安全通信 QSslSocket

时间：2022-04-05 14:35:20

The QSslSocket class provides an SSL encrypted socket for both clients and servers. More...

Header: #include <QSslSocket>
Since: Qt 4.3
Inherits: QTcpSocket

Note: All functions in this class are reentrant.

Public Types

enum PeerVerifyMode { VerifyNone, QueryPeer, VerifyPeer, AutoVerifyPeer }
enum SslMode { UnencryptedMode, SslClientMode, SslServerMode }

Public Functions

  QSslSocket(QObject * parent = 0)
  ~QSslSocket()
void abort()
void addCaCertificate(const QSslCertificate & certificate)
bool addCaCertificates(const QString & path, QSsl::EncodingFormat format = QSsl::Pem, QRegExp::PatternSyntax syntax = QRegExp::FixedString)
void addCaCertificates(const QList<QSslCertificate> & certificates)
QList<QSslCertificate> caCertificates() const
QList<QSslCipher> ciphers() const
void connectToHostEncrypted(const QString & hostName, quint16 port, OpenMode mode = ReadWrite)
void connectToHostEncrypted(const QString & hostName, quint16 port, const QString &sslPeerName, OpenMode mode = ReadWrite)
qint64 encryptedBytesAvailable() const
qint64 encryptedBytesToWrite() const
bool flush()
void ignoreSslErrors(const QList<QSslError> & errors)
bool isEncrypted() const
QSslCertificate localCertificate() const
SslMode mode() const
QSslCertificate peerCertificate() const
QList<QSslCertificate> peerCertificateChain() const
int peerVerifyDepth() const
QSslSocket::PeerVerifyMode peerVerifyMode() const
QString peerVerifyName() const
QSslKey privateKey() const
QSsl::SslProtocol protocol() const
QSslCipher sessionCipher() const
void setCaCertificates(const QList<QSslCertificate> & certificates)
void setCiphers(const QList<QSslCipher> & ciphers)
void setCiphers(const QString & ciphers)
void setLocalCertificate(const QSslCertificate & certificate)
void setLocalCertificate(const QString & path, QSsl::EncodingFormat format = QSsl::Pem)
void setPeerVerifyDepth(int depth)
void setPeerVerifyMode(QSslSocket::PeerVerifyMode mode)
void setPeerVerifyName(const QString & hostName)
void setPrivateKey(const QSslKey & key)
void setPrivateKey(const QString & fileName, QSsl::KeyAlgorithm algorithm = QSsl::Rsa, QSsl::EncodingFormat format = QSsl::Pem, const QByteArray & passPhrase = QByteArray())
void setProtocol(QSsl::SslProtocol protocol)
void setReadBufferSize(qint64 size)
bool setSocketDescriptor(int socketDescriptor, SocketState state = ConnectedState, OpenModeopenMode = ReadWrite)
void setSocketOption(QAbstractSocket::SocketOption option, const QVariant & value)
void setSslConfiguration(const QSslConfiguration & configuration)
QVariant socketOption(QAbstractSocket::SocketOption option)
QSslConfiguration sslConfiguration() const
QList<QSslError> sslErrors() const
bool waitForConnected(int msecs = 30000)
bool waitForDisconnected(int msecs = 30000)
bool waitForEncrypted(int msecs = 30000)

Reimplemented Public Functions

virtual bool atEnd() const
virtual qint64 bytesAvailable() const
virtual qint64 bytesToWrite() const
virtual bool canReadLine() const
virtual void close()
virtual bool waitForBytesWritten(int msecs = 30000)
virtual bool waitForReadyRead(int msecs = 30000)

Public Slots

  • 1 public slot inherited from QObject

Signals

void encrypted()
void encryptedBytesWritten(qint64 written)
void modeChanged(QSslSocket::SslMode mode)
void peerVerifyError(const QSslError & error)
void sslErrors(const QList<QSslError> & errors)

Static Public Members

void addDefaultCaCertificate(const QSslCertificate & certificate)
bool addDefaultCaCertificates(const QString & path, QSsl::EncodingFormat encoding = QSsl::Pem, QRegExp::PatternSyntax syntax = QRegExp::FixedString)
void addDefaultCaCertificates(const QList<QSslCertificate> & certificates)
QList<QSslCertificate> defaultCaCertificates()
QList<QSslCipher> defaultCiphers()
void setDefaultCaCertificates(const QList<QSslCertificate> & certificates)
void setDefaultCiphers(const QList<QSslCipher> & ciphers)
QList<QSslCipher> supportedCiphers()
bool supportsSsl()
QList<QSslCertificate> systemCaCertificates()
  • 7 static public members inherited from QObject

Reimplemented Protected Functions

virtual qint64 readData(char * data, qint64 maxlen)
virtual qint64 writeData(const char * data, qint64 len)

Additional Inherited Members

Detailed Description

The QSslSocket class provides an SSL encrypted socket for both clients and servers.

QSslSocket establishes a secure, encrypted TCP connection you can use for transmitting encrypted data. It can operate in both client and server mode, and it supports modern SSL protocols, including SSLv3 and TLSv1. By default, QSslSocket uses TLSv1, but you can change the SSL protocol by calling setProtocol() as long as you do it before the handshake has started.

