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仿nginx Http服务器的设计与实现(二)——http协议解析

时间:2014-04-30 22:17:40      阅读:449      评论:0      收藏:0      [点我收藏+]

标签:http服务器   nginx   http协议解析   实现   

上一篇文章《仿nginx Http服务器的设计与实现(一)——多进程和多路IO的实现》中实现了一个仿照nginx的支持高并发的服务器,但只是实现了端口监听和数据接收,并没有实现对http协议的解析,下面就对如何解析http协议进行说明。

我们可以通过浏览器访问之前所搭建的http服务器,可以看到终端输出如下:

GET / HTTP/1.1
Host: 127.0.0.1:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.131 Safari/537.36
Accept-Encoding: gzip,deflate,sdch
Accept-Language: zh-CN,zh;q=0.8

参考一些网上的资料可以知道,http协议主要有三部分组成,即请求行、若干请求字段、请求体。请求行主要包括所使用的http方法,访问的路径以及http的版本。请求字段主要包括若干个详细说明本次http请求的字段,每个字段由字段名+冒号+空格+字段值组成。请求体主要包括发送到客户端的数据。其中请求行和请求字段之间是连续的,而请求字段与请求体之间会有两个空白行(\r\n)分隔。

在明确了这些内容之后,我们就可以开始对接收到的http请求进行解析了。本文将使用两个类,CHttpRequest和CHttpResponse来实现这一功能。下面首先修改上一篇文章中的

handleRequest方法:

//处理http请求
bool handleRequest(int connFd) {
    if (connFd<=0) return false;
    //读取缓存
    char buff[4096];
    //读取http header
    int len = (int)recv(connFd, buff, sizeof(buff), 0);
    if (len<=0) {
        return false;
    }
    buff[len] = ‘\0‘;
    std::cout<<buff<<std::endl;

    CHttpRequest *httpRequest = new CHttpRequest();
    httpRequest->handleRequest(buff);
    CHttpResponse *httpResponse = new CHttpResponse(httpRequest);
    bool result = httpResponse->response(connFd);
    //返回是否需要中断连接
    std::string transformConnection(httpRequest->connection);
    std::transform(transformConnection.begin(), transformConnection.end(), transformConnection.begin(), ::tolower);
    return transformConnection == "Keep-Alive" && result;
}

该代码中采用了一个长度为4096的缓冲区接收http头,接收完成之后,调用CHttpRequest进行解析。下面来看看CHttpRequest的代码:

#include "CHttpRequest.h"
#include "define.h"

using namespace std;

CHttpRequest::CHttpRequest() {
    connection = "Close";
    modifiedTime = "";
    fileStart = 0;
    fileEnd = 0;
    
    fieldMap[TS_HTTP_HEADER_CONNECTION] = &CHttpRequest::handleConnection;
    fieldMap[TS_HTTP_HEADER_AUTHORIZATION] = &CHttpRequest::handleAuthorization;
    fieldMap[TS_HTTP_HEADER_RANGE] = &CHttpRequest::handleRange;
    fieldMap[TS_HTTP_HEADER_IF_MOD_SINCE] = &CHttpRequest::handleIfModSince;
}

void CHttpRequest::handleRequest(char *header) {
    stringstream stream;
    stream<<header;
    
    int count = 0;
    while (1) {
        if (stream.eof()) {
            break;
        }
        char line[1024];
        stream.getline(line, sizeof(line));
        if (strcmp(line, "")==0) {
            continue;
        }
        
        stringstream lineStream;
        lineStream<<line;
        //first line
        if (count == 0) {
            lineStream>>method;
            lineStream>>path;
            lineStream>>version;
        }else {
            string fieldName;
            lineStream>>fieldName;
            //remove \r
            line[strlen(line)-1] = ‘\0‘;
            void(CHttpRequest::*func)(char*) = fieldMap[fieldName];
            if (func!=NULL) {
                (this->*func)(line+fieldName.length()+1);
            }
        }
        count++;
    }
}

