tls

package
v1.19.0 Latest Latest
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 Go to latest Published: Sep 26, 2023 License: MIT Imports: 8 Imported by: 0

Documentation

Overview

Package tls partially implements TLS 1.2, as specified in RFC 5246, and TLS 1.3, as specified in RFC 8446.

Index

Examples

Constants

View Source 
const (
	// TLS 1.0 - 1.2 cipher suites.
	TLS_RSA_WITH_RC4_128_SHA                      uint16 = 0x0005
	TLS_RSA_WITH_3DES_EDE_CBC_SHA                 uint16 = 0x000a
	TLS_RSA_WITH_AES_128_CBC_SHA                  uint16 = 0x002f
	TLS_RSA_WITH_AES_256_CBC_SHA                  uint16 = 0x0035
	TLS_RSA_WITH_AES_128_CBC_SHA256               uint16 = 0x003c
	TLS_RSA_WITH_AES_128_GCM_SHA256               uint16 = 0x009c
	TLS_RSA_WITH_AES_256_GCM_SHA384               uint16 = 0x009d
	TLS_ECDHE_ECDSA_WITH_RC4_128_SHA              uint16 = 0xc007
	TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA          uint16 = 0xc009
	TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA          uint16 = 0xc00a
	TLS_ECDHE_RSA_WITH_RC4_128_SHA                uint16 = 0xc011
	TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA           uint16 = 0xc012
	TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA            uint16 = 0xc013
	TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA            uint16 = 0xc014
	TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256       uint16 = 0xc023
	TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256         uint16 = 0xc027
	TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256         uint16 = 0xc02f
	TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256       uint16 = 0xc02b
	TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384         uint16 = 0xc030
	TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384       uint16 = 0xc02c
	TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   uint16 = 0xcca8
	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 uint16 = 0xcca9

	// TLS 1.3 cipher suites.
	TLS_AES_128_GCM_SHA256       uint16 = 0x1301
	TLS_AES_256_GCM_SHA384       uint16 = 0x1302
	TLS_CHACHA20_POLY1305_SHA256 uint16 = 0x1303

	// TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
	// that the client is doing version fallback. See RFC 7507.
	TLS_FALLBACK_SCSV uint16 = 0x5600

	// Legacy names for the corresponding cipher suites with the correct _SHA256
	// suffix, retained for backward compatibility.
	TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305   = TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 = TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
)

A list of cipher suite IDs that are, or have been, implemented by this package.

See https://www.iana.org/assignments/tls-parameters/tls-parameters.xml

View Source 
const (
	VersionTLS10 = 0x0301
	VersionTLS11 = 0x0302
	VersionTLS12 = 0x0303
	VersionTLS13 = 0x0304

	// Deprecated: SSLv3 is cryptographically broken, and is no longer
	// supported by this package. See golang.org/issue/32716.
	VersionSSL30 = 0x0300
)

Variables

This section is empty.

Functions

func CipherSuiteName added in v1.14.0 

func CipherSuiteName(id uint16) string

CipherSuiteName returns the standard name for the passed cipher suite ID (e.g. "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"), or a fallback representation of the ID value if the cipher suite is not implemented by this package.

func Listen 

func Listen(network, laddr string, config *Config) (net.Listener, error)

Listen creates a TLS listener accepting connections on the given network address using net.Listen. The configuration config must be non-nil and must include at least one certificate or else set GetCertificate.

func NewListener 

func NewListener(inner net.Listener, config *Config) net.Listener

NewListener creates a Listener which accepts connections from an inner Listener and wraps each connection with Server. The configuration config must be non-nil and must include at least one certificate or else set GetCertificate.

Types

type Certificate 

type Certificate struct {
	Certificate [][]byte

	PrivateKey crypto.PrivateKey

	SupportedSignatureAlgorithms []SignatureScheme

	OCSPStaple []byte

	SignedCertificateTimestamps [][]byte

	Leaf *x509.Certificate
}

A Certificate is a chain of one or more certificates, leaf first.

func LoadX509KeyPair 

func LoadX509KeyPair(certFile, keyFile string) (Certificate, error)

LoadX509KeyPair reads and parses a public/private key pair from a pair of files. The files must contain PEM encoded data. The certificate file may contain intermediate certificates following the leaf certificate to form a certificate chain. On successful return, Certificate.Leaf will be nil because the parsed form of the certificate is not retained.