SSL encryption operates on top of the existing TCP stream after the socket enters the ConnectedState. There are two simple ways to establish a secure connection using QSslSocket: With an immediate SSL handshake, or with a delayed SSL handshake occurring after the connection has been established in unencrypted mode.

The most common way to use QSslSocket is to construct an object and start a secure connection by callingconnectToHostEncrypted(). This method starts an immediate SSL handshake once the connection has been established.

QSslSocket *socket = new QSslSocket(this);
connect(socket, SIGNAL(encrypted()), this, SLOT(ready()));

socket->connectToHostEncrypted("imap.example.com", 993);

As with a plain QTcpSocket, QSslSocket enters the HostLookupState, ConnectingState, and finally theConnectedState, if the connection is successful. The handshake then starts automatically, and if it succeeds, the encrypted() signal is emitted to indicate the socket has entered the encrypted state and is ready for use.

Note that data can be written to the socket immediately after the return from connectToHostEncrypted() (i.e., before the encrypted() signal is emitted). The data is queued in QSslSocket until after the encrypted() signal is emitted.

An example of using the delayed SSL handshake to secure an existing connection is the case where an SSL server secures an incoming connection. Suppose you create an SSL server class as a subclass of QTcpServer. You would override QTcpServer::incomingConnection() with something like the example below, which first constructs an instance of QSslSocket and then calls setSocketDescriptor() to set the new socket's descriptor to the existing one passed in. It then initiates the SSL handshake by calling startServerEncryption().

void SslServer::incomingConnection(int socketDescriptor)

{
QSslSocket *serverSocket = new QSslSocket;

    if (serverSocket->setSocketDescriptor(socketDescriptor)) {

        connect(serverSocket, SIGNAL(encrypted()), this, SLOT(ready()));

        serverSocket->startServerEncryption();

    } else {

        delete serverSocket;

    }

}

If an error occurs, QSslSocket emits the sslErrors() signal. In this case, if no action is taken to ignore the error(s), the connection is dropped. To continue, despite the occurrence of an error, you can callignoreSslErrors(), either from within this slot after the error occurs, or any time after construction of theQSslSocket and before the connection is attempted. This will allow QSslSocket to ignore the errors it encounters when establishing the identity of the peer. Ignoring errors during an SSL handshake should be used with caution, since a fundamental characteristic of secure connections is that they should be established with a successful handshake.

Once encrypted, you use QSslSocket as a regular QTcpSocket. When readyRead() is emitted, you can callread(), canReadLine() and readLine(), or getChar() to read decrypted data from QSslSocket's internal buffer, and you can call write() or putChar() to write data back to the peer. QSslSocket will automatically encrypt the written data for you, and emit encryptedBytesWritten() once the data has been written to the peer.

As a convenience, QSslSocket supports QTcpSocket's blocking functions waitForConnected(),waitForReadyRead(), waitForBytesWritten(), and waitForDisconnected(). It also provides waitForEncrypted(), which will block the calling thread until an encrypted connection has been established.

QSslSocket socket;

socket.connectToHostEncrypted("http.example.com", 443);

if (!socket.waitForEncrypted()) {
qDebug() << socket.errorString();

    return false;

}

socket.write("GET / HTTP/1.0\r\n\r\n");

while (socket.waitForReadyRead())
qDebug() << socket.readAll().data();

QSslSocket provides an extensive, easy-to-use API for handling cryptographic ciphers, private keys, and local, peer, and Certification Authority (CA) certificates. It also provides an API for handling errors that occur during the handshake phase.

The following features can also be customized:

Note: If available, root certificates on Unix (excluding Mac OS X) will be loaded on demand from the standard certificate directories. If you do not want to load root certificates on demand, you need to call either the static function setDefaultCaCertificates() before the first SSL handshake is made in your application, (e.g. via "QSslSocket::setDefaultCaCertificates(QSslSocket::systemCaCertificates());"), or callsetCaCertificates() on your QSslSocket instance prior to the SSL handshake.

For more information about ciphers and certificates, refer to QSslCipher and QSslCertificate.

This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/).

Note: Be aware of the difference between the bytesWritten() signal and the encryptedBytesWritten() signal. For a QTcpSocket, bytesWritten() will get emitted as soon as data has been written to the TCP socket. For aQSslSocket, bytesWritten() will get emitted when the data is being encrypted and encryptedBytesWritten() will get emitted as soon as data has been written to the TCP socket.

Symbian Platform Security Requirements

On Symbian, processes which use this class must have the NetworkServices platform security capability. If the client process lacks this capability, operations will fail.

Platform security capabilities are added via the TARGET.CAPABILITY qmake variable.

See also QSslCertificate, QSslCipher, and QSslError.

Member Type Documentation

enum QSslSocket::PeerVerifyMode

Describes the peer verification modes for QSslSocket. The default mode is AutoVerifyPeer, which selects an appropriate mode depending on the socket's QSocket::SslMode.

