Java example source code file (NameConstraintsExtension.java)
The NameConstraintsExtension.java Java example source code/*
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package sun.security.x509;
import java.io.IOException;
import java.io.OutputStream;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.*;
import javax.security.auth.x500.X500Principal;
import sun.security.util.*;
import sun.security.pkcs.PKCS9Attribute;
/**
* This class defines the Name Constraints Extension.
* <p>
* The name constraints extension provides permitted and excluded
* subtrees that place restrictions on names that may be included within
* a certificate issued by a given CA. Restrictions may apply to the
* subject distinguished name or subject alternative names. Any name
* matching a restriction in the excluded subtrees field is invalid
* regardless of information appearing in the permitted subtrees.
* <p>
* The ASN.1 syntax for this is:
* <pre>
* NameConstraints ::= SEQUENCE {
* permittedSubtrees [0] GeneralSubtrees OPTIONAL,
* excludedSubtrees [1] GeneralSubtrees OPTIONAL
* }
* GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
* </pre>
*
* @author Amit Kapoor
* @author Hemma Prafullchandra
* @see Extension
* @see CertAttrSet
*/
public class NameConstraintsExtension extends Extension
implements CertAttrSet<String>, Cloneable {
/**
* Identifier for this attribute, to be used with the
* get, set, delete methods of Certificate, x509 type.
*/
public static final String IDENT = "x509.info.extensions.NameConstraints";
/**
* Attribute names.
*/
public static final String NAME = "NameConstraints";
public static final String PERMITTED_SUBTREES = "permitted_subtrees";
public static final String EXCLUDED_SUBTREES = "excluded_subtrees";
// Private data members
private static final byte TAG_PERMITTED = 0;
private static final byte TAG_EXCLUDED = 1;
private GeneralSubtrees permitted = null;
private GeneralSubtrees excluded = null;
private boolean hasMin;
private boolean hasMax;
private boolean minMaxValid = false;
// Recalculate hasMin and hasMax flags.
private void calcMinMax() throws IOException {
hasMin = false;
hasMax = false;
if (excluded != null) {
for (int i = 0; i < excluded.size(); i++) {
GeneralSubtree subtree = excluded.get(i);
if (subtree.getMinimum() != 0)
hasMin = true;
if (subtree.getMaximum() != -1)
hasMax = true;
}
}
if (permitted != null) {
for (int i = 0; i < permitted.size(); i++) {
GeneralSubtree subtree = permitted.get(i);
if (subtree.getMinimum() != 0)
hasMin = true;
if (subtree.getMaximum() != -1)
hasMax = true;
}
}
minMaxValid = true;
}
// Encode this extension value.
private void encodeThis() throws IOException {
minMaxValid = false;
if (permitted == null && excluded == null) {
this.extensionValue = null;
return;
}
DerOutputStream seq = new DerOutputStream();
DerOutputStream tagged = new DerOutputStream();
if (permitted != null) {
DerOutputStream tmp = new DerOutputStream();
permitted.encode(tmp);
tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
true, TAG_PERMITTED), tmp);
}
if (excluded != null) {
DerOutputStream tmp = new DerOutputStream();
excluded.encode(tmp);
tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
true, TAG_EXCLUDED), tmp);
}
seq.write(DerValue.tag_Sequence, tagged);
this.extensionValue = seq.toByteArray();
}
/**
* The default constructor for this class. Both parameters
* are optional and can be set to null. The extension criticality
* is set to true.
*
* @param permitted the permitted GeneralSubtrees (null for optional).
* @param excluded the excluded GeneralSubtrees (null for optional).
*/
public NameConstraintsExtension(GeneralSubtrees permitted,
GeneralSubtrees excluded)
throws IOException {
this.permitted = permitted;
this.excluded = excluded;
this.extensionId = PKIXExtensions.NameConstraints_Id;
this.critical = true;
encodeThis();
}
/**
* Create the extension from the passed DER encoded value.
*
* @param critical true if the extension is to be treated as critical.
* @param value an array of DER encoded bytes of the actual value.
* @exception ClassCastException if value is not an array of bytes
* @exception IOException on error.