Example 
package main

import (
	"crypto/tls"
	"log"
)

func main() {
	cert, err := tls.LoadX509KeyPair("testdata/example-cert.pem", "testdata/example-key.pem")
	if err != nil {
		log.Fatal(err)
	}
	cfg := &tls.Config{Certificates: []tls.Certificate{cert}}
	listener, err := tls.Listen("tcp", ":2000", cfg)
	if err != nil {
		log.Fatal(err)
	}
	_ = listener
}

Output:

func X509KeyPair 

func X509KeyPair(certPEMBlock, keyPEMBlock []byte) (Certificate, error)

X509KeyPair parses a public/private key pair from a pair of PEM encoded data. On successful return, Certificate.Leaf will be nil because the parsed form of the certificate is not retained.

Example 
package main

import (
	"crypto/tls"
	"log"
)

func main() {
	certPem := []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)
	keyPem := []byte(`-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIIrYSSNQFaA2Hwf1duRSxKtLYX5CB04fSeQ6tF1aY/PuoAoGCCqGSM49
AwEHoUQDQgAEPR3tU2Fta9ktY+6P9G0cWO+0kETA6SFs38GecTyudlHz6xvCdz8q
EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
-----END EC PRIVATE KEY-----`)
	cert, err := tls.X509KeyPair(certPem, keyPem)
	if err != nil {
		log.Fatal(err)
	}
	cfg := &tls.Config{Certificates: []tls.Certificate{cert}}
	listener, err := tls.Listen("tcp", ":2000", cfg)
	if err != nil {
		log.Fatal(err)
	}
	_ = listener
}

Output:
Example (HttpServer) 
package main

import (
	"crypto/tls"
	"log"
	"net/http"
	"time"
)

func main() {
	certPem := []byte(`-----BEGIN CERTIFICATE-----
MIIBhTCCASugAwIBAgIQIRi6zePL6mKjOipn+dNuaTAKBggqhkjOPQQDAjASMRAw
DgYDVQQKEwdBY21lIENvMB4XDTE3MTAyMDE5NDMwNloXDTE4MTAyMDE5NDMwNlow
EjEQMA4GA1UEChMHQWNtZSBDbzBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABD0d
7VNhbWvZLWPuj/RtHFjvtJBEwOkhbN/BnnE8rnZR8+sbwnc/KhCk3FhnpHZnQz7B
5aETbbIgmuvewdjvSBSjYzBhMA4GA1UdDwEB/wQEAwICpDATBgNVHSUEDDAKBggr
BgEFBQcDATAPBgNVHRMBAf8EBTADAQH/MCkGA1UdEQQiMCCCDmxvY2FsaG9zdDo1
NDUzgg4xMjcuMC4wLjE6NTQ1MzAKBggqhkjOPQQDAgNIADBFAiEA2zpJEPQyz6/l
Wf86aX6PepsntZv2GYlA5UpabfT2EZICICpJ5h/iI+i341gBmLiAFQOyTDT+/wQc
6MF9+Yw1Yy0t
-----END CERTIFICATE-----`)
	keyPem := []byte(`-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIIrYSSNQFaA2Hwf1duRSxKtLYX5CB04fSeQ6tF1aY/PuoAoGCCqGSM49
AwEHoUQDQgAEPR3tU2Fta9ktY+6P9G0cWO+0kETA6SFs38GecTyudlHz6xvCdz8q
EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
-----END EC PRIVATE KEY-----`)
	cert, err := tls.X509KeyPair(certPem, keyPem)
	if err != nil {
		log.Fatal(err)
	}
	cfg := &tls.Config{Certificates: []tls.Certificate{cert}}
	srv := &http.Server{
		TLSConfig:    cfg,
		ReadTimeout:  time.Minute,
		WriteTimeout: time.Minute,
	}
	log.Fatal(srv.ListenAndServeTLS("", ""))
}

Output:

type CertificateRequestInfo added in v1.8.0 

type CertificateRequestInfo struct {
	AcceptableCAs [][]byte

	SignatureSchemes []SignatureScheme

	Version uint16
	// contains filtered or unexported fields
}

CertificateRequestInfo contains information from a server's CertificateRequest message, which is used to demand a certificate and proof of control from a client.