Constant Value Description
QSslSocket::VerifyNone 0 QSslSocket will not request a certificate from the peer. You can set this mode if you are not interested in the identity of the other side of the connection. The connection will still be encrypted, and your socket will still send its local certificate to the peer if it's requested.
QSslSocket::QueryPeer 1 QSslSocket will request a certificate from the peer, but does not require this certificate to be valid. This is useful when you want to display peer certificate details to the user without affecting the actual SSL handshake. This mode is the default for servers.
QSslSocket::VerifyPeer 2 QSslSocket will request a certificate from the peer during the SSL handshake phase, and requires that this certificate is valid. On failure,QSslSocket will emit the QSslSocket::sslErrors() signal. This mode is the default for clients.
QSslSocket::AutoVerifyPeer 3 QSslSocket will automatically use QueryPeer for server sockets and VerifyPeer for client sockets.

This enum was introduced or modified in Qt 4.4.

See also QSslSocket::peerVerifyMode().

enum QSslSocket::SslMode

Describes the connection modes available for QSslSocket.

Constant Value Description
QSslSocket::UnencryptedMode 0 The socket is unencrypted. Its behavior is identical to QTcpSocket.
QSslSocket::SslClientMode 1 The socket is a client-side SSL socket. It is either alreayd encrypted, or it is in the SSL handshake phase (see QSslSocket::isEncrypted()).
QSslSocket::SslServerMode 2 The socket is a server-side SSL socket. It is either already encrypted, or it is in the SSL handshake phase (see QSslSocket::isEncrypted()).

Member Function Documentation

QSslSocket::QSslSocket(QObject * parent = 0)

Constructs a QSslSocket object. parent is passed to QObject's constructor. The new socket's cipher suite is set to the one returned by the static method defaultCiphers().

QSslSocket::~QSslSocket()

Destroys the QSslSocket.

void QSslSocket::abort()

Aborts the current connection and resets the socket. Unlike disconnectFromHost(), this function immediately closes the socket, clearing any pending data in the write buffer.

See also disconnectFromHost() and close().

void QSslSocket::addCaCertificate(const QSslCertificate & certificate)

Adds the certificate to this socket's CA certificate database. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

To add multiple certificates, use addCaCertificates().

See also caCertificates() and setCaCertificates().

bool QSslSocket::addCaCertificates(const QString & path, QSsl::EncodingFormat format = QSsl::Pem, QRegExp::PatternSyntax syntax = QRegExp::FixedString)

Searches all files in the path for certificates encoded in the specified format and adds them to this socket's CA certificate database. path can be explicit, or it can contain wildcards in the format specified by syntax. Returns true if one or more certificates are added to the socket's CA certificate database; otherwise returns false.

The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

For more precise control, use addCaCertificate().

See also addCaCertificate() and QSslCertificate::fromPath().

void QSslSocket::addCaCertificates(const QList<QSslCertificate> & certificates)

Adds the certificates to this socket's CA certificate database. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

For more precise control, use addCaCertificate().

See also caCertificates() and addDefaultCaCertificate().

[static]void QSslSocket::addDefaultCaCertificate(const QSslCertificate & certificate)

Adds certificate to the default CA certificate database. Each SSL socket's CA certificate database is initialized to the default CA certificate database.

See also defaultCaCertificates() and addCaCertificates().

[static]bool QSslSocket::addDefaultCaCertificates(const QString & path,QSsl::EncodingFormat encoding = QSsl::Pem, QRegExp::PatternSyntax syntax = QRegExp::FixedString)

Searches all files in the path for certificates with the specified encoding and adds them to the default CA certificate database. path can be an explicit file, or it can contain wildcards in the format specified by syntax. Returns true if any CA certificates are added to the default database.

Each SSL socket's CA certificate database is initialized to the default CA certificate database.

See also defaultCaCertificates(), addCaCertificates(), and addDefaultCaCertificate().

[static]void QSslSocket::addDefaultCaCertificates(const QList<QSslCertificate> &certificates)

Adds certificates to the default CA certificate database. Each SSL socket's CA certificate database is initialized to the default CA certificate database.

See also defaultCaCertificates() and addCaCertificates().

[virtual]bool QSslSocket::atEnd() const

Reimplemented from QIODevice::atEnd().

[virtual]qint64 QSslSocket::bytesAvailable() const

Reimplemented from QIODevice::bytesAvailable().

Returns the number of decrypted bytes that are immediately available for reading.

[virtual]qint64 QSslSocket::bytesToWrite() const

Reimplemented from QIODevice::bytesToWrite().

Returns the number of unencrypted bytes that are waiting to be encrypted and written to the network.

QList<QSslCertificate> QSslSocket::caCertificates() const

Returns this socket's CA certificate database. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate. It can be moodified prior to the handshake withaddCaCertificate(), addCaCertificates(), and setCaCertificates().

Note: On Unix, this method may return an empty list if the root certificates are loaded on demand.

See also addCaCertificate(), addCaCertificates(), and setCaCertificates().

[virtual]bool QSslSocket::canReadLine() const

Reimplemented from QIODevice::canReadLine().

Returns true if you can read one while line (terminated by a single ASCII '\n' character) of decrypted characters; otherwise, false is returned.

