func Add()

in cmd/egress-cni-plugin/snat/snat.go [50:90]
33 lines of code
11 McCabe index (conditional complexity)

func Add(ipt iptableswrapper.IPTablesIface, nodeIP, src net.IP, multicastRange, chain, comment, rndSNAT string) error {
	//Defaults to `random-fully` unless a different option is explicitly set via
	//`AWS_VPC_K8S_CNI_RANDOMIZESNAT`. If the underlying iptables version doesn't support
	//'random-fully`, we will fall back to `random`.
	useRandomFully, useHashRandom := true, false
	if rndSNAT == "none" {
		useRandomFully = false
	} else if rndSNAT == "hashrandom" || !ipt.HasRandomFully() {
		useHashRandom, useRandomFully = true, false
	}

	rules := iptRules(nodeIP, src, multicastRange, chain, comment, useRandomFully, useHashRandom)

	chains, err := ipt.ListChains("nat")
	if err != nil {
		return err
	}
	existingChains := make(map[string]bool, len(chains))
	for _, ch := range chains {
		existingChains[ch] = true
	}

	for _, rule := range rules {
		_chain := rule[0]
		if !existingChains[_chain] {
			if err = ipt.NewChain("nat", _chain); err != nil {
				return err
			}
			existingChains[_chain] = true
		}
	}

	for _, rule := range rules {
		_chain := rule[0]
		if err = ipt.AppendUnique("nat", _chain, rule[1:]...); err != nil {
			return err
		}
	}

	return nil
}