func (*CertificateRequestInfo) Context added in v1.17.0 

func (c *CertificateRequestInfo) Context() context.Context

Context returns the context of the handshake that is in progress. This context is a child of the context passed to HandshakeContext, if any, and is canceled when the handshake concludes.

func (*CertificateRequestInfo) SupportsCertificate added in v1.14.0 

func (cri *CertificateRequestInfo) SupportsCertificate(c *Certificate) error

SupportsCertificate returns nil if the provided certificate is supported by the server that sent the CertificateRequest. Otherwise, it returns an error describing the reason for the incompatibility.

type CipherSuite added in v1.14.0 

type CipherSuite struct {
	ID   uint16
	Name string

	SupportedVersions []uint16

	Insecure bool
}

CipherSuite is a TLS cipher suite. Note that most functions in this package accept and expose cipher suite IDs instead of this type.

func CipherSuites added in v1.14.0 

func CipherSuites() []*CipherSuite

CipherSuites returns a list of cipher suites currently implemented by this package, excluding those with security issues, which are returned by InsecureCipherSuites.

The list is sorted by ID. Note that the default cipher suites selected by this package might depend on logic that can't be captured by a static list, and might not match those returned by this function.

func InsecureCipherSuites added in v1.14.0 

func InsecureCipherSuites() []*CipherSuite

InsecureCipherSuites returns a list of cipher suites currently implemented by this package and which have security issues.

Most applications should not use the cipher suites in this list, and should only use those returned by CipherSuites.

type ClientAuthType 

type ClientAuthType int

ClientAuthType declares the policy the server will follow for TLS Client Authentication. 

const (
	// NoClientCert indicates that no client certificate should be requested
	// during the handshake, and if any certificates are sent they will not
	// be verified.
	NoClientCert ClientAuthType = iota
	// RequestClientCert indicates that a client certificate should be requested
	// during the handshake, but does not require that the client send any
	// certificates.
	RequestClientCert
	// RequireAnyClientCert indicates that a client certificate should be requested
	// during the handshake, and that at least one certificate is required to be
	// sent by the client, but that certificate is not required to be valid.
	RequireAnyClientCert
	// VerifyClientCertIfGiven indicates that a client certificate should be requested
	// during the handshake, but does not require that the client sends a
	// certificate. If the client does send a certificate it is required to be
	// valid.
	VerifyClientCertIfGiven
	// RequireAndVerifyClientCert indicates that a client certificate should be requested
	// during the handshake, and that at least one valid certificate is required
	// to be sent by the client.
	RequireAndVerifyClientCert
)

func (ClientAuthType) String added in v1.15.0 

func (i ClientAuthType) String() string

type ClientHelloInfo added in v1.4.0 

type ClientHelloInfo struct {
	CipherSuites []uint16

	ServerName string

	SupportedCurves []CurveID

	SupportedPoints []uint8

	SignatureSchemes []SignatureScheme

	SupportedProtos []string

	SupportedVersions []uint16

	Conn net.Conn
	// contains filtered or unexported fields
}

ClientHelloInfo contains information from a ClientHello message in order to guide application logic in the GetCertificate and GetConfigForClient callbacks.

func (*ClientHelloInfo) Context added in v1.17.0 

func (c *ClientHelloInfo) Context() context.Context

Context returns the context of the handshake that is in progress. This context is a child of the context passed to HandshakeContext, if any, and is canceled when the handshake concludes.

func (*ClientHelloInfo) SupportsCertificate added in v1.14.0 

func (chi *ClientHelloInfo) SupportsCertificate(c *Certificate) error

SupportsCertificate returns nil if the provided certificate is supported by the client that sent the ClientHello. Otherwise, it returns an error describing the reason for the incompatibility.

If this ClientHelloInfo was passed to a GetConfigForClient or GetCertificate callback, this method will take into account the associated Config. Note that if GetConfigForClient returns a different Config, the change can't be accounted for by this method.