QList<QSslCipher> QSslSocket::ciphers() const

Returns this socket's current cryptographic cipher suite. This list is used during the socket's handshake phase for choosing a session cipher. The returned list of ciphers is ordered by descending preference. (i.e., the first cipher in the list is the most preferred cipher). The session cipher will be the first one in the list that is also supported by the peer.

By default, the handshake phase can choose any of the ciphers supported by this system's SSL libraries, which may vary from system to system. The list of ciphers supported by this system's SSL libraries is returned by supportedCiphers(). You can restrict the list of ciphers used for choosing the session cipher for this socket by calling setCiphers() with a subset of the supported ciphers. You can revert to using the entire set by calling setCiphers() with the list returned by supportedCiphers().

You can restrict the list of ciphers used for choosing the session cipher for all sockets by callingsetDefaultCiphers() with a subset of the supported ciphers. You can revert to using the entire set by callingsetCiphers() with the list returned by supportedCiphers().

See also setCiphers(), defaultCiphers(), setDefaultCiphers(), and supportedCiphers().

[virtual]void QSslSocket::close()

Reimplemented from QIODevice::close().

void QSslSocket::connectToHostEncrypted(const QString & hostName, quint16 port,OpenMode mode = ReadWrite)

Starts an encrypted connection to the device hostName on port, using mode as the OpenMode. This is equivalent to calling connectToHost() to establish the connection, followed by a call tostartClientEncryption().

QSslSocket first enters the HostLookupState. Then, after entering either the event loop or one of the waitFor...() functions, it enters the ConnectingState, emits connected(), and then initiates the SSL client handshake. At each state change, QSslSocket emits signal stateChanged().

After initiating the SSL client handshake, if the identity of the peer can't be established, signal sslErrors() is emitted. If you want to ignore the errors and continue connecting, you must call ignoreSslErrors(), either from inside a slot function connected to the sslErrors() signal, or prior to entering encrypted mode. IfignoreSslErrors() is not called, the connection is dropped, signal disconnected() is emitted, and QSslSocketreturns to the UnconnectedState.

If the SSL handshake is successful, QSslSocket emits encrypted().

QSslSocket socket;
connect(&socket, SIGNAL(encrypted()), receiver, SLOT(socketEncrypted()));

socket.connectToHostEncrypted("imap", 993);

socket->write("1 CAPABILITY\r\n");

Note: The example above shows that text can be written to the socket immediately after requesting the encrypted connection, before the encrypted() signal has been emitted. In such cases, the text is queued in the object and written to the socket after the connection is established and the encrypted() signal has been emitted.

The default for mode is ReadWrite.

If you want to create a QSslSocket on the server side of a connection, you should instead callstartServerEncryption() upon receiving the incoming connection through QTcpServer.

See also connectToHost(), startClientEncryption(), waitForConnected(), and waitForEncrypted().

void QSslSocket::connectToHostEncrypted(const QString & hostName, quint16 port, const QString & sslPeerName, OpenMode mode = ReadWrite)

This is an overloaded function.

In addition to the original behaviour of connectToHostEncrypted, this overloaded method enables the usage of a different hostname (sslPeerName) for the certificate validation instead of the one used for the TCP connection (hostName).

This function was introduced in Qt 4.6.

See also connectToHostEncrypted().

[static]QList<QSslCertificate> QSslSocket::defaultCaCertificates()

Returns the current default CA certificate database. This database is originally set to your system's default CA certificate database. If no system default database is found, an empty database will be returned. You can override the default CA certificate database with your own CA certificate database usingsetDefaultCaCertificates().

Each SSL socket's CA certificate database is initialized to the default CA certificate database.

Note: On Unix, this method may return an empty list if the root certificates are loaded on demand.

See also setDefaultCaCertificates() and caCertificates().

[static]QList<QSslCipher> QSslSocket::defaultCiphers()

Returns the default cryptographic cipher suite for all sockets in this application. This list is used during the socket's handshake phase when negotiating with the peer to choose a session cipher. The list is ordered by preference (i.e., the first cipher in the list is the most preferred cipher).

By default, the handshake phase can choose any of the ciphers supported by this system's SSL libraries, which may vary from system to system. The list of ciphers supported by this system's SSL libraries is returned by supportedCiphers().

See also setDefaultCiphers() and supportedCiphers().

[signal]void QSslSocket::encrypted()

This signal is emitted when QSslSocket enters encrypted mode. After this signal has been emitted,QSslSocket::isEncrypted() will return true, and all further transmissions on the socket will be encrypted.

See also QSslSocket::connectToHostEncrypted() and QSslSocket::isEncrypted().

qint64 QSslSocket::encryptedBytesAvailable() const

Returns the number of encrypted bytes that are awaiting decryption. Normally, this function will return 0 because QSslSocket decrypts its incoming data as soon as it can.

This function was introduced in Qt 4.4.

qint64 QSslSocket::encryptedBytesToWrite() const

Returns the number of encrypted bytes that are waiting to be written to the network.

This function was introduced in Qt 4.4.

