Apparent bug in TLS 1.0 (upstream) about tls-tris

[cjpatton]

Actually, this behavior is intended. From conn.go:

    // SSL 3.0 and TLS 1.0 are susceptible to a chosen-plaintext
    // attack when using block mode ciphers due to predictable IVs.
    // This can be prevented by splitting each Application Data
    // record into two records, effectively randomizing the IV.
    //   
    // http://www.openssl.org/~bodo/tls-cbc.txt
    // https://bugzilla.mozilla.org/show_bug.cgi?id=665814
    // http://www.imperialviolet.org/2012/01/15/beastfollowup.html

    var m int
    if len(b) > 1 && c.vers <= VersionTLS10 {
        if _, ok := c.out.cipher.(cipher.BlockMode); ok { 
            n, err := c.writeRecordLocked(recordTypeApplicationData, b[:1])
            if err != nil {
                return n, c.out.setErrorLocked(err)
            }
            m, b = 1, b[1:]
        }
    }