This function will call x509.ParseCertificate unless c.Leaf is set, which can incur a significant performance cost.

type ClientSessionCache added in v1.3.0 

type ClientSessionCache interface {
	Get(sessionKey string) (session *ClientSessionState, ok bool)

	Put(sessionKey string, cs *ClientSessionState)
}

ClientSessionCache is a cache of ClientSessionState objects that can be used by a client to resume a TLS session with a given server. ClientSessionCache implementations should expect to be called concurrently from different goroutines. Up to TLS 1.2, only ticket-based resumption is supported, not SessionID-based resumption. In TLS 1.3 they were merged into PSK modes, which are supported via this interface.

func NewLRUClientSessionCache added in v1.3.0 

func NewLRUClientSessionCache(capacity int) ClientSessionCache

NewLRUClientSessionCache returns a ClientSessionCache with the given capacity that uses an LRU strategy. If capacity is < 1, a default capacity is used instead.

type ClientSessionState added in v1.3.0 

type ClientSessionState struct {
	// contains filtered or unexported fields
}

ClientSessionState contains the state needed by clients to resume TLS sessions.

type Config 

type Config struct {
	Rand io.Reader

	Time func() time.Time

	Certificates []Certificate

	NameToCertificate map[string]*Certificate

	GetCertificate func(*ClientHelloInfo) (*Certificate, error)

	GetClientCertificate func(*CertificateRequestInfo) (*Certificate, error)

	GetConfigForClient func(*ClientHelloInfo) (*Config, error)

	VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error

	VerifyConnection func(ConnectionState) error

	RootCAs *x509.CertPool

	NextProtos []string

	ServerName string

	ClientAuth ClientAuthType

	ClientCAs *x509.CertPool

	InsecureSkipVerify bool

	CipherSuites []uint16

	PreferServerCipherSuites bool

	SessionTicketsDisabled bool

	SessionTicketKey [32]byte

	ClientSessionCache ClientSessionCache

	MinVersion uint16

	MaxVersion uint16

	CurvePreferences []CurveID

	DynamicRecordSizingDisabled bool

	Renegotiation RenegotiationSupport

	KeyLogWriter io.Writer
	// contains filtered or unexported fields
}

A Config structure is used to configure a TLS client or server. After one has been passed to a TLS function it must not be modified. A Config may be reused; the tls package will also not modify it.

Example (KeyLogWriter) 
// Debugging TLS applications by decrypting a network traffic capture.

// WARNING: Use of KeyLogWriter compromises security and should only be
// used for debugging.

// Dummy test HTTP server for the example with insecure random so output is
// reproducible.
server := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
server.TLS = &tls.Config{
	Rand: zeroSource{}, // for example only; don't do this.
}
server.StartTLS()
defer server.Close()

// Typically the log would go to an open file:
// w, err := os.OpenFile("tls-secrets.txt", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
w := os.Stdout

client := &http.Client{
	Transport: &http.Transport{
		TLSClientConfig: &tls.Config{
			KeyLogWriter: w,

			Rand:               zeroSource{}, // for reproducible output; don't do this.
			InsecureSkipVerify: true,         // test server certificate is not trusted.
		},
	},
}
resp, err := client.Get(server.URL)
if err != nil {
	log.Fatalf("Failed to get URL: %v", err)
}
resp.Body.Close()

// The resulting file can be used with Wireshark to decrypt the TLS
// connection by setting (Pre)-Master-Secret log filename in SSL Protocol
// preferences.

Output:
Example (VerifyConnection) 
package main

import (
	"crypto/tls"
	"crypto/x509"
)

func main() {
	// VerifyConnection can be used to replace and customize connection
	// verification. This example shows a VerifyConnection implementation that
	// will be approximately equivalent to what crypto/tls does normally to
	// verify the peer's certificate.

	// Client side configuration.
	_ = &tls.Config{
		// Set InsecureSkipVerify to skip the default validation we are
		// replacing. This will not disable VerifyConnection.
		InsecureSkipVerify: true,
		VerifyConnection: func(cs tls.ConnectionState) error {
			opts := x509.VerifyOptions{
				DNSName:       cs.ServerName,
				Intermediates: x509.NewCertPool(),
			}
			for _, cert := range cs.PeerCertificates[1:] {
				opts.Intermediates.AddCert(cert)
			}
			_, err := cs.PeerCertificates[0].Verify(opts)
			return err
		},
	}

