dns-updater/ip/resolver/http/service.go

package http

import (
	"bufio"
	"context"
	"io"
	"net"
	"net/http"
	"strings"

	httputils "dnsupdater/http"
	"dnsupdater/ip/internal"
)

type Decoder func(io.Reader) (string, error)

type Service struct {
	ServiceName string
	Url         string
	Headers     http.Header
	Decoder     Decoder
}

func (s Service) Name() string {
	return s.ServiceName
}

func (s Service) Lookup(ctx context.Context) (net.IP, error) {
	resp, err := httputils.Get(ctx, s.Url, s.Headers)
	if err != nil {
		return nil, err
	}

	if s.Decoder == nil {
		s.Decoder = func(r io.Reader) (string, error) {
			line, err := bufio.NewReader(r).ReadString('\n')
			if err == nil || err == io.EOF {
				line = strings.TrimRight(line, "\r\n")
				line = strings.TrimSpace(line)
			}
			return line, err
		}
	}

	body, err := s.Decoder(resp.Body)
	if err != nil && err != io.EOF {
		return nil, err
	}
	return internal.ParseIP(string(body))
}