1 files changed, 42 insertions, 0 deletions
diff --git a/chromium/third_party/tlslite/tlslite/utils/asn1parser.py b/chromium/third_party/tlslite/tlslite/utils/asn1parser.py
new file mode 100644
index 00000000000..618e8559c9b
--- /dev/null
+++ b/chromium/third_party/tlslite/tlslite/utils/asn1parser.py
@@ -0,0 +1,42 @@
+# Author: Trevor Perrin
+# Patch from Google adding getChildBytes()
+#
+# See the LICENSE file for legal information regarding use of this file.
+
+"""Class for parsing ASN.1"""
+from .compat import *
+from .codec import *
+
+#Takes a byte array which has a DER TLV field at its head
+class ASN1Parser(object):
+    def __init__(self, bytes):
+        p = Parser(bytes)
+        p.get(1) #skip Type
+
+        #Get Length
+        self.length = self._getASN1Length(p)
+
+        #Get Value
+        self.value = p.getFixBytes(self.length)
+
+    #Assuming this is a sequence...
+    def getChild(self, which):
+        return ASN1Parser(self.getChildBytes(which))
+
+    def getChildBytes(self, which):
+        p = Parser(self.value)
+        for x in range(which+1):
+            markIndex = p.index
+            p.get(1) #skip Type
+            length = self._getASN1Length(p)
+            p.getFixBytes(length)
+        return p.bytes[markIndex : p.index]
+
+    #Decode the ASN.1 DER length field
+    def _getASN1Length(self, p):
+        firstLength = p.get(1)
+        if firstLength<=127:
+            return firstLength
+        else:
+            lengthLength = firstLength & 0x7F
+            return p.get(lengthLength)