一、HTTP响应报文格式

HTTP/1.1 200 OK
Bdpagetype: 1
Bdqid: 0xf3c9743300024ee4
Cache-Control: private
Connection: keep-alive
Content-Encoding: gzip
Content-Type: text/html;charset=utf-8
Date: Fri, 26 Feb 2021 08:44:35 GMT
Expires: Fri, 26 Feb 2021 08:44:35 GMT
Server: BWS/1.1
Set-Cookie: BDSVRTM=13; path=/
Set-Cookie: BD_HOME=1; path=/
Set-Cookie: H_PS_PSSID=33514_33257_33273_31660_33570_26350; path=/; domain=.baidu.com
Strict-Transport-Security: max-age=172800
Traceid: 1614329075128412289017566699583927635684
X-Ua-Compatible: IE=Edge,chrome=1
Transfer-Encoding: chunked

二、根据解析出的原始数据，对客户端的请求做出处理 processHttpRequest 

// 处理http请求协议
bool processHttpRequest(struct HttpRequest* req,struct HttpResponse* response);

// 处理基于get的http请求
bool processHttpRequest(struct HttpRequest* req,struct HttpResponse* response) {if(strcasecmp(req->method,"get") != 0) {return -1;}decodeMsg(req->url,req->url); // 解码字符串// 处理客户端请求的静态资源（目录或者文件）char* file = NULL;if(strcmp(req->url,"/") == 0) {file = "./";}else {file = req->url + 1;}// 获取文件属性struct stat st;int ret = stat(file,&st);if(ret == -1) {// 文件不存在 -- 回复404// sendHeadMsg(cfd,404,"Not Found",getFileType(".html"),-1);// sendFile("404.html",cfd);strcpy(response->fileName,"404.html");response->statusCode = NotFound;strcpy(response->statusMsg,"Not Found");// 响应头httpResponseAddHeader(response,"Content-Type",getFileType(".html"));response->sendDataFunc = sendFile;return 0;}strcpy(response->fileName,file);response->statusCode = OK;strcpy(response->statusMsg,"OK!");// 判断文件类型if(S_ISDIR(st.st_mode)) {// 把这个目录中的内容发送给客户端// sendHeadMsg(cfd,200,"OK",getFileType(".html"),-1);// sendDir(file,cfd);// 响应头httpResponseAddHeader(response,"Content-Type",getFileType(".html"));response->sendDataFunc = sendDir;}else {// 把文件的内容发送给客户端// sendHeadMsg(cfd,200,"OK",getFileType(file),st.st_size);// sendFile(file,cfd);// 响应头char tmp[12] = {0};sprintf(tmp,"%ld",st.st_size);httpResponseAddHeader(response,"content-type",getFileType(file));httpResponseAddHeader(response,"content-length",tmp);response->sendDataFunc = sendFile;}return 0;
}

1.解码字符串  

• 解决浏览器无法访问带特殊字符的文件得到问题

// 将字符转换为整型数
int hexToDec(char c){if (c >= '0' && c <= '9')return c - '0';if (c >= 'a' && c <= 'f')return c - 'a' + 10;if (c >= 'A' && c <= 'F')return c - 'A' + 10;return 0;
}// 解码字符串
// to 存储解码之后的数据, 传出参数, from被解码的数据, 传入参数
void decodeMsg(char* to,char* from) {for(;*from!='\0';++to,++from) {// isxdigit -> 判断字符是不是16进制格式, 取值在 0-f// Linux%E5%86%85%E6%A0%B8.jpgif(from[0] == '%' && isxdigit(from[1]) && isxdigit(from[2])){// 将16进制的数 -> 十进制 将这个数值赋值给了字符 int -> char// B2 == 178// 将3个字符, 变成了一个字符, 这个字符就是原始数据// *to = (hexToDec(from[1]) * 16) + hexToDec(from[2]);*to = (hexToDec(from[1]) << 4) + hexToDec(from[2]);// 跳过 from[1] 和 from[2] ，因此在当前循环中已经处理过了from += 2;}else{// 字符拷贝，赋值*to = *from;}}*to = '\0';
}

2.判断文件扩展名，返回对应的 Content-Type(Mime-Type)

const char* getFileType(const char* name);

