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--- dropbear-0.45/options.h
+++ dropbear-0.45/options.h
@@ -148,6 +148,10 @@
/* prngd must be manually set up to produce output */
/*#define DROPBEAR_PRNGD_SOCKET "/var/run/dropbear-rng"*/
+/* If the normal random source would block for a while, fall back to
+ * the urandom source so that connections don't hang forever. */
+#define DROPBEAR_URANDOM_DEV "/dev/urandom"
+
/* Specify the number of clients we will allow to be connected but
* not yet authenticated. After this limit, connections are rejected */
#ifndef MAX_UNAUTH_CLIENTS
--- dropbear-0.45/random.c
+++ dropbear-0.45/random.c
@@ -57,9 +57,14 @@
struct sockaddr_un egdsock;
char egdcmd[2];
#endif
+ mode_t readmode = O_RDONLY;
+#ifdef DROPBEAR_URANDOM_DEV
+ unsigned int readtries = 0;
+ readmode |= O_NONBLOCK;
+#endif
#ifdef DROPBEAR_RANDOM_DEV
- readfd = open(DROPBEAR_RANDOM_DEV, O_RDONLY);
+ readfd = open(DROPBEAR_RANDOM_DEV, readmode);
if (readfd < 0) {
dropbear_exit("couldn't open random device");
}
@@ -97,6 +102,24 @@
if (readlen < 0 && errno == EINTR) {
continue;
}
+#ifdef DROPBEAR_URANDOM_DEV
+ /* if the main random source blocked, lets retry a few times,
+ * but then give up and try a constant random source. */
+ if (readlen < 0 && errno == EAGAIN) {
+ ++readtries;
+ if (readtries < 5) {
+ sleep(1);
+ continue;
+ } else if (readtries == 5) {
+ close (readfd);
+ readfd = open(DROPBEAR_URANDOM_DEV, readmode);
+ if (readfd < 0) {
+ dropbear_exit("couldn't open secondary random device");
+ }
+ continue;
+ }
+ }
+#endif
dropbear_exit("error reading random source");
}
readpos += readlen;
|
