1package eu.siacs.conversations.crypto;
2
3import android.os.Build;
4import android.util.Log;
5import android.util.Pair;
6
7import org.bouncycastle.asn1.ASN1Primitive;
8import org.bouncycastle.asn1.DERIA5String;
9import org.bouncycastle.asn1.DERTaggedObject;
10import org.bouncycastle.asn1.DERUTF8String;
11import org.bouncycastle.asn1.DLSequence;
12import org.bouncycastle.asn1.x500.RDN;
13import org.bouncycastle.asn1.x500.X500Name;
14import org.bouncycastle.asn1.x500.style.BCStyle;
15import org.bouncycastle.asn1.x500.style.IETFUtils;
16import org.bouncycastle.cert.jcajce.JcaX509CertificateHolder;
17
18import java.io.IOException;
19import java.net.IDN;
20import java.security.cert.Certificate;
21import java.security.cert.CertificateEncodingException;
22import java.security.cert.X509Certificate;
23import java.util.ArrayList;
24import java.util.Collection;
25import java.util.List;
26import java.util.Locale;
27
28import javax.net.ssl.SSLSession;
29
30public class XmppDomainVerifier implements DomainHostnameVerifier {
31
32 private static final String LOGTAG = "XmppDomainVerifier";
33
34 private static final String SRV_NAME = "1.3.6.1.5.5.7.8.7";
35 private static final String XMPP_ADDR = "1.3.6.1.5.5.7.8.5";
36
37 private static List<String> getCommonNames(X509Certificate certificate) {
38 List<String> domains = new ArrayList<>();
39 try {
40 X500Name x500name = new JcaX509CertificateHolder(certificate).getSubject();
41 RDN[] rdns = x500name.getRDNs(BCStyle.CN);
42 for (int i = 0; i < rdns.length; ++i) {
43 domains.add(IETFUtils.valueToString(x500name.getRDNs(BCStyle.CN)[i].getFirst().getValue()));
44 }
45 return domains;
46 } catch (CertificateEncodingException e) {
47 return domains;
48 }
49 }
50
51 private static Pair<String, String> parseOtherName(byte[] otherName) {
52 try {
53 ASN1Primitive asn1Primitive = ASN1Primitive.fromByteArray(otherName);
54 if (asn1Primitive instanceof DERTaggedObject) {
55 ASN1Primitive inner = ((DERTaggedObject) asn1Primitive).getObject();
56 if (inner instanceof DLSequence) {
57 DLSequence sequence = (DLSequence) inner;
58 if (sequence.size() >= 2 && sequence.getObjectAt(1) instanceof DERTaggedObject) {
59 String oid = sequence.getObjectAt(0).toString();
60 ASN1Primitive value = ((DERTaggedObject) sequence.getObjectAt(1)).getObject();
61 if (value instanceof DERUTF8String) {
62 return new Pair<>(oid, ((DERUTF8String) value).getString());
63 } else if (value instanceof DERIA5String) {
64 return new Pair<>(oid, ((DERIA5String) value).getString());
65 }
66 }
67 }
68 }
69 return null;
70 } catch (IOException e) {
71 return null;
72 }
73 }
74
75 private static boolean matchDomain(String needle, List<String> haystack) {
76 for (String entry : haystack) {
77 if (entry.startsWith("*.")) {
78 int offset = 0;
79 while (offset < needle.length()) {
80 int i = needle.indexOf('.', offset);
81 if (i < 0) {
82 break;
83 }
84 Log.d(LOGTAG, "comparing " + needle.substring(i) + " and " + entry.substring(1));
85 if (needle.substring(i).equalsIgnoreCase(entry.substring(1))) {
86 Log.d(LOGTAG, "domain " + needle + " matched " + entry);
87 return true;
88 }
89 offset = i + 1;
90 }
91 } else {
92 if (entry.equalsIgnoreCase(needle)) {
93 Log.d(LOGTAG, "domain " + needle + " matched " + entry);
94 return true;
95 }
96 }
97 }
98 return false;
99 }
100
101 @Override
102 public boolean verify(final String unicodeDomain,final String unicodeHostname, SSLSession sslSession) {
103 final String domain = IDN.toASCII(unicodeDomain);
104 final String hostname = unicodeHostname == null ? null : IDN.toASCII(unicodeHostname);
105 try {
106 final Certificate[] chain = sslSession.getPeerCertificates();
107 if (chain.length == 0 || !(chain[0] instanceof X509Certificate)) {
108 return false;
109 }
110 final X509Certificate certificate = (X509Certificate) chain[0];
111 final List<String> commonNames = getCommonNames(certificate);
112 if (isSelfSigned(certificate)) {
113 if (commonNames.size() == 1 && matchDomain(domain, commonNames)) {
114 Log.d(LOGTAG, "accepted CN in self signed cert as work around for " + domain);
115 return true;
116 }
117 }
118 final Collection<List<?>> alternativeNames = certificate.getSubjectAlternativeNames();
119 final List<String> xmppAddrs = new ArrayList<>();
120 final List<String> srvNames = new ArrayList<>();
121 final List<String> domains = new ArrayList<>();
122 if (alternativeNames != null) {
123 for (List<?> san : alternativeNames) {
124 final Integer type = (Integer) san.get(0);
125 if (type == 0) {
126 final Pair<String, String> otherName = parseOtherName((byte[]) san.get(1));
127 if (otherName != null && otherName.first != null && otherName.second != null) {
128 switch (otherName.first) {
129 case SRV_NAME:
130 srvNames.add(otherName.second.toLowerCase(Locale.US));
131 break;
132 case XMPP_ADDR:
133 xmppAddrs.add(otherName.second.toLowerCase(Locale.US));
134 break;
135 default:
136 Log.d(LOGTAG, "oid: " + otherName.first + " value: " + otherName.second);
137 }
138 }
139 } else if (type == 2) {
140 final Object value = san.get(1);
141 if (value instanceof String) {
142 domains.add(((String) value).toLowerCase(Locale.US));
143 }
144 }
145 }
146 }
147 if (srvNames.size() == 0 && xmppAddrs.size() == 0 && domains.size() == 0) {
148 domains.addAll(commonNames);
149 }
150 Log.d(LOGTAG, "searching for " + domain + " in srvNames: " + srvNames + " xmppAddrs: " + xmppAddrs + " domains:" + domains);
151 if (hostname != null) {
152 Log.d(LOGTAG, "also trying to verify hostname " + hostname);
153 }
154 return xmppAddrs.contains(domain)
155 || srvNames.contains("_xmpp-client." + domain)
156 || matchDomain(domain, domains)
157 || (hostname != null && matchDomain(hostname, domains));
158 } catch (final Exception e) {
159 return false;
160 }
161 }
162
163 private boolean isSelfSigned(X509Certificate certificate) {
164 try {
165 certificate.verify(certificate.getPublicKey());
166 return true;
167 } catch (Exception e) {
168 return false;
169 }
170 }
171
172 @Override
173 public boolean verify(String domain, SSLSession sslSession) {
174 return verify(domain, null, sslSession);
175 }
176}