"""
Imported from pyasn1 project:

Copyright (c) 2005-2009 Ilya Etingof <ilya@glas.net>, all rights reserved.

THIS SOFTWARE IS NOT FAULT TOLERANT AND SHOULD NOT BE USED IN ANY SITUATION
ENDANGERING HUMAN LIFE OR PROPERTY.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice,
    this list of conditions and the following disclaimer.

  * Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

  * The name of the authors may not be used to endorse or promote products
    derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""

"""
Enhancements released under IPA GPLv2 only license
"""

# Read ASN.1/PEM X.509 certificates on stdin, parse each into plain text,
# then build substrate from it
import sys, string, base64
from pyasn1.type import tag,namedtype,namedval,univ,constraint,char,useful
from pyasn1.codec.der import decoder, encoder
from pyasn1 import error

# Would be autogenerated from ASN.1 source by a ASN.1 parser
# X.509 spec (rfc2459)

PEM = 0
DER = 1

# Common OIDs found in a subject
oidtable = { "2.5.4.3":  "CN",
             "2.5.4.6":  "C",
             "2.5.4.7":  "L",
             "2.5.4.8":  "ST",
             "2.5.4.10": "O",
             "2.5.4.11": "OU",
             "1.2.840.113549.1.9.1": "E",
             "0.9.2342.19200300.100.1.25": "DC",
           }

MAX = 64  # XXX ?

class DirectoryString(univ.Choice):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('teletexString', char.TeletexString().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
        namedtype.NamedType('printableString', char.PrintableString().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
        namedtype.NamedType('universalString', char.UniversalString().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
        namedtype.NamedType('utf8String', char.UTF8String().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
        namedtype.NamedType('bmpString', char.BMPString().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
        namedtype.NamedType('ia5String', char.IA5String().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, MAX))) # hm, this should not be here!? XXX
        )

class AttributeValue(DirectoryString): pass

class AttributeType(univ.ObjectIdentifier): pass

class AttributeTypeAndValue(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('type', AttributeType()),
        namedtype.NamedType('value', AttributeValue())
        )

class RelativeDistinguishedName(univ.SetOf):
    componentType = AttributeTypeAndValue()

class RDNSequence(univ.SequenceOf):
    componentType = RelativeDistinguishedName()

class Name(univ.Choice):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('', RDNSequence())
        )

    def get_components(self):
        components = self.getComponentByPosition(0)
        complist = []
        for idx in range(len(components)):
            attrandvalue = components[idx].getComponentByPosition(0)
            oid = attrandvalue.getComponentByPosition(0)
            # FIXME, should handle any string type
            value = attrandvalue.getComponentByPosition(1).getComponentByType(char.PrintableString.tagSet)
            if value is None:
                value = attrandvalue.getComponentByPosition(1).getComponentByType(char.UTF8String.tagSet)
                if value is None:
                    value = attrandvalue.getComponentByPosition(1).getComponentByType(char.IA5String.tagSet)
            vout = value.prettyOut(value).decode('utf-8')
            oidout = oid.prettyOut(oid).decode('utf-8')
            c = ((oidtable.get(oidout, oidout), vout))
            complist.append(c)

        return tuple(complist)

class AlgorithmIdentifier(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('algorithm', univ.ObjectIdentifier()),
        namedtype.OptionalNamedType('parameters', univ.Null())
        # XXX syntax screwed?
#        namedtype.OptionalNamedType('parameters', univ.ObjectIdentifier())
        )

class Extension(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('extnID', univ.ObjectIdentifier()),
        namedtype.DefaultedNamedType('critical', univ.Boolean('False')),
        namedtype.NamedType('extnValue', univ.OctetString())
        )

class Extensions(univ.SequenceOf):
    componentType = Extension()
    sizeSpec = univ.SequenceOf.sizeSpec + constraint.ValueSizeConstraint(1, MAX)

class SubjectPublicKeyInfo(univ.Sequence):
     componentType = namedtype.NamedTypes(
         namedtype.NamedType('algorithm', AlgorithmIdentifier()),
         namedtype.NamedType('subjectPublicKey', univ.BitString())
         )

