NOTE: The patch has been adjusted to match the base code before backporting.

From 16f8b0902c28b1eaab93ddf120ce40b89bcda8d1 Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@openldap.org>
Date: Tue, 10 Sep 2013 04:26:51 -0700
Subject: [PATCH] ITS#7398 add LDAP_OPT_X_TLS_PEERCERT

retrieve peer cert for an active TLS session
---
 doc/man/man3/ldap_get_option.3 |  8 ++++++++
 include/ldap.h                 |  1 +
 libraries/libldap/ldap-tls.h   |  2 ++
 libraries/libldap/tls2.c       | 23 +++++++++++++++++++++++
 libraries/libldap/tls_g.c      | 19 +++++++++++++++++++
 libraries/libldap/tls_m.c      | 17 +++++++++++++++++
 libraries/libldap/tls_o.c      | 16 ++++++++++++++++
 7 files changed, 86 insertions(+)

diff --git a/doc/man/man3/ldap_get_option.3 b/doc/man/man3/ldap_get_option.3
index e67de75e9..1bb55d357 100644
--- a/doc/man/man3/ldap_get_option.3
+++ b/doc/man/man3/ldap_get_option.3
@@ -732,6 +732,14 @@ A non-zero value pointed to by
 .BR invalue
 tells the library to create a context for a server.
 .TP
+.B LDAP_OPT_X_TLS_PEERCERT
+Gets the peer's certificate in DER format from an established TLS session.
+.BR outvalue
+must be
+.BR "struct berval *" ,
+and the data it returns needs to be freed by the caller using
+.BR ldap_memfree (3).
+.TP
 .B LDAP_OPT_X_TLS_PROTOCOL_MIN
 Sets/gets the minimum protocol version.
 .BR invalue
diff --git a/include/ldap.h b/include/ldap.h
index 4de3f7f32..97ca524d7 100644
--- a/include/ldap.h
+++ b/include/ldap.h
@@ -161,6 +161,7 @@ LDAP_BEGIN_DECL
 #define LDAP_OPT_X_TLS_CRLFILE		0x6010	/* GNUtls only */
 #define LDAP_OPT_X_TLS_PACKAGE		0x6011
 #define LDAP_OPT_X_TLS_ECNAME		0x6012
+#define LDAP_OPT_X_TLS_PEERCERT		0x6015	/* read-only */
 
 #define LDAP_OPT_X_TLS_NEVER	0
 #define LDAP_OPT_X_TLS_HARD		1
diff --git a/libraries/libldap/ldap-tls.h b/libraries/libldap/ldap-tls.h
index 548814d7f..890d20dc7 100644
--- a/libraries/libldap/ldap-tls.h
+++ b/libraries/libldap/ldap-tls.h
@@ -43,6 +43,7 @@ typedef int (TI_session_dn)(tls_session *sess, struct berval *dn);
 typedef int (TI_session_chkhost)(LDAP *ld, tls_session *s, const char *name_in);
 typedef int (TI_session_strength)(tls_session *sess);
 typedef int (TI_session_unique)(tls_session *sess, struct berval *buf, int is_server);
+typedef int (TI_session_peercert)(tls_session *s, struct berval *der);
 
 typedef void (TI_thr_init)(void);
 
@@ -69,6 +70,7 @@ typedef struct tls_impl {
	TI_session_chkhost *ti_session_chkhost;
	TI_session_strength *ti_session_strength;
 	TI_session_unique *ti_session_unique;
+	TI_session_peercert *ti_session_peercert;
 
 	Sockbuf_IO *ti_sbio;
 
diff --git a/libraries/libldap/tls2.c b/libraries/libldap/tls2.c
index 05fce3218..cbf73bdd5 100644
--- a/libraries/libldap/tls2.c
+++ b/libraries/libldap/tls2.c
@@ -718,6 +718,23 @@ ldap_pvt_tls_get_option( LDAP *ld, int option, void *arg )
 	case LDAP_OPT_X_TLS_CONNECT_ARG:
 		*(void **)arg = lo->ldo_tls_connect_arg;
 		break;
+	case LDAP_OPT_X_TLS_PEERCERT: {
+		void *sess = NULL;
+		struct berval *bv = arg;
+		bv->bv_len = 0;
+		bv->bv_val = NULL;
+		if ( ld != NULL ) {
+			LDAPConn *conn = ld->ld_defconn;
+			if ( conn != NULL ) {
+				Sockbuf *sb = conn->lconn_sb;
+				sess = ldap_pvt_tls_sb_ctx( sb );
+				if ( sess != NULL )
+					return ldap_pvt_tls_get_peercert( sess, bv );
+			}
+		}
+		break;
+	}
+
 	default:
 		return -1;
 	}
@@ -1050,6 +1066,13 @@ ldap_pvt_tls_get_unique( void *s, struct berval *buf, int is_server )
 	tls_session *session = s;
 	return tls_imp->ti_session_unique( session, buf, is_server );
 }
+
+int
+ldap_pvt_tls_get_peercert( void *s, struct berval *der )
+{
+	tls_session *session = s;
+	return tls_imp->ti_session_peercert( session, der );
+}
 #endif /* HAVE_TLS */
 
