http高并发服务器实现

基础知识

html，全称为html markup language，超文本标记语言。

http，全称hyper text transfer protocol，超文本传输协议。用于从万维网（WWW：World Wide Web）服务器传输超文本到本地浏览器的传送协议。

客户端请求的格式：

请求方法有：GET、POST等。URL：请求地址。协议版本：HTTP的版本。

服务器响应的格式：

-----	响应代号	代号描述
服务器上存在请求的内容，并可以响应给客户端	200	OK
客户端的请求有异常，方法有问题	501	Method Not Implemented
服务器收到请求后，因为自生的问题没法响应	500	Internal Server Error
请求的内容不存在	404	NOT FOUND
客户端发送的请求格式有问题等(一般不存在)	400	BAD REQUEST

http服务器实现

文件概念

文件的Inode元信息表示文件的索引节点，存储着文件的元信息，例如文件得创建者，文件创建日期，文件大小等。每个inode都有一个号码，操作系统用inode号码来识别不同的文件，使用命令ls -i可以查看inode号码。

stat函数

stat是C++用于读取文件资源管理器的库函数，头文件为：

#include<sys/stat.h>
#include<sys/types.h>
#include<unisted.h>int stat(const char *path,struct stat *buf);
int fstat(int fd,struct stat *buf);
int lstat(const char *path,struct stat *buf);parameter:path:文件路径buf:传入的保存文件状态的指针，用于保存文件的状态fd:文件描述符return:成功返回0，失败返回-1，并设置errno

stat的结构体内容如下所示：

struct stat {dev_t     st_dev;     /* ID of device containing file */ino_t     st_ino;     /* inode number */mode_t    st_mode;    /* S_ISREG(st_mode)  是一个普通文件  S_ISDIR(st_mode)  是一个目录*/nlink_t   st_nlink;   /* number of hard links */uid_t     st_uid;     /* user ID of owner */gid_t     st_gid;     /* group ID of owner */dev_t     st_rdev;    /* device ID (if special file) */off_t     st_size;    /* total size, in bytes */blksize_t st_blksize; /* blocksize for filesystem I/O */blkcnt_t  st_blocks;  /* number of 512B blocks allocated */time_t    st_atime;   /* time of last access */time_t    st_mtime;   /* time of last modification */time_t    st_ctime;   /* time of last status change */
};

并发和并行

并发与并行的区别（超级通俗易懂）这个博客十分清晰的展示了并发与并行的基本概念，简单来说所谓的并发指的是多个进程按照一定的时间间隔进行，只不过这个时间间隔很小，人类难以感受到而已，实际上在微观角度，进程的并发执行还是顺序执行。

高并发：高并发是互联网分布式框架设计中必须要考虑的因素之一，通常指的是，通过设计系统能够同时并行处理很多请求。

线程可以并行的执行任务，更多C++多线程的解析参考C++ 多线程

//头文件
#include<pthread.h>//函数
int pthread_create(pthread_t *thread,const pthread_attr_t *attr,void *(*start_routine)(void *),void *arg);pthread_t：当前Linux中可理解为：typedef unsigned long int pthread_t
args1:传出参数，保存系统为我们分配好的线程ID；
args2：通常传NULL，表示使用线程默认属性。若想使用具体属性也可以修改该参数。
args3：函数指针，指向线程主函数（线程体），函数运行结束，则线程结束。
args4：线程主函数执行期间所需要使用的函数。

在一个线程中调用pthread_create()创建新的线程后，当前线程从pthread_create()返回继续往下执行，而新的线程所执行的代码由我们传给pthread_create的函数指针start_routine决定。start_routine函数接收一个参数，是通过pthread_create的arg参数传递给它的，该参数的类型为void *，这个指针按什么类型解释由调用者自己定义。start_routine的返回值类型也是void *，这个指针的含义同样由调用者自己定义。start_routine返回时，这个线程就退出了，其它线程可以调用pthread_join得到start_routine的返回值。
pthread_create成功返回后，新创建的线程的id被填写到thread参数所指向的内存单元。
attr参数表示线程属性。

pthread_exit (status)

pthread_exit用于显式地退出一个线程。通常情况下，pthread_exit() 函数是在线程完成工作后无需继续存在时被调用。
如果 main() 是在它所创建的线程之前结束，并通过 pthread_exit() 退出，那么其他线程将继续执行。否则，它们将在 main() 结束时自动被终止。

