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CodeSource.javaAPI DocAndroid 1.5 API25054Wed May 06 22:41:06 BST 2009java.security

CodeSource

public class CodeSource extends Object implements Serializable
{@code CodeSource} encapsulates the location from where code is loaded and the certificates that were used to verify that code. This information is used by {@code SecureClassLoader} to define protection domains for loaded classes.
see
SecureClassLoader
see
ProtectionDomain
since
Android 1.0

Fields Summary
private static final long
serialVersionUID
private URL
location
private transient Certificate[]
certs
private transient CodeSigner[]
signers
private transient SocketPermission
sp
private transient CertificateFactory
factory
Constructors Summary
public CodeSource(URL location, Certificate[] certs)
Constructs a new instance of {@code CodeSource} with the specified {@code URL} and the {@code Certificate}s.

param
location the {@code URL} representing the location from where code is loaded, maybe {@code null}.
param
certs the {@code Certificate} used to verify the code, loaded from the specified {@code location}, maybe {@code null}.
since
Android 1.0


                                                                                                            
         
        this.location = location;
        if (certs != null) {
            this.certs = new Certificate[certs.length];
            System.arraycopy(certs, 0, this.certs, 0, certs.length);
        }
public CodeSource(URL location, CodeSigner[] signers)
Constructs a new instance of {@code CodeSource} with the specified {@code URL} and the {@code CodeSigner}s.

param
location the {@code URL} representing the location from where code is loaded, maybe {@code null}.
param
signers the {@code CodeSigner}s of the code, loaded from the specified {@code location}. Maybe {@code null}.
since
Android 1.0

        this.location = location;
        if (signers != null) {
            this.signers = new CodeSigner[signers.length];
            System.arraycopy(signers, 0, this.signers, 0, signers.length);
        }
Methods Summary
public booleanequals(java.lang.Object obj)
Compares the specified object with this {@code CodeSource} for equality. Returns {@code true} if the specified object is also an instance of {@code CodeSource}, points to the same {@code URL} location and the two code sources encapsulate the same {@code Certificate}s. The order of the {@code Certificate}s is ignored by this method.

param
obj object to be compared for equality with this {@code CodeSource}.
return
{@code true} if the specified object is equal to this {@code CodeSource}, otherwise {@code false}.
since
Android 1.0

        if (obj == this) {
            return true;
        }

        if (!(obj instanceof CodeSource)) {
            return false;
        }

        CodeSource that = (CodeSource) obj;

        if (this.location != null) {
            if (that.location == null) {
                return false;
            }
            if (!this.location.equals(that.location)) {
                return false;
            }
        } else if (that.location != null) {
            return false;
        }

        // do not use this.certs, as we also need to take care about 
        // CodeSigners' certificates
        Certificate[] thizCerts = getCertificatesNoClone();
        Certificate[] thatCerts = that.getCertificatesNoClone();
        if (!PolicyUtils.matchSubset(thizCerts, thatCerts)) {
            return false;
        }
        if (!PolicyUtils.matchSubset(thatCerts, thizCerts)) {
            return false;
        }
        return true;
public final java.security.cert.Certificate[]getCertificates()
Returns the certificates of this {@code CodeSource}. If the {@link #CodeSource(URL, CodeSigner[])} constructor was used to create this instance, the certificates are obtained from the supplied signers.

External modifications of the returned {@code Certificate[]} has no impact on this {@code CodeSource}.

return
the certificates of this {@code CodeSource} or {@code null} if there is none.
since
Android 1.0

        getCertificatesNoClone();
        if (certs == null) {
            return null;
        }
        Certificate[] tmp = new Certificate[certs.length];
        System.arraycopy(certs, 0, tmp, 0, certs.length);
        return tmp;
private java.security.cert.Certificate[]getCertificatesNoClone()

        if (certs != null) {
            return certs;
        }

        if (signers == null) {
            return null;
        }
        // Extract Certificates from the CodeSigner-s
        ArrayList<Certificate> v = new ArrayList<Certificate>();
        for (int i = 0; i < signers.length; i++) {
            v.addAll(signers[i].getSignerCertPath().getCertificates());
        }

        certs = v.toArray(new Certificate[v.size()]);
        return certs;
public final java.security.CodeSigner[]getCodeSigners()
Returns the {@code CodeSigner}s of this {@code CodeSource}. If the {@link #CodeSource(URL, Certificate[])} constructor was used to create this instance, the signers are obtained from the supplied certificates. Only X.509 certificates are analyzed.

