf, unsigned int buflen) {
 	/* read the actual random data */
 	readpos = 0;
 	do {
+		if (!already_blocked)
+		{
+			int ret;
+			struct timeval timeout;
+			fd_set read_fds;
+
+			timeout.tv_sec = 2; /* two seconds should be enough */
+			timeout.tv_usec = 0;
+
+			FD_ZERO(&read_fds);
+			FD_SET(readfd, &read_fds);
+			ret = select(readfd + 1, &read_fds, NULL, NULL, &timeout);
+			if (ret == 0)
+			{
+				dropbear_log(LOG_INFO, "Warning: Reading the random source seems to have blocked.\nIf you experience problems, you probably need to find a better entropy source.");
+				already_blocked = 1;
+			}
+		}
 		readlen = read(readfd, &buf[readpos], buflen - readpos);
 		if (readlen <= 0) {
 			if (readlen < 0 && errno == EINTR) {
@@ -159,3 +179,38 @@ void genrandom(unsigned char* buf, unsigned int len) {
 	}
 	m_burn(hash, sizeof(hash));
 }
+
+/* Generates a random mp_int. 
+ * max is a *mp_int specifying an upper bound.
+ * rand must be an initialised *mp_int for the result.
+ * the result rand satisfies:  0 < rand < max 
+ * */
+void gen_random_mpint(mp_int *max, mp_int *rand) {
+
+	unsigned char *randbuf = NULL;
+	unsigned int len = 0;
+	const char masks[] = {0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f};
+
+	const int size_bits = mp_count_bits(max);
+
+	len = size_bits / 8;
+	if ((size_bits % 8) != 0) {
+		len += 1;
+	}
+
+	randbuf = (unsigned char*)m_malloc(len);
+	do {
+		genrandom(randbuf, len);
+		/* Mask out the unrequired bits - mp_read_unsigned_bin expects
+		 * MSB first.*/
+		randbuf[0] &= masks[size_bits % 8];
+
+		bytes_to_mp(rand, randbuf, len);
+
+		/* keep regenerating until we get one satisfying
+		 * 0 < rand < max    */
+	} while ( ( (max != NULL) && (mp_cmp(rand, max) != MP_LT) )
+			|| (mp_cmp_d(rand, 0) != MP_GT) );
+	m_burn(randbuf, len);
+	m_free(randbuf);
+}