random: Properly handle errors when reading from /dev/[u]random

If -1 was returned on the first call to read() `done` got SIZE_MAX
and the function returned TRUE even though no actual random data had
been allocated.

Fixes #1156.

diff --git a/src/libstrongswan/plugins/random/random_rng.c b/src/libstrongswan/plugins/random/random_rng.c
index 36d5446..177b3c2 100644 (file)
--- a/src/libstrongswan/plugins/random/random_rng.c
+++ b/src/libstrongswan/plugins/random/random_rng.c
@@ -56,6 +56,7 @@ METHOD(rng_t, get_bytes, bool,
                        DBG1(DBG_LIB, "reading from random FD %d failed: %s, retrying...",
                                 this->fd, strerror(errno));
                        sleep(1);
+                       continue;
                }
                done += got;
        }