return
the signers of this {@code CodeSource}, or {@code null} if there is none.
since
Android 1.0

        if (signers != null) {
            CodeSigner[] tmp = new CodeSigner[signers.length];
            System.arraycopy(signers, 0, tmp, 0, tmp.length);
            return tmp;
        }
        if(certs == null || factory != null){
            // factory != null means we've done this exercise already.
            return null;
        }

        X500Principal prevIssuer = null;
        ArrayList<Certificate> list = new ArrayList<Certificate>(certs.length);
        ArrayList<CodeSigner> asigners = new ArrayList<CodeSigner>();

        // The presumption is that the chains of certificates are placed
        // according to the CertPath agreement:
        //
        // the lowest certs first; the CAs are at the last
        //
        // So the following loop scans trough the certs and checks
        // that every next certificate is an Issuer of the previous one. 
        // Any certificate that is not an Issuer of the previous one starts a 
        // new chain (== a new CertPath) 

        for (int i = 0; i < certs.length; i++) {
            if (!(certs[i] instanceof X509Certificate)) {
                // Only X509Certificate-s are taken into account - see API spec.
                continue;
            }
            X509Certificate x509 = (X509Certificate) certs[i];
            if (prevIssuer == null) {
                // start a very first chain
                prevIssuer = x509.getIssuerX500Principal();
                list.add(x509);
            } else {
                X500Principal subj = x509.getSubjectX500Principal();
                if (!prevIssuer.equals(subj)) {
                    // Ok, this ends the previous chain, 
                    // so transform this one into CertPath ...
                    CertPath cpath = makeCertPath(list);
                    if (cpath != null) {
                        asigners.add(new CodeSigner(cpath, null));
                    }
                    // ... and start a new one
                    list.clear();
                }// else { it's still the same chain }
                prevIssuer = x509.getSubjectX500Principal();
                list.add(x509);
            }
        }
        if (!list.isEmpty()) {
            CertPath cpath = makeCertPath(list);
            if (cpath != null) {
                asigners.add(new CodeSigner(cpath, null));
            }
        }
        if (asigners.isEmpty()) {
            // 'signers' is 'null' already
            return null;
        }
        signers = new CodeSigner[asigners.size()];
        asigners.toArray(signers);
        CodeSigner[] tmp = new CodeSigner[asigners.size()];
        System.arraycopy(signers, 0, tmp, 0, tmp.length);
        return tmp;
public final java.net.URLgetLocation()
Returns the location of this {@code CodeSource}.

return
the location of this {@code CodeSource}, maybe {@code null}.
since
Android 1.0

        return location;
public inthashCode()
Returns the hash code value for this {@code CodeSource}. Returns the same hash code for {@code CodeSource}s that are equal to each other as required by the general contract of {@link Object#hashCode}.

return
the hash code value for this {@code CodeSource}.
see
Object#equals(Object)
see
CodeSource#equals(Object)
since
Android 1.0

        //
        // hashCode() is undocumented there. Should we also use certs[i] to
        // compute the hash ?
        // for now, I don't take certs[] into account
        return location == null ? 0 : location.hashCode();
public booleanimplies(java.security.CodeSource cs)
Indicates whether the specified code source is implied by this {@code CodeSource}. Returns {@code true} if all of the following conditions are {@code true}, otherwise {@code false}:

  • {@code cs} is not {@code null}
  • if this {@code CodeSource} has associated certificates, all certificates are present in {@code cs}. The certificates are extracted from the signers if signers are present.
  • if this {@code CodeSource}'s location is not {@code null}, the following conditions are checked
    • this {@code CodeSource}'s location is not {@code null}
    • this {@code CodeSource}'s location protocol is equal to {@code cs}'s location protocol
    • if this {@code CodeSource}'s location host is not {@code null}, the following conditions are checked
      • {@code cs}'s host is not {@code null}
      • the {@link SocketPermission} of this {@code CodeSource}'s location host implies the {@code SocketPermission} of {@code cs}'s location host
    • if this {@code CodeSource}'s location port != -1 the port of {@code cs}'s location is equal to this {@code CodeSource}'s location port
    • this {@code CodeSource}'s location file matches {@code cs}'s file whereas special wildcard matching applies as described below
    • this {@code CodeSource}'s location reference is equal to to {@code cs}'s location reference

Note: If this {@code CodeSource} has a {@code null} location and not any certificates, this method returns {@code true}.

