providers/ldap: memory Query (#1681)

* outposts/ldap: modularise ldap outpost, to allow different searchers and binders

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

* outposts/ldap: add basic in-memory searcher

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

* providers/ldap: add search mode field

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

* outpost: add search mode field

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

internal/outpost/ldap/ldap_tls.go

@@ -0,0 +1,55 @@
+package ldap
+
+import (
+	"crypto/tls"
+	"net"
+
+	"github.com/pires/go-proxyproto"
+)
+
+func (ls *LDAPServer) getCertificates(info *tls.ClientHelloInfo) (*tls.Certificate, error) {
+	if len(ls.providers) == 1 {
+		if ls.providers[0].cert != nil {
+			ls.log.WithField("server-name", info.ServerName).Debug("We only have a single provider, using their cert")
+			return ls.providers[0].cert, nil
+		}
+	}
+	for _, provider := range ls.providers {
+		if provider.tlsServerName == &info.ServerName {
+			if provider.cert == nil {
+				ls.log.WithField("server-name", info.ServerName).Debug("Handler does not have a certificate")
+				return ls.defaultCert, nil
+			}
+			return provider.cert, nil
+		}
+	}
+	ls.log.WithField("server-name", info.ServerName).Debug("Fallback to default cert")
+	return ls.defaultCert, nil
+}
+
+func (ls *LDAPServer) StartLDAPTLSServer() error {
+	listen := "0.0.0.0:6636"
+	tlsConfig := &tls.Config{
+		MinVersion:     tls.VersionTLS12,
+		MaxVersion:     tls.VersionTLS12,
+		GetCertificate: ls.getCertificates,
+	}
+
+	ln, err := net.Listen("tcp", listen)
+	if err != nil {
+		ls.log.WithField("listen", listen).WithError(err).Fatalf("FATAL: listen failed")
+	}
+
+	proxyListener := &proxyproto.Listener{Listener: ln}
+	defer proxyListener.Close()
+
+	tln := tls.NewListener(proxyListener, tlsConfig)
+
+	ls.log.WithField("listen", listen).Info("Starting ldap tls server")
+	err = ls.s.Serve(tln)
+	if err != nil {
+		return err
+	}
+	ls.log.Printf("closing %s", ln.Addr())
+	return ls.s.ListenAndServe(listen)
+}