*/
public NameConstraintsExtension(Boolean critical, Object value)
throws IOException {
this.extensionId = PKIXExtensions.NameConstraints_Id;
this.critical = critical.booleanValue();
this.extensionValue = (byte[]) value;
DerValue val = new DerValue(this.extensionValue);
if (val.tag != DerValue.tag_Sequence) {
throw new IOException("Invalid encoding for" +
" NameConstraintsExtension.");
}
// NB. this is always encoded with the IMPLICIT tag
// The checks only make sense if we assume implicit tagging,
// with explicit tagging the form is always constructed.
// Note that all the fields in NameConstraints are defined as
// being OPTIONAL, i.e., there could be an empty SEQUENCE, resulting
// in val.data being null.
if (val.data == null)
return;
while (val.data.available() != 0) {
DerValue opt = val.data.getDerValue();
if (opt.isContextSpecific(TAG_PERMITTED) && opt.isConstructed()) {
if (permitted != null) {
throw new IOException("Duplicate permitted " +
"GeneralSubtrees in NameConstraintsExtension.");
}
opt.resetTag(DerValue.tag_Sequence);
permitted = new GeneralSubtrees(opt);
} else if (opt.isContextSpecific(TAG_EXCLUDED) &&
opt.isConstructed()) {
if (excluded != null) {
throw new IOException("Duplicate excluded " +
"GeneralSubtrees in NameConstraintsExtension.");
}
opt.resetTag(DerValue.tag_Sequence);
excluded = new GeneralSubtrees(opt);
} else
throw new IOException("Invalid encoding of " +
"NameConstraintsExtension.");
}
minMaxValid = false;
}
/**
* Return the printable string.
*/
public String toString() {
return (super.toString() + "NameConstraints: [" +
((permitted == null) ? "" :
("\n Permitted:" + permitted.toString())) +
((excluded == null) ? "" :
("\n Excluded:" + excluded.toString()))
+ " ]\n");
}
/**
* Write the extension to the OutputStream.
*
* @param out the OutputStream to write the extension to.
* @exception IOException on encoding errors.
*/
public void encode(OutputStream out) throws IOException {
DerOutputStream tmp = new DerOutputStream();
if (this.extensionValue == null) {
this.extensionId = PKIXExtensions.NameConstraints_Id;
this.critical = true;
encodeThis();
}
super.encode(tmp);
out.write(tmp.toByteArray());
}
/**
* Set the attribute value.
*/
public void set(String name, Object obj) throws IOException {
if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
if (!(obj instanceof GeneralSubtrees)) {
throw new IOException("Attribute value should be"
+ " of type GeneralSubtrees.");
}
permitted = (GeneralSubtrees)obj;
} else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
if (!(obj instanceof GeneralSubtrees)) {
throw new IOException("Attribute value should be "
+ "of type GeneralSubtrees.");
}
excluded = (GeneralSubtrees)obj;
} else {
throw new IOException("Attribute name not recognized by " +
"CertAttrSet:NameConstraintsExtension.");
}
encodeThis();
}
/**
* Get the attribute value.
*/
public GeneralSubtrees get(String name) throws IOException {
if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
return (permitted);
} else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
return (excluded);
} else {
throw new IOException("Attribute name not recognized by " +
"CertAttrSet:NameConstraintsExtension.");
}
}
/**
* Delete the attribute value.
*/
public void delete(String name) throws IOException {
if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
permitted = null;
} else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
excluded = null;
} else {
throw new IOException("Attribute name not recognized by " +
"CertAttrSet:NameConstraintsExtension.");
}
encodeThis();
}
/**
* Return an enumeration of names of attributes existing within this
* attribute.
*/
public Enumeration<String> getElements() {
AttributeNameEnumeration elements = new AttributeNameEnumeration();
elements.addElement(PERMITTED_SUBTREES);
elements.addElement(EXCLUDED_SUBTREES);
return (elements.elements());
}
/**
* Return the name of this attribute.
*/
public String getName() {
return (NAME);
}
/**
* Merge additional name constraints with existing ones.
* This function is used in certification path processing
* to accumulate name constraints from successive certificates
* in the path. Note that NameConstraints can never be
* expanded by a merge, just remain constant or become more
* limiting.
