X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/96a5a09cc7d5327fad4992a8e1000d409853a000..778b9e26bfb8fa2beba1f8915164d3655538cb3a:/base/keysz.c

diff --git a/base/keysz.c b/base/keysz.c
index 8e5e2caf..13d850a4 100644
--- a/base/keysz.c
+++ b/base/keysz.c
@@ -81,4 +81,43 @@ size_t keysz(size_t sz, const octet *ksz)
   return (0);
 }
 
+/* --- @keysz_pad@ --- *
+ *
+ * Arguments:	@size_t sz@ = a proposed key size
+ *		@const octet *ksz@ = pointer to key size table
+ *
+ * Returns:	A key size, at least as large as @sz@, or zero if no such
+ *		size is available.
+ */
+
+size_t keysz_pad(size_t sz, const octet *ksz)
+{
+  unsigned op = ksz[0]&KSZ_OPMASK;
+  unsigned wd = (ksz[0]&KSZ_16BIT) ? 2 : 1;
+  unsigned t, u, v;
+
+  ksz++;
+#define ARG(i) (wd == 1 ? ksz[i] : LOAD16(ksz + 2*i))
+  switch (op) {
+    case KSZ_ANY: return (sz);
+    case KSZ_RANGE:
+      t = ARG(1); u = ARG(2); v = ARG(3);
+      if (v) { sz += v - 1; sz -= sz%v; }
+      if (u && sz > u) return (0);
+      if (sz < t) return (t);
+      return (sz);
+    case KSZ_SET:
+      u = 0;
+      for (;;) {
+	t = ARG(0); ksz += wd; if (!t) break;
+	if (sz <= t && (!u || u > t)) u = t;
+      }
+      return (u);
+  }
+#undef ARG
+
+  assert(((void)"bad key size table", 0));
+  return (0);
+}
+
 /*----- That's all, folks -------------------------------------------------*/