1 files changed, 83 insertions, 0 deletions
diff --git a/Tools/scripts/get-remote-certificate.py b/Tools/scripts/get-remote-certificate.py
new file mode 100644
index 0000000..02f1c8a
--- /dev/null
+++ b/Tools/scripts/get-remote-certificate.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+#
+# fetch the certificate that the server(s) are providing in PEM form
+#
+# args are HOST:PORT [, HOST:PORT...]
+#
+# By Bill Janssen.
+
+import re
+import os
+import ssl
+import sys
+import tempfile
+
+
+def fetch_server_certificate (host, port):
+
+    def subproc(cmd):
+        from subprocess import Popen, PIPE, STDOUT
+        proc = Popen(cmd, stdout=PIPE, stderr=STDOUT, shell=True)
+        status = proc.wait()
+        output = proc.stdout.read()
+        return status, output
+
+    def strip_to_x509_cert(certfile_contents, outfile=None):
+        m = re.search(br"^([-]+BEGIN CERTIFICATE[-]+[\r]*\n"
+                      br".*[\r]*^[-]+END CERTIFICATE[-]+)$",
+                      certfile_contents, re.MULTILINE | re.DOTALL)
+        if not m:
+            return None
+        else:
+            tn = tempfile.mktemp()
+            fp = open(tn, "wb")
+            fp.write(m.group(1) + b"\n")
+            fp.close()
+            try:
+                tn2 = (outfile or tempfile.mktemp())
+                status, output = subproc(r'openssl x509 -in "%s" -out "%s"' %
+                                         (tn, tn2))
+                if status != 0:
+                    raise OperationError(status, tsig, output)
+                fp = open(tn2, 'rb')
+                data = fp.read()
+                fp.close()
+                os.unlink(tn2)
+                return data
+            finally:
+                os.unlink(tn)
+
+    if sys.platform.startswith("win"):
+        tfile = tempfile.mktemp()
+        fp = open(tfile, "w")
+        fp.write("quit\n")
+        fp.close()
+        try:
+            status, output = subproc(
+                'openssl s_client -connect "%s:%s" -showcerts < "%s"' %
+                (host, port, tfile))
+        finally:
+            os.unlink(tfile)
+    else:
+        status, output = subproc(
+            'openssl s_client -connect "%s:%s" -showcerts < /dev/null' %
+            (host, port))
+    if status != 0:
+        raise OSError(status)
+    certtext = strip_to_x509_cert(output)
+    if not certtext:
+        raise ValueError("Invalid response received from server at %s:%s" %
+                         (host, port))
+    return certtext
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 2:
+        sys.stderr.write(
+            "Usage:  %s HOSTNAME:PORTNUMBER [, HOSTNAME:PORTNUMBER...]\n" %
+            sys.argv[0])
+        sys.exit(1)
+    for arg in sys.argv[1:]:
+        host, port = arg.split(":")
+        sys.stdout.buffer.write(fetch_server_certificate(host, int(port)))
+    sys.exit(0)