gcc/g++ 编译时需要添加 -pthread进行编译。

gcc test.c -pthread -o test

简单的多线程实例：

#include <iostream>
#include <cstdlib>
#include <pthread.h>using namespace std;#define NUM_THREADS     5void *PrintHello(void *threadid)
{  // 对传入的参数进行强制类型转换，由无类型指针变为整形数指针，然后再读取int tid = *((int*)threadid);cout << "Hello Runoob! 线程 ID, " << tid << endl;pthread_exit(NULL);
}int main ()
{pthread_t threads[NUM_THREADS];int indexes[NUM_THREADS];// 用数组来保存i的值int rc;int i;for( i=0; i < NUM_THREADS; i++ ){      cout << "main() : 创建线程, " << i << endl;indexes[i] = i; //先保存i的值// 传入的时候必须强制转换为void* 类型，即无类型指针        rc = pthread_create(&threads[i], NULL, PrintHello, (void *)&(indexes[i]));if (rc){cout << "Error:无法创建线程," << rc << endl;exit(-1);}}pthread_exit(NULL);
}

最终代码

服务器代码样例：

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <ctype.h>
#include <arpa/inet.h>
#include <errno.h>
#include<pthread.h>#define SERVER_PORT 80void do_http_request(int client_sock);
int get_line(int client_sock, char *buf, int size);
void do_http_response(int client_sock, const char *path);
void headers(int client_sock, FILE *resource);
void cat(int client_sock, FILE *resource);
void not_found(int client_sock);
void inner_error(int client_sock);int main(void)
{int sock;struct sockaddr_in server_addr;sock = socket(AF_INET, SOCK_STREAM, 0);// printf("wait \n");bzero(&server_addr, sizeof(server_addr));server_addr.sin_family = AF_INET;server_addr.sin_addr.s_addr = htonl(INADDR_ANY);server_addr.sin_port = htons(SERVER_PORT);bind(sock, (struct sockaddr *)&server_addr, sizeof(server_addr));listen(sock, 128);printf("wait client connect\n");int done = 1;while (done){struct sockaddr_in client;int client_sock, len, i;char client_ip[64];char buf[256];socklen_t client_addr_len;client_addr_len = sizeof(client);client_sock = accept(sock, (struct sockaddr *)&client, &client_addr_len);printf("client ip: %s \t port is : %d \n", inet_ntop(AF_INET, &client.sin_addr.s_addr, client_ip, sizeof(client_ip)), ntohs(client.sin_port));pthread_t tid;int* ptr_int=NULL;int err=0;ptr_int=(int*)malloc(sizeof(int));*ptr_int=client_sock;if(err=pthread_create(&tid,NULL,do_http_request,(void*)ptr_int)){printf(stderr,"cannot create thread. reason: %s\n",strerror(errno));if(ptr_int) free(ptr_int);}// do_http_request(client_sock);// close(client_sock);}close(sock);return 0;
}void* do_http_request(void* p_client_sock)
{int len = 0;char buf[256], method[64], url[256], path[256];int client_sock=*(int *)p_client_sock;struct stat st;// http response struct: request_method url protocol_version \r\nlen = get_line(client_sock, buf, sizeof(buf));if (len > 0){int i = 0, j = 0;while (!isspace(buf[j]) && i < sizeof(method) - 1){method[i] = buf[j];i++;j++;}// set end tagmethod[i] = '\0';printf("method: %s\n", method);// method is GET requestif (strncasecmp(method, "GET", i) == 0){printf("request method is GET\n");while (isspace(buf[j])){j++;}i = 0;while (!isspace(buf[j]) && i < sizeof(url) - 1){url[i] = buf[j];i++;j++;}url[i] = '\0';if (strncasecmp(url, "/favicon.ico", i) == 0){strcpy(url, "/hello.html");}printf("url:%s\n", url);// read surplus requestdo{len = get_line(client_sock, buf, sizeof(buf));printf("%s\n", buf);} while (len > 0);// get local url file, and process ? in url, eg. url=128.0.0.2/hel.html?wang=dedefechar *pos = strchr(url, '?');if (pos){// \0 represent string end tag*pos = '\0';printf("real url: %s\n", url);}sprintf(path, "./html_doc%s", url);printf("path:%s\n", path);// execute http response// if file is exist, to response 200, ok,and send html file,else response 404 NOT FOUNDif (stat(path, &st) == -1){printf("--------------------");fprintf(stderr, "stat %s failed. reason :%s\n", strerror(errno));not_found(client_sock);}else{printf("*****************");if (S_ISDIR(st.st_mode)){strcat(path, "/index.html");}do_http_response(client_sock, path);}}else{// request method is not GET,read http head, and response client requestfprintf(stderr, "warning, other request [%s]\n", method);do{len = get_line(client_sock, buf, sizeof(buf));printf("%s\n", buf);} while (len > 0);// unimplement()}}else{printf("method is error");}close(client_sock);if(p_client_sock) free(p_client_sock);
