manifest: Support reading files containing OpenPGP signatures

3 files changed, 187 insertions, 0 deletions

diff --git a/gemato/exceptions.py b/gemato/exceptions.py
index c9cb646..790ff53 100644
--- a/gemato/exceptions.py
+++ b/gemato/exceptions.py
@@ -50,3 +50,14 @@ class ManifestCrossDevice(Exception):
         super(ManifestCrossDevice, self).__init__(
             "Path {} crosses filesystem boundaries, it must be IGNORE-d explicitly"
             .format(path))
+
+
+class ManifestUnsignedData(Exception):
+    """
+    An exception caused by a Manifest file containing non-whitespace
+    outside the OpenPGP-signed part.
+    """
+
+    def __init__(self):
+        super(ManifestUnsignedData, self).__init__(
+                "Unsigned data found in an OpenPGP signed Manifest")
diff --git a/gemato/manifest.py b/gemato/manifest.py
index 96b1110..0fae91f 100644
--- a/gemato/manifest.py
+++ b/gemato/manifest.py
@@ -273,6 +273,18 @@ MANIFEST_TAG_MAPPING = {
 }
 
 
+class ManifestState(object):
+    """
+    FSM constants for loading Manifest.
+    """
+
+    DATA = 0
+    SIGNED_PREAMBLE = 1
+    SIGNED_DATA = 2
+    SIGNATURE = 3
+    POST_SIGNED_DATA = 4
+
+
 class ManifestFile(object):
     """
     A class encapsulating a single Manifest file. It supports reading
@@ -296,11 +308,44 @@ class ManifestFile(object):
         """
 
         self.entries = []
+        state = ManifestState.DATA
+
         for l in f:
+            if state == ManifestState.DATA:
+                if l == '-----BEGIN PGP SIGNED MESSAGE-----\n':
+                    if self.entries:
+                        raise gemato.exceptions.ManifestUnsignedData()
+                    state = ManifestState.SIGNED_PREAMBLE
+                    continue
+            elif state == ManifestState.SIGNED_PREAMBLE:
+                # skip header lines up to the empty line
+                if l.strip():
+                    continue
+                state = ManifestState.SIGNED_DATA
+            elif state == ManifestState.SIGNED_DATA:
+                if l == '-----BEGIN PGP SIGNATURE-----\n':
+                    state = ManifestState.SIGNATURE
+                    continue
+                # dash-escaping, RFC 4880 says any line can suffer from it
+                if l.startswith('- '):
+                    l = l[2:]
+            elif state == ManifestState.SIGNATURE:
+                if l == '-----END PGP SIGNATURE-----\n':
+                    state = ManifestState.POST_SIGNED_DATA
+                    continue
+
+            if l.startswith('-----') and l.rstrip().endswith('-----'):
+                raise gemato.exceptions.ManifestSyntaxError(
+                        "Unexpected OpenPGP header: {}".format(l))
+            if state in (ManifestState.SIGNED_PREAMBLE, ManifestState.SIGNATURE):
+                continue
+
             sl = l.strip().split()
             # skip empty lines
             if not sl:
                 continue
+            if state == ManifestState.POST_SIGNED_DATA:
+                raise gemato.exceptions.ManifestUnsignedData()
             tag = sl[0]
             self.entries.append(MANIFEST_TAG_MAPPING[tag].from_list(sl))
 
