Function FetchConfig

core/nylon_distribution.go:19–75

fetches and unbundles central config from url

(repoStr string, key state.NyPublicKey, maxSize int64)

// fetches and unbundles central config from url
func FetchConfig(repoStr string, key state.NyPublicKey, maxSize int64) (*state.CentralCfg, error) {
	repo, err := url.Parse(repoStr)
	if err != nil {
		return nil, fmt.Errorf("failed to parse repo URL %s: %w", repoStr, err)
	}
	cfgBody := make([]byte, 0)

	if repo.Scheme == "file" {
		file, err := os.ReadFile(repo.Opaque)
		if err != nil {
			return nil, fmt.Errorf("failed to read file %s: %w", repo.Opaque, err)
		}
		cfgBody = file
	} else if repo.Scheme == "http" || repo.Scheme == "https" {
		client := &http.Client{
			Transport: &http.Transport{
				DialContext: func(ctx context.Context, network string, addr string) (conn net.Conn, err error) {
					host, port, err := net.SplitHostPort(addr)
					if err != nil {
						return nil, err
					}
					addrs, err := state.ResolveName(ctx, host)
					if err != nil {
						return nil, err
					}
					for _, ip := range addrs {
						var dialer net.Dialer
						conn, err = dialer.DialContext(ctx, network, net.JoinHostPort(ip.String(), port))
						if err == nil {
							break
						}
					}
					return
				},
			},
		}
		res, err := client.Get(repo.String())
		if err != nil {
			return nil, fmt.Errorf("failed to fetch %s: %w", repo.String(), err)
		}
		cfgBody, err = io.ReadAll(io.LimitReader(res.Body, maxSize))
		if err != nil {
			res.Body.Close()
			return nil, fmt.Errorf("failed to read response from %s: %w", repo.String(), err)
		}
		err = res.Body.Close()
		if err != nil {
			return nil, fmt.Errorf("failed to close response from %s: %w", repo.String(), err)
		}
	}

	config, err := state.UnbundleConfig(string(cfgBody), key)
	if err != nil {
		return nil, fmt.Errorf("failed to unbundle config from %s: %w", repoStr, err)
	}
	return config, nil
}