Support dual-stack when IPv6 is main family

Works only when $IPV6_PREFIX is used

.gitignore

@@ -1,4 +1,5 @@
 image/bin/list-nodes
+image/bin/ipv4
 image/opt/cni/bin/*
 image/build-date
 !image/opt/cni/bin/node-local

build.sh

@@ -52,6 +52,7 @@ cmd_image() {
 		go build -ldflags "-extldflags '-static' -X main.version=$__version" \
 		-o image/bin/list-nodes ./cmd/...
 	strip image/bin/list-nodes
+	gcc -o image/bin/ipv4 -static ./src/ipv4.c
 	date > image/build-date
 	docker build -t $__image:$__version .
 }

image/bin/xcluster-cni-router.sh

@@ -220,8 +220,13 @@ get_addresses() {
 		fi
 	done
 
-	test -n "$a6" && return 0
-	test -n "$a4" || return 0
+	test -n "$a6" -a -n "$a4" && return 0
+	if test -z "$a4"; then
+		# We have an ipv6 address, but no ipv4.
+		# We can only handle this case if $IPV6_PREFIX is used.
+		test -n "$IPV6_PREFIX" && a4=$(ipv4 $a6)
+		return 0
+	fi
 
 	# We have an ipv4 address, but no ipv6.
 

image/xcluster-cni.sh

@@ -44,11 +44,44 @@ cmd_env() {
 cmd_pod_cidrs() {
 	cmd_env
 	list-nodes | jq "select(.metadata.name == \"$K8S_NODE\")" > $my_node_info
-	if test "$(jq .spec.podCIDRs < $my_node_info)" != "null"; then
+	if test "$(jq .spec.podCIDRs < $my_node_info)" = "null"; then
+		# Pre v1.16 cluster
+		if test "$(jq .spec.podCIDR < $my_node_info)" != "null"; then
+			jq -r '.spec.podCIDR' < $my_node_info
+		fi
+		return 0
+	fi
+
+	if test "$(jq .spec.podCIDRs[1] < $my_node_info)" = "null"; then
+		# Single-stack cluster
 		jq -r '.spec.podCIDRs[]' < $my_node_info
+		return 0
+	fi
+
+	# For dual-stack the CNI-plugin must make sure that the first
+	# address is of the "main" family in the cluster ?!?!?!
+	if echo "$KUBERNETES_SERVICE_HOST" | grep -q : ; then
+		# Main family ipv6
+		if jq -r '.spec.podCIDRs[0]' < $my_node_info grep -q : ; then
+			# Ok, correct family
+			jq -r '.spec.podCIDRs[]' < $my_node_info
+		else
+			# Reverse the order
+			jq -r '.spec.podCIDRs[1]' < $my_node_info
+			jq -r '.spec.podCIDRs[0]' < $my_node_info
+		fi
 	else
-		jq -r '.spec.podCIDR' < $my_node_info
+		# Main family ipv4
+		if jq -r '.spec.podCIDRs[0]' < $my_node_info grep -q : ; then
+			# Reverse the order
+			jq -r '.spec.podCIDRs[1]' < $my_node_info
+			jq -r '.spec.podCIDRs[0]' < $my_node_info
+		else
+			# Ok, correct family
+			jq -r '.spec.podCIDRs[]' < $my_node_info
+		fi
 	fi
+	return 0
 }
 
 # Print the interface that holds the passed address

src/ipv4.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <arpa/inet.h>
+
+
+int
+main(int argc, char* argv[])
+{
+	if (argc < 2) {
+		printf("0.0.0.0\n");
+		return 0;
+	}
+	unsigned char buf[sizeof(struct in6_addr)];
+	if (inet_pton(AF_INET6, argv[1], buf) == 1) {
+		struct in6_addr* ap = (struct in6_addr*)buf;
+		struct in_addr a4 = {ap->s6_addr32[3]};
+		printf("%s\n", inet_ntoa(a4));
+		return 0;
+	}
+	if (inet_pton(AF_INET, argv[1], buf) == 1) {
+		printf("%s\n", argv[1]);
+		return 0;
+	}
+	return -1;
+}