add i2d_DHparams

lib/hcrypto/dh.c

@@ -37,6 +37,9 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <krb5-types.h>
+#include <rfc2459_asn1.h>
+
 #include <dh.h>
 
 #include <roken.h>
@@ -487,3 +490,63 @@ DH_get_default_method(void)
     return dh_default_method;
 }
 
+/*
+ *
+ */
+
+static int
+bn2heim_int(BIGNUM *bn, heim_integer *integer)
+{
+    integer->length = BN_num_bytes(bn);
+    integer->data = malloc(integer->length);
+    if (integer->data == NULL) {
+	integer->length = 0;
+	return ENOMEM;
+    }
+    BN_bn2bin(bn, integer->data);
+    integer->negative = BN_is_negative(bn);
+    return 0;
+}
+
+/**
+ *
+ */
+
+int
+i2d_DHparams(DH *dh, const char **pp)
+{
+    DHParameter data;
+    size_t size;
+    int ret;
+
+    memset(&data, 0, sizeof(data));
+
+    if (bn2heim_int(dh->p, &data.prime) ||
+	bn2heim_int(dh->g, &data.base))
+    {
+	free_DHParameter(&data);
+	return -1;
+    }
+
+    if (pp == NULL) {
+	size = length_DHParameter(&data);
+	free_DHParameter(&data);
+    } else {
+	void *p;
+	size_t len;
+
+	ASN1_MALLOC_ENCODE(DHParameter, p, len, &data, &size, ret);
+	free_DHParameter(&data);
+	if (ret)
+	    return -1;
+	if (len != size)
+	    abort();
+
+	memcpy(*pp, p, size);
+	free(p);
+
+	*pp += size;
+    }
+
+    return size;
+}