inplement BN_CTX

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@24812 ec53bebd-3082-4978-b11e-865c3cabbd6b

diff --git a/lib/hcrypto/bn.c b/lib/hcrypto/bn.c
index b91a65a7bfc6f21dd11d0e0c01dc4911de476e75..6ebba1fa63d3dac90fc4027e9edb47ce44b5fefe 100644 (file)
--- a/lib/hcrypto/bn.c
+++ b/lib/hcrypto/bn.c
@@ -443,3 +443,93 @@ BN_GENCB_call(BN_GENCB *cb, int a, int b)
        return 1;
     return cb->cb.cb_2(a, b, cb);
 }
+
+/*
+ *
+ */
+
+struct BN_CTX {
+    struct {
+       BIGNUM **val;
+       size_t used;
+       size_t len;
+    } bn;
+    struct {
+       size_t *val;
+       size_t used;
+       size_t len;
+    } stack;
+};
+
+BN_CTX *
+BN_CTX_new(void)
+{
+    struct BN_CTX *c;
+    c = calloc(sizeof(*c));
+    return c;
+}
+
+void
+BN_CTX_free(BN_CTX *c)
+{
+    size_t i;
+    for (i = 0; i < c->bn.len; i++)
+       BN_free(c->bn.val[i]);
+    free(c->bn.val);
+    free(c->stack.val);
+}
+
+BIGNUM *
+BN_CTX_get(BN_CTX *c)
+{
+    if (c->bn.used == c->bn.len) {
+       void *ptr;
+       size_t i;
+       c->bn.len += 16;
+       ptr = realloc(c->bn.val, c->bn.len * sizeof(c->bn.val[0]));
+       if (ptr == NULL)
+           return NULL;
+       c->bn.val = ptr;
+       for (i = c->bn.used; i < c->bn.len; i++) {
+           c->bn.val[i] = BN_new();
+           if (c->bn.val[i] == NULL) {
+               c->bn.len = i - 1;
+               return NULL;
+           }
+       }
+    }
+    return c->bn.val[c->bn.used++];
+}
+
+void
+BN_CTX_start(BN_CTX *c)
+{
+    if (c->stack.used == c->stack.len) {
+       void *ptr;
+       c->stack.len += 16;
+       ptr = realloc(c->stack.val, c->stack.len * sizeof(c->stack.val[0]));
+       if (ptr == NULL)
+           abort();
+       c->stack.val = ptr;
+    }
+    c->stack.val[c->stack.used++] = c->bn.used;
+}
+
+void
+BN_CTX_end(BN_CTX *c)
+{
+    const size_t stack_prev = c->stack.val[c->stack.used - 1];
+    const size_t stack_cur = c->stack.val[c->stack.used];
+    size_t i;
+
+    if (c->stack.used == 0)
+       abort();
+
+    for (i = stack_prev + 1; i < stack_cur; i++)
+       BN_clear(&c->bn.val[i]);
+
+    c->stack.val[c->stack.used] = 0;
+    c->stack.used--;
+    c->bn.used = stack_prev;
+}
+