Construct the early_data extension

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2737)

include/openssl/ssl.h

@@ -2330,6 +2330,7 @@ int ERR_load_SSL_strings(void);
 # define SSL_F_TLS_CONSTRUCT_CLIENT_VERIFY                489
 # define SSL_F_TLS_CONSTRUCT_CTOS_ALPN                    466
 # define SSL_F_TLS_CONSTRUCT_CTOS_CERTIFICATE             355
+# define SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA              521
 # define SSL_F_TLS_CONSTRUCT_CTOS_EC_PT_FORMATS           467
 # define SSL_F_TLS_CONSTRUCT_CTOS_EMS                     468
 # define SSL_F_TLS_CONSTRUCT_CTOS_ETM                     469

include/openssl/tls1.h

@@ -179,6 +179,7 @@ extern "C" {
 /* As defined for TLS1.3 */
 # define TLSEXT_TYPE_key_share                   40
 # define TLSEXT_TYPE_psk                         41
+# define TLSEXT_TYPE_early_data                  42
 # define TLSEXT_TYPE_supported_versions          43
 # define TLSEXT_TYPE_psk_kex_modes               45
 # define TLSEXT_TYPE_early_data_info             46

ssl/ssl_err.c

@@ -301,6 +301,8 @@ static ERR_STRING_DATA SSL_str_functs[] = {
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CTOS_ALPN), "tls_construct_ctos_alpn"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CTOS_CERTIFICATE),
      "TLS_CONSTRUCT_CTOS_CERTIFICATE"},
+    {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA),
+     "tls_construct_ctos_early_data"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CTOS_EC_PT_FORMATS),
      "tls_construct_ctos_ec_pt_formats"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CTOS_EMS), "tls_construct_ctos_ems"},

ssl/ssl_locl.h

@@ -1746,6 +1746,7 @@ typedef enum tlsext_index_en {
     TLSEXT_IDX_server_name,
     TLSEXT_IDX_srp,
     TLSEXT_IDX_early_data_info,
+    TLSEXT_IDX_early_data,
     TLSEXT_IDX_ec_point_formats,
     TLSEXT_IDX_supported_groups,
     TLSEXT_IDX_session_ticket,

ssl/statem/extensions.c

@@ -135,6 +135,11 @@ static const EXTENSION_DEFINITION ext_defs[] = {
         NULL, NULL, tls_parse_stoc_early_data_info,
         tls_construct_stoc_early_data_info, NULL, NULL
     },
+    {
+        TLSEXT_TYPE_early_data,
+        EXT_CLIENT_HELLO | EXT_TLS1_3_ENCRYPTED_EXTENSIONS,
+        NULL, NULL, NULL, NULL, tls_construct_ctos_early_data, NULL
+    },
 #ifndef OPENSSL_NO_EC
     {
         TLSEXT_TYPE_ec_point_formats,

ssl/statem/extensions_clnt.c

@@ -108,6 +108,26 @@ static int use_ecc(SSL *s)
     return i < end;
 }
 
+int tls_construct_ctos_early_data(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx, int *al)
+{
+    if (s->early_data_state != SSL_EARLY_DATA_CONNECTING
+            || s->session->ext.max_early_data == 0) {
+        s->max_early_data = 0;
+        return 1;
+    }
+    s->max_early_data = s->session->ext.max_early_data;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_early_data)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
 int tls_construct_ctos_ec_pt_formats(SSL *s, WPACKET *pkt, unsigned int context,
                                      X509 *x, size_t chainidx, int *al)
 {

ssl/statem/statem_locl.h

@@ -288,6 +288,8 @@ int tls_construct_ctos_supported_groups(SSL *s, WPACKET *pkt,
                                         unsigned int context, X509 *x,
                                         size_t chainidx, int *al);
 #endif
+int tls_construct_ctos_early_data(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx, int *al);
 int tls_construct_ctos_session_ticket(SSL *s, WPACKET *pkt,
                                       unsigned int context, X509 *x,
                                       size_t chainidx, int *al);

ssl/t1_trce.c

@@ -476,7 +476,8 @@ static ssl_trace_tbl ssl_exts_tbl[] = {
     {TLSEXT_TYPE_padding, "padding"},
     {TLSEXT_TYPE_encrypt_then_mac, "encrypt_then_mac"},
     {TLSEXT_TYPE_extended_master_secret, "extended_master_secret"},
-    {TLSEXT_TYPE_early_data_info, "ticket_early_data_info"}
+    {TLSEXT_TYPE_early_data_info, "ticket_early_data_info"},
+    {TLSEXT_TYPE_early_data, "early_data"}
 };
 
 static ssl_trace_tbl ssl_groups_tbl[] = {