HTTP协议、Wireshark抓包工具、json解析、天气爬虫

 HTTP超文本传输协议

• HTTP（Hyper Text Transfer Protocol）： 全称超文本传输协议，是用于从万维网（WWW:World Wide Web ）服务器传输超文本到本地浏览器的传送协议。

• HTTP 协议的重要特点： 一发一收，一问一答

• 明文传输 ，https密文 （加密了的）

现在的主流网站都是https

网址：URL 统一资源定位符

URL

互联网上每个文件都有一个唯一的 URL，它包含的信息指出文件的位置以及浏览器应该怎么处理它。
    <协议>://<主机>:<端口>/<路径>

    协议：HTTP       80         TCP 
          HTTPS     443         TCP 
    主机:  域名  ->  域名解析服务器 -> IP地址
    端口： 可以省略, HTTP 80
                    HTTPS 443
    路径: 想要获得对应的资源

https://www.example.com/path/to/resource?query=parameter#fragment

•https 是协议，

•www.example.com 是主机名，域名

•/path/to/resource 是路径，

•query=parameter 是查询参数，

•#fragment 是片段标识符。

HTTP交互过程:
    1.建立TCP连接
    2.发送HTTP请求报文
    3.回复HTTP相应报文
    4.关闭TCP连接

要一次建立一次tcp连接，关闭一次连接

HTTP请求报文的格式：

HTTP响应报文格式：

GET 方法
基本介绍：

以下几种方式都会触发 GET 方法的请求

Wireshark 抓包工具

sudo apt-get install wireshark

为什么很多软件都可以用apt-get install安装？

apt-get 是 Debian 及其衍生系统（如 Ubuntu、Linux Mint 等）中的高级包工具（Advanced Package Tool）的命令行接口。

1.集中化的软件仓库： Debian 和其衍生系统维护着庞大的软件仓库，这些仓库包含了成千上万个预编译的软件包。当软件开发者将他们的软件贡献给这些仓库时，软件就变得可供所有使用相同系统的用户通过 apt-get 安装。

2. 依赖关系管理： apt-get 能够解析和处理软件包之间的依赖关系。这意味着当你安装一个软件包时，apt-get 会自动安装所有必要的依赖包，确保软件能够正常运行。这种依赖关系管理大大简化了安装过程。

3.社区贡献和维护： 一个活跃的社区持续为 Debian 和其衍生系统贡献软件包。这些贡献者不仅提供新的软件包，还负责保持现有软件包的更新和维护，确保它们与最新系统兼容。

一般过滤条件先选择协议名  然后用端口过滤。 

先运行网站如何抓取http格式的数据

 Nowapi的ip地址和端口号 为  103.205.5.228：80   

         

GET /?app=weather.today&weaid=%E8%A5%BF%E5%AE%89&appkey=72317&sign=be43b728a4f27463d34f4fcbfea69134&format=json HTTP/1.1
Host: api.k780.com
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/113.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Upgrade-Insecure-Requests: 1

HTTP/1.1 200 OK
Server: nginx
Date: Thu, 18 Jul 2024 08:23:48 GMT
Content-Type: application/json; charset=utf-8;
Transfer-Encoding: chunked
Connection: keep-alive
Access-Control-Allow-Origin: *

{"success":"1","result":{"weaid":"316","days":"2024-07-18","week":".........","cityno":"xian","citynm":"......","cityid":"101110101","temperature":"33.../24...","temperature_curr":"33...","humidity":"75%","aqi":"40","weather":"......","weather_curr":"...","weather_icon":"http://api.k780.com/upload/weather/d/2.gif","weather_icon1":"","wind":"......","winp":"2...","temp_high":"33","temp_low":"24","temp_curr":"33","humi_high":"0","humi_low":"0","weatid":"3","weatid1":"","windid":"8","winpid":"2","weather_iconid":"2"}}

