Go Http请求海康摄像头拍照图片

package main

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"

	randomString "github.com/delphinus/random-string"
	"golang.org/x/net/context"
)

type httpClientKey struct{}

var HTTPClientKey httpClientKey

func ContextWithClient(parent context.Context, client *http.Client) context.Context {
	return context.WithValue(parent, HTTPClientKey, client)
}

func clientFromContext(ctx context.Context) *http.Client {
	if client, ok := ctx.Value(HTTPClientKey).(*http.Client); ok {
		return client
	}
	return http.DefaultClient
}

type DigestRequest struct {
	context.Context
	client             *http.Client
	username, password string
	nonceCount         nonceCount
}

type nonceCount int

func (nc nonceCount) String() string {
	c := int(nc)
	return fmt.Sprintf("%08x", c)
}

const authorization = "Authorization"
const contentType = "Content-Type"
const nonce = "nonce"
const opaque = "opaque"
const qop = "qop"
const realm = "realm"
const wwwAuthenticate = "Www-Authenticate"

var wanted = []string{nonce, qop, realm}

func NewDigestRequest(ctx context.Context, username, password string) *DigestRequest {
	return &DigestRequest{
		Context:  ctx,
		client:   clientFromContext(ctx),
		username: username,
		password: password,
	}
}

func (r *DigestRequest) Do(req *http.Request) (*http.Response, error) {
	parts, err := r.makeParts(req)
	if err != nil {
		return nil, err
	}

	if parts != nil {
		aut := r.makeAuthorization(req, parts)
		fmt.Println("header:", aut)
		req.Header.Set(authorization, aut)
	}

	return r.client.Do(req)
}

func (r *DigestRequest) makeParts(req *http.Request) (map[string]string, error) {
	authReq, _ := http.NewRequest(req.Method, req.URL.String(), nil)
	resp, err := r.client.Do(authReq)
	if err != nil {
		return nil, err
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode != http.StatusUnauthorized {
		return nil, nil
	}

	for _, vv := range resp.Header {
		fmt.Println(vv)
	}

	if len(resp.Header[wwwAuthenticate]) == 0 {
		return nil, fmt.Errorf("headers do not have %s", wwwAuthenticate)
	}

	headers := strings.Split(resp.Header[wwwAuthenticate][0], ",")
	parts := make(map[string]string, len(wanted))
	for _, r := range headers {
		for _, w := range wanted {
			if strings.Contains(r, w) {
				parts[w] = strings.Split(r, `"`)[1]
			}
		}
	}

	if len(parts) != len(wanted) {
		return nil, fmt.Errorf("header is invalid: %+v", parts)
	}

	return parts, nil
}

func getMD5(texts []string) string {
	h := md5.New()
	_, _ = io.WriteString(h, strings.Join(texts, ":"))
	return hex.EncodeToString(h.Sum(nil))
}

func (r *DigestRequest) getNonceCount() string {
	r.nonceCount++
	return r.nonceCount.String()
}

func (r *DigestRequest) makeAuthorization(req *http.Request, parts map[string]string) string {
	uri := req.URL.RequestURI()
	ha1 := getMD5([]string{r.username, parts[realm], r.password})
	ha2 := getMD5([]string{req.Method, uri})
	cnonce := randomString.Generate(16)
	nc := r.getNonceCount()
	response := getMD5([]string{
		ha1,
		parts[nonce],
		nc,
		cnonce,
		parts[qop],
		ha2,
	})
	return fmt.Sprintf(
		`Digest username="%s", realm="%s", nonce="%s", uri="%s", qop=%s, nc=%s, cnonce="%s", response="%s"`,
		r.username,
		parts[realm],
		parts[nonce],
		uri,
		parts[qop],
		nc,
		cnonce,
		response,
	)
}

func main() {
	url := "http://172.31.2.164:80/ISAPI/Streaming/channels/33/picture"
	username := "admin"
	password := "root123456"

	ctx := context.Background()
	r := NewDigestRequest(ctx, username, password) // username & password
	if r == nil {
		fmt.Println("unk")
		return
	}
	req, _ := http.NewRequest("GET", url, nil)
	resp, err := r.Do(req)

	if err != nil {
		fmt.Println("unk1", err)
		return
	}
	fmt.Println("Code:", resp.StatusCode)

	// 保存图片
	file, err := os.Create("1.jpeg")
	if err != nil {
		fmt.Println("Error creating file:", err)
		return
	}
	defer file.Close()

	_, err = io.Copy(file, resp.Body)
	if err != nil {
		fmt.Println("Error saving file:", err)
		return
	}

	fmt.Println("图片保存成功。")
}

这段代码实现了一个带有 Digest 认证的 HTTP 客户端，用于从指定 URL 获取图片并保存到本地。代码通过上下文传递 HTTP 客户端，并在需要时从上下文中提取客户端。代码还处理了 Digest 认证的具体细节，包括生成认证头和管理 nonce 计数。