[signal]void QSslSocket::encryptedBytesWritten(qint64 written)

This signal is emitted when QSslSocket writes its encrypted data to the network. The written parameter contains the number of bytes that were successfully written.

This function was introduced in Qt 4.4.

See also QIODevice::bytesWritten().

bool QSslSocket::flush()

This function writes as much as possible from the internal write buffer to the underlying network socket, without blocking. If any data was written, this function returns true; otherwise false is returned.

Call this function if you need QSslSocket to start sending buffered data immediately. The number of bytes successfully written depends on the operating system. In most cases, you do not need to call this function, because QAbstractSocket will start sending data automatically once control goes back to the event loop. In the absence of an event loop, call waitForBytesWritten() instead.

See also write() and waitForBytesWritten().

[slot]void QSslSocket::ignoreSslErrors()

This slot tells QSslSocket to ignore errors during QSslSocket's handshake phase and continue connecting. If you want to continue with the connection even if errors occur during the handshake phase, then you must call this slot, either from a slot connected to sslErrors(), or before the handshake phase. If you don't call this slot, either in response to errors or before the handshake, the connection will be dropped after thesslErrors() signal has been emitted.

If there are no errors during the SSL handshake phase (i.e., the identity of the peer is established with no problems), QSslSocket will not emit the sslErrors() signal, and it is unnecessary to call this function.

Warning: Be sure to always let the user inspect the errors reported by the sslErrors() signal, and only call this method upon confirmation from the user that proceeding is ok. If there are unexpected errors, the connection should be aborted. Calling this method without inspecting the actual errors will most likely pose a security risk for your application. Use it with great care!

See also sslErrors().

void QSslSocket::ignoreSslErrors(const QList<QSslError> & errors)

This is an overloaded function.

This method tells QSslSocket to ignore only the errors given in errors.

Note: Because most SSL errors are associated with a certificate, for most of them you must set the expected certificate this SSL error is related to. If, for instance, you want to connect to a server that uses a self-signed certificate, consider the following snippet:

QList<QSslCertificate> cert = QSslCertificate::fromPath(QLatin1String("server-certificate.pem"));
QSslError error(QSslError::SelfSignedCertificate, cert.at(0));
QList<QSslError> expectedSslErrors;

expectedSslErrors.append(error);

QSslSocket socket;

socket.ignoreSslErrors(expectedSslErrors);

socket.connectToHostEncrypted("server.tld", 443);

Multiple calls to this function will replace the list of errors that were passed in previous calls. You can clear the list of errors you want to ignore by calling this function with an empty list.

This function was introduced in Qt 4.6.

See also sslErrors().

bool QSslSocket::isEncrypted() const

Returns true if the socket is encrypted; otherwise, false is returned.

An encrypted socket encrypts all data that is written by calling write() or putChar() before the data is written to the network, and decrypts all incoming data as the data is received from the network, before you callread(), readLine() or getChar().

QSslSocket emits encrypted() when it enters encrypted mode.

You can call sessionCipher() to find which cryptographic cipher is used to encrypt and decrypt your data.

See also mode().

QSslCertificate QSslSocket::localCertificate() const

Returns the socket's local certificate, or an empty certificate if no local certificate has been assigned.

See also setLocalCertificate() and privateKey().

SslMode QSslSocket::mode() const

Returns the current mode for the socket; either UnencryptedMode, where QSslSocket behaves identially toQTcpSocket, or one of SslClientMode or SslServerMode, where the client is either negotiating or in encrypted mode.

When the mode changes, QSslSocket emits modeChanged()

See also SslMode.

[signal]void QSslSocket::modeChanged(QSslSocket::SslMode mode)

This signal is emitted when QSslSocket changes from QSslSocket::UnencryptedMode to eitherQSslSocket::SslClientMode or QSslSocket::SslServerMode. mode is the new mode.

See also QSslSocket::mode().

QSslCertificate QSslSocket::peerCertificate() const

Returns the peer's digital certificate (i.e., the immediate certificate of the host you are connected to), or a null certificate, if the peer has not assigned a certificate.

The peer certificate is checked automatically during the handshake phase, so this function is normally used to fetch the certificate for display or for connection diagnostic purposes. It contains information about the peer, including its host name, the certificate issuer, and the peer's public key.

Because the peer certificate is set during the handshake phase, it is safe to access the peer certificate from a slot connected to the sslErrors() signal or the encrypted() signal.

If a null certificate is returned, it can mean the SSL handshake failed, or it can mean the host you are connected to doesn't have a certificate, or it can mean there is no connection.

If you want to check the peer's complete chain of certificates, use peerCertificateChain() to get them all at once.

See also peerCertificateChain().

QList<QSslCertificate> QSslSocket::peerCertificateChain() const

Returns the peer's chain of digital certificates, or an empty list of certificates.

Peer certificates are checked automatically during the handshake phase. This function is normally used to fetch certificates for display, or for performing connection diagnostics. Certificates contain information about the peer and the certificate issuers, including host name, issuer names, and issuer public keys.

The peer certificates are set in QSslSocket during the handshake phase, so it is safe to call this function from a slot connected to the sslErrors() signal or the encrypted() signal.

