Add nonce generator vlc_rand_bytes

include/vlc_rand.h

+/*****************************************************************************
+ * vlc_rand.h: RNG
+ *****************************************************************************
+ * Copyright © 2007 Rémi Denis-Courmont
+ * $Id$
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#if !defined( __LIBVLC__ )
+  #error You are not libvlc or one of its plugins. You cannot include this file
+#endif
+
+#ifndef _VLC_RAND_H
+# define _VLC_RAND_H
+
+VLC_EXPORT( void, vlc_rand_bytes, (void *buf, size_t len) );
+
+#endif

src/Makefile.am

@@ -68,6 +68,7 @@ HEADERS_include = \
 	../include/vlc_os_specific.h \
 	../include/vlc_osd.h \
 	../include/vlc_playlist.h \
+	../include/vlc_rand.h \
 	../include/vlc_sout.h \
 	../include/vlc_stream.h \
 	../include/vlc_streaming.h \
@@ -275,6 +276,7 @@ SOURCES_libvlc_common = \
 	text/iso_lang.c \
 	text/iso-639_def.h \
 	misc/md5.c \
+	misc/rand.c \
 	misc/mtime.c \
 	misc/block.c \
 	modules/modules.h \

src/libvlc.sym

@@ -434,3 +434,4 @@ vout_vaControlDefault
 vout_VarCallback
 __xml_Create
 xml_Delete
+vlc_rand_bytes

src/misc/rand.c

+/*****************************************************************************
+ * rand.c : non-predictible random bytes generator
+ *****************************************************************************
+ * Copyright © 2007 Rémi Denis-Courmont
+ * $Id$
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#include <vlc/vlc.h>
+#include <vlc_rand.h>
+
+#ifndef WIN32
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include <vlc_md5.h>
+
+/*
+ * Pseudo-random number generator using a HMAC-MD5 in counter mode.
+ * Probably not very secure (expert patches welcome) but definitely
+ * better than rand() which is defined to be reproducible...
+ */
+#define BLOCK_SIZE 64
+
+static uint8_t okey[BLOCK_SIZE], ikey[BLOCK_SIZE];
+
+static void vlc_rand_init (void)
+{
+#if defined (__OpenBSD__) || defined (__OpenBSD_kernel__)
+    static const char randfile[] = "/dev/random";
+#else
+    static const char randfile[] = "/dev/urandom";
+#endif
+    uint8_t key[BLOCK_SIZE];
+
+    /* Get non-predictible value as key for HMAC */
+    int fd = open (randfile, O_RDONLY);
+    if (fd == -1)
+        return; /* Uho! */
+
+    for (size_t i = 0; i < sizeof (key);)
+    {
+         ssize_t val = read (fd, key + i, sizeof (key) - i);
+         if (val > 0)
+             i += val;
+    }
+
+    /* Precompute outer and inner keys for HMAC */
+    for (size_t i = 0; i < sizeof (key); i++)
+    {
+        okey[i] = key[i] ^ 0x5c;
+        ikey[i] = key[i] ^ 0x36;
+    }
+
+    close (fd);
+}
+
+
+void vlc_rand_bytes (void *buf, size_t len)
+{
+    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+    static uint64_t counter = 0;
+
+    struct md5_s md;
+    uint64_t stamp = NTPtime64 ();
+
+    while (len > 0)
+    {
+        uint64_t val;
+
+        pthread_mutex_lock (&lock);
+        if (counter == 0)
+            vlc_rand_init ();
+        val = counter++;
+        pthread_mutex_unlock (&lock);
+
+        InitMD5 (&md);
+        AddMD5 (&md, ikey, sizeof (ikey));
+        AddMD5 (&md, &stamp, sizeof (stamp));
+        AddMD5 (&md, &val, sizeof (val));
+        EndMD5 (&md);
+
+        if (len < sizeof (md.p_digest))
+        {
+            memcpy (buf, md.p_digest, len);
+            break;
+        }
+
+        memcpy (buf, md.p_digest, sizeof (md.p_digest));
+        len -= sizeof (md.p_digest);
+        buf = ((uint8_t *)buf) + sizeof (md.p_digest);
+    }
+}
+
+#else /* WIN32 */
+#define _CRT_RAND_S
+#include <stdlib.h>
+
+void vlc_rand_bytes (void *buf, size_t len)
+{
+    while (len > 0)
+    {
+        unsigned int val;
+        rand_s (&val);
+
+        if (len < sizeof (val))
+        {
+            memcpy (buf, &val, len);
+            break;
+        }
+
+        memcpy (buf, &val, sizeof (val));
+    }
+}
+#endif