Update vendor github.com/lib/pq (#2752)

vendor/github.com/lib/pq/ssl.go

@@ -0,0 +1,158 @@
+package pq
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"io/ioutil"
+	"net"
+	"os"
+	"os/user"
+	"path/filepath"
+)
+
+// ssl generates a function to upgrade a net.Conn based on the "sslmode" and
+// related settings. The function is nil when no upgrade should take place.
+func ssl(o values) func(net.Conn) net.Conn {
+	verifyCaOnly := false
+	tlsConf := tls.Config{}
+	switch mode := o["sslmode"]; mode {
+	// "require" is the default.
+	case "", "require":
+		// We must skip TLS's own verification since it requires full
+		// verification since Go 1.3.
+		tlsConf.InsecureSkipVerify = true
+
+		// From http://www.postgresql.org/docs/current/static/libpq-ssl.html:
+		//
+		// Note: For backwards compatibility with earlier versions of
+		// PostgreSQL, if a root CA file exists, the behavior of
+		// sslmode=require will be the same as that of verify-ca, meaning the
+		// server certificate is validated against the CA. Relying on this
+		// behavior is discouraged, and applications that need certificate
+		// validation should always use verify-ca or verify-full.
+		if sslrootcert, ok := o["sslrootcert"]; ok {
+			if _, err := os.Stat(sslrootcert); err == nil {
+				verifyCaOnly = true
+			} else {
+				delete(o, "sslrootcert")
+			}
+		}
+	case "verify-ca":
+		// We must skip TLS's own verification since it requires full
+		// verification since Go 1.3.
+		tlsConf.InsecureSkipVerify = true
+		verifyCaOnly = true
+	case "verify-full":
+		tlsConf.ServerName = o["host"]
+	case "disable":
+		return nil
+	default:
+		errorf(`unsupported sslmode %q; only "require" (default), "verify-full", "verify-ca", and "disable" supported`, mode)
+	}
+
+	sslClientCertificates(&tlsConf, o)
+	sslCertificateAuthority(&tlsConf, o)
+	sslRenegotiation(&tlsConf)
+
+	return func(conn net.Conn) net.Conn {
+		client := tls.Client(conn, &tlsConf)
+		if verifyCaOnly {
+			sslVerifyCertificateAuthority(client, &tlsConf)
+		}
+		return client
+	}
+}
+
+// sslClientCertificates adds the certificate specified in the "sslcert" and
+// "sslkey" settings, or if they aren't set, from the .postgresql directory
+// in the user's home directory. The configured files must exist and have
+// the correct permissions.
+func sslClientCertificates(tlsConf *tls.Config, o values) {
+	// user.Current() might fail when cross-compiling. We have to ignore the
+	// error and continue without home directory defaults, since we wouldn't
+	// know from where to load them.
+	user, _ := user.Current()
+
+	// In libpq, the client certificate is only loaded if the setting is not blank.
+	//
+	// https://github.com/postgres/postgres/blob/REL9_6_2/src/interfaces/libpq/fe-secure-openssl.c#L1036-L1037
+	sslcert := o["sslcert"]
+	if len(sslcert) == 0 && user != nil {
+		sslcert = filepath.Join(user.HomeDir, ".postgresql", "postgresql.crt")
+	}
+	// https://github.com/postgres/postgres/blob/REL9_6_2/src/interfaces/libpq/fe-secure-openssl.c#L1045
+	if len(sslcert) == 0 {
+		return
+	}
+	// https://github.com/postgres/postgres/blob/REL9_6_2/src/interfaces/libpq/fe-secure-openssl.c#L1050:L1054
+	if _, err := os.Stat(sslcert); os.IsNotExist(err) {
+		return
+	} else if err != nil {
+		panic(err)
+	}
+
+	// In libpq, the ssl key is only loaded if the setting is not blank.
+	//
+	// https://github.com/postgres/postgres/blob/REL9_6_2/src/interfaces/libpq/fe-secure-openssl.c#L1123-L1222
+	sslkey := o["sslkey"]
+	if len(sslkey) == 0 && user != nil {
+		sslkey = filepath.Join(user.HomeDir, ".postgresql", "postgresql.key")
+	}
+
+	if len(sslkey) > 0 {
+		if err := sslKeyPermissions(sslkey); err != nil {
+			panic(err)
+		}
+	}
+
+	cert, err := tls.LoadX509KeyPair(sslcert, sslkey)
+	if err != nil {
+		panic(err)
+	}
+	tlsConf.Certificates = []tls.Certificate{cert}
+}
+
+// sslCertificateAuthority adds the RootCA specified in the "sslrootcert" setting.
+func sslCertificateAuthority(tlsConf *tls.Config, o values) {
+	// In libpq, the root certificate is only loaded if the setting is not blank.
+	//
+	// https://github.com/postgres/postgres/blob/REL9_6_2/src/interfaces/libpq/fe-secure-openssl.c#L950-L951
+	if sslrootcert := o["sslrootcert"]; len(sslrootcert) > 0 {
+		tlsConf.RootCAs = x509.NewCertPool()
+
+		cert, err := ioutil.ReadFile(sslrootcert)
+		if err != nil {
+			panic(err)
+		}
+
+		if !tlsConf.RootCAs.AppendCertsFromPEM(cert) {
+			errorf("couldn't parse pem in sslrootcert")
+		}
+	}
+}
+
+// sslVerifyCertificateAuthority carries out a TLS handshake to the server and
+// verifies the presented certificate against the CA, i.e. the one specified in
+// sslrootcert or the system CA if sslrootcert was not specified.
+func sslVerifyCertificateAuthority(client *tls.Conn, tlsConf *tls.Config) {
+	err := client.Handshake()
+	if err != nil {
+		panic(err)
+	}
+	certs := client.ConnectionState().PeerCertificates
+	opts := x509.VerifyOptions{
+		DNSName:       client.ConnectionState().ServerName,
+		Intermediates: x509.NewCertPool(),
+		Roots:         tlsConf.RootCAs,
+	}
+	for i, cert := range certs {
+		if i == 0 {
+			continue
+		}
+		opts.Intermediates.AddCert(cert)
+	}
+	_, err = certs[0].Verify(opts)
+	if err != nil {
+		panic(err)
+	}
+}