如何在reactor的基础上实现业务？就是怎么利用reactor做服务器，并实现服务器的业务。
本文基于reactor，实现简单的http协议封装。只是为了说明reactor如何做业务，真正的http服务器业务逻辑是很复杂的。
服务器网络这一层，如nginx、redis，核心是epoll，实现使用的是reactor。
目录
http协议封装与reactor的关系
reactor包含内容
reactor_run，event loop，通过epoll进行io检测；accept_cb，处理网络连接；recv_cb 接收客户端http请求send_cb 发送http响应应用层什么场景使用accept_cb?
对特定ip的访问进行限制；负载均衡的功能，就是将请求转发到哪台服务器进行处理。如果http服务器没有特殊的需求，是不需要修改reactor中的accept_cb的。
如何在reactor基础上实现http
http使用的是reqeust-reply的模型进行通讯，客户端发送http请求，服务器处理请求并返回应答。http的传输层是基于TCP的。
http的tcp链接的生命周期：
accept_cbrecv_cbsend_cb对于服务器，首先需要使用recv_cb接收http数据，通过拆包粘包得到一帧完整的http数据；之后对http数据进行解析处理；最后通过send_cb向客户端发送response。
实现简单的response
先实现一个最简单的response，对于所有http请求，直接回复一个response，内容是一段html。返回给客户端后，浏览器可以直接显示。只在send_cb中调用发送数据就可以了。
int http_response(struct ntyevent *ev) { if (ev == NULL) return -1; memset(ev->buffer, 0, BUFFER_LENGTH); const char *html = "<html><head><title>hello http</title></head><body><H1>Cong</H1></body></html>\r\n\r\n"; ev->length = sprintf(ev->buffer, "HTTP/1.1 200 OK\r\n\ Date: Sun, 30 Jan 2022 05:55:32 GMT\r\n\ Content-Type: text/html;charset=UTF-8\r\n\ Content-Length: 81\r\n\r\n%s", html); return ev->length; } int send_cb(int fd, int events, void *arg) { struct ntyreactor *reactor = (struct ntyreactor*)arg; struct ntyevent *ev = ntyreactor_idx(reactor, fd); http_response(ev); // int len = send(fd, ev->buffer, ev->length, 0); if (len > 0) { printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer); nty_event_del(reactor->epfd, ev); nty_event_set(ev, fd, recv_cb, reactor); nty_event_add(reactor->epfd, EPOLLIN, ev); } else { close(ev->fd); nty_event_del(reactor->epfd, ev); printf("send[fd=%d] error %s\n", fd, strerror(errno)); } return len; }HTTP响应由四个部分组成，分别是：状态行、消息报头、空行和响应正文。
http get请求实现
实现http get请求获取静态资源。
客户端发送一个HTTP 请求到服务器的请求消息包括以下格式：请求行（ request line ）、请求头部（ header ）、空行和请求数据四个部分组成，下图给出了请求报文的一般格式。
读请求行
需要对http请求进行解析，判断请求类型(GET、POST等)，获取资源(uri)
int http_request(struct ntyevent *ev) { // GET, POST char linebuf[1024] = {0}; int idx = readline(ev->buffer, 0, linebuf); if (strstr(linebuf, "GET")) { ev->method = HTTP_METHOD_GET; //uri int i = 0; while (linebuf[sizeof("GET ") + i] !=) i++; linebuf[sizeof("GET ")+i] = \0; sprintf(ev->resource, "./%s/%s", HTTP_WEBSERVER_HTML_ROOT, linebuf+sizeof("GET ")); } else if (strstr(linebuf, "POST")) { } }在读取http请求头的时候，需要注意，http是以\r\n对每一行进行分隔的，第一行就是请求行，里面有请求类型(GET、POST)、uri、协议版本等。
自定义协议，如何界定包的完整性：
使用分隔符，比如http使用\r\n；协议头中加包的长度。C++后台开发系统学习地址：C/C++Linux服务器开发高级架构师/C++后台开发架构师
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http response
根据上面的uri找到静态资源，并准备好response状态行和消息头。
发送不同类型的静态资源的时候，可以使用相应的Content-Type。
发送response
mmap
发送静态资源文件的时候，需要先将文件读入内存，再将内存中的数据send到相应的网络fd。通过使用sendfile完成文件的发送，不再需要两步操作。
sendfile使用mmap
零拷贝，使用的是mmap方式，本质是DMA的方式，不需要CPU参与。普通copy，从磁盘copy数据到内存，需要CPU的move指令。
在进程中有一块区域叫内存分配区，当调用mmap的时候，会把文件映射到对应的区域，操作文件就跟操作内存一样。
完整代码
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/socket.h> #include <sys/epoll.h> #include <arpa/inet.h> #include <fcntl.h> #include <unistd.h> #include <errno.h> #include <time.h> #include <sys/stat.h> #include <sys/sendfile.h> #define BUFFER_LENGTH 4096 #define MAX_EPOLL_EVENTS 1024 #define SERVER_PORT 9105 #define PORT_COUNT 1 #define HTTP_WEBSERVER_HTML_ROOT "html" #define HTTP_METHOD_GET 0 #define HTTP_METHOD_POST 1 typedef int NCALLBACK(int ,int, void*); struct ntyevent { int fd; int events; void *arg; int (*callback)(int fd, int events, void *arg); int status; char buffer[BUFFER_LENGTH]; int length; long last_active; // http param int method; // char resource[BUFFER_LENGTH]; int ret_code; }; struct eventblock { struct eventblock *next; struct ntyevent *events; }; struct