From b952231df1e7d8f890d7af9d7ce5c81f0e08150d Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Sun, 24 Apr 2005 15:56:36 +0000
Subject: [PATCH] * warn if we seem to be blocking on /dev/random
--HG--
extra : convert_revision : a160efd238030ac4f7fd8304c5a87928145feccc
---
TODO | 3 ---
random.c | 19 +++++++++++++++++++
2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/TODO b/TODO
index 7acc8c03..cfd045b8 100644
--- a/TODO
+++ b/TODO
@@ -4,9 +4,6 @@ Things which might need doing:
- Make options.h generated from configure perhaps?
-- some sort of warning when blocking on random? (could be difficult,
- investigate alarm() perhaps)
-
- Improved queueing of unauthed connections
- handle /etc/environment in AIX
diff --git a/random.c b/random.c
index c69f6419..e45f4747 100644
--- a/random.c
+++ b/random.c
@@ -50,6 +50,7 @@ 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 +93,24 @@ 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) {
--
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