	// Server side configuration.
	_ = &tls.Config{
		// Require client certificates (or VerifyConnection will run anyway and
		// panic accessing cs.PeerCertificates[0]) but don't verify them with the
		// default verifier. This will not disable VerifyConnection.
		ClientAuth: tls.RequireAnyClientCert,
		VerifyConnection: func(cs tls.ConnectionState) error {
			opts := x509.VerifyOptions{
				DNSName:       cs.ServerName,
				Intermediates: x509.NewCertPool(),
				KeyUsages:     []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
			}
			for _, cert := range cs.PeerCertificates[1:] {
				opts.Intermediates.AddCert(cert)
			}
			_, err := cs.PeerCertificates[0].Verify(opts)
			return err
		},
	}

	// Note that when certificates are not handled by the default verifier
	// ConnectionState.VerifiedChains will be nil.
}

Output:

func (*Config) BuildNameToCertificate deprecated 

func (c *Config) BuildNameToCertificate()

BuildNameToCertificate parses c.Certificates and builds c.NameToCertificate from the CommonName and SubjectAlternateName fields of each of the leaf certificates.

Deprecated: NameToCertificate only allows associating a single certificate with a given name. Leave that field nil to let the library select the first compatible chain from Certificates.

func (*Config) Clone added in v1.8.0 

func (c *Config) Clone() *Config

Clone returns a shallow clone of c or nil if c is nil. It is safe to clone a Config that is being used concurrently by a TLS client or server.

func (*Config) SetSessionTicketKeys added in v1.5.0 

func (c *Config) SetSessionTicketKeys(keys [][32]byte)

SetSessionTicketKeys updates the session ticket keys for a server.

The first key will be used when creating new tickets, while all keys can be used for decrypting tickets. It is safe to call this function while the server is running in order to rotate the session ticket keys. The function will panic if keys is empty.

Calling this function will turn off automatic session ticket key rotation.

If multiple servers are terminating connections for the same host they should all have the same session ticket keys. If the session ticket keys leaks, previously recorded and future TLS connections using those keys might be compromised.

type Conn 

type Conn struct {
	// contains filtered or unexported fields
}

A Conn represents a secured connection. It implements the net.Conn interface.

func Client 

func Client(conn net.Conn, config *Config) *Conn

Client returns a new TLS client side connection using conn as the underlying transport. The config cannot be nil: users must set either ServerName or InsecureSkipVerify in the config.

func Dial 

func Dial(network, addr string, config *Config) (*Conn, error)

Dial connects to the given network address using net.Dial and then initiates a TLS handshake, returning the resulting TLS connection. Dial interprets a nil configuration as equivalent to the zero configuration; see the documentation of Config for the defaults.

Example 
package main

import (
	"crypto/tls"
	"crypto/x509"
)

func main() {
	// Connecting with a custom root-certificate set.

	const rootPEM = `
-- GlobalSign Root R2, valid until Dec 15, 2021
-----BEGIN CERTIFICATE-----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==
-----END CERTIFICATE-----`

	// First, create the set of root certificates. For this example we only
	// have one. It's also possible to omit this in order to use the
	// default root set of the current operating system.
	roots := x509.NewCertPool()
	ok := roots.AppendCertsFromPEM([]byte(rootPEM))
	if !ok {
		panic("failed to parse root certificate")
	}

	conn, err := tls.Dial("tcp", "mail.google.com:443", &tls.Config{
		RootCAs: roots,
	})
	if err != nil {
		panic("failed to connect: " + err.Error())
	}
	conn.Close()
}

Output:

func DialWithDialer added in v1.3.0 

func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*Conn, error)

DialWithDialer connects to the given network address using dialer.Dial and then initiates a TLS handshake, returning the resulting TLS connection. Any timeout or deadline given in the dialer apply to connection and TLS handshake as a whole.

DialWithDialer interprets a nil configuration as equivalent to the zero configuration; see the documentation of Config for the defaults.

DialWithDialer uses context.Background internally; to specify the context, use Dialer.DialContext with NetDialer set to the desired dialer.

func Server 

func Server(conn net.Conn, config *Config) *Conn

Server returns a new TLS server side connection using conn as the underlying transport. The configuration config must be non-nil and must include at least one certificate or else set GetCertificate.

func (*Conn) Close 

func (c *Conn) Close() error

Close closes the connection.

func (*Conn) CloseWrite added in v1.8.0 

func (c *Conn) CloseWrite() error

CloseWrite shuts down the writing side of the connection. It should only be called once the handshake has completed and does not call CloseWrite on the underlying connection. Most callers should just use Close.

func (*Conn) ConnectionState 

func (c *Conn) ConnectionState() ConnectionState

ConnectionState returns basic TLS details about the connection.

func (*Conn) Handshake 

func (c *Conn) Handshake() error

Handshake runs the client or server handshake protocol if it has not yet been run.

