From e40c469ad3d8b7b6cd8b6e21dfc0227dc73492b5 Mon Sep 17 00:00:00 2001
From: Gergely Budai <gbudai76@gmail.com>
Date: Wed, 22 Jan 2014 11:22:20 +0100
Subject: [PATCH] The default ECDH curve list will be dynamically built in the
 ecp module based on ecp_supported_curves[].

---
 include/polarssl/ecp.h |  7 +++++++
 library/ecp.c          | 43 +++++++++++++++++++++++++++++++++---------
 library/ssl_tls.c      | 42 +----------------------------------------
 3 files changed, 42 insertions(+), 50 deletions(-)

diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h
index 1635b702f..e79b0bced 100644
--- a/include/polarssl/ecp.h
+++ b/include/polarssl/ecp.h
@@ -255,6 +255,13 @@ const ecp_curve_info *ecp_curve_info_from_tls_id( uint16_t tls_id );
  */
 const ecp_curve_info *ecp_curve_info_from_name( const char *name );
 
+/**
+ * \brief           Get the default ECDH curve list
+ *
+ * \return          The default ECDH curve list
+ */
+ecp_group_id *ecp_get_default_echd_curve_list( void );
+
 /**
  * \brief           Initialize a point (as zero)
  */
diff --git a/library/ecp.c b/library/ecp.c
index a27d30e2a..992c43697 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -114,27 +114,33 @@ typedef enum
  *  - TLS NamedCurve ID (RFC 4492 sec. 5.1.1, RFC 7071 sec. 2)
  *  - size in bits
  *  - readable name
+ *
+ * The sequence of elements in this list also determines the default preference
+ * of the curves used by an ECHDE handshake.
+ * We start with the most secure curves. From the same sized curves, we prefer
+ * the SECP ones because they are much faster.
+ *
  */
 static const ecp_curve_info ecp_supported_curves[] =
 {
-#if defined(POLARSSL_ECP_DP_BP512R1_ENABLED)
-    { POLARSSL_ECP_DP_BP512R1,      28,     512,    "brainpoolP512r1"   },
-#endif
-#if defined(POLARSSL_ECP_DP_BP384R1_ENABLED)
-    { POLARSSL_ECP_DP_BP384R1,      27,     384,    "brainpoolP384r1"   },
-#endif
-#if defined(POLARSSL_ECP_DP_BP256R1_ENABLED)
-    { POLARSSL_ECP_DP_BP256R1,      26,     256,    "brainpoolP256r1"   },
-#endif
 #if defined(POLARSSL_ECP_DP_SECP521R1_ENABLED)
     { POLARSSL_ECP_DP_SECP521R1,    25,     521,    "secp521r1"         },
 #endif
+#if defined(POLARSSL_ECP_DP_BP512R1_ENABLED)
+    { POLARSSL_ECP_DP_BP512R1,      28,     512,    "brainpoolP512r1"   },
+#endif
 #if defined(POLARSSL_ECP_DP_SECP384R1_ENABLED)
     { POLARSSL_ECP_DP_SECP384R1,    24,     384,    "secp384r1"         },
 #endif
+#if defined(POLARSSL_ECP_DP_BP384R1_ENABLED)
+    { POLARSSL_ECP_DP_BP384R1,      27,     384,    "brainpoolP384r1"   },
+#endif
 #if defined(POLARSSL_ECP_DP_SECP256R1_ENABLED)
     { POLARSSL_ECP_DP_SECP256R1,    23,     256,    "secp256r1"         },
 #endif
+#if defined(POLARSSL_ECP_DP_BP256R1_ENABLED)
+    { POLARSSL_ECP_DP_BP256R1,      26,     256,    "brainpoolP256r1"   },
+#endif
 #if defined(POLARSSL_ECP_DP_SECP224R1_ENABLED)
     { POLARSSL_ECP_DP_SECP224R1,    21,     224,    "secp224r1"         },
 #endif
@@ -152,6 +158,8 @@ static const ecp_curve_info ecp_supported_curves[] =
 #endif
     { POLARSSL_ECP_DP_NONE,          0,     0,      NULL                },
 };
+#define ECP_NUM_SUPPORTED_CURVES ( sizeof( ecp_supported_curves ) / \
+                                   sizeof( ecp_curve_info )         )
 
 /*
  * List of supported curves and associated info
@@ -215,6 +223,23 @@ const ecp_curve_info *ecp_curve_info_from_name( const char *name )
     return( NULL );
 }
 
+/*
+ * Get the default ECDH curve list
+ */
+ecp_group_id *ecp_get_default_echd_curve_list( void )
+{
+    static ecp_group_id ecdh_default_curve_list[ECP_NUM_SUPPORTED_CURVES];
+    int i;
+
+    /* Build the list of default curves based on ecp_supported_curves[] */
+    for( i = 0; i < ECP_NUM_SUPPORTED_CURVES; i++)
+    {
+        ecdh_default_curve_list[i] = ecp_supported_curves[i].grp_id;
+    }
+
+    return ecdh_default_curve_list;
+}
+
 /*
  * Get the type of a curve
  */
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 79b4bb75c..dd84daa08 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3325,46 +3325,6 @@ static int ssl_handshake_init( ssl_context *ssl )
  */
 int ssl_init( ssl_context *ssl )
 {
-
-#if defined(POLARSSL_KEY_EXCHANGE__SOME__ECDHE_ENABLED)
-    /*
-    * ECDHE allowed curves and preference list
-    *
-    * We start with the most secure curves. From the same size curves, we prefer
-    * the SECP ones because they are much faster.
-    *
-    * TODO: Add the Montgomery curves
-    */
-    static const ecp_group_id default_curve_list[] =
-    {
-#if defined(POLARSSL_ECP_DP_SECP521R1_ENABLED)
-        POLARSSL_ECP_DP_SECP521R1,
-#endif
-#if defined(POLARSSL_ECP_DP_BP512R1_ENABLED)
-        POLARSSL_ECP_DP_BP512R1,
-#endif
-#if defined(POLARSSL_ECP_DP_SECP384R1_ENABLED)
-        POLARSSL_ECP_DP_SECP384R1,
-#endif
-#if defined(POLARSSL_ECP_DP_BP384R1_ENABLED)
-        POLARSSL_ECP_DP_BP384R1,
-#endif
-#if defined(POLARSSL_ECP_DP_SECP256R1_ENABLED)
-        POLARSSL_ECP_DP_SECP256R1,
-#endif
-#if defined(POLARSSL_ECP_DP_BP256R1_ENABLED)
-        POLARSSL_ECP_DP_BP256R1,
-#endif
-#if defined(POLARSSL_ECP_DP_SECP224R1_ENABLED)
-        POLARSSL_ECP_DP_SECP224R1,
-#endif
-#if defined(POLARSSL_ECP_DP_SECP192R1_ENABLED)
-        POLARSSL_ECP_DP_SECP192R1,
-#endif
-        POLARSSL_ECP_DP_NONE
-    };
-#endif
-
     int ret;
     int len = SSL_BUFFER_LEN;
 
@@ -3426,7 +3386,7 @@ int ssl_init( ssl_context *ssl )
 
 #if defined(POLARSSL_KEY_EXCHANGE__SOME__ECDHE_ENABLED) && \
     defined(POLARSSL_SSL_SET_CURVES)
-    ssl->curve_list = default_curve_list;
+    ssl->curve_list = ecp_get_default_echd_curve_list( );
 #endif
 
     if( ( ret = ssl_handshake_init( ssl ) ) != 0 )