Fix handling of SSL certificates with wildcard domain names

Merge-request: 731
Task-number: QTBUG-4455
Reviewed-by: Peter Hartmann
(cherry picked from commit 5f6018564668d368f75e431c4cdac88d7421cff0)

3 files changed, 63 insertions, 4 deletions

diff --git a/src/network/ssl/qsslsocket_openssl.cpp b/src/network/ssl/qsslsocket_openssl.cpp
index 02de9c3945..949b5097c9 100644
--- a/src/network/ssl/qsslsocket_openssl.cpp
+++ b/src/network/ssl/qsslsocket_openssl.cpp
@@ -827,17 +827,16 @@ bool QSslSocketBackendPrivate::startHandshake()
             QString peerName = (verificationPeerName.isEmpty () ? q->peerName() : verificationPeerName);
             QString commonName = configuration.peerCertificate.subjectInfo(QSslCertificate::CommonName);
 
-            QRegExp regexp(commonName, Qt::CaseInsensitive, QRegExp::Wildcard);
-            if (!regexp.exactMatch(peerName)) {
+            if (!isMatchingHostname(commonName.lower(), peerName.lower())) {
                 bool matched = false;
                 foreach (const QString &altName, configuration.peerCertificate
                          .alternateSubjectNames().values(QSsl::DnsEntry)) {
-                    regexp.setPattern(altName);
-                    if (regexp.exactMatch(peerName)) {
+                    if (isMatchingHostname(altName.lower(), peerName.lower())) {
                         matched = true;
                         break;
                     }
                 }
+
                 if (!matched) {
                     // No matches in common names or alternate names.
                     QSslError error(QSslError::HostNameMismatch, configuration.peerCertificate);
@@ -962,4 +961,39 @@ QList<QSslCertificate> QSslSocketBackendPrivate::STACKOFX509_to_QSslCertificates
     return certificates;
 }
 
+bool QSslSocketBackendPrivate::isMatchingHostname(const QString &cn, const QString &hostname)
+{
+    int wildcard = cn.indexOf(QLatin1Char('*'));
+
+    // Check this is a wildcard cert, if not then just compare the strings
+    if (wildcard < 0)
+        return cn == hostname;
+
+    int firstCnDot = cn.indexOf(QLatin1Char('.'));
+    int secondCnDot = cn.indexOf(QLatin1Char('.'), firstCnDot+1);
+
+    // Check at least 3 components
+    if ((-1 == secondCnDot) || (secondCnDot+1 >= cn.length()))
+        return false;
+
+    // Check * is last character of 1st component (ie. there's a following .)
+    if (wildcard+1 != firstCnDot)
+        return false;
+
+    // Check only one star
+    if (cn.lastIndexOf(QLatin1Char('*')) != wildcard)
+        return false;
+
+    // Check characters preceding * (if any) match
+    if (wildcard && (hostname.leftRef(wildcard) != cn.leftRef(wildcard)))
+        return false;
+
+    // Check characters following first . match
+    if (hostname.midRef(hostname.indexOf(QLatin1Char('.'))) != cn.midRef(firstCnDot))
+        return false;
+
+    // Ok, I guess this was a wildcard CN and the hostname matches.
+    return true;
+}
+
 QT_END_NAMESPACE
diff --git a/src/network/ssl/qsslsocket_openssl_p.h b/src/network/ssl/qsslsocket_openssl_p.h
index 6912d068cb..58defac458 100644
--- a/src/network/ssl/qsslsocket_openssl_p.h
+++ b/src/network/ssl/qsslsocket_openssl_p.h
@@ -115,6 +115,7 @@ public:
 
     static QSslCipher QSslCipher_from_SSL_CIPHER(SSL_CIPHER *cipher);
     static QList<QSslCertificate> STACKOFX509_to_QSslCertificates(STACK_OF(X509) *x509);
+    Q_AUTOTEST_EXPORT static bool isMatchingHostname(const QString &cn, const QString &hostname);
 };
 
 QT_END_NAMESPACE
diff --git a/tests/auto/qsslsocket/tst_qsslsocket.cpp b/tests/auto/qsslsocket/tst_qsslsocket.cpp
index 6ae4b10d06..7b63795f09 100644
--- a/tests/auto/qsslsocket/tst_qsslsocket.cpp
+++ b/tests/auto/qsslsocket/tst_qsslsocket.cpp
@@ -55,6 +55,7 @@
 #include <QAuthenticator>
 
 #include "private/qhostinfo_p.h"
+#include "private/qsslsocket_openssl_p.h"
 
 #include "../network-settings.h"
 
@@ -163,6 +164,7 @@ private slots:
     void setDefaultCiphers();
     void supportedCiphers();
     void systemCaCertificates();
+    void wildcardCertificateNames();
     void wildcard();
     void setEmptyKey();
     void spontaneousWrite();
@@ -1049,6 +1051,28 @@ void tst_QSslSocket::systemCaCertificates()
     QCOMPARE(certs, QSslSocket::defaultCaCertificates());
 }
 
+void tst_QSslSocket::wildcardCertificateNames()
+{
+    // Passing CN matches
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("www.example.com"), QString("www.example.com")), true );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*.example.com"), QString("www.example.com")), true );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("xxx*.example.com"), QString("xxxwww.example.com")), true );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("f*.example.com"), QString("foo.example.com")), true );
+
+    // Failing CN matches
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("xxx.example.com"), QString("www.example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*"), QString("www.example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*.*.com"), QString("www.example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*.example.com"), QString("baa.foo.example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("f*.example.com"), QString("baa.example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*.com"), QString("example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*fail.com"), QString("example.com")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*.example."), QString("www.example.")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*.example."), QString("www.example")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString(""), QString("www")), false );
+    QCOMPARE( QSslSocketBackendPrivate::isMatchingHostname(QString("*"), QString("www")), false );
+}
+
 void tst_QSslSocket::wildcard()
 {
     QSKIP("TODO: solve wildcard problem", SkipAll);