groups: add function to return group by curve

Two GOST groups will have two curves attached. Add function to retrieve
group by curve, rather than by group id.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/lib/algorithms.h b/lib/algorithms.h
index d0191312f7..0d14331154 100644
--- a/lib/algorithms.h
+++ b/lib/algorithms.h
@@ -437,6 +437,7 @@ const gnutls_ecc_curve_entry_st
 
 unsigned _gnutls_ecc_curve_is_supported(gnutls_ecc_curve_t);
 
+gnutls_group_t _gnutls_ecc_curve_get_group(gnutls_ecc_curve_t);
 const gnutls_group_entry_st *_gnutls_tls_id_to_group(unsigned num);
 const gnutls_group_entry_st * _gnutls_id_to_group(unsigned id);
 
diff --git a/lib/algorithms/ecc.c b/lib/algorithms/ecc.c
index 935bfb8672..8b4b78f67d 100644
--- a/lib/algorithms/ecc.c
+++ b/lib/algorithms/ecc.c
@@ -510,3 +510,24 @@ gnutls_pk_algorithm_t gnutls_ecc_curve_get_pk(gnutls_ecc_curve_t curve)
 	return ret;
 }
 
+/**
+ * _gnutls_ecc_curve_get_group:
+ * @curve: is an ECC curve
+ *
+ * Returns: the group associated with the named curve or %GNUTLS_GROUP_INVALID.
+ *
+ * Since: 3.6.11
+ */
+gnutls_group_t _gnutls_ecc_curve_get_group(gnutls_ecc_curve_t curve)
+{
+	gnutls_group_t ret = GNUTLS_GROUP_INVALID;
+
+	GNUTLS_ECC_CURVE_LOOP(
+		if (p->id == curve && p->supported && _gnutls_pk_curve_exists(p->id)) {
+			ret = p->group;
+			break;
+		}
+	);
+
+	return ret;
+}