Don't silently ignore RNG failures when creating strings / numbers.

webrtc/base/helpers.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 10 matching lines @@
 #if defined(WEBRTC_WIN)
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #include <ntsecapi.h>
 #endif  // WEBRTC_WIN
 #endif  // else
 #endif  // FEATURE_ENABLED_SSL
 
 #include "webrtc/base/base64.h"
 #include "webrtc/base/basictypes.h"
+#include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/timeutils.h"
 
 // Protect against max macro inclusion.
 #undef max
 
 namespace rtc {
 
 // Base class for RNG implementations.
 class RandomGenerator {
@@ skipping 167 matching lines @@
 bool InitRandom(const char* seed, size_t len) {
   if (!Rng().Init(seed, len)) {
     LOG(LS_ERROR) << "Failed to init random generator!";
     return false;
   }
   return true;
 }
 
 std::string CreateRandomString(size_t len) {
   std::string str;
-  CreateRandomString(len, &str);
+  RTC_CHECK(CreateRandomString(len, &str));
   return str;
 }
 
 bool CreateRandomString(size_t len,
                         const char* table, int table_size,
                         std::string* str) {
   str->clear();
   std::unique_ptr<uint8_t[]> bytes(new uint8_t[len]);
   if (!Rng().Generate(bytes.get(), len)) {
     LOG(LS_ERROR) << "Failed to generate random string!";
     return false;
   }
   str->reserve(len);
   for (size_t i = 0; i < len; ++i) {
     str->push_back(table[bytes[i] % table_size]);
   }
   return true;
 }
 
 bool CreateRandomString(size_t len, std::string* str) {
   return CreateRandomString(len, kBase64, 64, str);
 }
 
 bool CreateRandomString(size_t len, const std::string& table,
                         std::string* str) {
   return CreateRandomString(len, table.c_str(),
                             static_cast<int>(table.size()), str);
 }
 
+std::string CreateRandomUuid() {
+  std::string uuid;
+  RTC_CHECK(CreateRandomUuid(&uuid));
+  return uuid;
+}
+
 // Version 4 UUID is of the form:
 // xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
 // Where 'x' is a hex digit, and 'y' is 8, 9, a or b.
-std::string CreateRandomUuid() {
-  std::string str;
+bool CreateRandomUuid(std::string *str) {
+  str->clear();
   std::unique_ptr<uint8_t[]> bytes(new uint8_t[31]);
   if (!Rng().Generate(bytes.get(), 31)) {
     LOG(LS_ERROR) << "Failed to generate random string!";
-    return str;
+    return false;
   }
-  str.reserve(36);
+  str->reserve(36);
   for (size_t i = 0; i < 8; ++i) {
-    str.push_back(kHex[bytes[i] % 16]);
+    str->push_back(kHex[bytes[i] % 16]);
   }
-  str.push_back('-');
+  str->push_back('-');
   for (size_t i = 8; i < 12; ++i) {
-    str.push_back(kHex[bytes[i] % 16]);
+    str->push_back(kHex[bytes[i] % 16]);
   }
-  str.push_back('-');
-  str.push_back('4');
+  str->push_back('-');
+  str->push_back('4');
   for (size_t i = 12; i < 15; ++i) {
-    str.push_back(kHex[bytes[i] % 16]);
+    str->push_back(kHex[bytes[i] % 16]);
   }
-  str.push_back('-');
-  str.push_back(kUuidDigit17[bytes[15] % 4]);
+  str->push_back('-');
+  str->push_back(kUuidDigit17[bytes[15] % 4]);
   for (size_t i = 16; i < 19; ++i) {
-    str.push_back(kHex[bytes[i] % 16]);
+    str->push_back(kHex[bytes[i] % 16]);
   }
-  str.push_back('-');
+  str->push_back('-');
   for (size_t i = 19; i < 31; ++i) {
-    str.push_back(kHex[bytes[i] % 16]);
+    str->push_back(kHex[bytes[i] % 16]);
   }
-  return str;
+  return true;
 }
 
 uint32_t CreateRandomId() {
   uint32_t id;
-  if (!Rng().Generate(&id, sizeof(id))) {
-    LOG(LS_ERROR) << "Failed to generate random id!";
-  }
+  RTC_CHECK(CreateRandomId(&id));
   return id;
 }
 
+bool CreateRandomId(uint32_t* id) {
+  if (!Rng().Generate(id, sizeof(*id))) {
+    LOG(LS_ERROR) << "Failed to generate random id!";
+    return false;
+  }
+  return true;
+}
+
 uint64_t CreateRandomId64() {
-  return static_cast<uint64_t>(CreateRandomId()) << 32 | CreateRandomId();
+  uint64_t id;
+  RTC_CHECK(CreateRandomId64(&id));
+  return id;
+}
+
+bool CreateRandomId64(uint64_t* id) {
+  uint32_t high;
+  uint32_t low;
+  if (!CreateRandomId(&high) || !CreateRandomId(&low)) {

[joachim, 2016/07/01 23:12:29]

Maybe get the uint64_t directly from the RNG?

+    return false;
+  }
+  *id = static_cast<uint64_t>(high) << 32 | low;
+  return true;
 }
 
 uint32_t CreateRandomNonZeroId() {
   uint32_t id;
-  do {
-    id = CreateRandomId();
-  } while (id == 0);
+  RTC_CHECK(CreateRandomNonZeroId(&id));
   return id;
 }
 
+bool CreateRandomNonZeroId(uint32_t* id) {
+  do {
+    if (!CreateRandomId(id)) {
+      return false;
+    }
+  } while (*id == 0);
+  return true;
+}
+
 double CreateRandomDouble() {
-  return CreateRandomId() / (std::numeric_limits<uint32_t>::max() +
-                             std::numeric_limits<double>::epsilon());
+  double value;
+  RTC_CHECK(CreateRandomDouble(&value));
+  return value;
+}
+
+bool CreateRandomDouble(double* value) {
+  uint32_t id;
+  if (!CreateRandomId(&id)) {
+    return false;
+  }
+  *value = id / (std::numeric_limits<uint32_t>::max() +
+                 std::numeric_limits<double>::epsilon());
+  return true;
 }
 
 }  // namespace rtc