Most uses of this package need not call Handshake explicitly: the first Read or Write will call it automatically.

For control over canceling or setting a timeout on a handshake, use HandshakeContext or the Dialer's DialContext method instead.

In order to avoid denial of service attacks, the maximum RSA key size allowed in certificates sent by either the TLS server or client is limited to 8192 bits. This limit can be overridden by setting tlsmaxrsasize in the GODEBUG environment variable (e.g. GODEBUG=tlsmaxrsasize=4096).

func (*Conn) HandshakeContext added in v1.17.0 

func (c *Conn) HandshakeContext(ctx context.Context) error

HandshakeContext runs the client or server handshake protocol if it has not yet been run.

The provided Context must be non-nil. If the context is canceled before the handshake is complete, the handshake is interrupted and an error is returned. Once the handshake has completed, cancellation of the context will not affect the connection.

Most uses of this package need not call HandshakeContext explicitly: the first Read or Write will call it automatically.

func (*Conn) LocalAddr 

func (c *Conn) LocalAddr() net.Addr

LocalAddr returns the local network address.

func (*Conn) NetConn added in v1.18.0 

func (c *Conn) NetConn() net.Conn

NetConn returns the underlying connection that is wrapped by c. Note that writing to or reading from this connection directly will corrupt the TLS session.

func (*Conn) OCSPResponse 

func (c *Conn) OCSPResponse() []byte

OCSPResponse returns the stapled OCSP response from the TLS server, if any. (Only valid for client connections.)

func (*Conn) Read 

func (c *Conn) Read(b []byte) (int, error)

Read reads data from the connection.

As Read calls Handshake, in order to prevent indefinite blocking a deadline must be set for both Read and Write before Read is called when the handshake has not yet completed. See SetDeadline, SetReadDeadline, and SetWriteDeadline.

func (*Conn) RemoteAddr 

func (c *Conn) RemoteAddr() net.Addr

RemoteAddr returns the remote network address.

func (*Conn) SetDeadline 

func (c *Conn) SetDeadline(t time.Time) error

SetDeadline sets the read and write deadlines associated with the connection. A zero value for t means Read and Write will not time out. After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.

func (*Conn) SetReadDeadline 

func (c *Conn) SetReadDeadline(t time.Time) error

SetReadDeadline sets the read deadline on the underlying connection. A zero value for t means Read will not time out.

func (*Conn) SetWriteDeadline 

func (c *Conn) SetWriteDeadline(t time.Time) error

SetWriteDeadline sets the write deadline on the underlying connection. A zero value for t means Write will not time out. After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.

func (*Conn) VerifyHostname 

func (c *Conn) VerifyHostname(host string) error

VerifyHostname checks that the peer certificate chain is valid for connecting to host. If so, it returns nil; if not, it returns an error describing the problem.

func (*Conn) Write 

func (c *Conn) Write(b []byte) (int, error)

Write writes data to the connection.

As Write calls Handshake, in order to prevent indefinite blocking a deadline must be set for both Read and Write before Write is called when the handshake has not yet completed. See SetDeadline, SetReadDeadline, and SetWriteDeadline.

type ConnectionState 

type ConnectionState struct {
	Version uint16

	HandshakeComplete bool

	DidResume bool

	CipherSuite uint16

	NegotiatedProtocol string

	NegotiatedProtocolIsMutual bool

	ServerName string

	PeerCertificates []*x509.Certificate

	VerifiedChains [][]*x509.Certificate

	SignedCertificateTimestamps [][]byte

	OCSPResponse []byte

	TLSUnique []byte
	// contains filtered or unexported fields
}

ConnectionState records basic TLS details about the connection.

func (*ConnectionState) ExportKeyingMaterial added in v1.11.0 

func (cs *ConnectionState) ExportKeyingMaterial(label string, context []byte, length int) ([]byte, error)

ExportKeyingMaterial returns length bytes of exported key material in a new slice as defined in RFC 5705. If context is nil, it is not used as part of the seed. If the connection was set to allow renegotiation via Config.Renegotiation, this function will return an error.

type CurveID added in v1.3.0 

type CurveID uint16

CurveID is the type of a TLS identifier for an elliptic curve. See https://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-8.

