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server/vendor/github.com/pion/dtls/v2/certificate.go

@@ -0,0 +1,157 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package dtls
+
+import (
+	"bytes"
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"strings"
+)
+
+// ClientHelloInfo contains information from a ClientHello message in order to
+// guide application logic in the GetCertificate.
+type ClientHelloInfo struct {
+	// ServerName indicates the name of the server requested by the client
+	// in order to support virtual hosting. ServerName is only set if the
+	// client is using SNI (see RFC 4366, Section 3.1).
+	ServerName string
+
+	// CipherSuites lists the CipherSuites supported by the client (e.g.
+	// TLS_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256).
+	CipherSuites []CipherSuiteID
+}
+
+// CertificateRequestInfo contains information from a server's
+// CertificateRequest message, which is used to demand a certificate and proof
+// of control from a client.
+type CertificateRequestInfo struct {
+	// AcceptableCAs contains zero or more, DER-encoded, X.501
+	// Distinguished Names. These are the names of root or intermediate CAs
+	// that the server wishes the returned certificate to be signed by. An
+	// empty slice indicates that the server has no preference.
+	AcceptableCAs [][]byte
+}
+
+// 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.
+// NOTE: original src: https://github.com/golang/go/blob/29b9a328d268d53833d2cc063d1d8b4bf6852675/src/crypto/tls/common.go#L1273
+func (cri *CertificateRequestInfo) SupportsCertificate(c *tls.Certificate) error {
+	if len(cri.AcceptableCAs) == 0 {
+		return nil
+	}
+
+	for j, cert := range c.Certificate {
+		x509Cert := c.Leaf
+		// Parse the certificate if this isn't the leaf node, or if
+		// chain.Leaf was nil.
+		if j != 0 || x509Cert == nil {
+			var err error
+			if x509Cert, err = x509.ParseCertificate(cert); err != nil {
+				return fmt.Errorf("failed to parse certificate #%d in the chain: %w", j, err)
+			}
+		}
+
+		for _, ca := range cri.AcceptableCAs {
+			if bytes.Equal(x509Cert.RawIssuer, ca) {
+				return nil
+			}
+		}
+	}
+	return errNotAcceptableCertificateChain
+}
+
+func (c *handshakeConfig) setNameToCertificateLocked() {
+	nameToCertificate := make(map[string]*tls.Certificate)
+	for i := range c.localCertificates {
+		cert := &c.localCertificates[i]
+		x509Cert := cert.Leaf
+		if x509Cert == nil {
+			var parseErr error
+			x509Cert, parseErr = x509.ParseCertificate(cert.Certificate[0])
+			if parseErr != nil {
+				continue
+			}
+		}
+		if len(x509Cert.Subject.CommonName) > 0 {
+			nameToCertificate[strings.ToLower(x509Cert.Subject.CommonName)] = cert
+		}
+		for _, san := range x509Cert.DNSNames {
+			nameToCertificate[strings.ToLower(san)] = cert
+		}
+	}
+	c.nameToCertificate = nameToCertificate
+}
+
+func (c *handshakeConfig) getCertificate(clientHelloInfo *ClientHelloInfo) (*tls.Certificate, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.localGetCertificate != nil &&
+		(len(c.localCertificates) == 0 || len(clientHelloInfo.ServerName) > 0) {
+		cert, err := c.localGetCertificate(clientHelloInfo)
+		if cert != nil || err != nil {
+			return cert, err
+		}
+	}
+
+	if c.nameToCertificate == nil {
+		c.setNameToCertificateLocked()
+	}
+
+	if len(c.localCertificates) == 0 {
+		return nil, errNoCertificates
+	}
+
+	if len(c.localCertificates) == 1 {
+		// There's only one choice, so no point doing any work.
+		return &c.localCertificates[0], nil
+	}
+
+	if len(clientHelloInfo.ServerName) == 0 {
+		return &c.localCertificates[0], nil
+	}
+
+	name := strings.TrimRight(strings.ToLower(clientHelloInfo.ServerName), ".")
+
+	if cert, ok := c.nameToCertificate[name]; ok {
+		return cert, nil
+	}
+
+	// try replacing labels in the name with wildcards until we get a
+	// match.
+	labels := strings.Split(name, ".")
+	for i := range labels {
+		labels[i] = "*"
+		candidate := strings.Join(labels, ".")
+		if cert, ok := c.nameToCertificate[candidate]; ok {
+			return cert, nil
+		}
+	}
+
+	// If nothing matches, return the first certificate.
+	return &c.localCertificates[0], nil
+}
+
+// NOTE: original src: https://github.com/golang/go/blob/29b9a328d268d53833d2cc063d1d8b4bf6852675/src/crypto/tls/handshake_client.go#L974
+func (c *handshakeConfig) getClientCertificate(cri *CertificateRequestInfo) (*tls.Certificate, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.localGetClientCertificate != nil {
+		return c.localGetClientCertificate(cri)
+	}
+
+	for i := range c.localCertificates {
+		chain := c.localCertificates[i]
+		if err := cri.SupportsCertificate(&chain); err != nil {
+			continue
+		}
+		return &chain, nil
+	}
+
+	// No acceptable certificate found. Don't send a certificate.
+	return new(tls.Certificate), nil
+}