fixup! Verify config file signaturekey-management

1 files changed, 54 insertions, 0 deletions

diff --git a/tools/readconfig.py b/tools/readconfig.py
new file mode 100644
index 0000000..5079691
--- /dev/null
+++ b/tools/readconfig.py
@@ -0,0 +1,54 @@
+import io
+import ecdsa
+import hashlib
+import yaml
+import base64
+import sys
+
+class ErrorHandlingDict(dict):
+    def __init__(self, filename, path):
+        self._filename = filename
+        self._path = path
+        dict.__init__({})
+    def __missing__(self, key):
+        if self._path:
+            path = ", ".join(self._path)
+        else:
+            path = "the top level"
+        print >>sys.stderr, "error: could not find configuration key '%s' at %s in %s" % (key, path, self._filename)
+        sys.exit(1)
+
+def errorhandlify(term, filename, path=[]):
+    if isinstance(term, basestring):
+        return term
+    elif isinstance(term, int):
+        return term
+    elif isinstance(term, dict):
+        result = ErrorHandlingDict(filename, path)
+        for k, v in term.items():
+            result[k] = errorhandlify(v, filename, path + [k])
+        return result
+    elif isinstance(term, list):
+        return [errorhandlify(e, filename, path + ["item %d" % i]) for i, e in enumerate(term, start=1)]
+    else:
+        print "unknown type", type(term)
+        sys.exit(1)
+
+def verify_and_read_config(filename, publickey_base64):
+    rawconfig = open(filename).read()
+    signature = open(filename + ".sig").read()
+
+    publickey = base64.decodestring(publickey_base64)
+
+    try:
+        vk = ecdsa.VerifyingKey.from_der(publickey)
+        vk.verify(signature, rawconfig, hashfunc=hashlib.sha256,
+                sigdecode=ecdsa.util.sigdecode_der)
+    except ecdsa.keys.BadSignatureError:
+        print >>sys.stderr, "error: configuration file %s did not have a correct signature" % (filename,)
+        sys.exit(1)
+
+    return errorhandlify(yaml.load(io.BytesIO(rawconfig), yaml.SafeLoader), filename)
+
+def read_config(filename):
+    return errorhandlify(yaml.load(open(filename), yaml.SafeLoader), filename)