Examples with Feature org.jivesoftware.smackx.disco.packet.DiscoverInfo.Feature used on opensource projects

Example 1 with Feature

use of org.jivesoftware.smackx.disco.packet.DiscoverInfo.Feature in project Smack by igniterealtime.

the class EntityCapsManager method generateVerificationString.

/**
     * Generates a XEP-115 Verification String
     * 
     * @see <a href="http://xmpp.org/extensions/xep-0115.html#ver">XEP-115
     *      Verification String</a>
     * 
     * @param discoverInfo
     * @param hash
     *            the used hash function, if null, default hash will be used
     * @return The generated verification String or null if the hash is not
     *         supported
     */
protected static CapsVersionAndHash generateVerificationString(DiscoverInfo discoverInfo, String hash) {
    if (hash == null) {
        hash = DEFAULT_HASH;
    }
    // SUPPORTED_HASHES uses the format of MessageDigest, which is uppercase, e.g. "SHA-1" instead of "sha-1"
    MessageDigest md = SUPPORTED_HASHES.get(hash.toUpperCase(Locale.US));
    if (md == null)
        return null;
    // Then transform the hash to lowercase, as this value will be put on the wire within the caps element's hash
    // attribute. I'm not sure if the standard is case insensitive here, but let's assume that even it is, there could
    // be "broken" implementation in the wild, so we *always* transform to lowercase.
    hash = hash.toLowerCase(Locale.US);
    DataForm extendedInfo = DataForm.from(discoverInfo);
    // 1. Initialize an empty string S ('sb' in this method).
    // Use StringBuilder as we don't
    StringBuilder sb = new StringBuilder();
    // need thread-safe StringBuffer
    // 2. Sort the service discovery identities by category and then by
    // type and then by xml:lang
    // (if it exists), formatted as CATEGORY '/' [TYPE] '/' [LANG] '/'
    // [NAME]. Note that each slash is included even if the LANG or
    // NAME is not included (in accordance with XEP-0030, the category and
    // type MUST be included.
    SortedSet<DiscoverInfo.Identity> sortedIdentities = new TreeSet<DiscoverInfo.Identity>();
    for (DiscoverInfo.Identity i : discoverInfo.getIdentities()) sortedIdentities.add(i);
    // followed by the '<' character.
    for (DiscoverInfo.Identity identity : sortedIdentities) {
        sb.append(identity.getCategory());
        sb.append('/');
        sb.append(identity.getType());
        sb.append('/');
        sb.append(identity.getLanguage() == null ? "" : identity.getLanguage());
        sb.append('/');
        sb.append(identity.getName() == null ? "" : identity.getName());
        sb.append('<');
    }
    // 4. Sort the supported service discovery features.
    SortedSet<String> features = new TreeSet<String>();
    for (Feature f : discoverInfo.getFeatures()) features.add(f.getVar());
    // character
    for (String f : features) {
        sb.append(f);
        sb.append('<');
    }
    // see XEP-0115 5.4 step 3.6
    if (extendedInfo != null && extendedInfo.hasHiddenFormTypeField()) {
        synchronized (extendedInfo) {
            // 6. If the service discovery information response includes
            // XEP-0128 data forms, sort the forms by the FORM_TYPE (i.e.,
            // by the XML character data of the <value/> element).
            SortedSet<FormField> fs = new TreeSet<FormField>(new Comparator<FormField>() {

                @Override
                public int compare(FormField f1, FormField f2) {
                    return f1.getVariable().compareTo(f2.getVariable());
                }
            });
            FormField ft = null;
            for (FormField f : extendedInfo.getFields()) {
                if (!f.getVariable().equals("FORM_TYPE")) {
                    fs.add(f);
                } else {
                    ft = f;
                }
            }
            // Add FORM_TYPE values
            if (ft != null) {
                formFieldValuesToCaps(ft.getValues(), sb);
            }
            // followed by the '<' character.
            for (FormField f : fs) {
                sb.append(f.getVariable());
                sb.append('<');
                formFieldValuesToCaps(f.getValues(), sb);
            }
        }
    }
    // 8. Ensure that S is encoded according to the UTF-8 encoding (RFC
    // 3269).
    // 9. Compute the verification string by hashing S using the algorithm
    // specified in the 'hash' attribute (e.g., SHA-1 as defined in RFC
    // 3174).
    // The hashed data MUST be generated with binary output and
    // encoded using Base64 as specified in Section 4 of RFC 4648
    // (note: the Base64 output MUST NOT include whitespace and MUST set
    // padding bits to zero).
    byte[] bytes;
    try {
        bytes = sb.toString().getBytes(StringUtils.UTF8);
    } catch (UnsupportedEncodingException e) {
        throw new AssertionError(e);
    }
    byte[] digest;
    synchronized (md) {
        digest = md.digest(bytes);
    }
    String version = Base64.encodeToString(digest);
    return new CapsVersionAndHash(version, hash);
}