Mailing List Archive

commit 51523bc883525005a0d87c83467e753a88abb0ed
Author: Nils Goroll <nils.goroll@uplex.de>
Date: Fri Dec 13 18:08:59 2019 +0100

vcc_acl: change compare functions to differentiate cases

This is in preparation of a follow-up commit to merge acl entries and
detect supersedes from supernets, but these changes are backwards
compatible with the previous CMP() if being used as a comparison
function for which only negative, zero and positive result are
relevant.

The A in CMPA() stands for "adjacent". CMPA() returns -3/3 for left
of/right of.

diff --git a/lib/libvcc/vcc_acl.c b/lib/libvcc/vcc_acl.c
index c8219dcc8..d4b78ad8d 100644
--- a/lib/libvcc/vcc_acl.c
+++ b/lib/libvcc/vcc_acl.c
@@ -74,14 +74,29 @@ struct acl_e {
struct token *t_mask;
};

-/* Compare two acl rules for ordering */
+/*
+ * Compare two acl rules for ordering
+ * returns:
+ * 0 same
+ * -1/1 strictly less/greater
+ * -2/2 b contains a / a contains b
+ * -3/3 a left of b / b left of a
+ */

-#define CMP(a, b) \
+#define CMP(n, a, b) \
do { \
if ((a) < (b)) \
- return (-1); \
+ return (-n); \
else if ((b) < (a)) \
- return (1); \
+ return (n); \
+ } while (0)
+
+#define CMPA(a, b) \
+ do { \
+ if (((a) | 1) == (b)) \
+ return (-3); \
+ else if (((b) | 1) == (a)) \
+ return (3); \
} while (0)

static void
@@ -99,6 +114,7 @@ vcl_acl_cmp(const struct acl_e *ae1, const struct acl_e *ae2)
{
const unsigned char *p1, *p2;
unsigned m;
+ unsigned char a1, a2;

CHECK_OBJ_NOTNULL(ae1, VCC_ACL_E_MAGIC);
CHECK_OBJ_NOTNULL(ae2, VCC_ACL_E_MAGIC);
@@ -107,17 +123,22 @@ vcl_acl_cmp(const struct acl_e *ae1, const struct acl_e *ae2)
p2 = ae2->data;
m = vmin_t(unsigned, ae1->mask, ae2->mask);
for (; m >= 8; m -= 8) {
- CMP(*p1, *p2);
+ CMP(1, *p1, *p2);
p1++;
p2++;
}
if (m) {
- m = 0xff00 >> m;
- m &= 0xff;
- CMP(*p1 & m, *p2 & m);
+ assert (m < 8);
+ a1 = *p1 >> (8 - m);
+ a2 = *p2 >> (8 - m);
+ if (ae1->mask == ae2->mask)
+ CMPA(a1, a2);
+ CMP(1, a1, a2);
+ } else if (ae1->mask == ae2->mask) {
+ CMPA(*p1, *p2);
}
/* Long mask is less than short mask */
- CMP(ae2->mask, ae1->mask);
+ CMP(2, ae2->mask, ae1->mask);

return (0);
}
@@ -135,14 +156,14 @@ vcl_acl_disjoint(const struct acl_e *ae1, const struct acl_e *ae2)
p2 = ae2->data;
m = vmin_t(unsigned, ae1->mask, ae2->mask);
for (; m >= 8; m -= 8) {
- CMP(*p1, *p2);
+ CMP(1, *p1, *p2);
p1++;
p2++;
}
if (m) {
m = 0xff00 >> m;
m &= 0xff;
- CMP(*p1 & m, *p2 & m);
+ CMP(1, *p1 & m, *p2 & m);
}
return (0);
}
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