* <p>
* IETF RFC2459 specifies the processing of Name Constraints as
* follows:
* <p>
* (j) If permittedSubtrees is present in the certificate, set the
* constrained subtrees state variable to the intersection of its
* previous value and the value indicated in the extension field.
* <p>
* (k) If excludedSubtrees is present in the certificate, set the
* excluded subtrees state variable to the union of its previous
* value and the value indicated in the extension field.
* <p>
* @param newConstraints additional NameConstraints to be applied
* @throws IOException on error
*/
public void merge(NameConstraintsExtension newConstraints)
throws IOException {
if (newConstraints == null) {
// absence of any explicit constraints implies unconstrained
return;
}
/*
* If excludedSubtrees is present in the certificate, set the
* excluded subtrees state variable to the union of its previous
* value and the value indicated in the extension field.
*/
GeneralSubtrees newExcluded = newConstraints.get(EXCLUDED_SUBTREES);
if (excluded == null) {
excluded = (newExcluded != null) ?
(GeneralSubtrees)newExcluded.clone() : null;
} else {
if (newExcluded != null) {
// Merge new excluded with current excluded (union)
excluded.union(newExcluded);
}
}
/*
* If permittedSubtrees is present in the certificate, set the
* constrained subtrees state variable to the intersection of its
* previous value and the value indicated in the extension field.
*/
GeneralSubtrees newPermitted = newConstraints.get(PERMITTED_SUBTREES);
if (permitted == null) {
permitted = (newPermitted != null) ?
(GeneralSubtrees)newPermitted.clone() : null;
} else {
if (newPermitted != null) {
// Merge new permitted with current permitted (intersection)
newExcluded = permitted.intersect(newPermitted);
// Merge new excluded subtrees to current excluded (union)
if (newExcluded != null) {
if (excluded != null) {
excluded.union(newExcluded);
} else {
excluded = (GeneralSubtrees)newExcluded.clone();
}
}
}
}
// Optional optimization: remove permitted subtrees that are excluded.
// This is not necessary for algorithm correctness, but it makes
// subsequent operations on the NameConstraints faster and require
// less space.
if (permitted != null) {
permitted.reduce(excluded);
}
// The NameConstraints have been changed, so re-encode them. Methods in
// this class assume that the encodings have already been done.
encodeThis();
}
/**
* check whether a certificate conforms to these NameConstraints.
* This involves verifying that the subject name and subjectAltName
* extension (critical or noncritical) is consistent with the permitted
* subtrees state variables. Also verify that the subject name and
* subjectAltName extension (critical or noncritical) is consistent with
* the excluded subtrees state variables.
*
* @param cert X509Certificate to be verified
* @returns true if certificate verifies successfully
* @throws IOException on error
*/
public boolean verify(X509Certificate cert) throws IOException {
if (cert == null) {
throw new IOException("Certificate is null");
}
// Calculate hasMin and hasMax booleans (if necessary)
if (!minMaxValid) {
calcMinMax();
}
if (hasMin) {
throw new IOException("Non-zero minimum BaseDistance in"
+ " name constraints not supported");
}
if (hasMax) {
throw new IOException("Maximum BaseDistance in"
+ " name constraints not supported");
}
X500Principal subjectPrincipal = cert.getSubjectX500Principal();
X500Name subject = X500Name.asX500Name(subjectPrincipal);
if (subject.isEmpty() == false) {
if (verify(subject) == false) {
return false;
}
}
GeneralNames altNames = null;
// extract altNames
try {
// extract extensions, if any, from certInfo
// following returns null if certificate contains no extensions
X509CertImpl certImpl = X509CertImpl.toImpl(cert);
SubjectAlternativeNameExtension altNameExt =
certImpl.getSubjectAlternativeNameExtension();
if (altNameExt != null) {
// extract altNames from extension; this call does not
// return an IOException on null altnames
altNames = altNameExt.get(
SubjectAlternativeNameExtension.SUBJECT_NAME);
}
} catch (CertificateException ce) {
throw new IOException("Unable to extract extensions from " +
"certificate: " + ce.getMessage());
}
// If there are no subjectAlternativeNames, perform the special-case
// check where if the subjectName contains any EMAILADDRESS
// attributes, they must be checked against RFC822 constraints.
