From b952231df1e7d8f890d7af9d7ce5c81f0e08150d Mon Sep 17 00:00:00 2001 From: Matt Johnston 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 7acc8c0..cfd045b 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 c69f641..e45f474 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) {