func processHTTPFilters()

in xds/client/resource/unmarshal_lds.go [230:283]
48 lines of code
15 McCabe index (conditional complexity)

func processHTTPFilters(filters []*v3httppb.HttpFilter, server bool) ([]HTTPFilter, error) {
	ret := make([]HTTPFilter, 0, len(filters))
	seenNames := make(map[string]bool, len(filters))
	for _, filter := range filters {
		name := filter.GetName()
		if name == "" {
			return nil, errors.New("filter missing name field")
		}
		if seenNames[name] {
			return nil, fmt.Errorf("duplicate filter name %q", name)
		}
		seenNames[name] = true

		httpFilter, config, err := validateHTTPFilterConfig(filter.GetTypedConfig(), true, filter.GetIsOptional())
		if err != nil {
			return nil, err
		}
		if httpFilter == nil {
			// Optional configs are ignored.
			continue
		}
		if server {
			if _, ok := httpFilter.(httpfilter.ServerInterceptorBuilder); !ok {
				if filter.GetIsOptional() {
					continue
				}
				return nil, fmt.Errorf("HTTP filter %q not supported server-side", name)
			}
		} else if _, ok := httpFilter.(httpfilter.ClientInterceptorBuilder); !ok {
			if filter.GetIsOptional() {
				continue
			}
			return nil, fmt.Errorf("HTTP filter %q not supported client-side", name)
		}

		// Save name/config
		ret = append(ret, HTTPFilter{Name: name, Filter: httpFilter, Config: config})
	}
	// "Validation will fail if a terminal filter is not the last filter in the
	// chain or if a non-terminal filter is the last filter in the chain." - A39
	if len(ret) == 0 {
		return nil, fmt.Errorf("http filters list is empty")
	}
	var i int
	for ; i < len(ret)-1; i++ {
		if ret[i].Filter.IsTerminal() {
			return nil, fmt.Errorf("http filter %q is a terminal filter but it is not last in the filter chain", ret[i].Name)
		}
	}
	if !ret[i].Filter.IsTerminal() {
		return nil, fmt.Errorf("http filter %q is not a terminal filter", ret[len(ret)-1].Name)
	}
	return ret, nil
}