 用httl协议获取今日天气的信息（json格式）

#include"head.h"int CreatTcpClient(char *pip,int port)
{int ret = 0;int sockfd = 0;struct sockaddr_in seraddr;sockfd = socket(AF_INET,SOCK_STREAM,0);if(-1 == sockfd){perror("fail to socket");return -1;}seraddr.sin_family = AF_INET;seraddr.sin_port = htons(port);seraddr.sin_addr.s_addr = inet_addr(pip);ret = connect(sockfd,(struct sockaddr *)&seraddr,sizeof(seraddr));if(-1 == ret){perror("fail to connect ");return -1;}return sockfd;}int SendHttpRequest(int sockfd,char *purl)
{char tmpbuff[4096] = {0};ssize_t nsize = 0;sprintf(tmpbuff,"GET %s HTTP/1.1\r\n",purl);      //%s  用于将 purl里存放的内容拼接到 tmpbuffsprintf(tmpbuff,"%sHost: api.k780.com\r\n",tmpbuff);sprintf(tmpbuff,"%sUser-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/113.0\r\n",tmpbuff);sprintf(tmpbuff,"%sAccept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8\r\n",tmpbuff);sprintf(tmpbuff,"%sAccept-Language: en-US,en;q=0.5\r\n",tmpbuff);sprintf(tmpbuff,"%sConnection: keep-alive\r\n\r\n",tmpbuff);nsize = send(sockfd,tmpbuff,strlen(tmpbuff),0);if(-1 == nsize){perror("fail to send");return -1;}return 0;}int main(int argc, const char *argv[])
{int sockfd = 0;ssize_t nsize = 0;char tmpbuff[4096] = {0};sockfd = CreatTcpClient("103.205.5.228",80);SendHttpRequest(sockfd,"/?app=weather.today&weaid=%E8%A5%BF%E5%AE%89&appkey=72317&sign=be43b728a4f27463d34f4fcbfea69134&format=json");nsize = recv(sockfd,tmpbuff,sizeof(tmpbuff),0);if(-1 == nsize){perror("fial to recv");return -1;}printf("*********RECV***********\n");printf("%s\n",tmpbuff);printf("************************\n");close(sockfd);return 0;
}

 json数据解析

{"success":"1","result":{"weaid":"316","days":"2024-07-18","week":"星期四","cityno":"xian","citynm":"西安","cityid":"101110101","temperature":"33℃/24℃","temperature_curr":"32℃","humidity":"82%","aqi":"41","weather":"多云","weather_curr":"多云","weather_icon":"http://api.k780.com/upload/weather/d/1.gif","weather_icon1":"","wind":"西南风","winp":"1级","temp_high":"33","temp_low":"24","temp_curr":"32","humi_high":"0","humi_low":"0","weatid":"2","weatid1":"","windid":"5","winpid":"1","weather_iconid":"1"}
}

这是一个两层的

JSON格式

一种数据格式

JSON（JavaScript Object Notation）通常用于Web应用程序之间以及客户端与服务器之间的数据交换。

JSON的基本结构包括对象和数组：‘

•对象是一系列无序的键值对。对象以  {   开始 ，以  }  结束。每个键后面跟一个冒号 : 每个键值对之间用逗号 , 分隔。

•数组是值的有序集合。数组以 [ 开始，以 ] 结束。值之间使用逗号 , 分隔。

字符串： 

{"name":"code","gender":"male"
}

数字：

{"key1":10,"key2":20.0
}

 数组：

 {"key1" : [0, 1],"key2" : [2, 3]}

允许嵌套 

{"name": "John Doe","age": 30,"isEmployed": true,"address": {"street": "123 Main St","city": "Anytown"},"phoneNumbers": [{"type": "home","number": "555-1234"},{"type": "mobile","number": "555-5678"}]
}

name、age 和 isEmployed 是简单的键值对。address 是一个嵌套的对象，phoneNumbers 是一个包含对象的数组。 

利用cJOSN解析json格式：

http://t.csdnimg.cn/KbuRZ

NowAPI天气爬虫

 json请求

URL: http://api.k780.com/?app=weather.today&weaId=1&appkey=APPKEY&sign=SIGN&format=json

 注意:
        appkey:换成自己的APPKey
        sign:换成自己的sign标识 

1.正常返回
{"success": "1","result": {"weaid": "1","days": "2014-07-30","week": "星期三","cityno": "beijing","citynm": "北京","cityid": "101010100","temperature": "31℃/24℃", /*白天 夜间温度  (注: 夜间只有一个温度如24℃/24℃)*/"temperature_curr": "25℃", /*当前温度*/"humidity": "50%",/*湿度*/"aqi": "100",/*pm2.5 说明详见weather.pm25*/"weather": "多云转晴", /*天气*/"weather_icon": "http://api.k780.com/upload/weather/d/1.gif", /*气象图标 全部气象图标下载*/"weather_icon1": "", /*无意义不必理会*/"wind": "微风",/*风向*/"winp": "小于3级", /*风力*/"temp_high": "31", /*最高温度*/"temp_low": "24", /*最低温度*/"humi_high": "87.8", /*最大湿度 [历史遗留栏位不再更新]*/"humi_low": "75.2", /*最小湿度 [历史遗留栏位不再更新]*/"weatid": "2", /*天气ID，可对照weather.wtype接口中weaid*/"weatid1": "", /*无意义不必理会*/"windid": "1", /*风向ID(暂无对照表)*/"winpid": "2" /*风力ID(暂无对照表)*/"weather_iconid": "1"  /*气象图标编号,对应weather_icon 1.gif*/}
}

 请求报文格式:
 

