Make Exceptions more verbose

pgpdump/__main__.py

@@ -9,16 +9,19 @@ def parsefile(name):
             data = AsciiData(infile.read())
         else:
             data = BinaryData(infile.read())
-    counter = length = 0
+
     for packet in data.packets():
-        counter += 1
-        length += packet.length
-    print('%d packets, length %d' % (counter, length))
+        yield packet
 
 
 def main():
+    counter = length = 0
     for filename in sys.argv[1:]:
-        parsefile(filename)
+        for packet in parsefile(filename):
+            counter += 1
+            length += packet.length
+
+    print('%d packets, length %d' % (counter, length))
 
 
 if __name__ == '__main__':

pgpdump/data.py

@@ -11,15 +11,19 @@ class BinaryData(object):
 
     def __init__(self, data):
         if not data:
-            raise PgpdumpException("no data to parse")
+            raise PgpdumpException("no data to parse, "
+                "data is %s" % repr(data)[:25])
         if len(data) <= 1:
-            raise PgpdumpException("data too short")
+            raise PgpdumpException("data too short: len=%d" % len(data))
 
         data = bytearray(data)
 
         # 7th bit of the first byte must be a 1
-        if not bool(data[0] & self.binary_tag_flag):
-            raise PgpdumpException("incorrect binary data")
+        binary_tag = bool(data[0] & self.binary_tag_flag)
+        if not binary_tag:
+            raise PgpdumpException("incorrect binary data. expected 7th bit "
+                "in first byte (%02x) to be 1, not %d."  % (
+                data[0], binary_tag))
         self.data = data
         self.length = len(data)
 
@@ -75,8 +79,9 @@ def strip_magic(data):
             if nl_idx < 0:
                 nl_idx = data.find(b'\r\n\r\n', idx)
             if nl_idx < 0:
-                raise PgpdumpException(
-                        "found magic, could not find start of data")
+                raise PgpdumpException("found magic, could not find start "
+                    "of data. Expected two newlines "
+                    r"(\r\n\r\n or \n\n)")
             # now find the end of the data.
             end_idx = data.find(b'-----', nl_idx)
             if end_idx:

pgpdump/packet.py

@@ -1,5 +1,6 @@
 from datetime import datetime, timedelta
 import hashlib
+from math import ceil, log
 import re
 from warnings import warn
 
@@ -160,7 +161,9 @@ def parse(self):
 
             # "hash material" byte must be 0x05
             if self.data[offset] != 0x05:
-                raise PgpdumpException("Invalid v3 signature packet")
+                raise PgpdumpException("Invalid v3 signature packet. "
+                    "Expected data at offset %d to be 0x05, but it is "
+                    "%02x" % (offset, self.data[offset]))
             offset += 1
 
             self.raw_sig_type = self.data[offset]
@@ -303,6 +306,7 @@ def __init__(self, *args, **kwargs):
         self.raw_pub_algorithm = None
         self.pub_algorithm_type = None
         self.modulus = None
+        self.modulus_bitlen = None
         self.exponent = None
         self.prime = None
         self.group_order = None
@@ -345,8 +349,9 @@ def parse(self):
                 md5.update(get_int_bytes(self.prime))
                 md5.update(get_int_bytes(self.group_gen))
             else:
-                raise PgpdumpException("Invalid non-RSA v%d public key" %
-                        self.pubkey_version)
+                raise PgpdumpException("Invalid non-RSA (%s) v%d public key" % (
+                        self.pub_algorithm_type, self.pubkey_version))
+
             self.fingerprint = md5.hexdigest().upper().encode('ascii')
         elif self.pubkey_version == 4:
             sha1 = hashlib.sha1()
@@ -375,6 +380,8 @@ def parse_key_material(self, offset):
             # n, e
             self.modulus, offset = get_mpi(self.data, offset)
             self.exponent, offset = get_mpi(self.data, offset)
+            # the length of the modulus in bits
+            self.modulus_bitlen = int(ceil(log(self.modulus, 2)))
         elif self.raw_pub_algorithm == 17:
             self.pub_algorithm_type = "dsa"
             # p, q, g, y

pgpdump/test.py

@@ -1,9 +1,17 @@
+#!/usr/bin/env python
+
 import base64
 from datetime import datetime
 from itertools import repeat
 import os.path
+import sys
 from unittest import main, TestCase
 