In TLS 1.3, this type is called NamedGroup, but at this time this library only supports Elliptic Curve based groups. See RFC 8446, Section 4.2.7. 

const (
	CurveP256 CurveID = 23
	CurveP384 CurveID = 24
	CurveP521 CurveID = 25
	X25519    CurveID = 29
)

func (CurveID) String added in v1.15.0 

func (i CurveID) String() string

type Dialer added in v1.15.0 

type Dialer struct {
	NetDialer *net.Dialer

	Config *Config
}

Dialer dials TLS connections given a configuration and a Dialer for the underlying connection.

func (*Dialer) Dial added in v1.15.0 

func (d *Dialer) Dial(network, addr string) (net.Conn, error)

Dial connects to the given network address and initiates a TLS handshake, returning the resulting TLS connection.

The returned Conn, if any, will always be of type *Conn.

Dial uses context.Background internally; to specify the context, use DialContext.

func (*Dialer) DialContext added in v1.15.0 

func (d *Dialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error)

DialContext connects to the given network address and initiates a TLS handshake, returning the resulting TLS connection.

The provided Context must be non-nil. If the context expires before the connection is complete, an error is returned. Once successfully connected, any expiration of the context will not affect the connection.

The returned Conn, if any, will always be of type *Conn.

type RecordHeaderError added in v1.6.0 

type RecordHeaderError struct {
	Msg string

	RecordHeader [5]byte

	Conn net.Conn
}

RecordHeaderError is returned when a TLS record header is invalid.

func (RecordHeaderError) Error added in v1.6.0 

func (e RecordHeaderError) Error() string

type RenegotiationSupport added in v1.7.0 

type RenegotiationSupport int

RenegotiationSupport enumerates the different levels of support for TLS renegotiation. TLS renegotiation is the act of performing subsequent handshakes on a connection after the first. This significantly complicates the state machine and has been the source of numerous, subtle security issues. Initiating a renegotiation is not supported, but support for accepting renegotiation requests may be enabled.

Even when enabled, the server may not change its identity between handshakes (i.e. the leaf certificate must be the same). Additionally, concurrent handshake and application data flow is not permitted so renegotiation can only be used with protocols that synchronise with the renegotiation, such as HTTPS.

Renegotiation is not defined in TLS 1.3. 

const (
	// RenegotiateNever disables renegotiation.
	RenegotiateNever RenegotiationSupport = iota

	// RenegotiateOnceAsClient allows a remote server to request
	// renegotiation once per connection.
	RenegotiateOnceAsClient

	// RenegotiateFreelyAsClient allows a remote server to repeatedly
	// request renegotiation.
	RenegotiateFreelyAsClient
)

type SignatureScheme added in v1.8.0 

type SignatureScheme uint16

SignatureScheme identifies a signature algorithm supported by TLS. See RFC 8446, Section 4.2.3. 

const (
	// RSASSA-PKCS1-v1_5 algorithms.
	PKCS1WithSHA256 SignatureScheme = 0x0401
	PKCS1WithSHA384 SignatureScheme = 0x0501
	PKCS1WithSHA512 SignatureScheme = 0x0601

	// RSASSA-PSS algorithms with public key OID rsaEncryption.
	PSSWithSHA256 SignatureScheme = 0x0804
	PSSWithSHA384 SignatureScheme = 0x0805
	PSSWithSHA512 SignatureScheme = 0x0806

	// ECDSA algorithms. Only constrained to a specific curve in TLS 1.3.
	ECDSAWithP256AndSHA256 SignatureScheme = 0x0403
	ECDSAWithP384AndSHA384 SignatureScheme = 0x0503
	ECDSAWithP521AndSHA512 SignatureScheme = 0x0603

	// EdDSA algorithms.
	Ed25519 SignatureScheme = 0x0807

	// Legacy signature and hash algorithms for TLS 1.2.
	PKCS1WithSHA1 SignatureScheme = 0x0201
	ECDSAWithSHA1 SignatureScheme = 0x0203
)

func (SignatureScheme) String added in v1.15.0 

func (i SignatureScheme) String() string

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