From 14ff78dfe7021691d722f2608a36e947d71b65a7 Mon Sep 17 00:00:00 2001
From: Leonid Evdokimov <leon@darkk.net.ru>
Date: Tue, 8 Mar 2016 20:53:19 +0300
Subject: [PATCH] Replace inconsistent rand()/random() with call to libevent2
 rng

---
 http-connect.c |  3 +--
 http-relay.c   |  3 +--
 main.c         | 10 +---------
 parser.c       |  2 +-
 redsocks.c     |  2 +-
 utils.c        |  7 +++++++
 utils.h        |  1 +
 7 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/http-connect.c b/http-connect.c
index e243528..685ab54 100644
--- a/http-connect.c
+++ b/http-connect.c
@@ -210,8 +210,7 @@ static struct evbuffer *httpc_mkconnect(redsocks_client *client)
 
 			/* prepare an random string for cnounce */
 			char cnounce[17];
-			snprintf(cnounce, sizeof(cnounce), "%04x%04x%04x%04x",
-			         rand() & 0xffff, rand() & 0xffff, rand() & 0xffff, rand() & 0xffff);
+			snprintf(cnounce, sizeof(cnounce), "%08x%08x", red_randui32(), red_randui32());
 
 			auth_string = digest_authentication_encode(auth->last_auth_query + 7, //line
 					client->instance->config.login, client->instance->config.password, //user, pass
diff --git a/http-relay.c b/http-relay.c
index 4a39451..51c6f4c 100644
--- a/http-relay.c
+++ b/http-relay.c
@@ -320,8 +320,7 @@ static void httpr_relay_write_cb(struct bufferevent *buffev, void *_arg)
 
 				/* prepare an random string for cnounce */
 				char cnounce[17];
-				snprintf(cnounce, sizeof(cnounce), "%04x%04x%04x%04x",
-				         rand() & 0xffff, rand() & 0xffff, rand() & 0xffff, rand() & 0xffff);
+				snprintf(cnounce, sizeof(cnounce), "%08x%08x", red_randui32(), red_randui32());
 
 				auth_string = digest_authentication_encode(auth->last_auth_query + 7, //line
 						client->instance->config.login, client->instance->config.password, //user, pass
diff --git a/main.c b/main.c
index 9f497c6..c9ac20a 100644
--- a/main.c
+++ b/main.c
@@ -48,14 +48,6 @@ static void terminate(int sig, short what, void *_arg)
 		log_error(LOG_WARNING, "event_loopbreak");
 }
 
-static void red_srand()
-{
-	struct timeval tv;
-	gettimeofday(&tv, NULL);
-	// using tv_usec is a bit less predictable than tv_sec
-	srand(tv.tv_sec*1000000+tv.tv_usec);
-}
-
 int main(int argc, char **argv)
 {
 	int error;
@@ -66,7 +58,7 @@ int main(int argc, char **argv)
 	int opt;
 	int i;
 
-	red_srand();
+	evutil_secure_rng_init();
 	while ((opt = getopt(argc, argv, "h?vtc:p:")) != -1) {
 		switch (opt) {
 		case 't':
diff --git a/parser.c b/parser.c
index b3a0bb6..8803a51 100644
--- a/parser.c
+++ b/parser.c
@@ -319,7 +319,7 @@ static int vp_in_addr(parser_context *context, void *addr, const char *token)
 			struct sockaddr_in *resolved_addr;
 			for (iter = ainfo, count = 0; iter; iter = iter->ai_next, ++count)
 				;
-			taken = rand() % count;
+			taken = red_randui32() % count;
 			for (iter = ainfo; taken > 0; iter = iter->ai_next, --taken)
 				;
 			resolved_addr = (struct sockaddr_in*)iter->ai_addr;
diff --git a/redsocks.c b/redsocks.c
index 82320e5..c600282 100644
--- a/redsocks.c
+++ b/redsocks.c
@@ -634,7 +634,7 @@ static void redsocks_accept_client(int fd, short what, void *_arg)
 		if (errno == ENFILE || errno == EMFILE || errno == ENOBUFS || errno == ENOMEM) {
 			self->accept_backoff_ms = (self->accept_backoff_ms << 1) + 1;
 			clamp_value(self->accept_backoff_ms, self->config.min_backoff_ms, self->config.max_backoff_ms);
-			int delay = (random() % self->accept_backoff_ms) + 1;
+			int delay = (red_randui32() % self->accept_backoff_ms) + 1;
 			log_errno(LOG_WARNING, "accept: out of file descriptors, backing off for %u ms", delay);
 			struct timeval tvdelay = { delay / 1000, (delay % 1000) * 1000 };
 			if (tracked_event_del(&self->listener) != 0)
diff --git a/utils.c b/utils.c
index 7de3969..0bbc2e6 100644
--- a/utils.c
+++ b/utils.c
@@ -90,6 +90,13 @@ int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inadd
 	return pktlen;
 }
 
+uint32_t red_randui32()
+{
+	uint32_t ret;
+	evutil_secure_rng_get_bytes(&ret, sizeof(ret));
+	return ret;
+}
+
 time_t redsocks_time(time_t *t)
 {
 	time_t retval;
diff --git a/utils.h b/utils.h
index 991af9c..2297393 100644
--- a/utils.h
+++ b/utils.h
@@ -47,6 +47,7 @@ struct sockaddr_in;
 } while (0)
 
 
+uint32_t red_randui32();
 time_t redsocks_time(time_t *t);
 char *redsocks_evbuffer_readline(struct evbuffer *buf);
 struct bufferevent* red_connect_relay(struct sockaddr_in *addr, evbuffercb writecb, everrorcb errorcb, void *cbarg);