Socket相关函数(1)- socket(), bind(), listen(), accept(), connect(), TCP模型

tcp_server.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <unistd.h>


#define SOCK_PORT 49128
#define MAXLINE 80

int main()
{
    int sockfd, connfd;    
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    char buf[MAXLINE];
    char str[INET_ADDRSTRLEN];
    int i, n;    

    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        exit(1);
    }
    
    /*Construct sockaddr_in struct*/
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(SOCK_PORT);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    if (bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
        perror("connect");
        exit(1);
    }

    if (listen(sockfd, 128) < 0) {
        perror("listen");
        exit(1);
    }
    
    while (1) {
        cliaddr_len = sizeof(cliaddr);
        connfd = accept(sockfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
        n = read(connfd, buf, MAXLINE);
        printf("received from %s at PORT %d
", inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
            ntohs(cliaddr.sin_port));
        for (i = 0; i < n; i++)
            buf[i] = toupper(buf[i]);
        write(connfd, buf, n);
        close(connfd);
    }
    
    close(sockfd);
    return 0;
}

tcp_client.c

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

#define SERV_PORT 49128
#define MAXLINE 80

int main(int argc, char *argv[])
{
    
    int sockfd, n;
    struct sockaddr_in servaddr;
    char *str;
    char buf[MAXLINE];

    if (argc != 2) {
        fputs("usage: ./client message
", stderr);
        exit(1);
    }
    str = argv[1];

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        exit(1);
    }
    
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
    servaddr.sin_port = htons(SERV_PORT);    
    
    connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    
    write(sockfd, str, strlen(str));
    n = read(sockfd, buf, MAXLINE);
    printf("Response from server:
");
    write(STDOUT_FILENO, buf, n);
    close(sockfd);
    return 0;
}

运行：

Client:

./client app
Response from server:
APP

Server:

received from 127.0.0.1 at PORT 48041