If an empty list is returned, it can mean the SSL handshake failed, or it can mean the host you are connected to doesn't have a certificate, or it can mean there is no connection.

If you want to get only the peer's immediate certificate, use peerCertificate().

See also peerCertificate().

int QSslSocket::peerVerifyDepth() const

Returns the maximum number of certificates in the peer's certificate chain to be checked during the SSL handshake phase, or 0 (the default) if no maximum depth has been set, indicating that the whole certificate chain should be checked.

The certificates are checked in issuing order, starting with the peer's own certificate, then its issuer's certificate, and so on.

This function was introduced in Qt 4.4.

See also setPeerVerifyDepth() and peerVerifyMode().

[signal]void QSslSocket::peerVerifyError(const QSslError & error)

QSslSocket can emit this signal several times during the SSL handshake, before encryption has been established, to indicate that an error has occurred while establishing the identity of the peer. The error is usually an indication that QSslSocket is unable to securely identify the peer.

This signal provides you with an early indication when something's wrong. By connecting to this signal, you can manually choose to tear down the connection from inside the connected slot before the handshake has completed. If no action is taken, QSslSocket will proceed to emitting QSslSocket::sslErrors().

This function was introduced in Qt 4.4.

See also sslErrors().

QSslSocket::PeerVerifyMode QSslSocket::peerVerifyMode() const

Returns the socket's verify mode. This mode mode decides whether QSslSocket should request a certificate from the peer (i.e., the client requests a certificate from the server, or a server requesting a certificate from the client), and whether it should require that this certificate is valid.

The default mode is AutoVerifyPeer, which tells QSslSocket to use VerifyPeer for clients and QueryPeer for servers.

This function was introduced in Qt 4.4.

See also setPeerVerifyMode(), peerVerifyDepth(), and mode().

QString QSslSocket::peerVerifyName() const

Returns the different hostname for the certificate validation, as set by setPeerVerifyName or byconnectToHostEncrypted.

This function was introduced in Qt 4.8.

See also setPeerVerifyName() and connectToHostEncrypted().

QSslKey QSslSocket::privateKey() const

Returns this socket's private key.

See also setPrivateKey() and localCertificate().

QSsl::SslProtocol QSslSocket::protocol() const

Returns the socket's SSL protocol. By default, QSsl::SecureProtocols is used.

See also setProtocol().

[virtual protected]qint64 QSslSocket::readData(char * data, qint64 maxlen)

Reimplemented from QIODevice::readData().

QSslCipher QSslSocket::sessionCipher() const

Returns the socket's cryptographic cipher, or a null cipher if the connection isn't encrypted. The socket's cipher for the session is set during the handshake phase. The cipher is used to encrypt and decrypt data transmitted through the socket.

QSslSocket also provides functions for setting the ordered list of ciphers from which the handshake phase will eventually select the session cipher. This ordered list must be in place before the handshake phase begins.

See also ciphers(), setCiphers(), setDefaultCiphers(), defaultCiphers(), and supportedCiphers().

void QSslSocket::setCaCertificates(const QList<QSslCertificate> & certificates)

Sets this socket's CA certificate database to be certificates. The certificate database must be set prior to the SSL handshake. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

The CA certificate database can be reset to the current default CA certificate database by calling this function with the list of CA certificates returned by defaultCaCertificates().

See also caCertificates() and defaultCaCertificates().

void QSslSocket::setCiphers(const QList<QSslCipher> & ciphers)

Sets the cryptographic cipher suite for this socket to ciphers, which must contain a subset of the ciphers in the list returned by supportedCiphers().

Restricting the cipher suite must be done before the handshake phase, where the session cipher is chosen.

See also ciphers(), setDefaultCiphers(), and supportedCiphers().

void QSslSocket::setCiphers(const QString & ciphers)

Sets the cryptographic cipher suite for this socket to ciphers, which is a colon-separated list of cipher suite names. The ciphers are listed in order of preference, starting with the most preferred cipher. For example:

QSslSocket socket;

socket.setCiphers("DHE-RSA-AES256-SHA:DHE-DSS-AES256-SHA:AES256-SHA");

Each cipher name in ciphers must be the name of a cipher in the list returned by supportedCiphers(). Restricting the cipher suite must be done before the handshake phase, where the session cipher is chosen.

See also ciphers(), setDefaultCiphers(), and supportedCiphers().

[static]void QSslSocket::setDefaultCaCertificates(const QList<QSslCertificate> &certificates)

Sets the default CA certificate database to certificates. The default CA certificate database is originally set to your system's default CA certificate database. You can override the default CA certificate database with your own CA certificate database using this function.

Each SSL socket's CA certificate database is initialized to the default CA certificate database.

See also defaultCaCertificates() and addDefaultCaCertificate().

[static]void QSslSocket::setDefaultCiphers(const QList<QSslCipher> & ciphers)

Sets the default cryptographic cipher suite for all sockets in this application to ciphers, which must contain a subset of the ciphers in the list returned by supportedCiphers().

Restricting the default cipher suite only affects SSL sockets that perform their handshake phase after the default cipher suite has been changed.