}void do_http_response(int client_sock, const char *path)
{FILE *resource = NULL;resource = fopen(path, "r");if (resource == NULL){not_found(client_sock);return;}// send http headheaders(client_sock, resource);// send http bodycat(client_sock, resource);// printf("end response!!!!");fclose(resource);
}void headers(int client_sock, FILE *resource)
{struct stat st;int fileid = 0;char temp[64];char buf[1024] = {0};strcpy(buf, "HTTP/1.0 200 OK\r\n");strcat(buf, "Server: Martin Server\r\n");strcat(buf, "Content-Type: text/html\r\n");strcat(buf, "Connection: Close\r\n");fileid = fileno(resource);/* fstat: Get file attributes for the file, device, pipe, or socketthat file descriptor FD is open on and put them in BUF.  */if (fstat(fileid, &st) == -1){inner_error(client_sock);}snprintf(temp, 64, "Content-Length:%d\r\n\r\n", st.st_size);strcat(buf, temp);printf(stdout, "header: %s", buf);if (send(client_sock, buf, strlen(buf), 0) < 0){fprintf(stderr, "send fail,data %s, reason %s", buf, strerror(errno));}
}
void cat(int client_sock, FILE *resource)
{char buf[1024];fgets(buf, sizeof(buf), resource);while (!feof(resource)){int len = write(client_sock, buf, strlen(buf));if (len < 0){fprintf(stderr, "send boady error. reason %s\n", strerror(errno));break;}fprintf(stdout, "%s", buf);fgets(buf, sizeof(buf), resource);}
}int get_line(int client_sock, char *buf, int size)
{int count = 0;char ch = '\0';int len = 0;while (count < size - 1 && ch != '\n'){len = read(client_sock, &ch, 1);if (len == 1){if (ch == '\r')continue;else if (ch == '\n')break;buf[count] = ch;count++;}else if (len == -1){perror("read fail");count = -1;break;}else{fprintf(stderr, "client close.\n");count = -1;break;}}if (count >= 0)buf[count] = '\0';return count;
}void not_found(int client_sock)
{const char *reply = "HTTP/1.0 404 NOT FOUND\r\n\
Content-Type: text/html\r\n\
\r\n\
<HTML lang=\"zh-CN\">\r\n\
<meta content=\"text/html; charset=utf-8\" http-equiv=\"Content-Type\">\r\n\
<HEAD>\r\n\
<TITLE>NOT FOUND</TITLE>\r\n\
</HEAD>\r\n\
<BODY>\r\n\<P>文件不存在！\r\n\<P>The server could not fulfill your request because the resource specified is unavailable or none xistent.\r\n\
</BODY>\r\n\
</HTML>";int len = write(client_sock, reply, strlen(reply));fprintf(stdout, reply);if (len < 0){fprintf(stderr, "send reply failed. reason: %s\n", strerror(errno));}
}
void inner_error(int client_sock)
{const char *reply = "HTTP/1.0 500 Internal Sever Error\r\n\
Content-Type: text/html\r\n\
\r\n\
<HTML lang=\"zh-CN\">\r\n\
<meta content=\"text/html; charset=utf-8\" http-equiv=\"Content-Type\">\r\n\
<HEAD>\r\n\
<TITLE>Inner Error</TITLE>\r\n\
</HEAD>\r\n\
<BODY>\r\n\<P>服务器内部出错.\r\n\
</BODY>\r\n\
</HTML>";int len = write(client_sock, reply, strlen(reply));fprintf(stdout, reply);if (len <= 0){fprintf(stderr, "send reply failed. reason: %s\n", strerror(errno));}
}

客户端代码样例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>#define SERVER_PORT 666
#define SERVER_IP "127.0.0.1"int main(int argc, char *argv[])
{int sockfd;char *message;struct sockaddr_in servaddr;int n;char buf[64];if (argc != 2){fputs("Usage: ./echo_client message \n", stderr);exit(1);}message = argv[1];printf("message: %s\n", message);sockfd = socket(AF_INET, SOCK_STREAM, 0);// 重置结构体的内存空间memset(&servaddr, '\0', sizeof(struct sockaddr_in));servaddr.sin_family = AF_INET;inet_pton(AF_INET, SERVER_IP, &servaddr.sin_addr);servaddr.sin_port = htons(SERVER_PORT);connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));write(sockfd, message, strlen(message));n = read(sockfd, buf, sizeof(buf) - 1);if (n > 0){buf[n] = '\0';printf("receive: %s\n", buf);}else{perror("error!!!");}printf("finished.\n");close(sockfd);return 0;
}