1 files changed, 88 insertions, 0 deletions
diff --git a/libtac/lib/magic.c b/libtac/lib/magic.c
new file mode 100644
index 0000000..d42e620
--- /dev/null
+++ b/libtac/lib/magic.c
@@ -0,0 +1,88 @@
+/* magic.c - PPP Magic Number routines.
+ *
+ * Copyright (C) 1989 Carnegie Mellon University.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program - see the file COPYING.
+ *
+ * See `CHANGES' file for revision history.
+ */
+
+#ifdef HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+/* if OpenSSL library is available this legacy code will not be compiled in */
+#if !defined(HAVE_OPENSSL_RAND_H) && !defined(HAVE_LIBCRYPTO)
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "magic.h"
+
+static int magic_initialised = 0;
+
+/*
+ * magic_init - Initialize the magic number generator.
+ *
+ * Attempts to compute a random number seed which will not repeat.
+ */
+static void
+tac_magic_init()
+{
+    struct stat statbuf;
+    long seed = 0;
+    struct timeval t;
+
+    if (magic_initialised)
+        return;
+
+    // try to initialise seed from urandom
+    if (!lstat("/dev/urandom", &statbuf) && S_ISCHR(statbuf.st_mode)) {
+        int rfd = open("/dev/urandom", O_RDONLY);
+        if(rfd >= 0) {
+            if (read(rfd, &seed, sizeof(seed)) < 0)
+                seed = 0;
+            close(rfd);
+        }
+    }
+
+    // fallback
+    gettimeofday(&t, NULL);
+    seed ^= gethostid() ^ t.tv_sec ^ t.tv_usec ^ getpid();
+
+    // finally seed the PRNG
+    srandom(seed);
+    magic_initialised = 1;
+}
+
+#include <pthread.h>
+/*
+ * magic - Returns the next magic number.
+ */
+u_int32_t
+tac_magic()
+{
+    static pthread_once_t magic_control = PTHREAD_ONCE_INIT;
+
+    pthread_once(&magic_control, &tac_magic_init);
+
+    return (u_int32_t)random();
+}
+
+#endif