ESP32 Arduino http协议digest认证 接入海康威视摄像机

注意：使用的是ArduinoHttpClient，与ESP32内部的HTTPClient库有较大的差别

1. 海康摄像机http接入时候，由于没有认证信息，会返回401无权限信息，这时需要进行digest认证；
2. 首次请求后返回digest认证信息，使用字符处理提取出qop、realm、nonce这几个关键字
3. 然后就需要进行digest加密了，这个时候可以参考如下几篇博文确认加密原理
   1. http Digest认证计算方法整理_TYINY的博客-CSDN博客_digest 算法
   2. http://web.chacuo.net/safedigestauth
   3. md5加密,sha1加密--md5在线解密
4. 通过ESP内部的MD5库进行加密，将认证信息放入到header中再次请求，即可实现摄像机的连接

#include <Arduino.h>
#include <HttpClient.h>
#include <WiFi.h>
#include <WiFiMulti.h>
#include "MD5Builder.h"



char ssid[] = "xxxxx";    //按需调整
char pass[] = "xxxxx";    //按需调整

WiFiClient wifi;
HttpClient client = HttpClient(wifi, "10.17.97.117", 80);  //IP为摄像机的IP，80为http的端口

void setup() {

    Serial.begin(115200);
    Serial.println();
    Serial.println();
    Serial.println();

    //wifi连接
    WiFi.begin(ssid, pass);
    while ( WiFi.status()  != WL_CONNECTED) {
      Serial.print("Attempting to connect to Network named: ");
      Serial.println(ssid);   // print the network name (SSID);
      // Connect to WPA/WPA2 network:
      sleep(2);
    }
    
    Serial.println("");
    Serial.println("WiFi connected");
    Serial.println("IP address: ");
    Serial.println(WiFi.localIP());
}

void loop() {
    String devAuthStr;
    String retAuthStr;
    String response;
    String qop;
    String realm;
    String nonce;
    String nc="00000001";
    String cnonce = "f66f3849aa2540cb";
    String stra1,stra2;
    String strUri = "/ISAPI/System/deviceInfo";

    
    Serial.print("[HTTP] begin...\n");

    client.get("/ISAPI/System/deviceInfo");

    // read the status code and body of the response
    int statusCode = client.responseStatusCode();
    Serial.printf("[HTTP] GET... code: %d\n", statusCode);

    // httpCode will be negative on error
    if(statusCode == 200) 
    {
        String response = client.responseBody();
        Serial.print("Response: ");
        Serial.println(response);
    } 
    else if(401 == statusCode) //需要进行digest认证
    {
        // from header get auth info
        while(client.headerAvailable())
        {
          
          if(0 == client.readHeaderName().compareTo("WWW-Authenticate"))
          {
            devAuthStr = client.readHeaderValue();
            break;
          }
        }
        Serial.println(devAuthStr);
        int index1=0;
        int index2=0;
        index1 = devAuthStr.indexOf("qop");
        index2 = devAuthStr.indexOf(",", index1);
        qop = devAuthStr.substring(index1+5, index2-1);
        index1 = devAuthStr.indexOf("realm");
        index2 = devAuthStr.indexOf(",", index1);
        realm = devAuthStr.substring(index1+7, index2-1);
        index1 = devAuthStr.indexOf("nonce");
        index2 = devAuthStr.indexOf(",", index1);
        nonce = devAuthStr.substring(index1+7, index2-1);
        Serial.println(qop);
        Serial.println(realm);
        Serial.println(nonce);
        MD5Builder md5;
        
        md5.begin();
        md5.add("admin:");
        md5.add(realm);
        md5.add(":abcd1234");
        md5.calculate();
        stra1 = md5.toString();
        
        md5.begin();
        md5.add("GET:");
        md5.add(strUri);
        md5.calculate();
        stra2 = md5.toString();

        md5.begin();
        md5.add(stra1);
        md5.add(":");
        md5.add(nonce);
        md5.add(":");
        md5.add(nc);
        md5.add(":");
        md5.add(cnonce);
        md5.add(":");
        md5.add(qop);
        md5.add(":");
        md5.add(stra2);
        md5.calculate();
        response = md5.toString();

        retAuthStr = "Authorization: Digest username=\"admin\", realm=\""+realm+"\", nonce=\""+nonce+"\", uri=\""+strUri+"\", response=\""+response+"\", qop=\""+qop+"\", nc="+nc+", cnonce=\""+cnonce+"\"";  
        Serial.println(retAuthStr);  
        
        client.beginRequest();
        client.get(strUri);
        client.sendHeader(retAuthStr);
        client.endRequest();

        statusCode = client.responseStatusCode();
        Serial.printf("[HTTP] GET... code: %d\n", statusCode);
        String responseRes = client.responseBody();
        Serial.print(responseRes);

    }
    else
    {
        Serial.printf("[ERROR][HTTP] GET... code: %d, can not process!\n", statusCode);      
    }

    Serial.println();
    Serial.println();
    Serial.println();

    delay(60000);
}