See also setCiphers(), defaultCiphers(), and supportedCiphers().

void QSslSocket::setLocalCertificate(const QSslCertificate & certificate)

Sets the socket's local certificate to certificate. The local certificate is necessary if you need to confirm your identity to the peer. It is used together with the private key; if you set the local certificate, you must also set the private key.

The local certificate and private key are always necessary for server sockets, but are also rarely used by client sockets if the server requires the client to authenticate.

See also localCertificate() and setPrivateKey().

void QSslSocket::setLocalCertificate(const QString & path, QSsl::EncodingFormat format= QSsl::Pem)

This is an overloaded function.

Sets the socket's local certificate to the first one found in file path, which is parsed according to the specifiedformat.

void QSslSocket::setPeerVerifyDepth(int depth)

Sets the maximum number of certificates in the peer's certificate chain to be checked during the SSL handshake phase, to depth. Setting a depth of 0 means that no maximum depth is set, indicating that the whole certificate chain should be checked.

The certificates are checked in issuing order, starting with the peer's own certificate, then its issuer's certificate, and so on.

This function was introduced in Qt 4.4.

See also peerVerifyDepth() and setPeerVerifyMode().

void QSslSocket::setPeerVerifyMode(QSslSocket::PeerVerifyMode mode)

Sets the socket's verify mode to mode. This mode decides whether QSslSocket should request a certificate from the peer (i.e., the client requests a certificate from the server, or a server requesting a certificate from the client), and whether it should require that this certificate is valid.

The default mode is AutoVerifyPeer, which tells QSslSocket to use VerifyPeer for clients and QueryPeer for servers.

Setting this mode after encryption has started has no effect on the current connection.

This function was introduced in Qt 4.4.

See also peerVerifyMode(), setPeerVerifyDepth(), and mode().

void QSslSocket::setPeerVerifyName(const QString & hostName)

Sets a different host name, given by hostName, for the certificate validation instead of the one used for the TCP connection.

This function was introduced in Qt 4.8.

See also peerVerifyName() and connectToHostEncrypted().

void QSslSocket::setPrivateKey(const QSslKey & key)

Sets the socket's private key to key. The private key and the local certificate are used by clients and servers that must prove their identity to SSL peers.

Both the key and the local certificate are required if you are creating an SSL server socket. If you are creating an SSL client socket, the key and local certificate are required if your client must identify itself to an SSL server.

See also privateKey() and setLocalCertificate().

void QSslSocket::setPrivateKey(const QString & fileName, QSsl::KeyAlgorithm algorithm = QSsl::Rsa, QSsl::EncodingFormat format = QSsl::Pem, const QByteArray & passPhrase = QByteArray())

This is an overloaded function.

Reads the string in file fileName and decodes it using a specified algorithm and encoding format to construct an SSL key. If the encoded key is encrypted, passPhrase is used to decrypt it.

The socket's private key is set to the constructed key. The private key and the local certificate are used by clients and servers that must prove their identity to SSL peers.

Both the key and the local certificate are required if you are creating an SSL server socket. If you are creating an SSL client socket, the key and local certificate are required if your client must identify itself to an SSL server.

See also privateKey() and setLocalCertificate().

void QSslSocket::setProtocol(QSsl::SslProtocol protocol)

Sets the socket's SSL protocol to protocol. This will affect the next initiated handshake; calling this function on an already-encrypted socket will not affect the socket's protocol.

See also protocol().

void QSslSocket::setReadBufferSize(qint64 size)

Sets the size of QSslSocket's internal read buffer to be size bytes.

This function was introduced in Qt 4.4.

bool QSslSocket::setSocketDescriptor(int socketDescriptor, SocketState state = ConnectedState, OpenMode openMode = ReadWrite)

Initializes QSslSocket with the native socket descriptor socketDescriptor. Returns true if socketDescriptor is accepted as a valid socket descriptor; otherwise returns false. The socket is opened in the mode specified byopenMode, and enters the socket state specified by state.

Note: It is not possible to initialize two sockets with the same native socket descriptor.

See also socketDescriptor().

void QSslSocket::setSocketOption(QAbstractSocket::SocketOption option, const QVariant& value)

Sets the given option to the value described by value.

This function was introduced in Qt 4.6.

See also socketOption().

void QSslSocket::setSslConfiguration(const QSslConfiguration & configuration)

Sets the socket's SSL configuration to be the contents of configuration. This function sets the local certificate, the ciphers, the private key and the CA certificates to those stored in configuration.

It is not possible to set the SSL-state related fields.

This function was introduced in Qt 4.4.

See also sslConfiguration(), setLocalCertificate(), setPrivateKey(), setCaCertificates(), and setCiphers().

QVariant QSslSocket::socketOption(QAbstractSocket::SocketOption option)

Returns the value of the option option.

This function was introduced in Qt 4.6.

See also setSocketOption().

QSslConfiguration QSslSocket::sslConfiguration() const

Returns the socket's SSL configuration state. The default SSL configuration of a socket is to use the default ciphers, default CA certificates, no local private key or certificate.

The SSL configuration also contains fields that can change with time without notice.

This function was introduced in Qt 4.4.