 int
diff --git a/libraries/libldap/tls_g.c b/libraries/libldap/tls_g.c
index ce422387c..739680439 100644
--- a/libraries/libldap/tls_g.c
+++ b/libraries/libldap/tls_g.c
@@ -830,6 +830,24 @@ tlsg_session_unique( tls_session *sess, struct berval *buf, int is_server)
 	return 0;
 }
 
+static int
+tlsg_session_peercert( tls_session *sess, struct berval *der )
+{
+	tlsg_session *s = (tlsg_session *)sess;
+	const gnutls_datum_t *peer_cert_list;
+	unsigned int list_size;
+
+	peer_cert_list = gnutls_certificate_get_peers( s->session, &list_size );
+	if (!peer_cert_list)
+		return -1;
+	der->bv_len = peer_cert_list[0].size;
+	der->bv_val = LDAP_MALLOC( der->bv_len );
+	if (!der->bv_val)
+		return -1;
+	memcpy(der->bv_val, peer_cert_list[0].data, der->bv_len);
+	return 0;
+}
+
 /* suites is a string of colon-separated cipher suite names. */
 static int
 tlsg_parse_ciphers( tlsg_ctx *ctx, char *suites )
@@ -1166,6 +1184,7 @@ tls_impl ldap_int_tls_impl = {
 	tlsg_session_chkhost,
 	tlsg_session_strength,
 	tlsg_session_unique,
+	tlsg_session_peercert,
 
 	&tlsg_sbio,
 
diff --git a/libraries/libldap/tls_m.c b/libraries/libldap/tls_m.c
index 4bd9e63cb..36dc989ef 100644
--- a/libraries/libldap/tls_m.c
+++ b/libraries/libldap/tls_m.c
@@ -2891,6 +2891,22 @@ tlsm_session_unique( tls_session *sess, struct berval *buf, int is_server)
 	return 0;
 }
 
+static int
+tlsm_session_peercert( tls_session *sess, struct berval *der )
+{
+	tlsm_session *s = (tlsm_session *)sess;
+	CERTCertificate *cert;
+	cert = SSL_PeerCertificate( s );
+	if (!cert)
+		return -1;
+	der->bv_len = cert->derCert.len;
+	der->bv_val = LDAP_MALLOC( der->bv_len );
+	if (!der->bv_val)
+		return -1;
+	memcpy( der->bv_val, cert->derCert.data, der->bv_len );
+	return 0;
+}
+
 /*
  * TLS support for LBER Sockbufs
  */
@@ -3322,6 +3338,7 @@ tls_impl ldap_int_tls_impl = {
 	tlsm_session_chkhost,
 	tlsm_session_strength,
 	tlsm_session_unique,
+	tlsm_session_peercert,
 
 	&tlsm_sbio,
 
diff --git a/libraries/libldap/tls_o.c b/libraries/libldap/tls_o.c
index 6288456d3..1fa50392f 100644
--- a/libraries/libldap/tls_o.c
+++ b/libraries/libldap/tls_o.c
@@ -721,6 +721,21 @@ tlso_session_unique( tls_session *sess, struct berval *buf, int is_server)
 	return buf->bv_len;
 }
 
+static int
+tlso_session_peercert( tls_session *sess, struct berval *der )
+{
+	tlso_session *s = (tlso_session *)sess;
+	unsigned char *ptr;
+	X509 *x = SSL_get_peer_certificate(s);
+	der->bv_len = i2d_X509(x, NULL);
+	der->bv_val = LDAP_MALLOC(der->bv_len);
+	if ( !der->bv_val )
+		return -1;
+	ptr = der->bv_val;
+	i2d_X509(x, &ptr);
+	return 0;
+}
+
 /*
  * TLS support for LBER Sockbufs
  */
@@ -1229,6 +1244,7 @@ tls_impl ldap_int_tls_impl = {
 	tlso_session_chkhost,
 	tlso_session_strength,
 	tlso_session_unique,
+	tlso_session_peercert,
 
 	&tlso_sbio,
 
-- 
2.26.2