ntyreactor { int epfd; int blkcnt; struct eventblock *evblk; //fd --> 100w }; int recv_cb(int fd, int events, void *arg); int send_cb(int fd, int events, void *arg); struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd); void nty_event_set(struct ntyevent *ev, int fd, NCALLBACK callback, void *arg) { ev->fd = fd; ev->callback = callback; ev->events = 0; ev->arg = arg; ev->last_active = time(NULL); return ; } int nty_event_add(int epfd, int events, struct ntyevent *ev) { struct epoll_event ep_ev = {0, {0}}; ep_ev.data.ptr = ev; ep_ev.events = ev->events = events; int op; if (ev->status == 1) { op = EPOLL_CTL_MOD; } else { op = EPOLL_CTL_ADD; ev->status = 1; } if (epoll_ctl(epfd, op, ev->fd, &ep_ev) < 0) { printf("event add failed [fd=%d], events[%d]\n", ev->fd, events); return -1; } return 0; } int nty_event_del(int epfd, struct ntyevent *ev) { struct epoll_event ep_ev = {0, {0}}; if (ev->status != 1) { return -1; } ep_ev.data.ptr = ev; ev->status = 0; epoll_ctl(epfd, EPOLL_CTL_DEL, ev->fd, &ep_ev); return 0; } int readline(char *allbuf, int idx, char *linebuf) { int len = strlen(allbuf); for(;idx < len;idx ++) { if (allbuf[idx] == \r && allbuf[idx+1] == \n) { return idx+2; } else { *(linebuf++) = allbuf[idx]; } } return -1; } int http_request(struct ntyevent *ev) { // GET, POST char linebuf[1024] = {0}; int idx = readline(ev->buffer, 0, linebuf); if (strstr(linebuf, "GET")) { ev->method = HTTP_METHOD_GET; //uri int i = 0; while (linebuf[sizeof("GET ") + i] !=) i++; linebuf[sizeof("GET ")+i] = \0; sprintf(ev->resource, "./%s/%s", HTTP_WEBSERVER_HTML_ROOT, linebuf+sizeof("GET ")); } else if (strstr(linebuf, "POST")) { } } int recv_cb(int fd, int events, void *arg) { struct ntyreactor *reactor = (struct ntyreactor*)arg; struct ntyevent *ev = ntyreactor_idx(reactor, fd); int len = recv(fd, ev->buffer, BUFFER_LENGTH, 0); // if (len > 0) { ev->length = len; ev->buffer[len] = \0; printf("C[%d]:%s\n", fd, ev->buffer); //http http_request(ev); //send(); nty_event_del(reactor->epfd, ev); nty_event_set(ev, fd, send_cb, reactor); nty_event_add(reactor->epfd, EPOLLOUT, ev); } else if (len == 0) { nty_event_del(reactor->epfd, ev); close(ev->fd); //printf("[fd=%d] pos[%ld], closed\n", fd, ev-reactor->events); } else { nty_event_del(reactor->epfd, ev); close(ev->fd); printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno)); } return len; } int http_response(struct ntyevent *ev) { if (ev == NULL) return -1; memset(ev->buffer, 0, BUFFER_LENGTH); #if 0 const char *html = "<html><head><title>hello http</title></head><body><H1>Cong</H1></body></html>\r\n\r\n"; ev->length = sprintf(ev->buffer, "HTTP/1.1 200 OK\r\n\ Date: Thu, 11 Nov 2021 12:28:52 GMT\r\n\ Content-Type: text/html;charset=ISO-8859-1\r\n\ Content-Length: 83\r\n\r\n%s", html); #else printf("resource: %s\n", ev->resource); int filefd = open(ev->resource, O_RDONLY); if (filefd == -1) { // return 404 ev->ret_code = 404; ev->length = sprintf(ev->buffer, "HTTP/1.1 404 Not Found\r\n" "Date: Thu, 11 Nov 2021 12:28:52 GMT\r\n" "Content-Type: text/html;charset=ISO-8859-1\r\n" "Content-Length: 85\r\n\r\n" "<html><head><title>404 Not Found</title></head><body><H1>404</H1></body></html>\r\n\r\n" ); } else { struct stat stat_buf; fstat(filefd, &stat_buf); close(filefd); if (S_ISDIR(stat_buf.st_mode)) { ev->ret_code = 404; ev->length = sprintf(ev->buffer, "HTTP/1.1 404 Not Found\r\n" "Date: Sun, 30 Jan 2022 05:55:32 GMT\r\n" "Content-Type: text/html;charset=ISO-8859-1\r\n" "Content-Length: 85\r\n\r\n" "<html><head><title>404 Not Found</title></head><body><H1>404</H1></body></html>\r\n\r\n" ); } else