Method getCertificate

common.go:1296–1337

getCertificate returns the best certificate for the given ClientHelloInfo, defaulting to the first element of c.Certificates.

(clientHello *ClientHelloInfo)

// getCertificate returns the best certificate for the given ClientHelloInfo,
// defaulting to the first element of c.Certificates.
func (c *Config) getCertificate(clientHello *ClientHelloInfo) (*Certificate, error) {
	if c.GetCertificate != nil &&
		(len(c.Certificates) == 0 || len(clientHello.ServerName) > 0) {
		cert, err := c.GetCertificate(clientHello)
		if cert != nil || err != nil {
			return cert, err
		}
	}

	if len(c.Certificates) == 0 {
		return nil, errNoCertificates
	}

	if len(c.Certificates) == 1 {
		// There's only one choice, so no point doing any work.
		return &c.Certificates[0], nil
	}

	if c.NameToCertificate != nil {
		name := strings.ToLower(clientHello.ServerName)
		if cert, ok := c.NameToCertificate[name]; ok {
			return cert, nil
		}
		if len(name) > 0 {
			labels := strings.Split(name, ".")
			labels[0] = "*"
			wildcardName := strings.Join(labels, ".")
			if cert, ok := c.NameToCertificate[wildcardName]; ok {
				return cert, nil
			}
		}
	}

	for _, cert := range c.Certificates {
		if err := clientHello.SupportsCertificate(&cert); err == nil {
			return &cert, nil
		}
	}

	// If nothing matches, return the first certificate.
	return &c.Certificates[0], nil
}

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