1 files changed, 90 insertions, 0 deletions
diff --git a/dom/media/eme/clearkey/ClearKeyBase64.cpp b/dom/media/eme/clearkey/ClearKeyBase64.cpp
new file mode 100644
index 0000000000..bb610afd1b
--- /dev/null
+++ b/dom/media/eme/clearkey/ClearKeyBase64.cpp
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2015, Mozilla Foundation and contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ClearKeyBase64.h"
+
+#include <algorithm>
+
+using std::string;
+using std::vector;
+
+/**
+ * Take a base64-encoded string, convert (in-place) each character to its
+ * corresponding value in the [0x00, 0x3f] range, and truncate any padding.
+ */
+static bool Decode6Bit(string& aStr) {
+  for (size_t i = 0; i < aStr.length(); i++) {
+    if (aStr[i] >= 'A' && aStr[i] <= 'Z') {
+      aStr[i] -= 'A';
+    } else if (aStr[i] >= 'a' && aStr[i] <= 'z') {
+      aStr[i] -= 'a' - 26;
+    } else if (aStr[i] >= '0' && aStr[i] <= '9') {
+      aStr[i] -= '0' - 52;
+    } else if (aStr[i] == '-' || aStr[i] == '+') {
+      aStr[i] = 62;
+    } else if (aStr[i] == '_' || aStr[i] == '/') {
+      aStr[i] = 63;
+    } else {
+      // Truncate '=' padding at the end of the aString.
+      if (aStr[i] != '=') {
+        aStr.erase(i, string::npos);
+        return false;
+      }
+      aStr[i] = '\0';
+      aStr.resize(i);
+      break;
+    }
+  }
+
+  return true;
+}
+
+bool DecodeBase64(const string& aEncoded, vector<uint8_t>& aOutDecoded) {
+  if (aEncoded.empty()) {
+    aOutDecoded.clear();
+    return true;
+  }
+  if (aEncoded.size() == 1) {
+    // Invalid Base64 encoding.
+    return false;
+  }
+  string encoded = aEncoded;
+  if (!Decode6Bit(encoded)) {
+    return false;
+  }
+
+  // The number of bytes we haven't yet filled in the current byte, mod 8.
+  int shift = 0;
+
+  aOutDecoded.resize((encoded.size() * 3) / 4);
+  vector<uint8_t>::iterator out = aOutDecoded.begin();
+  for (size_t i = 0; i < encoded.length(); i++) {
+    if (!shift) {
+      *out = encoded[i] << 2;
+    } else {
+      *out |= encoded[i] >> (6 - shift);
+      out++;
+      if (out == aOutDecoded.end()) {
+        // Hit last 6bit octed in encoded, which is padding and can be ignored.
+        break;
+      }
+      *out = encoded[i] << (shift + 2);
+    }
+    shift = (shift + 2) % 8;
+  }
+
+  return true;
+}