// If that passes, we're fine.
if (altNames == null) {
return verifyRFC822SpecialCase(subject);
}
// verify each subjectAltName
for (int i = 0; i < altNames.size(); i++) {
GeneralNameInterface altGNI = altNames.get(i).getName();
if (!verify(altGNI)) {
return false;
}
}
// All tests passed.
return true;
}
/**
* check whether a name conforms to these NameConstraints.
* This involves verifying that the name is consistent with the
* permitted and excluded subtrees variables.
*
* @param name GeneralNameInterface name to be verified
* @returns true if certificate verifies successfully
* @throws IOException on error
*/
public boolean verify(GeneralNameInterface name) throws IOException {
if (name == null) {
throw new IOException("name is null");
}
// Verify that the name is consistent with the excluded subtrees
if (excluded != null && excluded.size() > 0) {
for (int i = 0; i < excluded.size(); i++) {
GeneralSubtree gs = excluded.get(i);
if (gs == null)
continue;
GeneralName gn = gs.getName();
if (gn == null)
continue;
GeneralNameInterface exName = gn.getName();
if (exName == null)
continue;
// if name matches or narrows any excluded subtree,
// return false
switch (exName.constrains(name)) {
case GeneralNameInterface.NAME_DIFF_TYPE:
case GeneralNameInterface.NAME_WIDENS: // name widens excluded
case GeneralNameInterface.NAME_SAME_TYPE:
break;
case GeneralNameInterface.NAME_MATCH:
case GeneralNameInterface.NAME_NARROWS: // subject name excluded
return false;
}
}
}
// Verify that the name is consistent with the permitted subtrees
if (permitted != null && permitted.size() > 0) {
boolean sameType = false;
for (int i = 0; i < permitted.size(); i++) {
GeneralSubtree gs = permitted.get(i);
if (gs == null)
continue;
GeneralName gn = gs.getName();
if (gn == null)
continue;
GeneralNameInterface perName = gn.getName();
if (perName == null)
continue;
// if Name matches any type in permitted,
// and Name does not match or narrow some permitted subtree,
// return false
switch (perName.constrains(name)) {
case GeneralNameInterface.NAME_DIFF_TYPE:
continue; // continue checking other permitted names
case GeneralNameInterface.NAME_WIDENS: // name widens permitted
case GeneralNameInterface.NAME_SAME_TYPE:
sameType = true;
continue; // continue to look for a match or narrow
case GeneralNameInterface.NAME_MATCH:
case GeneralNameInterface.NAME_NARROWS:
// name narrows permitted
return true; // name is definitely OK, so break out of loop
}
}
if (sameType) {
return false;
}
}
return true;
}
/**
* Perform the RFC 822 special case check. We have a certificate
* that does not contain any subject alternative names. Check that
* any EMAILADDRESS attributes in its subject name conform to these
* NameConstraints.
*
* @param subject the certificate's subject name
* @returns true if certificate verifies successfully
* @throws IOException on error
*/
public boolean verifyRFC822SpecialCase(X500Name subject) throws IOException {
for (AVA ava : subject.allAvas()) {
ObjectIdentifier attrOID = ava.getObjectIdentifier();
if (attrOID.equals((Object)PKCS9Attribute.EMAIL_ADDRESS_OID)) {
String attrValue = ava.getValueString();
if (attrValue != null) {
RFC822Name emailName;
try {
emailName = new RFC822Name(attrValue);
} catch (IOException ioe) {
continue;
}
if (!verify(emailName)) {
return(false);
}
}
}
}
return true;
}
/**
* Clone all objects that may be modified during certificate validation.
*/
public Object clone() {
try {
NameConstraintsExtension newNCE =
(NameConstraintsExtension) super.clone();
if (permitted != null) {
newNCE.permitted = (GeneralSubtrees) permitted.clone();
}
if (excluded != null) {
newNCE.excluded = (GeneralSubtrees) excluded.clone();
}
return newNCE;
} catch (CloneNotSupportedException cnsee) {
throw new RuntimeException("CloneNotSupportedException while " +
"cloning NameConstraintsException. This should never happen.");
}
}
}
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