const char* getFileType(const char* name) {// a.jpg a.mp4 a.html// 自右向左查找 '.' 字符，如不存在返回NULLconst char* dot = strrchr(name,'.');if(dot == NULL) return "text/plain; charset=utf-8";//纯文本if(strcmp(dot,".html") == 0 || strcmp(dot,".htm") == 0) return "text/html; charset=utf-8";if(strcmp(dot,".jpg")==0 || strcmp(dot,".jpeg")==0) return "image/jpeg";if(strcmp(dot,".gif")==0)return "image/gif";if(strcmp(dot,".png")==0)return "image/png";if(strcmp(dot,".css")==0) return "text/css";if(strcmp(dot,".au")==0)return "audio/basic";if(strcmp(dot,".wav")==0)return "audio/wav";if(strcmp(dot,".avi")==0)return "video/x-msvideo";if(strcmp(dot,".mov")==0 || strcmp(dot,".qt")==0)return "video/quicktime";if(strcmp(dot,".mpeg")==0 || strcmp(dot,".mpe")==0)return "video/mpeg";if(strcmp(dot,".vrml")==0 || strcmp(dot,".wrl")==0)return "model/vrml";if(strcmp(dot,".midi")==0 || strcmp(dot,".mid")==0)return "audio/midi";if(strcmp(dot,".mp3")==0)return "audio/mpeg";if(strcmp(dot,".ogg") == 0) return "application/ogg";if(strcmp(dot,".pac") == 0)return "application/x-ns-proxy-autoconfig";if(strcmp(dot,".pdf") == 0)return "application/pdf";return "text/plain; charset=utf-8";//纯文本
}

3.发送文件  sendFile

// 发送文件
void sendFile(const char* fileName,struct Buffer* sendBuf,int cfd);

void sendFile(const char* fileName,struct Buffer* sendBuf,int cfd) {// 打开文件int fd = open(fileName,O_RDONLY);assert(fd > 0); 
#if 1while (1) {char buf[1024];int len = read(fd,buf,sizeof(buf));if(len > 0) {// send(cfd,buf,len,0);bufferAppendData(sendBuf,buf,len);}else if(len == 0) {break;}else{close(fd);perror("read");}}
#else// 把文件内容发送给客户端off_t offset = 0;int size = lseek(fd,0,SEEK_END);// 文件指针移动到了尾部lseek(fd,0,SEEK_SET);// 移动到文件头部while (offset < size){int ret = sendfile(cfd,fd,&offset,size - offset);printf("ret value: %d\n",ret);if (ret == -1 && errno == EAGAIN) {printf("没数据...\n");}}
#endifclose(fd);
}

4.发送目录

// 发送目录
void sendDir(const char* dirName,struct Buffer* sendBuf,int cfd); 

void sendDir(const char* dirName,struct Buffer* sendBuf,int cfd) {char buf[4096] = {0};sprintf(buf,"<html><head><title>%s</title></head><body><table>",dirName);struct dirent** nameList;int num = scandir(dirName,&nameList,NULL,alphasort);for(int i=0;i<num;i++) {// 取出文件名 nameList 指向的是一个指针数组 struct dirent* tmp[]char* name = nameList[i]->d_name;struct stat st;char subPath[1024] = {0};sprintf(subPath,"%s/%s",dirName,name);stat(subPath,&st);if(S_ISDIR(st.st_mode)) {// 从当前目录跳到子目录里边，/sprintf(buf+strlen(buf),"<tr><td><a href=\"%s/\">%s</a></td><td>%ld</td></tr>",name,name,st.st_size);}else{sprintf(buf+strlen(buf),"<tr><td><a href=\"%s\">%s</a></td><td>%ld</td></tr>",name,name,st.st_size);}// send(cfd,buf,strlen(buf),0);bufferAppendString(sendBuf,buf);memset(buf,0,sizeof(buf));free(nameList[i]); } sprintf(buf,"</table></body></html>");// send(cfd,buf,strlen(buf),0);bufferAppendString(sendBuf,buf);free(nameList);
}

三、解析http请求协议 parseHttpRequest  

可以看这篇关于httpResponsePrepareMsg函数具体是如何组织响应数据的：HttpResponse的定义和初始化 以及组织 HttpResponse 响应消息https://blog.csdn.net/weixin_41987016/article/details/135464760

// 解析http请求协议
bool parseHttpRequest(struct HttpRequest* req,struct Buffer* readBuf,struct HttpResponse* response,struct Buffer* sendBuf,int socket);

// 解析http请求协议
bool parseHttpRequest(struct HttpRequest* req,struct Buffer* readBuf,struct HttpResponse* response,struct Buffer* sendBuf,int socket) {bool flag = true;while(req->curState!=ParseReqDone) {switch(req->curState) {case ParseReqLine:// 解析请求行flag = parseHttpRequestLine(req,readBuf);break;case ParseReqHeaders:// 解析请求头flag = parseHttpRequestHeader(req,readBuf);break;case ParseReqBody:break;default:break;}if(!flag) {return flag;}// 判断是否解析完毕了，如果完毕了，需要准备回复的数据if(req->curState==ParseReqDone) {// 1.根据解析出的原始数据，对客户端的请求做出处理processHttpRequest(req,response);// 2.组织响应数据并发送给客户端httpResponsePrepareMsg(response,sendBuf,socket);}}req->curState = ParseReqLine;// 状态还原，保证还能继续处理第二条及以后的请求return flag;
}