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tlsClientHeaders.go
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tlsClientHeaders.go
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package middlewares
import (
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"net/http"
"net/url"
"strings"
"github.com/containous/traefik/log"
"github.com/containous/traefik/types"
)
const (
xForwardedTLSClientCert = "X-Forwarded-Tls-Client-Cert"
xForwardedTLSClientCertInfos = "X-Forwarded-Tls-Client-Cert-Infos"
)
var attributeTypeNames = map[string]string{
"0.9.2342.19200300.100.1.25": "DC", // Domain component OID - RFC 2247
}
// TLSClientCertificateInfos is a struct for specifying the configuration for the tlsClientHeaders middleware.
type TLSClientCertificateInfos struct {
Issuer *DistinguishedNameOptions
NotAfter bool
NotBefore bool
Sans bool
Subject *DistinguishedNameOptions
}
// DistinguishedNameOptions is a struct for specifying the configuration for the distinguished name info.
type DistinguishedNameOptions struct {
CommonName bool
CountryName bool
DomainComponent bool
LocalityName bool
OrganizationName bool
SerialNumber bool
StateOrProvinceName bool
}
// TLSClientHeaders is a middleware that helps setup a few tls info features.
type TLSClientHeaders struct {
Infos *TLSClientCertificateInfos // pass selected informations from the client certificate
PEM bool // pass the sanitized pem to the backend in a specific header
}
func newDistinguishedNameOptions(infos *types.TLSCLientCertificateDNInfos) *DistinguishedNameOptions {
if infos == nil {
return nil
}
return &DistinguishedNameOptions{
CommonName: infos.CommonName,
CountryName: infos.Country,
DomainComponent: infos.DomainComponent,
LocalityName: infos.Locality,
OrganizationName: infos.Organization,
SerialNumber: infos.SerialNumber,
StateOrProvinceName: infos.Province,
}
}
func newTLSClientInfos(infos *types.TLSClientCertificateInfos) *TLSClientCertificateInfos {
if infos == nil {
return nil
}
return &TLSClientCertificateInfos{
Issuer: newDistinguishedNameOptions(infos.Issuer),
NotAfter: infos.NotAfter,
NotBefore: infos.NotBefore,
Sans: infos.Sans,
Subject: newDistinguishedNameOptions(infos.Subject),
}
}
// NewTLSClientHeaders constructs a new TLSClientHeaders instance from supplied frontend header struct.
func NewTLSClientHeaders(frontend *types.Frontend) *TLSClientHeaders {
if frontend == nil {
return nil
}
var addPEM bool
var infos *TLSClientCertificateInfos
if frontend.PassTLSClientCert != nil {
conf := frontend.PassTLSClientCert
addPEM = conf.PEM
infos = newTLSClientInfos(conf.Infos)
}
return &TLSClientHeaders{
Infos: infos,
PEM: addPEM,
}
}
func (s *TLSClientHeaders) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
s.ModifyRequestHeaders(r)
// If there is a next, call it.
if next != nil {
next(w, r)
}
}
// sanitize As we pass the raw certificates, remove the useless data and make it http request compliant
func sanitize(cert []byte) string {
s := string(cert)
r := strings.NewReplacer("-----BEGIN CERTIFICATE-----", "",
"-----END CERTIFICATE-----", "",
"\n", "")
cleaned := r.Replace(s)
return url.QueryEscape(cleaned)
}
// extractCertificate extract the certificate from the request
func extractCertificate(cert *x509.Certificate) string {
b := pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw}
certPEM := pem.EncodeToMemory(&b)
if certPEM == nil {
log.Error("Cannot extract the certificate content")
return ""
}
return sanitize(certPEM)
}
// getXForwardedTLSClientCert Build a string with the client certificates
func getXForwardedTLSClientCert(certs []*x509.Certificate) string {
var headerValues []string
for _, peerCert := range certs {
headerValues = append(headerValues, extractCertificate(peerCert))
}
return strings.Join(headerValues, ",")
}
// getSANs get the Subject Alternate Name values
func getSANs(cert *x509.Certificate) []string {
var sans []string
if cert == nil {
return sans
}
sans = append(cert.DNSNames, cert.EmailAddresses...)
var ips []string
for _, ip := range cert.IPAddresses {
ips = append(ips, ip.String())
}
sans = append(sans, ips...)
var uris []string
for _, uri := range cert.URIs {
uris = append(uris, uri.String())
}
return append(sans, uris...)
