From fc5da5d3ff5c26e6ab17d70e3a121db0ac85eb05 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gerg=C3=B6=20Barany?= <gergo@complang.tuwien.ac.at>
Date: Fri, 12 Jul 2013 12:16:34 +0200
Subject: [PATCH] Refactor type 2 message decoding, drop any extra lines from
 subject. This allows other clients to insert headers in extra lines of text
 between the Subject and Body fields of the message, as discussed on the 24x7
 mailing list. The PyBitmessage client was never able to meaningfully display
 multi-line subjects, so this does not break anything. The extra lines are
 thrown away and never stored anywhere, so this also protects against
 watermarking attacks.

---
 src/class_receiveDataThread.py | 41 +++++++++++++++-------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/src/class_receiveDataThread.py b/src/class_receiveDataThread.py
index ad5e7b34..e73f3d2b 100644
--- a/src/class_receiveDataThread.py
+++ b/src/class_receiveDataThread.py
@@ -528,13 +528,7 @@ class receiveDataThread(threading.Thread):
                     print 'fromAddress:', fromAddress
 
                 if messageEncodingType == 2:
-                    bodyPositionIndex = string.find(message, '\nBody:')
-                    if bodyPositionIndex > 1:
-                        subject = message[8:bodyPositionIndex]
-                        body = message[bodyPositionIndex + 6:]
-                    else:
-                        subject = ''
-                        body = message
+                    subject, body = self.decodeType2Message(message)
                 elif messageEncodingType == 1:
                     body = message
                     subject = ''
@@ -684,13 +678,7 @@ class receiveDataThread(threading.Thread):
                 print 'fromAddress:', fromAddress
 
             if messageEncodingType == 2:
-                bodyPositionIndex = string.find(message, '\nBody:')
-                if bodyPositionIndex > 1:
-                    subject = message[8:bodyPositionIndex]
-                    body = message[bodyPositionIndex + 6:]
-                else:
-                    subject = ''
-                    body = message
+                subject, body = self.decodeType2Message(message)
             elif messageEncodingType == 1:
                 body = message
                 subject = ''
@@ -1005,15 +993,7 @@ class receiveDataThread(threading.Thread):
                     toLabel = toAddress
 
                 if messageEncodingType == 2:
-                    bodyPositionIndex = string.find(message, '\nBody:')
-                    if bodyPositionIndex > 1:
-                        subject = message[8:bodyPositionIndex]
-                        subject = subject[
-                            :500]  # Only save and show the first 500 characters of the subject. Any more is probably an attak.
-                        body = message[bodyPositionIndex + 6:]
-                    else:
-                        subject = ''
-                        body = message
+                    subject, body = self.decodeType2Message(message)
                 elif messageEncodingType == 1:
                     body = message
                     subject = ''
@@ -1086,6 +1066,21 @@ class receiveDataThread(threading.Thread):
                 print 'Time to decrypt this message successfully:', timeRequiredToAttemptToDecryptMessage
                 print 'Average time for all message decryption successes since startup:', sum / len(shared.successfullyDecryptMessageTimings)
 
+    def decodeType2Message(self, message):
+        bodyPositionIndex = string.find(message, '\nBody:')
+        if bodyPositionIndex > 1:
+            subject = message[8:bodyPositionIndex]
+            # Only save and show the first 500 characters of the subject.
+            # Any more is probably an attack.
+            subject = subject[:500]
+            body = message[bodyPositionIndex + 6:]
+        else:
+            subject = ''
+            body = message
+        # Throw away any extra lines (headers) after the subject.
+        if subject:
+            subject = subject.splitlines()[0]
+        return subject, body
 
     def isAckDataValid(self, ackData):
         if len(ackData) < 24: