Add oid_get_ec_grp() and associated data
diff --git a/include/polarssl/oid.h b/include/polarssl/oid.h
index d9a1f8f..a39055b 100644
--- a/include/polarssl/oid.h
+++ b/include/polarssl/oid.h
@@ -31,7 +31,6 @@
 #include "config.h"
 #include "asn1.h"
 #include "pk.h"
-
 #if defined(POLARSSL_CIPHER_C)
 #include "cipher.h"
 #endif
@@ -241,7 +240,7 @@
 #define OID_PKCS12_PBE_SHA1_RC2_40_CBC      OID_PKCS12_PBE "\x06" /**< pbeWithSHAAnd40BitRC2-CBC OBJECT IDENTIFIER ::= {pkcs-12PbeIds 6} */
 
 /*
- * EC key algorithms from RFC 5420
+ * EC key algorithms from RFC 5480
  */
 
 /* id-ecPublicKey OBJECT IDENTIFIER ::= {
@@ -253,6 +252,30 @@
  *     schemes(1) ecdh(12) } */
 #define OID_EC_ALG_ECDH                 OID_CERTICOM "\x01\x0c"
 
+/*
+ * ECParameters namedCurve identifiers, from RFC 5480
+ */
+
+/* secp192r1 OBJECT IDENTIFIER ::= {
+ *   iso(1) member-body(2) us(840) ansi-X9-62(10045) curves(3) prime(1) 1 } */
+#define OID_EC_GRP_SECP192R1        OID_ANSI_X9_62 "\x03\x01\x01"
+
+/* secp224r1 OBJECT IDENTIFIER ::= {
+ *   iso(1) identified-organization(3) certicom(132) curve(0) 33 } */
+#define OID_EC_GRP_SECP224R1        OID_CERTICOM "\x00\x21"
+
+/* secp256r1 OBJECT IDENTIFIER ::= {
+ *   iso(1) member-body(2) us(840) ansi-X9-62(10045) curves(3) prime(1) 7 } */
+#define OID_EC_GRP_SECP256R1        OID_ANSI_X9_62 "\x03\x01\x07"
+
+/* secp384r1 OBJECT IDENTIFIER ::= {
+ *   iso(1) identified-organization(3) certicom(132) curve(0) 34 } */
+#define OID_EC_GRP_SECP384R1        OID_CERTICOM "\x00\x22"
+
+/* secp521r1 OBJECT IDENTIFIER ::= {
+ *   iso(1) identified-organization(3) certicom(132) curve(0) 35 } */
+#define OID_EC_GRP_SECP521R1        OID_CERTICOM "\x00\x23"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -311,6 +334,16 @@
  */
 int oid_get_pk_alg( const asn1_buf *oid, pk_type_t *pk_alg );
 
+/**
+ * \brief          Translate ECParameters OID into an EC group identifier
+ *
+ * \param oid      OID to use
+ * \param grp_id   place to store group id
+ *
+ * \return         0 if successful, or POLARSSL_ERR_OID_NOT_FOUND
+ */
+int oid_get_ec_grp( const asn1_buf *oid, ecp_group_id *grp_id );
+
 #if defined(POLARSSL_MD_C)
 /**
  * \brief          Translate SignatureAlgorithm OID into md_type and pk_type
diff --git a/library/oid.c b/library/oid.c
index 3f7857d..dd4cbf0 100644
--- a/library/oid.c
+++ b/library/oid.c
@@ -249,7 +249,6 @@
 
 FN_OID_TYPED_FROM_ASN1(oid_descriptor_t, ext_key_usage, oid_ext_key_usage);
 FN_OID_GET_ATTR1(oid_get_extended_key_usage, oid_descriptor_t, ext_key_usage, const char *, description);
-
 #endif /* POLARSSL_X509_PARSE_C || POLARSSL_X509_WRITE_C */
 
 #if defined(POLARSSL_MD_C)
@@ -343,6 +342,45 @@
 FN_OID_TYPED_FROM_ASN1(oid_pk_alg_t, pk_alg, oid_pk_alg);
 FN_OID_GET_ATTR1(oid_get_pk_alg, oid_pk_alg_t, pk_alg, pk_type_t, pk_alg);
 
+/*
+ * For namedCurve (RFC 5480)
+ */
+typedef struct {
+    oid_descriptor_t    descriptor;
+    ecp_group_id        grp_id;
+} oid_ecp_grp_t;
+
+static const oid_ecp_grp_t oid_ecp_grp[] =
+{
+    {
+        { OID_EC_GRP_SECP192R1, "secp192r1",    "secp192r1" },
+        POLARSSL_ECP_DP_SECP192R1,
+    },
+    {
+        { OID_EC_GRP_SECP224R1, "secp224r1",    "secp224r1" },
+        POLARSSL_ECP_DP_SECP224R1,
+    },
+    {
+        { OID_EC_GRP_SECP256R1, "secp256r1",    "secp256r1" },
+        POLARSSL_ECP_DP_SECP256R1,
+    },
+    {
+        { OID_EC_GRP_SECP384R1, "secp384r1",    "secp384r1" },
+        POLARSSL_ECP_DP_SECP384R1,
+    },
+    {
+        { OID_EC_GRP_SECP521R1, "secp521r1",    "secp521r1" },
+        POLARSSL_ECP_DP_SECP521R1,
+    },
+    {
+        { NULL, NULL, NULL },
+        0,
+    },
+};
+
+FN_OID_TYPED_FROM_ASN1(oid_ecp_grp_t, grp_id, oid_ecp_grp);
+FN_OID_GET_ATTR1(oid_get_ec_grp, oid_ecp_grp_t, grp_id, ecp_group_id, grp_id);
+
 #if defined(POLARSSL_CIPHER_C)
 /*
  * For PKCS#5 PBES2 encryption algorithm