[XFRM] IPV6: Add sort functions to combine templates/states for IPsec.

Add sort functions to combine templates/states for IPsec.
Think of outbound transformation order we should be careful with transport AH
which must be the last of all transport ones.
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/xfrm6_state.c

@@ -156,12 +156,109 @@ __xfrm6_find_acq(u8 mode, u32 reqid, u8 proto,
 	return x0;
 }
 
+static int
+__xfrm6_state_sort(struct xfrm_state **dst, struct xfrm_state **src, int n)
+{
+	int i;
+	int j = 0;
+
+	/* Rule 1: select IPsec transport except AH */
+	for (i = 0; i < n; i++) {
+		if (src[i]->props.mode == XFRM_MODE_TRANSPORT &&
+		    src[i]->id.proto != IPPROTO_AH) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+	if (j == n)
+		goto end;
+
+	/* XXX: Rule 2: select MIPv6 RO or inbound trigger */
+
+	/* Rule 3: select IPsec transport AH */
+	for (i = 0; i < n; i++) {
+		if (src[i] &&
+		    src[i]->props.mode == XFRM_MODE_TRANSPORT &&
+		    src[i]->id.proto == IPPROTO_AH) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+	if (j == n)
+		goto end;
+
+	/* Rule 4: select IPsec tunnel */
+	for (i = 0; i < n; i++) {
+		if (src[i] &&
+		    src[i]->props.mode == XFRM_MODE_TUNNEL) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+	if (likely(j == n))
+		goto end;
+
+	/* Final rule */
+	for (i = 0; i < n; i++) {
+		if (src[i]) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+
+ end:
+	return 0;
+}
+
+static int
+__xfrm6_tmpl_sort(struct xfrm_tmpl **dst, struct xfrm_tmpl **src, int n)
+{
+	int i;
+	int j = 0;
+
+	/* Rule 1: select IPsec transport */
+	for (i = 0; i < n; i++) {
+		if (src[i]->mode == XFRM_MODE_TRANSPORT) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+	if (j == n)
+		goto end;
+
+	/* XXX: Rule 2: select MIPv6 RO or inbound trigger */
+
+	/* Rule 3: select IPsec tunnel */
+	for (i = 0; i < n; i++) {
+		if (src[i] &&
+		    src[i]->mode == XFRM_MODE_TUNNEL) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+	if (likely(j == n))
+		goto end;
+
+	/* Final rule */
+	for (i = 0; i < n; i++) {
+		if (src[i]) {
+			dst[j++] = src[i];
+			src[i] = NULL;
+		}
+	}
+
+ end:
+	return 0;
+}
+
 static struct xfrm_state_afinfo xfrm6_state_afinfo = {
 	.family			= AF_INET6,
 	.init_tempsel		= __xfrm6_init_tempsel,
 	.state_lookup		= __xfrm6_state_lookup,
 	.state_lookup_byaddr	= __xfrm6_state_lookup_byaddr,
 	.find_acq		= __xfrm6_find_acq,
+	.tmpl_sort		= __xfrm6_tmpl_sort,
+	.state_sort		= __xfrm6_state_sort,
 };
 
 void __init xfrm6_state_init(void)