void CHttpRequest::handleConnection(char *field) {
    if (ENABLE_KEEP_ALIVE) {
        connection = string(field);
    }
}

void CHttpRequest::handleAuthorization(char *field) {
    char authName[10], authInfo[256];
    sscanf(field, "%s %s", authName, authInfo);
    authorize = string(authInfo);
}

void CHttpRequest::handleRange(char *field) {
    if (strstr(field, "bytes=")==field) {
        char *start = strtok(field+strlen("bytes="), "-");
        fileStart = start==NULL?0:atol(start);
        char *end = strtok(NULL, "-");
        fileEnd = end==NULL?0:atol(end);
    }
}

void CHttpRequest::handleIfModSince(char *field) {
    modifiedTime = string(field);
}

为了保证http解析的效率,本文采用了与nginx中类似的做法,将字段名与解析函数放到了map中(nginx中使用的是hash表,在这里简化为map)。在解析完成之后,调用CHttpResponse构造响应。CHttpResponse代码如下:

#include "CHttpResponse.h"
#include "CHttpRequest.h"
#include <sys/socket.h>
#include "define.h"
#include <string.h>

#define HTTP_RESPONSE_404 "<html><head><title>404 Not Found</title></head><body><h1>Not Found</h1><p>The requested URL was not found on this server.</p></body></html>"

std::string getStringFromTime(time_t time) {
    char timeBuff[64];
    struct tm tm = *gmtime(&time);
    strftime(timeBuff, sizeof timeBuff, "%a, %d %b %Y %H:%M:%S %Z", &tm);
    return std::string(timeBuff);
}

CHttpResponse::CHttpResponse(CHttpRequest *request) {
    m_request = request;
    if (m_request->method.compare(TS_HTTP_METHOD_GET_S)==0 || m_request->method.compare(TS_HTTP_METHOD_HEAD_S)==0) {
        std::string path = ROOT_PATH;
        if (m_request->path.compare("/")==0) {
            path += ROOT_HTML;
        }else {
            path += m_request->path;
        }
        
        m_statusCode = 0;
        //if file exist
        if (isFileExist(path.c_str())) {
            //if receive modified time
            if (!m_request->modifiedTime.empty()) {
                time_t time = fileModifiedTime(path.c_str());
                if (getStringFromTime(time) == m_request->modifiedTime) {
                    m_statusCode = TS_HTTP_STATUS_NOT_MODIFIED;
                    m_statusMsg = TS_HTTP_STATUS_NOT_MODIFIED_S;
                }
            }
            //if file modified
            if (m_statusCode == 0) {
                if (m_request->fileStart || m_request->fileEnd) {
                    long long fileSize = getFileSize(path.c_str());
                    //if request range satisfied
                    if (m_request->fileStart<fileSize && m_request->fileEnd<fileSize) {
                        m_statusCode = TS_HTTP_STATUS_PARTIAL_CONTENT;
                        m_statusMsg = TS_HTTP_STATUS_PARTIAL_CONTENT_S;
                        m_sendFilePath = path;
                    }else {
                        m_statusCode = TS_HTTP_STATUS_REQUEST_RANGE_NOT_SATISFIABLE;
                        m_statusMsg = TS_HTTP_STATUS_REQUEST_RANGE_NOT_SATISFIABLE_S;
                    }
                }else {
                    m_statusCode = TS_HTTP_STATUS_OK;
                    m_statusMsg = TS_HTTP_STATUS_OK_S;
                    m_sendFilePath = path;
                }
            }
        } else {
            m_statusCode = TS_HTTP_STATUS_NOT_FOUND;
            m_statusMsg = TS_HTTP_STATUS_NOT_FOUND_S;
            m_sendStr = HTTP_RESPONSE_404;
        }
    }
}

bool CHttpResponse::response(int connFd) {
    bool result = true;
    std::stringstream responseStream;
    
    responseStream<<m_request->version<<" "<<m_statusMsg<<"\r\n";
    //time
    responseStream<<"Date: "<<getStringFromTime(time(0))<<"\r\n";
    