diff --git a/tests/test_openpgp.py b/tests/test_openpgp.py
new file mode 100644
index 0000000..b829078
--- /dev/null
+++ b/tests/test_openpgp.py
@@ -0,0 +1,131 @@
+# gemato: OpenPGP signature support tests
+# vim:fileencoding=utf-8
+# (c) 2017 Michał Górny
+# Licensed under the terms of 2-clause BSD license
+
+import io
+import unittest
+
+import gemato.manifest
+
+
+SIGNED_MANIFEST = u'''
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA512
+
+TIMESTAMP 2017-10-22T18:06:41Z
+MANIFEST eclass/Manifest 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+IGNORE local
+DATA myebuild-0.ebuild 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+MISC metadata.xml 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+OPTIONAL ChangeLog
+DIST mydistfile.tar.gz 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+-----BEGIN PGP SIGNATURE-----
+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+=9naF
+-----END PGP SIGNATURE-----
+'''
+
+DASH_ESCAPED_SIGNED_MANIFEST = u'''
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA512
+
+- TIMESTAMP 2017-10-22T18:06:41Z
+- MANIFEST eclass/Manifest 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+IGNORE local
+- DATA myebuild-0.ebuild 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+MISC metadata.xml 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+- OPTIONAL ChangeLog
+- DIST mydistfile.tar.gz 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+-----BEGIN PGP SIGNATURE-----
+
+iQGTBAEBCgB9FiEEgeEsFr2NzWC+GAhFE2iA5yp7E4QFAlnwXQpfFIAAAAAALgAo
+aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldDgx
+RTEyQzE2QkQ4RENENjBCRTE4MDg0NTEzNjg4MEU3MkE3QjEzODQACgkQE2iA5yp7
+E4ScZAf+IF4suRtuN3bJki2zyYV/1VtSekK96tO+IzXxXDY0OKXmf61R6ZuuXcUD
+Q+DlBONMILG+CDY+qiDp6snEWPmeLuh57qjkxilTgEX88W7OSCSdvGzSbC5WIRQG
+KHtfZWtVVrZHTzQ6MF3u2Vombkpra/CQrf4Yx+8zdkorsoXwZ6ZjriB3W/zTUWIJ
+XUy2tNfupdu72q9ske3dhVLhUEjtBzq5MlTf6gUjLBEsIHCGSafO2VG00lii3q4E
+14EEilADJlKAOwK5WQUmAOjeeC60ck5EW5tGBotncd954v6n42pwlVXVmqSOJdYy
+9F1V8N1m6n9UEUQ7Hhrv/+BTDPJO0A==
+=9naF
+-----END PGP SIGNATURE-----
+'''
+
+MODIFIED_SIGNED_MANIFEST = u'''
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA512
+
+TIMESTAMP 2017-10-22T18:06:41Z
+MANIFEST eclass/Manifest 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+IGNORE local
+DATA myebuild-0.ebuild 32
+MISC metadata.xml 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+OPTIONAL ChangeLog
+DIST mydistfile.tar.gz 0 MD5 d41d8cd98f00b204e9800998ecf8427e SHA1 da39a3ee5e6b4b0d3255bfef95601890afd80709
+-----BEGIN PGP SIGNATURE-----
+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+=9naF
+-----END PGP SIGNATURE-----
+'''
+
+
+class SignedManifestTest(unittest.TestCase):
+    """
+    Test whether signed Manifest is read correctly.
+    """
+
+    def test_manifest_load(self):
+        m = gemato.manifest.ManifestFile()
+        with io.StringIO(SIGNED_MANIFEST) as f:
+            m.load(f)
+        self.assertIsNotNone(m.find_timestamp())
+        self.assertIsNotNone(m.find_path_entry('myebuild-0.ebuild'))
+
+    def test_dash_escaped_manifest_load(self):
+        m = gemato.manifest.ManifestFile()
+        with io.StringIO(DASH_ESCAPED_SIGNED_MANIFEST) as f:
+            m.load(f)
+        self.assertIsNotNone(m.find_timestamp())
+        self.assertIsNotNone(m.find_path_entry('myebuild-0.ebuild'))
+
+    def test_modified_manifest_load(self):
+        """
+        Modified Manifest should load correctly since we do not enforce
+        implicit verification.
+        """
+        m = gemato.manifest.ManifestFile()
+        with io.StringIO(MODIFIED_SIGNED_MANIFEST) as f:
+            m.load(f)
+        self.assertIsNotNone(m.find_timestamp())
+        self.assertIsNotNone(m.find_path_entry('myebuild-0.ebuild'))
+
+    def test_junk_before_manifest_load(self):
+        m = gemato.manifest.ManifestFile()
+        with io.StringIO('OPTIONAL test\n' + SIGNED_MANIFEST) as f:
+            self.assertRaises(gemato.exceptions.ManifestUnsignedData,
+                    m.load, f)
+
+    def test_junk_after_manifest_load(self):
+        m = gemato.manifest.ManifestFile()
+        with io.StringIO(SIGNED_MANIFEST + 'OPTIONAL test\n') as f:
+            self.assertRaises(gemato.exceptions.ManifestUnsignedData,
+                    m.load, f)