if (S_ISREG(stat_buf.st_mode)) { ev->ret_code = 200; ev->length = sprintf(ev->buffer, "HTTP/1.1 200 OK\r\n" "Date: Sun, 30 Jan 2022 05:55:32 GMT\r\n" // "Content-Type: text/html;charset=ISO-8859-1\r\n" // "Content-Type: application/pdf\r\n" "Content-Type: image/jpeg\r\n" "Content-Length: %ld\r\n\r\n", stat_buf.st_size ); } } #endif return ev->length; } int send_cb(int fd, int events, void *arg) { struct ntyreactor *reactor = (struct ntyreactor*)arg; struct ntyevent *ev = ntyreactor_idx(reactor, fd); http_response(ev); // int len = send(fd, ev->buffer, ev->length, 0); if (len > 0) { // http header和body分两次发送 printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer); if (ev->ret_code == 200) { int filefd = open(ev->resource, O_RDONLY); struct stat stat_buf; fstat(filefd, &stat_buf); // sendfile使用mmap sendfile(fd, filefd, NULL, stat_buf.st_size); close(filefd); } nty_event_del(reactor->epfd, ev); nty_event_set(ev, fd, recv_cb, reactor); nty_event_add(reactor->epfd, EPOLLIN, ev); } else { close(ev->fd); nty_event_del(reactor->epfd, ev); printf("send[fd=%d] error %s\n", fd, strerror(errno)); } return len; } int accept_cb(int fd, int events, void *arg) { struct ntyreactor *reactor = (struct ntyreactor*)arg; if (reactor == NULL) return -1; struct sockaddr_in client_addr; socklen_t len = sizeof(client_addr); int clientfd; if ((clientfd = accept(fd, (struct sockaddr*)&client_addr, &len)) == -1) { if (errno != EAGAIN && errno != EINTR) { } printf("accept: %s\n", strerror(errno)); return -1; } int flag = 0; if ((flag = fcntl(clientfd, F_SETFL, O_NONBLOCK)) < 0) { printf("%s: fcntl nonblocking failed, %d\n", __func__, MAX_EPOLL_EVENTS); return -1; } struct ntyevent *event = ntyreactor_idx(reactor, clientfd); nty_event_set(event, clientfd, recv_cb, reactor); nty_event_add(reactor->epfd, EPOLLIN, event); printf("new connect [%s:%d], pos[%d]\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), clientfd); return 0; } int init_sock(short port) { int fd = socket(AF_INET, SOCK_STREAM, 0); fcntl(fd, F_SETFL, O_NONBLOCK); struct sockaddr_in server_addr; memset(&server_addr, 0, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_addr.s_addr = htonl(INADDR_ANY); server_addr.sin_port = htons(port); bind(fd, (struct sockaddr*)&server_addr, sizeof(server_addr)); if (listen(fd, 20) < 0) { printf("listen failed : %s\n", strerror(errno)); } return fd; } int ntyreactor_alloc(struct ntyreactor *reactor) { if (reactor == NULL) return -1; if (reactor->evblk == NULL) return -1; struct eventblock *blk = reactor->evblk; while (blk->next != NULL) { blk = blk->next; } struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent)); if (evs == NULL) { printf("ntyreactor_alloc ntyevents failed\n"); return -2; } memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent)); struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock)); if (block == NULL) { printf("ntyreactor_alloc eventblock failed\n"); return -2; } memset(block, 0, sizeof(struct eventblock)); block->events = evs; block->next = NULL; blk->next = block; reactor->blkcnt ++; // return 0; } struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd) { int blkidx = sockfd / MAX_EPOLL_EVENTS; while (blkidx >= reactor->blkcnt) { ntyreactor_alloc(reactor); } int i = 0; struct eventblock *blk = reactor->evblk; while(i ++ < blkidx && blk != NULL) { blk = blk->next; } return &blk->events[sockfd % MAX_EPOLL_EVENTS]; } int ntyreactor_init(struct ntyreactor *reactor) { if (reactor == NULL) return -1; memset(reactor, 0, sizeof(struct ntyreactor)); reactor->epfd = epoll_create(1); if (reactor->epfd <= 0) { printf("create epfd