    //server name
    responseStream<<"Server: "<<SERVER_NAME<<"\r\n";
    
    //keep alive
    responseStream<<"Connection: "<<m_request->connection<<"\r\n";
    
    //content length
    long long contentLength = 0;
    //if file exist
    if (!m_sendFilePath.empty()) {
        //if define file end
        if (m_request->fileEnd) {
            contentLength = m_request->fileEnd - m_request->fileStart + 1;
        }
        //if define file start
        else if (m_request->fileStart) {
            contentLength = getFileSize(m_sendFilePath.c_str()) - m_request->fileStart + 1;
        }
        //if undefine start or end
        else {
            contentLength = getFileSize(m_sendFilePath.c_str());
        }
    } else if (!m_sendStr.empty()) {
        contentLength = m_sendStr.length();
    }
    if (contentLength) {
        responseStream<<"Content-Length: "<<contentLength<<"\r\n";
    }
    
    //last modified
    if (!m_sendFilePath.empty()) {
        responseStream<<"Last-Modified: "<<getStringFromTime(fileModifiedTime(m_sendFilePath.c_str()))<<"\r\n";
        
        responseStream<<"Accept-Ranges: "<<"bytes"<<"\r\n";
    }
    
    //content type
    if (!m_sendFilePath.empty()) {
        char path[256];
        strcpy(path, m_sendFilePath.c_str());
        char *ext = strtok(path, ".");
        char *lastExt = ext;
        while (ext!=NULL) {
            ext = strtok(NULL, ".");
            if (ext) lastExt = ext;
        }
        for (int i=0; i<38; i++) {
            if (strcmp(mmt[i].ext, lastExt)==0) {
                responseStream<<"Content-Type: "<<mmt[i].type<<"\r\n";
                break;
            }
        }
    }
    
    //other
    switch (m_statusCode) {
        case TS_HTTP_STATUS_UNAUTHORIZED:
            responseStream<<"WWW-Authenticate: Basic realm=\"zhaoxy.com\"\r\n";
            break;
        case TS_HTTP_STATUS_FOUND:
            responseStream<<"Location: /index.html\r\n";
            break;
        case TS_HTTP_STATUS_PARTIAL_CONTENT:
            responseStream<<"Content-Range: "<<"bytes "<<m_request->fileStart<<"-"<<(m_request->fileEnd==0?contentLength:m_request->fileEnd)<<"/"<<getFileSize(m_sendFilePath.c_str())<<"\r\n";
            break;
        default:
            break;
    }
    
    //seperator
    responseStream<<"\r\n";
    
    //send response header
    std::string responseStr = responseStream.str();
    std::cout<<responseStr<<std::endl;
    
    send(connFd, responseStr.c_str(), responseStr.length(), 0);
    
    //content
    
    //if not head method
    if (m_request->method.compare(TS_HTTP_METHOD_HEAD_S)!=0) {
        if (!m_sendFilePath.empty()) {
            std::ifstream file(m_sendFilePath);
            file.seekg(m_request->fileStart, std::ifstream::beg);
            while(file.tellg() != -1)
            {
                char *p = new char[1024];
                bzero(p, 1024);
                file.read(p, 1024);
                int n = (int)send(connFd, p, 1024, 0);
                if (n < 0) {
                    std::cout<<"ERROR writing to socket"<<std::endl;
                    result = false;
                    break;
                }
                delete p;
            }
            file.close();
        }else {
            send(connFd, m_sendStr.c_str(), m_sendStr.length(), 0);
        }
    }
    
    return result;
}

该代码支持断点续传、last modified和authorization字段。具体的逻辑不作详细说明,有疑问的可以留言。

该Http服务器的代码已经上传到GitHub上,大家可以直接下载


如果大家觉得对自己有帮助的话,还希望能帮顶一下,谢谢:)
转载请注明出处,谢谢!

仿nginx Http服务器的设计与实现(二)——http协议解析

标签:http服务器   nginx   http协议解析   实现   

原文地址:http://blog.csdn.net/zhaoxy_thu/article/details/24716221

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