目的：
一个WEB服务器需要解析客户端（浏览器）发来的请求，两种常见的请求方式是GET和POST。
GET的请求格式：
GET请求没有请求体只有请求头GET请求的请求参数放在URL后加上一个"?"的后面，参数以key=value的形式传递，参数与参数之间使用"&"进行连接。
GET /signin?next=%2F HTTP/2\r\nHost: \r\nUser-Agent: Mozilla/5.0\r\nAccept: */*\r\nAccept-Language: zh-CN\r\nAccept-Encoding: gzip, deflate\r\nConnection: keep-alive\r\nUpgrade-Insecure-Requests: 1\r\nCache-Control: max-age=0\r\nTE: trailers\r\n\r\n
请求头中每一行的后面都要加"\r\n"结尾；第一行是状态行，分别是请求方法(GET)、请求路径(/signin?next=%2F)、协议版本(HTTP/2)；其余所有行均以XXX: XXXX的格式表示；最后需要一个"\r\n"的空行作为请求头结束的标志。
POST的请求格式：
POST请求传送的数据放在请求体中；POST请求的请求参数放在请求体中，由请求头中的"Content-Type"字段决定其格式；如果是"Content-Type: application/x-www-form-urlencoded"，则请求参数以key=value的形式传递，参数与参数之间使用"&"进行连接如果是"Content-Type: multipart/form-data"，则使用boundary(分割线)充当参数与参数之间的连接(相当于&)
POST /login HTTP/1.1\r\nHost: 127.0.0.1:8888\r\nUser-Agent: Mozilla/5.0\r\nAccept: */*\r\nAccept-Language: zh-CN\r\nAccept-Encoding: gzip, deflate\r\nContent-Type: application/x-www-form-urlencoded\r\nContent-Length: 29\r\nConnection: keep-alive\r\n\r\nusername=root&password=123456
请求头中每一行的后面都要加"\r\n"结尾；第一行是状态行，分别是请求方法(POST)、请求路径(/login)、协议版本(HTTP/1.1)；请求头内的剩余内容均以XXX: XXXX的格式表示；请求头最后需要一个"\r\n"的空行作为结束的标志；放在请求体内的请求参数以key=value的形式传递，参数与参数之间使用"&"进行连接。
功能介绍：
使用状态机和正则表达式完成了对HTTP请求报文的解析，支持解析GET报文和POST报文(仅限Content-Type: application/x-www-form-urlencoded)。
由于计划完成的web服务器需要实现展示主页(GET)、用户登录(POST)、用户注册(POST)、获取图片(GET)、获取视频(GET)五个功能，所以web服务器的请求解析模块满足：
若为GET请求，可根据状态行信息，完成对请求内容地址的转换，以及请求头内其他内容的提取。
若为POST请求，可根据请求参数，完成登录和注册这两个功能(登录：根据后台数据库表中的信息判断用户名与密码是否正确；注册：向后台数据库表中插入符合条件的新用户名和密码)。
状态机流程：
enum PARSE_STATE{REQUEST_LINE,HEADERS,BODY,FINISH};
如果为GET请求：REQUEST_LINE——>HEADERS——>FINISH；
如果为POST请求：REQUEST_LINE——>HEADERS——>BODY——>FINISH。
用到的正则表达式：
1、^([^ ]*) ([^ ]*) HTTP/([^ ]*)$ 匹配状态行
2、^([^:]*): ?(.*)$ 匹配请求头内的XXX: XXXX字段
3、(?!&)(.*?)=(.*?)(?=&|$) 匹配POST的请求参数
HttpRequest类结构 httprequest.h
#ifndef HTTPREQUEST_H#define HTTPREQUEST_H#include <unordered_set>#include <unordered_map>#include <string>#include <regex>#include <algorithm>#include <memory>#include <mysql/mysql.h>#include "buffer.h"#include "log.h"#include "sqlconnpool.h"using std::string;class HttpRequest{public:enum PARSE_STATE//解析流程的状态{REQUEST_LINE,HEADERS,BODY,FINISH};HttpRequest();~HttpRequest()=default;bool parse(Buffer& buffer);//解析全过程const string& getMethod() const;const string& getPath() const;const string& getVersion() const;bool isKeepAlive() const;private:void parseRequestLine(const string& line);//解析状态行void parseHeader(const string& line);//解析请求头void parseBody(const string& line);//解析请求体void parsePath();//解析请求路径void parsePost();//解析POST请求void parseUrlencoded();//解析POST请求的请求参数bool userVertify(const string& username,const string& password,int tag);//身份验证PARSE_STATE state;string method;string path;string version;string body;std::unordered_map<string,string> header;//存储请求头字段std::unordered_map<string,string> post; //存储POST请求参数static const std::unordered_set<string> DEFAULT_HTML;static const std::unordered_map<string,int> DEFAULT_HTML_TAG;};#endif // !HTTPREQUEST_H
HttpRequest类实现 httprequest.cpp
#include "httprequest.h"const std::unordered_set<string> HttpRequest::DEFAULT_HTML={"/home","/register","/login","/video","/picture"};const std::unordered_map<string,int> HttpRequest::DEFAULT_HTML_TAG={{"/register.html", 0},{"/login.html", 1}};HttpRequest::HttpRequest(){Log::getInstance()->init();init();}void HttpRequest::init(){method="";path="";version="";body="";state = REQUEST_LINE;header.clear();post.clear();}bool HttpRequest::parse(Buffer& buffer){if(buffer.readableBytes()<=0)return false;while(buffer.readableBytes()&&state!=FINISH){const char CRLF[3]="\r\n";const char* lineEnd=std::search(buffer.peek(),static_cast<const char*>(buffer.beginWrite()),CRLF,CRLF+2);string line(buffer.peek(),lineEnd);switch (state){case REQUEST_LINE:parseRequestLine(line);parsePath();break;case HEADERS:parseHeader(line);break;case BODY:parseBody(line);break;default:break;}if(lineEnd==buffer.beginWrite())//解析完请求体(不由"\r\n"结尾)break;buffer.retrieveUntil(lineEnd+2);//解析完一行Headers(由"\r\n"结尾)}return true;}void HttpRequest::parsePath(){if(path=="/") path="/home.html";elseif(DEFAULT_HTML.count(path))path+=".html";}void HttpRequest::parseRequestLine(const string& line){std::regex patten("^([^ ]*) ([^ ]*) HTTP/([^ ]*)$");std::smatch match;if(!std::regex_match(line,match,patten)){LOG_ERROR("%s","Parse RequestLine Error");}method=match[1];path=match[2];version=match[3];state=HEADERS;}void HttpRequest::parseHeader(const string& line){std::regex patten("^([^:]*): ?