Add current version of libSRTP from CVS.

libsrtp/crypto/rng/rand_source.c

+/*
+ * rand_source.c
+ *
+ * implements a random source based on /dev/random
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ */
+/*
+ *      
+ * Copyright(c) 2001-2006 Cisco Systems, Inc.
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ *   Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ * 
+ *   Neither the name of the Cisco Systems, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "config.h"
+
+#ifdef DEV_URANDOM
+# include <fcntl.h>          /* for open()  */
+# include <unistd.h>         /* for close() */
+#elif defined(HAVE_RAND_S)
+# define _CRT_RAND_S
+# include <stdlib.h>         
+#else
+# include <stdio.h>
+#endif
+
+#include "rand_source.h"
+
+
+/* 
+ * global dev_rand_fdes is file descriptor for /dev/random 
+ * 
+ * This variable is also used to indicate that the random source has
+ * been initialized.  When this variable is set to the value of the
+ * #define RAND_SOURCE_NOT_READY, it indicates that the random source
+ * is not ready to be used.  The value of the #define
+ * RAND_SOURCE_READY is for use whenever that variable is used as an
+ * indicator of the state of the random source, but not as a file
+ * descriptor.
+ */
+
+#define RAND_SOURCE_NOT_READY (-1)
+#define RAND_SOURCE_READY     (17)
+
+static int dev_random_fdes = RAND_SOURCE_NOT_READY;
+
+
+err_status_t
+rand_source_init(void) {
+  if (dev_random_fdes >= 0) {
+    /* already open */
+    return err_status_ok;
+  }
+#ifdef DEV_URANDOM
+  /* open random source for reading */
+  dev_random_fdes = open(DEV_URANDOM, O_RDONLY);
+  if (dev_random_fdes < 0)
+    return err_status_init_fail;
+#elif defined(HAVE_RAND_S)
+  dev_random_fdes = RAND_SOURCE_READY;
+#else
+  /* no random source available; let the user know */
+  fprintf(stderr, "WARNING: no real random source present!\n");
+  dev_random_fdes = RAND_SOURCE_READY;
+#endif
+  return err_status_ok;
+}
+
+err_status_t
+rand_source_get_octet_string(void *dest, uint32_t len) {
+
+  /* 
+   * read len octets from /dev/random to dest, and
+   * check return value to make sure enough octets were
+   * written 
+   */
+#ifdef DEV_URANDOM
+  uint8_t *dst = (uint8_t *)dest;
+  while (len)
+  {
+    ssize_t num_read = read(dev_random_fdes, dst, len);
+    if (num_read <= 0 || num_read > len)
+      return err_status_fail;
+    len -= num_read;
+    dst += num_read;
+  }
+#elif defined(HAVE_RAND_S)
+  uint8_t *dst = (uint8_t *)dest;
+  while (len)
+  {
+    unsigned int val;
+    errno_t err = rand_s(&val);
+
+    if (err != 0)
+      return err_status_fail;
+  
+    *dst++ = val & 0xff;
+    len--;
+  }
+#else
+  /* Generic C-library (rand()) version */
+  /* This is a random source of last resort */
+  uint8_t *dst = (uint8_t *)dest;
+  while (len)
+  {
+          int val = rand();
+          /* rand() returns 0-32767 (ugh) */
+          /* Is this a good enough way to get random bytes?
+             It is if it passes FIPS-140... */
+          *dst++ = val & 0xff;
+          len--;
+  }
+#endif
+  return err_status_ok;
+}
+ 
+err_status_t
+rand_source_deinit(void) {
+  if (dev_random_fdes < 0)
+    return err_status_dealloc_fail;  /* well, we haven't really failed, *
+                                      * but there is something wrong    */
+#ifdef DEV_URANDOM
+  close(dev_random_fdes);  
+#endif
+  dev_random_fdes = RAND_SOURCE_NOT_READY;
+  
+  return err_status_ok;  
+}