chat服务端-多线程

一次能处理多个请求
- 把收到的某个client的消息原样发回给所有连接中的client
chat_server.c

#include <stdio.h> //printf、fput
#include <stdlib.h> //atoi
#include <string.h> //memset
#include <unistd.h> //write、close
#include <arpa/inet.h> //sockaddr_in结构、INADDR_ANY
#include <sys/socket.h>
#include <pthread.h>
#define BUF_SIZE 100
#define MAX_CLNT 256

void* handle_clnt(void* arg);

int clnt_cnt = 0;
int clnt_socks[MAX_CLNT];
pthread_mutex_t mutx;

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    pthread_mutex_init(&mutx, NULL);
    
    int serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1) {
        fputs("socket() error", stderr);
        exit(1);
    }

    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr)); //全部位置0
    serv_addr.sin_family = AF_INET; //
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); //等价于绑定到"0.0.0.0"
    serv_addr.sin_port = htons(atoi(argv[1])); //取1号参数作为端口

    if (bind(serv_sock, (struct sockaddr*) &serv_addr, sizeof(serv_addr)) == -1) {
        fputs("bind() error", stderr);
        exit(1);
    }

    if (listen(serv_sock, 5) == -1) {
        fputs("listen() error", stderr);
        exit(1);
    }

    while(1) {
        struct sockaddr_in clnt_addr;
        socklen_t clnt_addr_size = sizeof(clnt_addr);
        int clnt_sock = accept(serv_sock, (struct sockaddr*) &clnt_addr, &clnt_addr_size);
        if (clnt_sock == -1) {
            fputs("accept() error", stderr);
            continue;
        }

        pthread_mutex_lock(&mutx);
        clnt_socks[clnt_cnt++] = clnt_sock;
        pthread_mutex_unlock(&mutx);

        pthread_t t_id;
        pthread_create(&t_id, NULL, handle_clnt, (void*)&clnt_sock);
        pthread_detach(t_id);
        printf("Connect to client, IP: %s\n", inet_ntoa(clnt_addr.sin_addr));
    }
    
    close(serv_sock);
    return 0;
}

void* handle_clnt(void* arg) {
    int clnt_sock = *((int*)arg);
    int str_len = 0;
    char buf[BUF_SIZE];

    while(1) {
        int str_len = read(clnt_sock, buf, BUF_SIZE);
        if (str_len == 0) {
            pthread_mutex_lock(&mutx);
            for (int i = 0; i < clnt_cnt; i++) {
                if (clnt_sock == clnt_socks[i]) {
                    while (i++ < clnt_cnt - 1)
                        clnt_socks[i] = clnt_socks[i + 1];
                    break;
                }
            }
            clnt_cnt--;
            pthread_mutex_unlock(&mutx);
            close(clnt_sock);
            printf("close client sock: %d \n", clnt_sock);
            return NULL;
        } else {
            pthread_mutex_lock(&mutx);
            for (int i = 0; i < clnt_cnt; i++) {
                write(clnt_socks[i], buf, str_len); //chat
            }
            pthread_mutex_unlock(&mutx);
        }
    }
}
编译
```
gcc chat_server.c -o cserver
```
执行
```
./cserver 8100
```
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chat服务端-多线程

chat_server.c