+# Prepend the parent directory of this file to the PYTHONPATH,
+# to use this very module and not a system wide installed one
+ROOTDIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), '..')
+sys.path.insert(0, ROOTDIR)
+
 from pgpdump import AsciiData, BinaryData
 from pgpdump.packet import (TAG_TYPES, SignaturePacket, PublicKeyPacket,
         PublicSubkeyPacket, UserIDPacket, old_tag_length, new_tag_length)
@@ -239,6 +247,7 @@ def test_parse_linus_binary(self):
                 self.assertEqual(1316554898, packet.raw_creation_time)
                 self.assertEqual(1, packet.raw_pub_algorithm)
                 self.assertIsNotNone(packet.modulus)
+                self.assertEqual(2048, packet.modulus_bitlen)
                 self.assertEqual(65537, packet.exponent)
                 self.assertEqual(b"012F54CA", packet.fingerprint[32:])
 
@@ -249,6 +258,7 @@ def test_parse_linus_binary(self):
                 self.assertEqual(1, packet.raw_pub_algorithm)
                 self.assertEqual("RSA Encrypt or Sign", packet.pub_algorithm)
                 self.assertIsNotNone(packet.modulus)
+                self.assertEqual(2048, packet.modulus_bitlen)
                 self.assertEqual(65537, packet.exponent)
                 self.assertEqual(b"ABAF11C65A2970B130ABE3C479BE3E4300411886",
                         packet.fingerprint)
@@ -344,6 +354,7 @@ def test_parse_v3_pubkeys(self):
         self.assertEqual(944849149, packet.raw_creation_time)
         self.assertIsNone(packet.expiration_time)
         self.assertIsNotNone(packet.modulus)
+        self.assertEqual(2048, packet.modulus_bitlen)
         self.assertIsNotNone(packet.exponent)
         self.assertEqual(b"3FC0BF6B", packet.key_id)
         self.assertEqual(b"7D263C88A1AB7737E31150CB4F3A211A",
@@ -356,6 +367,7 @@ def test_parse_v3_pubkeys(self):
         self.assertEqual(904151571, packet.raw_creation_time)
         self.assertIsNone(packet.expiration_time)
         self.assertIsNotNone(packet.modulus)
+        self.assertEqual(1024, packet.modulus_bitlen)
         self.assertIsNotNone(packet.exponent)
         self.assertEqual(b"3DDE776D", packet.key_id)
         self.assertEqual(b"48A4F9F891F093019BC7FC532A3C5692",
@@ -375,6 +387,7 @@ def test_parse_v3_elgamal_pk(self):
         self.assertEqual(888716291, packet.raw_creation_time)
         self.assertIsNone(packet.expiration_time)
         self.assertIsNone(packet.modulus)
+        self.assertIsNone(packet.modulus_bitlen)
         self.assertIsNone(packet.exponent)
         self.assertIsNotNone(packet.prime)
         self.assertIsNotNone(packet.group_gen)
@@ -427,6 +440,11 @@ def test_new_tag_length(self):
         for expected, invals in data:
             self.assertEqual(expected, new_tag_length(invals, 0))
 
-
 if __name__ == '__main__':
+    print("""The recommended way of invocation is
+        python2 -m unittest pgpdump.test""")
+    print("We have, however, added %s to the PYTHONPATH. Please review "
+        "your PYTHONPATH which currently is:" % ROOTDIR)
+    print(sys.path)
+
     main()