class UniqueIdentifier(univ.BitString): pass

class Time(univ.Choice):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('utcTime', useful.UTCTime()),
        namedtype.NamedType('generalTime', useful.GeneralizedTime())
        )

class Validity(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('notBefore', Time()),
        namedtype.NamedType('notAfter', Time())
        )

class CertificateSerialNumber(univ.Integer): pass

class Version(univ.Integer):
    namedValues = namedval.NamedValues(
        ('v1', 0), ('v2', 1), ('v3', 2)
        )

class TBSCertificate(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.DefaultedNamedType('version', Version('v1', tagSet=Version.tagSet.tagExplicitly(tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 0)))),
        namedtype.NamedType('serialNumber', CertificateSerialNumber()),
        namedtype.NamedType('signature', AlgorithmIdentifier()),
        namedtype.NamedType('issuer', Name()),
        namedtype.NamedType('validity', Validity()),
        namedtype.NamedType('subject', Name()),
        namedtype.NamedType('subjectPublicKeyInfo', SubjectPublicKeyInfo()),
        namedtype.OptionalNamedType('issuerUniqueID', UniqueIdentifier().subtype(implicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 1))),
        namedtype.OptionalNamedType('subjectUniqueID', UniqueIdentifier().subtype(implicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 2))),
        namedtype.OptionalNamedType('extensions', Extensions().subtype(explicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 3)))
        )

class Certificate(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('tbsCertificate', TBSCertificate()),
        namedtype.NamedType('signatureAlgorithm', AlgorithmIdentifier()),
        namedtype.NamedType('signatureValue', univ.BitString())
        )

    def get_version(self):
        info = self.getComponentByName('tbsCertificate')
        version = info.getComponentByName('version')
        return version._value

    def get_subject(self):
        info = self.getComponentByName('tbsCertificate')
        return info.getComponentByName('subject')

    def get_serial_number(self):
        'return the serial number as a Python long object'
        info = self.getComponentByName('tbsCertificate')
        return long(info.getComponentByName('serialNumber'))

# end of ASN.1 data structures

def strip_header(pem):
    """
    Remove the header and footer from a certificate.
    """
    s = pem.find("-----BEGIN CERTIFICATE-----")
    if s >= 0:
        e = pem.find("-----END CERTIFICATE-----")
        pem = pem[s+27:e]

    return pem


def load_certificate(data, type=PEM):
    """
    Given a base64-encoded certificate, with or without the
    header/footer, return a request object.
    """
    if (type == PEM):
        data = strip_header(data)
        data = base64.b64decode(data)

    return decoder.decode(data, asn1Spec=Certificate())[0]

def get_subject_components(certificate, type=PEM):
    """
    Load an X509.3 certificate and get the subject.

    Return a tuple of a certificate subject.
       (('CN', u'www.example.com'), ('O', u'IPA'))
    """

    x509cert = load_certificate(certificate, type)
    return x509cert.get_subject().get_components()

def get_serial_number(certificate, type=PEM):
    """
    Return the serial number of a certificate as a Python long object.
    """
    x509cert = load_certificate(certificate, type)
    return x509cert.get_serial_number()

if __name__ == '__main__':
    certType = Certificate()

    # Read PEM certs from stdin and print them out in plain text

    stSpam, stHam, stDump = 0, 1, 2
    state = stSpam
    certCnt = 0

    for certLine in sys.stdin.readlines():
        certLine = string.strip(certLine)
        if state == stSpam:
            if state == stSpam:
                if certLine == '-----BEGIN CERTIFICATE-----':
                    certLines = []
                    state = stHam
                    continue
        if state == stHam:
            if certLine == '-----END CERTIFICATE-----':
                state = stDump
            else:
                certLines.append(certLine)
        if state == stDump:
            substrate = ''
            for certLine in certLines:
                substrate = substrate + base64.b64decode(certLine)

            cert = decoder.decode(substrate, asn1Spec=certType)[0]
            print cert.prettyPrint()

            assert encoder.encode(cert) == substrate, 'cert recode fails'

            certCnt = certCnt + 1
            state = stSpam

    print '*** %s PEM cert(s) de/serialized' % certCnt