}
func getDNInfos(prefix string, options *DistinguishedNameOptions, cs *pkix.Name) string {
if options == nil {
return ""
}
content := &strings.Builder{}
// Manage non standard attributes
for _, name := range cs.Names {
// Domain Component - RFC 2247
if options.DomainComponent && attributeTypeNames[name.Type.String()] == "DC" {
content.WriteString(fmt.Sprintf("DC=%s,", name.Value))
}
}
if options.CountryName {
writeParts(content, cs.Country, "C")
}
if options.StateOrProvinceName {
writeParts(content, cs.Province, "ST")
}
if options.LocalityName {
writeParts(content, cs.Locality, "L")
}
if options.OrganizationName {
writeParts(content, cs.Organization, "O")
}
if options.SerialNumber {
writePart(content, cs.SerialNumber, "SN")
}
if options.CommonName {
writePart(content, cs.CommonName, "CN")
}
if content.Len() > 0 {
return prefix + `="` + strings.TrimSuffix(content.String(), ",") + `"`
}
return ""
}
func writeParts(content *strings.Builder, entries []string, prefix string) {
for _, entry := range entries {
writePart(content, entry, prefix)
}
}
func writePart(content *strings.Builder, entry string, prefix string) {
if len(entry) > 0 {
content.WriteString(fmt.Sprintf("%s=%s,", prefix, entry))
}
}
// getXForwardedTLSClientCertInfo Build a string with the wanted client certificates informations
// like Subject="DC=%s,C=%s,ST=%s,L=%s,O=%s,CN=%s",NB=%d,NA=%d,SAN=%s;
func (s *TLSClientHeaders) getXForwardedTLSClientCertInfo(certs []*x509.Certificate) string {
var headerValues []string
for _, peerCert := range certs {
var values []string
var sans string
var nb string
var na string
if s.Infos != nil {
subject := getDNInfos("Subject", s.Infos.Subject, &peerCert.Subject)
if len(subject) > 0 {
values = append(values, subject)
}
issuer := getDNInfos("Issuer", s.Infos.Issuer, &peerCert.Issuer)
if len(issuer) > 0 {
values = append(values, issuer)
}
}
ci := s.Infos
if ci != nil {
if ci.NotBefore {
nb = fmt.Sprintf("NB=%d", uint64(peerCert.NotBefore.Unix()))
values = append(values, nb)
}
if ci.NotAfter {
na = fmt.Sprintf("NA=%d", uint64(peerCert.NotAfter.Unix()))
values = append(values, na)
}
if ci.Sans {
sans = fmt.Sprintf("SAN=%s", strings.Join(getSANs(peerCert), ","))
values = append(values, sans)
}
}
value := strings.Join(values, ",")
headerValues = append(headerValues, value)
}
return strings.Join(headerValues, ";")
}
// ModifyRequestHeaders set the wanted headers with the certificates informations
func (s *TLSClientHeaders) ModifyRequestHeaders(r *http.Request) {
if s.PEM {
if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
r.Header.Set(xForwardedTLSClientCert, getXForwardedTLSClientCert(r.TLS.PeerCertificates))
} else {
log.Warn("Try to extract certificate on a request without TLS")
}
}
if s.Infos != nil {
if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
headerContent := s.getXForwardedTLSClientCertInfo(r.TLS.PeerCertificates)
r.Header.Set(xForwardedTLSClientCertInfos, url.QueryEscape(headerContent))
} else {
log.Warn("Try to extract certificate on a request without TLS")
}
}
}