TCP/IP网络编程学习笔记（八）基于多任务的并发处理器、分割TCP的I/O程序

1.基于进程的并发服务器模型

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<signal.h>
#include<sys/wait.h>
#include<arpa/inet.h>
#include<sys/socket.h>

#define BUF_SIZE 30

void error_handling(char* message) {
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

void read_childproc(int sig) {
    int status;
    pid_t pid = waitpid(-1, &status, WNOHANG);
    printf("removed proc id: %d \n", pid);
}

int main(int argc, char* argv[]) {
    pid_t pid;
    struct sigaction act;
    int serv_sock, clnt_sock;
    struct sockaddr_in serv_addr, clnt_addr;
    char buf[BUF_SIZE];
    int state;
    
    if (argc != 2) {
        printf("Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    act.sa_handler = read_childproc;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    state = sigaction(SIGCHLD, &act, 0);

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1)
        error_handling("socket() error");

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(atoi(argv[1]));

    if (bind(serv_sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1)
        error_handling("bind() error");

    if (listen(serv_sock, 5) == -1)
        error_handling("listen() error");

    while (1) {
        socklen_t clnt_addr_size = sizeof(clnt_addr);
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_addr_size);
        if (clnt_sock == -1)
            continue;
        else
            puts("new client connected.....");

        pid = fork();
        if (pid == -1) {
            close(clnt_sock);
            continue;
        }
        if (pid == 0) {
            close(serv_sock);
            int str_len;
            while ((str_len = read(clnt_sock, buf, BUF_SIZE)) != 0)
                write(clnt_sock, buf, str_len);

            close(clnt_sock);
            puts("client disconnected...");
            return 0;
        }
        else {
            close(clnt_sock);
        }
    }

    close(serv_sock);
    return 0;
}

2.回声客户端的 I/O 程序分割

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<sys/socket.h>

#define BUF_SIZE 30

void error_handling(char* message) {
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

void read_routine(int sock, char* buf) {
    while (1) {
        int str_len = read(sock, buf, BUF_SIZE);
        if (str_len == 0)
            return;

        buf[str_len] = 0;
        printf("Message form server: %s \n", buf);
    }
}

void write_routine(int sock, char* buf) {
    while (1) {
        fgets(buf, BUF_SIZE, stdin);
        if (!strcmp(buf, "q\n") || !strcmp(buf, "Q\n")) {
            shutdown(sock, SHUT_WR);
            return;
        }
        write(sock, buf, strlen(buf));
    }
}

int main(int argc, char* argv[]) {
    int sock;
    struct sockaddr_in serv_addr;
    pid_t pid;
    char buf[BUF_SIZE];
    
    if (argc != 3) {
        printf("Usage: %s <IP> <port>\n", argv[0]);
        exit(1);
    }

    sock = socket(PF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(atoi(argv[2]));

    if (connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1)
        error_handling("connect() error!");

    pid = fork();
    if (pid == 0)
        write_routine(sock, buf);
    else
        read_routine(sock, buf);

    close(sock);
    return 0;
}

运行结果：

3.保存消息的回声服务器端

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<signal.h>
#include<sys/wait.h>
#include<arpa/inet.h>
#include<sys/socket.h>

#define BUF_SIZE 30

void error_handling(char* message) {
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

void read_childproc(int sig) {
    pid_t pid;
    int status;
    pid = waitpid(-1, &status, WNOHANG);
    printf("removed proc id: %d \n", pid);
}

int main(int argc, char* argv[]) {
    pid_t pid;
    struct sigaction act;
    int serv_sock, clnt_sock;
    struct sockaddr_in serv_addr, clnt_addr;
    char buf[BUF_SIZE];   
    int state;
    int fds[2];

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

    act.sa_handler = read_childproc;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    state = sigaction(SIGCHLD, &act, 0);

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1)
        error_handling("socket() error");

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(atoi(argv[1]));

    if (bind(serv_sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1)
        error_handling("bind() error");

    if (listen(serv_sock, 5) == -1)
        error_handling("listen() error");

    pipe(fds);
    pid = fork();
    if (pid == 0) {
        FILE* fp = fopen("echomsg.txt", "wt");
        char msgbuf[BUF_SIZE];
        for (int i = 0; i < 10; i++) {
            int len = read(fds[0], msgbuf, BUF_SIZE);
            fwrite((void*)msgbuf, 1, len, fp);
        }
        fclose(fp);
        return 0;
    }


    while (1) {
        socklen_t clnt_addr_size = sizeof(clnt_addr);
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_addr_size);
        if (clnt_sock == -1)
            continue;
        else
            puts("new client connected.....");

        pid = fork();
        if (pid == -1) {
            close(clnt_sock);
            continue;
        }
        if (pid == 0) {
            close(serv_sock);
            int str_len;
            while ((str_len = read(clnt_sock, buf, BUF_SIZE)) != 0) {
                write(clnt_sock, buf, str_len);
                write(fds[1], buf, str_len);
            }

            close(clnt_sock);
            puts("client disconnected...");
            return 0;
        }
        else {
            close(clnt_sock);
        }
    }
    close(serv_sock);
    return 0;
}

参考书籍：《TCP/IP网络编程》尹圣雨 著，金果哲 译