source: fedd/federation/fedid.py @ 02786fc

#!/usr/local/bin/python

import os, sys
import subprocess
import tempfile
import logging

from M2Crypto import SSL, X509, EVP
from pyasn1.codec.der import decoder

# The version of M2Crypto on users is pretty old and doesn't have all the
# features that are useful.  The legacy code is somewhat more brittle than the
# main line, but will work.
if "as_der" not in dir(EVP.PKey):
    from asn1_raw import get_key_bits_from_file, get_key_bits_from_cert
    legacy = True
else:
    legacy = False

class fedid:
    """
    Wrapper around the federated ID from an X509 certificate. 
    """
    HASHSIZE=20
    def __init__(self, bits=None, hexstr=None, cert=None, file=None):
        if bits != None:
            self.set_bits(bits)
        elif hexstr != None:
            self.set_hexstr(hexstr)
        elif cert != None:
            self.set_cert(cert)
        elif file != None:
            self.set_file(file)
        else:
            self.buf = None

    def __hash__(self):
        return hash(self.buf)

    def __eq__(self, other):
        if isinstance(other, type(self)):
            return self.buf == other.buf
        elif isinstance(other, type(str())):
            return self.buf == other;
        else:
            return False

    def __ne__(self, other): return not self.__eq__(other)

    def __str__(self):
        if self.buf != None:
            return str().join([ "%02x" % ord(x) for x in self.buf])
        else: return ""

    def __repr__(self):
        return "fedid(hexstr='%s')" % self.__str__()

    def pack_soap(self):
        return self.buf

    def pack_xmlrpc(self):
        return self.buf

    def digest_bits(self, bits):
        """Internal function.  Compute the fedid from bits and store in buf"""
        d = EVP.MessageDigest('sha1')
        d.update(bits)
        self.buf = d.final()


    def set_hexstr(self, hexstr):
        h = hexstr.replace(':','')
        self.buf= str().join([chr(int(h[i:i+2],16)) \
                for i in range(0,2*fedid.HASHSIZE,2)])

    def get_hexstr(self):
        """Return the hexstring representation of the fedid"""
        return __str__(self)

    def set_bits(self, bits):
        """Set the fedid to bits(a 160 bit buffer)"""
        self.buf = bits

    def get_bits(self):
        """Get the 160 bit buffer from the fedid"""
        return self.buf

    def set_file(self, file):
        """Get the fedid from a certificate file

        Calculate the SHA1 hash over the bit string of the public key as
        defined in RFC3280.
        """
        self.buf = None
        if legacy: self.digest_bits(get_key_bits_from_file(file))
        else: self.set_cert(X509.load_cert(file))

    def set_cert(self, cert):
        """Get the fedid from a certificate.

        Calculate the SHA1 hash over the bit string of the public key as
        defined in RFC3280.
        """

        self.buf = None
        if (cert != None):
            if legacy:
                self.digest_bits(get_key_bits_from_cert(cert))
            else:
                b = []
                k = cert.get_pubkey()

                # Getting the key was easy, but getting the bit string of the
                # key requires a side trip through ASN.1
                dec = decoder.decode(k.as_der())

                # kv is a tuple of the bits in the key.  The loop below
                # recombines these into bytes and then into a buffer for the
                # SSL digest function.
                kv =  dec[0].getComponentByPosition(1)
                for i in range(0, len(kv), 8):
                    v = 0
                    for j in range(0, 8):
                        v = (v << 1) + kv[i+j]
                    b.append(v)
                # The comprehension turns b from a list of bytes into a buffer
                # (string) of bytes
                self.digest_bits(str().join([chr(x) for x in b]))

def generate_fedid(subj, bits=2048, log=None, dir=None, trace=sys.stderr,
        ssl_prog="/usr/bin/openssl"):
    """
    Create a new certificate and derive a fedid from it.

    The fedid and the certificate are returned as a tuple.
    """

    keypath = None
    certpath = None
    try:
        try:
            kd, keypath = tempfile.mkstemp(dir=dir, prefix="key",
                    suffix=".pem")
            cd, certpath = tempfile.mkstemp(dir=dir, prefix="cert",
                    suffix=".pem")

            cmd = [ssl_prog, "req", "-text", "-newkey", 
                    "rsa:%d" % bits, "-keyout", keypath,  "-nodes", 
                    "-subj", "/CN=%s" % subj, "-x509", "-days", "30", 
                    "-out", certpath]

            if log:
                log.debug("[generate_fedid] %s" % " ".join(cmd))

            if trace: call_out = trace
            else: 
                call_out = open("/dev/null", "w")

            rv = subprocess.call(cmd, stdout=call_out, stderr=call_out)
            log.debug("rv = %d" % rv)
            if rv == 0:
                cert = ""
                for p in (certpath, keypath):
                    f = open(p)
                    for line in f:
                        cert += line
                
                fid = fedid(file=certpath)
                return (fid, cert)
            else:
                return (None, None)
        except IOError, e:
            raise e
    finally:
        if keypath: os.remove(keypath)
        if certpath: os.remove(certpath)