Add max_early_data_size option for ssl_sever2

- to set max_early_data_set
- to set callback for received data

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>

programs/ssl/ssl_server2.c

@@ -129,6 +129,7 @@ int main( void )
 #define DFL_SNI                 NULL
 #define DFL_ALPN_STRING         NULL
 #define DFL_CURVES              NULL
+#define DFL_MAX_EARLY_DATA_SIZE 0
 #define DFL_SIG_ALGS            NULL
 #define DFL_DHM_FILE            NULL
 #define DFL_TRANSPORT           MBEDTLS_SSL_TRANSPORT_STREAM
@@ -424,6 +425,16 @@ int main( void )
 #define USAGE_ECJPAKE ""
 #endif
 
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+#define USAGE_EARLY_DATA \
+    "    max_early_data_size=%%d default: 0 (disabled)\n"             \
+    "                            options: 0     (disabled), "           \
+    "                                     -1    (enabled, builtin max size), " \
+    "                                     n > 0 (enabled, max amount data for 0-RTT )\n"
+#else
+#define USAGE_EARLY_DATA ""
+#endif /* MBEDTLS_SSL_EARLY_DATA */
+
 #if defined(MBEDTLS_ECP_C)
 #define USAGE_CURVES \
     "    curves=a,b,c,d      default: \"default\" (library default)\n"  \
@@ -680,6 +691,7 @@ struct options
     const char *cid_val_renego; /* the CID to use for incoming messages
                                  * after renegotiation                      */
     int reproducible;           /* make communication reproducible          */
+    uint32_t max_early_data_size; /* max amount early data                   */
     int query_config_mode;      /* whether to read config                   */
     int use_srtp;               /* Support SRTP                             */
     int force_srtp_profile;     /* SRTP protection profile to use or all    */
@@ -1027,6 +1039,38 @@ int psk_callback( void *p_info, mbedtls_ssl_context *ssl,
 }
 #endif /* MBEDTLS_SSL_HANDSHAKE_WITH_PSK_ENABLED */
 
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+/*
+* Early data callback.
+*/
+static unsigned char early_data_buffer[MBEDTLS_SSL_MAX_EARLY_DATA_SIZE];
+static int head = tail = 0;
+static int early_data_write_cb( void *context,
+                         const unsigned char *buffer,
+                         size_t len )
+{
+    if( len > MBEDTLS_SSL_MAX_EARLY_DATA_SIZE - tail)
+        len = MBEDTLS_SSL_MAX_EARLY_DATA_SIZE - tail;
+
+    if(len)
+        memcpy( &early_data_buffer, buffer, len );
+    tail += len;
+    return((int) len);
+}
+int early_data_read_cb( void *context,
+                         const unsigned char *buffer,
+                         size_t len )
+{
+    if( len > tail - head )
+        len = tail - head;
+
+    if(len && buffer )
+        memcpy( buffer, &early_data_buffer, len );
+    head += len;
+    return((int) len);
+}
+#endif /* MBEDTLS_SSL_EARLY_DATA */
+
 static mbedtls_net_context listen_fd, client_fd;
 
 /* Interruption handler to ensure clean exit (for valgrind testing) */
@@ -1695,6 +1739,7 @@ int main( int argc, char *argv[] )
     opt.sni                 = DFL_SNI;
     opt.alpn_string         = DFL_ALPN_STRING;
     opt.curves              = DFL_CURVES;
+    opt.max_early_data_size = DFL_MAX_EARLY_DATA_SIZE;
     opt.sig_algs            = DFL_SIG_ALGS;
     opt.dhm_file            = DFL_DHM_FILE;
     opt.transport           = DFL_TRANSPORT;
@@ -1891,6 +1936,12 @@ int main( int argc, char *argv[] )
         else if( strcmp( p, "sig_algs" ) == 0 )
             opt.sig_algs = q;
 #endif
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+        else if( strcmp( p, "max_early_data_size" ) == 0 )
+        {
+            opt.max_early_data_size = atoi( q );
+        }
+#endif /* MBEDTLS_SSL_EARLY_DATA */
         else if( strcmp( p, "renegotiation" ) == 0 )
         {
             opt.renegotiation = (atoi( q )) ?
@@ -2886,6 +2937,11 @@ int main( int argc, char *argv[] )
     if( opt.cert_req_ca_list != DFL_CERT_REQ_CA_LIST )
         mbedtls_ssl_conf_cert_req_ca_list( &conf, opt.cert_req_ca_list );
 
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+    mbedtls_ssl_tls13_conf_early_data( &conf, opt.max_early_data_size );
+    mbedtls_ssl_tls13_conf_early_data_cb( &conf, early_data_write_cb, early_data_read_cb, NULL );
+#endif /* MBEDTLS_SSL_EARLY_DATA */
+
 #if defined(MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED)
     /* exercise setting DN hints for server certificate request
      * (Intended for use where the client cert expected has been signed by