See also setSslConfiguration(), localCertificate(), peerCertificate(), peerCertificateChain(), sessionCipher(),privateKey(), ciphers(), and caCertificates().

QList<QSslError> QSslSocket::sslErrors() const

Returns a list of the last SSL errors that occurred. This is the same list as QSslSocket passes via the sslErrors() signal. If the connection has been encrypted with no errors, this function will return an empty list.

See also connectToHostEncrypted().

[signal]void QSslSocket::sslErrors(const QList<QSslError> & errors)

QSslSocket emits this signal after the SSL handshake to indicate that one or more errors have occurred while establishing the identity of the peer. The errors are usually an indication that QSslSocket is unable to securely identify the peer. Unless any action is taken, the connection will be dropped after this signal has been emitted.

If you want to continue connecting despite the errors that have occurred, you must callQSslSocket::ignoreSslErrors() from inside a slot connected to this signal. If you need to access the error list at a later point, you can call sslErrors() (without arguments).

errors contains one or more errors that prevent QSslSocket from verifying the identity of the peer.

Note: You cannot use Qt::QueuedConnection when connecting to this signal, or callingQSslSocket::ignoreSslErrors() will have no effect.

Note:Signal sslErrors is overloaded in this class. To connect to this one using the function pointer syntax, you must specify the signal type in a static cast, as shown in this example:

connect(sslSocket, static_cast<void(QSslSocket::*)(const QList<QSslError> &)>(&QSslSocket::sslErrors),

    [=](const QList<QSslError> &errors){ /* ... */ });

See also peerVerifyError().

[slot]void QSslSocket::startClientEncryption()

Starts a delayed SSL handshake for a client connection. This function can be called when the socket is in theConnectedState but still in the UnencryptedMode. If it is not yet connected, or if it is already encrypted, this function has no effect.

Clients that implement STARTTLS functionality often make use of delayed SSL handshakes. Most other clients can avoid calling this function directly by using connectToHostEncrypted() instead, which automatically performs the handshake.

See also connectToHostEncrypted() and startServerEncryption().

[slot]void QSslSocket::startServerEncryption()

Starts a delayed SSL handshake for a server connection. This function can be called when the socket is in theConnectedState but still in UnencryptedMode. If it is not connected or it is already encrypted, the function has no effect.

For server sockets, calling this function is the only way to initiate the SSL handshake. Most servers will call this function immediately upon receiving a connection, or as a result of having received a protocol-specific command to enter SSL mode (e.g, the server may respond to receiving the string "STARTTLS\r\n" by calling this function).

The most common way to implement an SSL server is to create a subclass of QTcpServer and reimplementQTcpServer::incomingConnection(). The returned socket descriptor is then passed toQSslSocket::setSocketDescriptor().

See also connectToHostEncrypted() and startClientEncryption().

[static]QList<QSslCipher> QSslSocket::supportedCiphers()

Returns the list of cryptographic ciphers supported by this system. This list is set by the system's SSL libraries and may vary from system to system.

See also defaultCiphers(), ciphers(), and setCiphers().

[static]bool QSslSocket::supportsSsl()

Returns true if this platform supports SSL; otherwise, returns false. If the platform doesn't support SSL, the socket will fail in the connection phase.

[static]QList<QSslCertificate> QSslSocket::systemCaCertificates()

This function provides the CA certificate database provided by the operating system. The CA certificate database returned by this function is used to initialize the database returned by defaultCaCertificates(). You can replace that database with your own with setDefaultCaCertificates().

See also caCertificates(), defaultCaCertificates(), and setDefaultCaCertificates().

[virtual]bool QSslSocket::waitForBytesWritten(int msecs = 30000)

Reimplemented from QIODevice::waitForBytesWritten().

bool QSslSocket::waitForConnected(int msecs = 30000)

Waits until the socket is connected, or msecs milliseconds, whichever happens first. If the connection has been established, this function returns true; otherwise it returns false.

See also QAbstractSocket::waitForConnected().

bool QSslSocket::waitForDisconnected(int msecs = 30000)

Waits until the socket has disconnected or msecs milliseconds, whichever comes first. If the connection has been disconnected, this function returns true; otherwise it returns false.

See also QAbstractSocket::waitForDisconnected().

bool QSslSocket::waitForEncrypted(int msecs = 30000)

Waits until the socket has completed the SSL handshake and has emitted encrypted(), or msecs milliseconds, whichever comes first. If encrypted() has been emitted, this function returns true; otherwise (e.g., the socket is disconnected, or the SSL handshake fails), false is returned.

The following example waits up to one second for the socket to be encrypted:

socket->connectToHostEncrypted("imap", 993);

if (socket->waitForEncrypted(1000))
qDebug("Encrypted!");

If msecs is -1, this function will not time out.

See also startClientEncryption(), startServerEncryption(), encrypted(), and isEncrypted().

[virtual]bool QSslSocket::waitForReadyRead(int msecs = 30000)

Reimplemented from QIODevice::waitForReadyRead().

[virtual protected]qint64 QSslSocket::writeData(const char * data, qint64 len)

Reimplemented from QIODevice::writeData().

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