in %s err %s\n", __func__, strerror(errno)); return -2; } struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent)); if (evs == NULL) { printf("ntyreactor_alloc ntyevents failed\n"); return -2; } memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent)); struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock)); if (block == NULL) { printf("ntyreactor_alloc eventblock failed\n"); return -2; } memset(block, 0, sizeof(struct eventblock)); block->events = evs; block->next = NULL; reactor->evblk = block; reactor->blkcnt = 1; return 0; } int ntyreactor_destory(struct ntyreactor *reactor) { close(reactor->epfd); //free(reactor->events); struct eventblock *blk = reactor->evblk; struct eventblock *blk_next = NULL; while (blk != NULL) { blk_next = blk->next; free(blk->events); free(blk); blk = blk_next; } return 0; } int ntyreactor_addlistener(struct ntyreactor *reactor, int sockfd, NCALLBACK *acceptor) { if (reactor == NULL) return -1; if (reactor->evblk == NULL) return -1; //reactor->evblk->events[sockfd]; struct ntyevent *event = ntyreactor_idx(reactor, sockfd); nty_event_set(event, sockfd, acceptor, reactor); nty_event_add(reactor->epfd, EPOLLIN, event); return 0; } int ntyreactor_run(struct ntyreactor *reactor) { if (reactor == NULL) return -1; if (reactor->epfd < 0) return -1; if (reactor->evblk == NULL) return -1; struct epoll_event events[MAX_EPOLL_EVENTS+1]; int checkpos = 0, i; while (1) { /* long now = time(NULL); for (i = 0;i < 100;i ++, checkpos ++) { if (checkpos == MAX_EPOLL_EVENTS) { checkpos = 0; } if (reactor->events[checkpos].status != 1) { continue; } long duration = now - reactor->events[checkpos].last_active; if (duration >= 60) { close(reactor->events[checkpos].fd); printf("[fd=%d] timeout\n", reactor->events[checkpos].fd); nty_event_del(reactor->epfd, &reactor->events[checkpos]); } } */ int nready = epoll_wait(reactor->epfd, events, MAX_EPOLL_EVENTS, 1000); if (nready < 0) { printf("epoll_wait error, exit\n"); continue; } for (i = 0;i < nready;i ++) { struct ntyevent *ev = (struct ntyevent*)events[i].data.ptr; if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN)) { ev->callback(ev->fd, events[i].events, ev->arg); } if ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT)) { ev->callback(ev->fd, events[i].events, ev->arg); } } } } // 3, 6w, 1, 100 == // <remoteip, remoteport, localip, localport> int main(int argc, char *argv[]) { unsigned short port = SERVER_PORT; // listen 8888 if (argc == 2) { port = atoi(argv[1]); } struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor)); ntyreactor_init(reactor); int i = 0; int sockfds[PORT_COUNT] = {0}; for (i = 0;i < PORT_COUNT;i ++) { sockfds[i] = init_sock(port+i); ntyreactor_addlistener(reactor, sockfds[i], accept_cb); } //dup2(sockfd, STDIN); ntyreactor_run(reactor); ntyreactor_destory(reactor); for (i = 0;i < PORT_COUNT;i ++) { close(sockfds[i]); } free(reactor); return 0; } nts[i].events, ev->arg); } } } } // 3, 6w, 1, 100 == // <remoteip, remoteport, localip, localport> int main(int argc, char *argv[]) { unsigned short port = SERVER_PORT; // listen 8888 if (argc == 2) { port = atoi(argv[1]); } struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor)); ntyreactor_init(reactor); int i = 0; int sockfds[PORT_COUNT] = {0}; for (i = 0;i < PORT_COUNT;i ++) { sockfds[i] = init_sock(port+i); ntyreactor_addlistener(reactor, sockfds[i], accept_cb); } //dup2(sockfd, STDIN); ntyreactor_run(reactor); ntyreactor_destory(reactor); for (i = 0;i < PORT_COUNT;i ++) { close(sockfds[i]); } free(reactor); return 0; }技术参考
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