Matching rules for the {@code CodeSource}'s location file:

  • if this {@code CodeSource}'s location file ends with {@code "/-"}, then {@code cs}'s file must start with {@code CodeSource}'s location file (exclusive the trailing '-')
  • if this {@code CodeSource}'s location file ends with {@code "/*"}, then {@code cs}'s file must start with {@code CodeSource}'s location file (exclusive the trailing '*') and must not have any further '/'
  • if this {@code CodeSource}'s location file ends with {@code "/"}, then {@code cs}'s file must start with {@code CodeSource}'s location file
  • if this {@code CodeSource}'s location file does not end with {@code "/"}, then {@code cs}'s file must start with {@code CodeSource}'s location file with the '/' appended to it.
Examples for locations that imply the location "http://code.google.com/android/security.apk": 
http:
http://*/android/*
http://*.google.com/android/*
http://code.google.com/android/-
http://code.google.com/android/security.apk

param
cs the code source to check.
return
{@code true} if the argument code source is implied by this {@code CodeSource}, otherwise {@code false}.
since
Android 1.0

        //
        // Here, javadoc:N refers to the appropriate item in the API spec for 
        // the CodeSource.implies()
        // The info was taken from the 1.5 final API spec

        // javadoc:1
        if (cs == null) {
            return false;
        }

        // javadoc:2
        // with a comment: the javadoc says only about certificates and does 
        // not explicitly mention CodeSigners' certs.
        // It seems more convenient to use getCerts() to get the real 
        // certificates - with a certificates got form the signers
        Certificate[] thizCerts = getCertificatesNoClone();
        if (thizCerts != null) {
            Certificate[] thatCerts = cs.getCertificatesNoClone();
            if (thatCerts == null
                    || !PolicyUtils.matchSubset(thizCerts, thatCerts)) {
                return false;
            }
        }

        // javadoc:3
        if (this.location != null) {
            //javadoc:3.1
            if (cs.location == null) {
                return false;
            }
            //javadoc:3.2
            if (this.location.equals(cs.location)) {
                return true;
            }
            //javadoc:3.3
            if (!this.location.getProtocol().equals(cs.location.getProtocol())) {
                return false;
            }
            //javadoc:3.4
            String thisHost = this.location.getHost();
            if (thisHost != null) {
                String thatHost = cs.location.getHost();
                if (thatHost == null) {
                    return false;
                }

                // 1. According to the spec, an empty string will be considered 
                // as "localhost" in the SocketPermission
                // 2. 'file://' URLs will have an empty getHost()
                // so, let's make a special processing of localhost-s, I do 
                // believe this'll improve performance of file:// code sources 

                //
                // Don't have to evaluate both the boolean-s each time.
                // It's better to evaluate them directly under if() statement.
                // 
                // boolean thisIsLocalHost = thisHost.length() == 0 || "localhost".equals(thisHost);
                // boolean thatIsLocalHost = thatHost.length() == 0 || "localhost".equals(thatHost);
                // 
                // if( !(thisIsLocalHost && thatIsLocalHost) &&
                // !thisHost.equals(thatHost)) {

                if (!((thisHost.length() == 0 || "localhost".equals(thisHost)) && (thatHost //$NON-NLS-1$
                        .length() == 0 || "localhost".equals(thatHost))) //$NON-NLS-1$
                        && !thisHost.equals(thatHost)) {

                    // Obvious, but very slow way....
                    // 
                    // SocketPermission thisPerm = new SocketPermission(
                    //          this.location.getHost(), "resolve");
                    // SocketPermission thatPerm = new SocketPermission(
                    //          cs.location.getHost(), "resolve");
                    // if (!thisPerm.implies(thatPerm)) { 
                    //      return false;
                    // }
                    //
                    // let's cache it: 

                    if (this.sp == null) {
                        this.sp = new SocketPermission(thisHost, "resolve"); //$NON-NLS-1$
                    }

                    if (cs.sp == null) {
                        cs.sp = new SocketPermission(thatHost, "resolve"); //$NON-NLS-1$
                    }

                    if (!this.sp.implies(cs.sp)) {
                        return false;
                    }
                } // if( ! this.location.getHost().equals(cs.location.getHost())
            } // if (this.location.getHost() != null)

            //javadoc:3.5
            if (this.location.getPort() != -1) {
                if (this.location.getPort() != cs.location.getPort()) {
                    return false;
                }
            }

            //javadoc:3.6
            String thisFile = this.location.getFile();
            String thatFile = cs.location.getFile();

            if (thisFile.endsWith("/-")) { //javadoc:3.6."/-" //$NON-NLS-1$
                if (!thatFile.startsWith(thisFile.substring(0, thisFile
                        .length() - 2))) {
                    return false;
                }
            } else if (thisFile.endsWith("/*")) { //javadoc:3.6."/*" //$NON-NLS-1$
                if (!thatFile.startsWith(thisFile.substring(0, thisFile
                        .length() - 2))) {
                    return false;
                }
                // no further separators(s) allowed
                if (thatFile.indexOf("/", thisFile.length() - 1) != -1) { //$NON-NLS-1$
                    return false;
                }
            } else {
                // javadoc:3.6."/"
                if (!thisFile.equals(thatFile)) {
                    if (!thisFile.endsWith("/")) { //$NON-NLS-1$
                        if (!thatFile.equals(thisFile + "/")) { //$NON-NLS-1$
                            return false;
                        }
                    } else {
                        return false;
                    }
                }
            }

