Reactor 实现 http 服务器，附完整代码
作者：Linux服务器开发
- 2022 年 4 月 11 日
本文字数：8356 字
阅读完需：约 27 分钟
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。
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_cb
recv_cb
send_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;}复制代码
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")) {
}
}复制代码
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。
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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;}复制代码
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发布于: 2022 年 04 月 11 日阅读数: 4
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