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85 lines
2.7 KiB
85 lines
2.7 KiB
6 years ago
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#!/usr/bin/env python3
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#
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# fetch the certificate that the server(s) are providing in PEM form
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#
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# args are HOST:PORT [, HOST:PORT...]
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#
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# By Bill Janssen.
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import re
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import os
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import sys
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import tempfile
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def fetch_server_certificate (host, port):
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def subproc(cmd):
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from subprocess import Popen, PIPE, STDOUT
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proc = Popen(cmd, stdout=PIPE, stderr=STDOUT, shell=True)
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status = proc.wait()
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output = proc.stdout.read()
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return status, output
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def strip_to_x509_cert(certfile_contents, outfile=None):
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m = re.search(br"^([-]+BEGIN CERTIFICATE[-]+[\r]*\n"
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br".*[\r]*^[-]+END CERTIFICATE[-]+)$",
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certfile_contents, re.MULTILINE | re.DOTALL)
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if not m:
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return None
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else:
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tn = tempfile.mktemp()
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fp = open(tn, "wb")
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fp.write(m.group(1) + b"\n")
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fp.close()
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try:
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tn2 = (outfile or tempfile.mktemp())
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status, output = subproc(r'openssl x509 -in "%s" -out "%s"' %
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(tn, tn2))
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if status != 0:
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raise RuntimeError('OpenSSL x509 failed with status %s and '
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'output: %r' % (status, output))
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fp = open(tn2, 'rb')
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data = fp.read()
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fp.close()
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os.unlink(tn2)
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return data
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finally:
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os.unlink(tn)
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if sys.platform.startswith("win"):
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tfile = tempfile.mktemp()
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fp = open(tfile, "w")
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fp.write("quit\n")
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fp.close()
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try:
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status, output = subproc(
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'openssl s_client -connect "%s:%s" -showcerts < "%s"' %
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(host, port, tfile))
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finally:
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os.unlink(tfile)
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else:
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status, output = subproc(
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'openssl s_client -connect "%s:%s" -showcerts < /dev/null' %
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(host, port))
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if status != 0:
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raise RuntimeError('OpenSSL connect failed with status %s and '
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'output: %r' % (status, output))
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certtext = strip_to_x509_cert(output)
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if not certtext:
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raise ValueError("Invalid response received from server at %s:%s" %
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(host, port))
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return certtext
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if __name__ == "__main__":
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if len(sys.argv) < 2:
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sys.stderr.write(
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"Usage: %s HOSTNAME:PORTNUMBER [, HOSTNAME:PORTNUMBER...]\n" %
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sys.argv[0])
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sys.exit(1)
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for arg in sys.argv[1:]:
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host, port = arg.split(":")
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sys.stdout.buffer.write(fetch_server_certificate(host, int(port)))
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sys.exit(0)
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