Add support for parsing certificate formats other than raw, DER-encoded cert...

net/base/pem_tokenizer.cc

Index: net/base/pem_tokenizer.cc
diff --git a/net/base/pem_tokenizer.cc b/net/base/pem_tokenizer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0abe5dbd5546fe5e5f1339c349b63c67150daecb
--- /dev/null
+++ b/net/base/pem_tokenizer.cc
@@ -0,0 +1,95 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/base/pem_tokenizer.h"
+
+#include "base/base64.h"
+#include "base/string_util.h"
+
+namespace {
+
+const char kPEMSearchBlock[] = "-----BEGIN ";
+const char kPEMBeginBlock[] = "-----BEGIN %s-----";
+const char kPEMEndBlock[] = "-----END %s-----";
+
+}  // namespace
+
+namespace net {
+
+using base::StringPiece;
+
+PEMTokenizer::PEMTokenizer(
+    const StringPiece& str,
+    const std::vector<std::string>& allowed_block_types) {
+  Init(str, allowed_block_types);
+}
+
+bool PEMTokenizer::GetNext() {
+  while (pos_ != StringPiece::npos) {
+    // Scan for the beginning of the next PEM encoded block.
+    pos_ = str_.find(kPEMSearchBlock, pos_);
+    if (pos_ == StringPiece::npos)
+      return false;  // No more PEM blocks
+
+    std::vector<PEMType>::const_iterator it;
+    // Check to see if it is of an acceptable block type.
+    for (it = block_types_.begin(); it != block_types_.end(); ++it) {
+      if (!str_.substr(pos_).starts_with(it->header))
+        continue;
+
+      // Look for a footer matching the header. If none is found, then all
+      // data following this point is invalid and should not be parsed.
+      StringPiece::size_type footer_pos = str_.find(it->footer, pos_);
+      if (footer_pos == StringPiece::npos) {
+        pos_ = StringPiece::npos;
+        return false;
+      }
+
+      // Chop off the header and footer and parse the data in between.
+      StringPiece::size_type data_begin = pos_ + it->header.size();
+      pos_ = footer_pos + it->footer.size();
+      block_type_ = it->type;
+
+      StringPiece encoded = str_.substr(data_begin,
+                                        footer_pos - data_begin);
+      if (!base::Base64Decode(CollapseWhitespaceASCII(encoded.as_string(),
+                                                      true), &data_)) {
+        // The most likely cause for a decode failure is a datatype that
+        // includes PEM headers, which are not supported.
+        break;
+      }
+
+      return true;
+    }
+
+    // If the block did not match any acceptable type, move past it and
+    // continue the search. Otherwise, |pos_| has been updated to the most
+    // appropriate search position to continue searching from and should not
+    // be adjusted.
+    if (it == block_types_.end())
+      pos_ += sizeof(kPEMSearchBlock);
+  }
+
+  return false;
+}
+
+void PEMTokenizer::Init(
+    const StringPiece& str,
+    const std::vector<std::string>& allowed_block_types) {
+  str_ = str;
+  pos_ = 0;
+
+  // Construct PEM header/footer strings for all the accepted types, to
+  // reduce parsing later.
+  for (std::vector<std::string>::const_iterator it =
+       allowed_block_types.begin(); it != allowed_block_types.end(); ++it) {
+    PEMType allowed_type;
+    allowed_type.type = *it;
+    allowed_type.header = StringPrintf(kPEMBeginBlock, it->c_str());
+    allowed_type.footer = StringPrintf(kPEMEndBlock, it->c_str());
+    block_types_.push_back(allowed_type);
+  }
+}
+
+}  // namespace net