(.*)$");std::smatch match;if(std::regex_match(line,match,patten)){header[match[1]]=match[2];} else{state=BODY;}}void HttpRequest::parseBody(const string& line){body=line;parsePost();state=FINISH;}void HttpRequest::parsePost(){if(method=="POST"&&header["Content-Type"]=="application/x-www-form-urlencoded"){parseUrlencoded();if(DEFAULT_HTML_TAG.count(path)){int tag=DEFAULT_HTML_TAG.find(path)->second;if(userVertify(post["username"],post["password"],tag)){path="/home.html";}else{path="/error.html";}}}}void HttpRequest::parseUrlencoded(){std::regex patten("(?!&)(.*?)=(.*?)(?=&|$)");std::smatch match;string::const_iterator begin=body.begin();string::const_iterator end=body.end();while(std::regex_search(begin,end,match,patten)){post[match[1]]=match[2];begin=match[0].second;}}bool HttpRequest::userVertify(const string& username,const string& password,int tag){SqlConnPool* pool = SqlConnPool::getInstance();std::shared_ptr<SqlConn> conn=pool->getConn();string order1="SELECT username,password FROM user WHERE username='"+username+"' LIMIT 1";string order2="INSERT INTO user(username, password) VALUES('"+username+"','"+password+"')";MYSQL_RES* res=conn->query(order1);string user;string pwd;MYSQL_ROW row=nullptr;while((row=mysql_fetch_row(res))!=nullptr) {user=row[0];pwd=row[1];}if(tag)//登录{if(pwd!=password)//密码错误{LOG_ERROR("%s","Password Error");return false;}LOG_INFO("%s Login Success",username);}else//注册{if(!user.empty())//用户名已被使用{LOG_ERROR("%s","Username Used");return false;}if(!conn->update(order2))//数据库插入失败{LOG_ERROR("%s","Insert Error");return false;}LOG_INFO("%s Register Success",username);}mysql_free_result(res);return true;}const string& HttpRequest::getMethod() const{return method;}const string& HttpRequest::getPath() const{return path;}const string& HttpRequest::getVersion() const{return version;}bool HttpRequest::isKeepAlive() const{if(header.count("Connection")){return header.find("Connection")->second=="keep-alive";}return false;}
测试程序 testHttpRequest.cpp
分别解析GET请求和POST请求，根据解析内容进行判断。
#include "httprequest.h"#include <iostream>using namespace std;void testPost(){HttpRequest request;Buffer input;input.append("POST /login HTTP/1.1\r\n""Host: 127.0.0.1:8888\r\n""User-Agent: Mozilla/5.0\r\n" "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9\r\n""Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6\r\n""Accept-Encoding: gzip, deflate\r\n""Content-Type: application/x-www-form-urlencoded\r\n""Content-Length: 29\r\n""Connection: keep-alive\r\n""\r\n""username=root&password=123456");request.parse(input);cout<<"method:"<<request.getMethod()<<endl;cout<<"path:"<<request.getPath()<<endl;cout<<"version:"<<request.getVersion()<<endl;if(request.isKeepAlive()) cout<<"isKeepAlive"<<endl;}void testGet(){HttpRequest request;Buffer input;input.append("GET /signin?next=%2F HTTP/2\r\n""Host: \r\n""User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/0101 Firefox/91.0\r\n""Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8\r\n""Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2\r\n""Accept-Encoding: gzip, deflate, br\r\n""Connection: keep-alive\r\n""Upgrade-Insecure-Requests: 1\r\n""Cache-Control: max-age=0\r\n""TE: trailers\r\n""\r\n");request.parse(input);cout<<"method:"<<request.getMethod()<<endl;cout<<"path:"<<request.getPath()<<endl;cout<<"version:"<<request.getVersion()<<endl;if(request.isKeepAlive()) cout<<"isKeepAlive"<<endl;}int main(){cout<<"POST------------------------------------------"<<endl;testPost();cout<<"GET-------------------------------------------"<<endl;testGet();}
运行结果：
由日志信息可以判断，对GET和POST的请求解析正确。
附：
Makefile
CXX = g++CFLAGS = -std=c++14 -O2 -Wall -g TARGET = testHttpRequestOBJS = buffer.cpp log.cpp blockqueue.h\sqlconn.cpp sqlconnpool.cpp httprequest.cpp\testHttpRequest.cppall: $(OBJS)$(CXX) $(CFLAGS) $(OBJS) -o $(TARGET) -pthread -L/usr/lib64/mysql -lmysqlclientclean:rm -rf $(OBJS) $(TARGET)
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