Connection state¶

ConnectionState¶

Conn.ConnectionState() describes a connection. Until the handshake has completed, every field except HandshakeComplete is zero.

Field or method	Content
`Version uint16`	Always `VersionTLS12`
`HandshakeComplete bool`	Whether the handshake has completed
`CipherSuite uint16`	The cipher suite in use, such as `TLS_SRP_SHA_WITH_AES_256_CBC_SHA`
`ServerName string`	The SNI host name the client sent. On the client it is empty when `Config.ServerName` is empty or an IP address
`SRPUsername string`	The username the client proved it holds the password of. On the client it is `Config.Username`
`ExtendedMasterSecret bool`	Whether the connection used Extended Master Secret
`TLSUnique []byte`	The `tls-unique` channel binding, the client's 12-byte Finished message
`ExportKeyingMaterial(label string, context []byte, length int) ([]byte, error)`	RFC 5705 key material. Needs Extended Master Secret

Channel binding and Extended Master Secret explains the last three.

Conn¶

*Conn implements net.Conn.

Method	Behavior
`Handshake() error`	Runs the handshake if it has not run. After a failure every call returns the stored error
`HandshakeContext(ctx context.Context) error`	Like `Handshake`. Canceling `ctx` during the handshake closes the connection and returns the context error. Later calls return the error of the closed connection. Once the handshake has completed, the context has no effect
`Read(b []byte) (int, error)` and `Write(b []byte) (int, error)`	Run the handshake first if needed
`Close() error`	Sends a `close_notify` alert when the handshake has completed and closes the connection
`CloseWrite() error`	Sends `close_notify` without closing the underlying connection. Fails before the handshake has completed
`SetDeadline`, `SetReadDeadline` and `SetWriteDeadline`	Set the deadlines of the underlying connection. After a write times out, every later write fails
`NetConn() net.Conn`	The underlying connection. Reading from it or writing to it corrupts the TLS connection
`LocalAddr()` and `RemoteAddr()`	The addresses of the underlying connection

Read and Write call Handshake, so set a deadline for both before the first call when the handshake has not run yet. Otherwise a silent peer blocks them indefinitely.

Constants¶

Constant	Value
`VersionTLS10`	`0x0301`
`VersionTLS11`	`0x0302`
`VersionTLS12`	`0x0303`
`TLS_SRP_SHA_WITH_3DES_EDE_CBC_SHA`	`0xC01A`
`TLS_SRP_SHA_WITH_AES_128_CBC_SHA`	`0xC01D`
`TLS_SRP_SHA_WITH_AES_256_CBC_SHA`	`0xC020`

CipherSuiteName(id uint16) string returns the name of a cipher suite ID.