GET 是最常用的 HTTP 方法，常用于获取服务器上的某个资源。

在浏览器中直接输入 URL 回车或点击浏览器收藏夹中的链接，此时浏览器就会发送出一个 GET 请求。

响应报文格式:
HTTP/1.1 200 OK\r\n
Server: nginx\r\n
Date: Fri, 08 Mar 2024 06:33:44 GMT\r\n
Content-Type: application/json; charset=utf-8;\r\n
Transfer-Encoding: chunked\r\n
Connection: keep-alive\r\n                         
Access-Control-Allow-Origin: *\r\n
\r\n
{"success":"1","result":{"weaid":"316","days":"2024-03-08","week":".........","cityno":"xian","citynm":"......","cityid":"101110101","temperature":"13.../0...","temperature_curr":"12...","humidity":"29%","aqi":"65","weather":"............","weather_curr":"...","weather_icon":"http://api.k780.com/upload/weather/d/0.gif","weather_icon1":"","wind":"......","winp":"2...","temp_high":"13","temp_low":"0","temp_curr":"12","humi_high":"0","humi_low":"0","weatid":"1","weatid1":"","windid":"4","winpid":"2","weather_iconid":"0"}}\r\n
 

• HTTP 在传输层依赖 TCP 协议，TCP 是面向字节流的。如果没有这个空行，就会出现”粘包问题“所以报文中会有很多 \r\n        
• 因为 HTTP 协议并没有规定报头部分的键值对有多少个，使用空行就相当于是报文的结束标记或报文和正文之间的分隔符

#include"head.h"
#include "cJSON.h"
int CreatTcpClient(char *pip,int port)
{int ret = 0;int sockfd = 0;struct sockaddr_in seraddr;sockfd = socket(AF_INET,SOCK_STREAM,0);if(-1 == sockfd){perror("fail to socket");return -1;}seraddr.sin_family = AF_INET;seraddr.sin_port = htons(port);seraddr.sin_addr.s_addr = inet_addr(pip);ret = connect(sockfd,(struct sockaddr *)&seraddr,sizeof(seraddr));if(-1 == ret){perror("fail to connect ");return -1;}return sockfd;}int SendHttpRequest(int sockfd,char *purl)
{char tmpbuff[4096] = {0};ssize_t nsize = 0;sprintf(tmpbuff,"GET %s HTTP/1.1\r\n",purl);      //%s  用于将 purl里存放的内容拼接到 tmpbuffsprintf(tmpbuff,"%sHost: api.k780.com\r\n",tmpbuff);sprintf(tmpbuff,"%sUser-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/113.0\r\n",tmpbuff);sprintf(tmpbuff,"%sAccept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8\r\n",tmpbuff);sprintf(tmpbuff,"%sAccept-Language: en-US,en;q=0.5\r\n",tmpbuff);sprintf(tmpbuff,"%sConnection: keep-alive\r\n\r\n",tmpbuff);nsize = send(sockfd,tmpbuff,strlen(tmpbuff),0);if(-1 == nsize){perror("fail to send");return -1;}return 0;}int get_json(char *all_tmpbuff)
{char *start, *end;size_t json_length;cJSON *json = NULL;cJSON *json_result = NULL;cJSON *json_days = NULL;cJSON *json_cityno = NULL;cJSON *json_weather = NULL;// 直接使用 all_tmpbuff，避免不必要的字符串复制start = strchr(all_tmpbuff, '{');if (start == NULL){printf("json data not find\n");return -1;}end = strrchr(all_tmpbuff, '}');if (end == NULL){printf("closing brace not find\n");return -1;}json_length = end - start + 1;// 使用 all_tmpbuff[start, end] 进行解析，无需复制// 解析 JSONjson = cJSON_Parse(start);if (!json){printf("cJSON_Parse error: %s\n", cJSON_GetErrorPtr());return -1;}// 获取 "result" 对象json_result = cJSON_GetObjectItem(json, "result");if (!json_result){printf("Failed to find 'result' object\n");cJSON_Delete(json);return -1;}// 从 "result" 中获取 "days"json_days = cJSON_GetObjectItem(json_result, "days");json_cityno = cJSON_GetObjectItem(json_result, "cityno");json_weather = cJSON_GetObjectItem(json_result, "weather");/*if (!json_days || !cJSON_IsString(json_days)){printf("Failed to find 'days' string\n");cJSON_Delete(json);return -1;}*/printf("days: %s\tcity: %s\tweather %s\n", json_days->valuestring,json_cityno->valuestring,json_weather->valuestring);cJSON_Delete(json);return 0;
}int main(int argc, const char *argv[])
{int sockfd = 0;ssize_t nsize = 0;char tmpbuff[4096] = {0};sockfd = CreatTcpClient("103.205.5.228",80);SendHttpRequest(sockfd,"/?app=weather.today&weaid=%E8%A5%BF%E5%AE%89&appkey=72317&sign=be43b728a4f27463d34f4fcbfea69134&format=json");nsize = recv(sockfd,tmpbuff,sizeof(tmpbuff),0);if(-1 == nsize){perror("fial to recv");return -1;}printf("*********RECV***********\n");printf("%s\n",tmpbuff);printf("************************\n");get_json(tmpbuff);close(sockfd);return 0;
}

 运行结果：