            //javadoc:3.7
            if (this.location.getRef() != null) {
                if (!this.location.getRef().equals(cs.location.getRef())) {
                    return false;
                }
            }
            // ok, every check was made, and they all were successful. 
            // it's ok to return true.
        } // if this.location != null

        // javadoc: a note about CodeSource with null location and null Certs 
        // is applicable here 
        return true;
private java.security.cert.CertPathmakeCertPath(java.util.List list)

        if (factory == null) {
            try {
                factory = CertificateFactory.getInstance("X.509"); //$NON-NLS-1$
            } catch (CertificateException ex) {
                //? throw new Error("X.509 is a 'must be'", ex);
                return null;
            }
        }
        try {
            return factory.generateCertPath(list);
        } catch (CertificateException ex) {
            // ignore(ex)
        }
        return null;
private voidreadObject(java.io.ObjectInputStream ois)

        
        ois.defaultReadObject();
        
        int certsCount = ois.readInt();
        certs = null;
        if (certsCount != 0) {
            certs = new Certificate[certsCount];
            for (int i = 0; i < certsCount; i++) {
                String type = ois.readUTF();
                CertificateFactory factory;
                try {
                    factory = CertificateFactory.getInstance(type);
                } catch (CertificateException ex) {
                    throw new ClassNotFoundException(
                            Messages.getString("security.19", type), //$NON-NLS-1$
                            ex);
                }
                int dataLen = ois.readInt();
                byte[] data = new byte[dataLen];
                ois.readFully(data);
                ByteArrayInputStream bais = new ByteArrayInputStream(data);
                try {
                    certs[i] = factory.generateCertificate(bais);
                } catch (CertificateException ex) {
                    throw (IOException) new IOException(
                            Messages.getString("security.1A")).initCause(ex); //$NON-NLS-1$
                }
            }
        }
        try {
            signers = (CodeSigner[]) ois.readObject();
        } catch (OptionalDataException ex) {
            if (!ex.eof) {
                throw ex;
            }
            // no signers (ex.eof==true <= no data left) is allowed
        }
public java.lang.StringtoString()
Returns a string containing a concise, human-readable description of the this {@code CodeSource} including its location, its certificates and its signers.

return
a printable representation for this {@code CodeSource}.
since
Android 1.0

        StringBuilder buf = new StringBuilder();
        buf.append("CodeSource, url="); //$NON-NLS-1$
        buf.append(location == null ? "<null>" : location.toString()); //$NON-NLS-1$

        if (certs == null) {
            buf.append(", <no certificates>"); //$NON-NLS-1$
        } else {
            buf.append("\nCertificates [\n"); //$NON-NLS-1$
            for (int i = 0; i < certs.length; i++) {
                buf.append(i + 1).append(") ").append(certs[i]).append("\n"); //$NON-NLS-1$ //$NON-NLS-2$
            }
            buf.append("]\n"); //$NON-NLS-1$
        }
        if (signers != null) {
            buf.append("\nCodeSigners [\n"); //$NON-NLS-1$
            for (int i = 0; i < signers.length; i++) {
                buf.append(i + 1).append(") ").append(signers[i]).append("\n"); //$NON-NLS-1$ //$NON-NLS-2$
            }
            buf.append("]\n"); //$NON-NLS-1$
        }
        return buf.toString();
private voidwriteObject(java.io.ObjectOutputStream oos)


        oos.defaultWriteObject();

        if (certs == null || certs.length == 0) {
            oos.writeInt(0);
        } else {
            oos.writeInt(certs.length);
            for (int i = 0; i < certs.length; i++) {
                try {
                    oos.writeUTF(certs[i].getType());
                    byte[] data = certs[i].getEncoded();
                    // hope there are no certificates with 'data==null'
                    oos.writeInt(data.length);
                    oos.write(data);
                } catch (CertificateEncodingException ex) {
                    throw (IOException) new IOException(
                            Messages.getString("security.18")).initCause(ex); //$NON-NLS-1$
                }
            }
        }
        if (signers != null && signers.length != 0) {
            oos.writeObject(signers);
        }