unify random number generation

4 files changed, 36 insertions, 18 deletions

diff --git a/src/QXmppSaslAuth.cpp b/src/QXmppSaslAuth.cpp
index 6b642f13..89f4edd4 100644
--- a/src/QXmppSaslAuth.cpp
+++ b/src/QXmppSaslAuth.cpp
@@ -106,9 +106,7 @@ void QXmppSaslDigestMd5::setPassword(const QByteArray &password)
 
 QByteArray QXmppSaslDigestMd5::generateNonce()
 {
-    QByteArray nonce(32, 'm');
-    for(int n = 0; n < nonce.size(); ++n)
-        nonce[n] = (char)(256.0*qrand()/(RAND_MAX+1.0));
+    QByteArray nonce = generateRandomBytes(32);
 
     // The random data can the '=' char is not valid as it is a delimiter,
     // so to be safe, base64 the nonce
diff --git a/src/QXmppStun.cpp b/src/QXmppStun.cpp
index 092484b4..283d0ba8 100644
--- a/src/QXmppStun.cpp
+++ b/src/QXmppStun.cpp
@@ -124,14 +124,6 @@ static void encodeString(QDataStream &stream, quint16 type, const QString &strin
     }
 }
 
-static QByteArray randomByteArray(int length)
-{
-    QByteArray result(length, 0);
-    for (int i = 0; i < length; ++i)
-        result[i] = quint8(qrand() % 255);
-    return result;
-}
-
 /// Constructs a new QXmppStunMessage.
 
 QXmppStunMessage::QXmppStunMessage()
@@ -653,7 +645,7 @@ QXmppStunSocket::Pair::Pair()
 {
     // FIXME : calculate priority
     priority = 1862270975;
-    transaction = randomByteArray(ID_SIZE);
+    transaction = generateRandomBytes(ID_SIZE);
 }
 
 QString QXmppStunSocket::Pair::toString() const
@@ -891,7 +883,7 @@ void QXmppStunSocket::setStunServer(const QHostAddress &host, quint16 port)
 {
     m_stunHost = host;
     m_stunPort = port;
-    m_stunId = randomByteArray(ID_SIZE);
+    m_stunId = generateRandomBytes(ID_SIZE);
 }
 
 void QXmppStunSocket::readyRead()
@@ -1046,7 +1038,7 @@ void QXmppStunSocket::readyRead()
 #if 0
         // send a binding indication
         QXmppStunMessage indication;
-        indication.setId(randomByteArray(ID_SIZE));
+        indication.setId(generateRandomBytes(ID_SIZE));
         indication.setType(BindingIndication);
         m_socket->writeStun(indication, pair);
 #endif
diff --git a/src/QXmppUtils.cpp b/src/QXmppUtils.cpp
index fcf12b1d..8b560cc3 100644
--- a/src/QXmppUtils.cpp
+++ b/src/QXmppUtils.cpp
@@ -216,14 +216,41 @@ QByteArray generateHmacSha1(const QByteArray &key, const QByteArray &text)
     return generateHmac(QCryptographicHash::Sha1, key, text);
 }
 
+/// Generates a random integer x between 0 and N-1. 
+///
+/// \param N
+
+static int generateRandomInteger(int N)
+{
+    Q_ASSERT(N > 0 && N <= RAND_MAX);
+    int val;
+    while (N <= (val = qrand() / (RAND_MAX/N)));
+    return val;
+}
+
+/// Returns a random byte array of the specified size.
+///
+/// \param length
+
+QByteArray generateRandomBytes(int length)
+{
+    QByteArray bytes(length, 'm');
+    for (int i = 0; i < length; ++i)
+        bytes[i] = (char)generateRandomInteger(256);
+    return bytes;
+}
+
+/// Returns a random alphanumerical string of the specified size.
+///
+/// \param length
+
 QString generateStanzaHash(int length)
 {
-    QString somechars = "1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    const QString somechars = "1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    const int N = somechars.size();
     QString hashResult;
     for ( int idx = 0; idx < length; ++idx )
-    {
-        hashResult += somechars[(qrand() % 61)];
-    }
+        hashResult += somechars[generateRandomInteger(N)];
     return hashResult;
 }
 
diff --git a/src/QXmppUtils.h b/src/QXmppUtils.h
index fce000b9..1757238d 100644
--- a/src/QXmppUtils.h
+++ b/src/QXmppUtils.h
@@ -50,6 +50,7 @@ QString jidToBareJid(const QString& jid);
 quint32 generateCrc32(const QByteArray &input);
 QByteArray generateHmacMd5(const QByteArray &key, const QByteArray &text);
 QByteArray generateHmacSha1(const QByteArray &key, const QByteArray &text);
+QByteArray generateRandomBytes(int length);
 QString generateStanzaHash(int length=32);
 
 void helperToXmlAddAttribute(QXmlStreamWriter* stream, const QString& name,