网络编程1

#运行方法
gcc -o hello_server hello_server.c
./hello_server 8899

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

void error_handling(char *message);


int main(int argc, char *argv[]) 
{
    int server_sock, client_sock;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_addr_size;
    char send_message[] = "hello client\n";
    if (argc != 2) 
    {
        printf("Usage : %s <port>\n", argv[0]);
        exit(1);
    }
    //创建套接字
    server_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (server_sock == -1)
    {
        error_handling("socket() error");
    }
    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(atoi(argv[1]));

    //分配IP地址和端口号
    if (bind(server_sock, (struct sockaddr*) &server_addr, sizeof(server_addr)) == -1)
    {
        error_handling("bind() error");
    }
    //将套接字转为可接收连接状态
    if (listen(server_sock, 5) == -1) 
    {
        error_handling("listen() error");
    }
    client_addr_size = sizeof(client_addr);
    //调用accpet函数接收连接请求
    client_sock = accept(server_sock, (struct sockaddr*)&client_addr, &client_addr_size);
    if (client_sock == -1)
    {
        error_handling("accept() error");
    }
    //将消息写到客户端
    write(client_sock, send_message, sizeof(send_message));
    close(client_sock);
    close(server_sock);
    return 0;
}

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

#运行方法
gcc -o hello_client hello_client.c
./hello_client 127.0.0.1 8899

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

void error_handling(char *message);


int main(int argc, char *argv[]) 
{
    int sock;
    struct sockaddr_in server_addr;
    char message[30];
    int str_len;

    if (argc != 3)
    {
        printf("Usage : %s <IP> <port> \n", argv[0]);
        exit(1);
    }
    sock = socket(PF_INET, SOCK_STREAM, 0);
    if (sock == -1) 
    {
        error_handling("socket() error");
    }
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);
    server_addr.sin_port = htons(atoi(argv[2]));
    if (connect(sock, (struct sockaddr*)&server_addr, sizeof(server_addr))) 
    {
        error_handling("connect() error");
    }
    str_len = read(sock, message, sizeof(message) - 1);
    if (str_len == -1) {
        error_handling("read() error!");
    }
    printf("%s \n", message);
    close(sock);
    return 0;
}

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

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

#define BUF_SIZE 1024
void error_handling(char *message);

int main(int argc, char *argv[])
{
    //未传递端口时给默认值
    int port = 8899;
    if (argc == 2)
    {
        port = atoi(argv[1]);        
    }

    //创建socket
    int server_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (server_sock == -1)
    {
        error_handling("socker() error!");
    }
    //设置在TIME_WAIT状态下套接字端口可以重新分配给新的套接字
    int option = 1;
    socklen_t option_len = sizeof(option);
    setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &option, option_len);
    //绑定端口
    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);
    if (bind(server_sock, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1)
    {
        error_handling("bind() error");
    }
    //监听连接请求，并指定了5个等待队列
    if (listen(server_sock, 5) == -1)
    {
        error_handling("listen() error");
    }
    for (int i = 0; i < 5; i++)
    {
        struct sockaddr_in client_addr;
        int client_addr_size = sizeof(client_addr);
        //接收连接请求
        int client_sock = accept(server_sock, (struct sockaddr *)&client_addr, &client_addr_size);
        if (client_sock == -1)
        {
            error_handling("accept() error");
        }
        printf("---Connected client %d---\n", client_sock);
        char buf[BUF_SIZE];
        int str_len;
        while ((str_len = read(client_sock, buf, BUF_SIZE - 1)) != 0)
        {
            //收到客户端数据，打印到标准输出，并回显给客户端
            ////手动字符串的结束位置
            buf[str_len] = 0;
            printf("%s", buf);
            write(client_sock, buf, str_len);
        }
        printf("---Disconnected---\n");
        close(client_sock);
    }
    close(server_sock);
}

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

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

#define BUF_SIZE 1024
void error_handling(char *message);

int main(int argc, char *argv[])
{
    //未传递服务端信息时给默认值
    char ip[15] = "127.0.0.1";
    int port = 8899;
    if (argc == 3)
    {
        strcpy(ip, argv[1]);
        port = atoi(argv[2]);
        
    }
    //连接服务端
    int sock = socket(PF_INET, SOCK_STREAM, 0);
    struct sockaddr_in client_addr;
    memset(&client_addr, 0, sizeof(client_addr));
    client_addr.sin_family = AF_INET;
    client_addr.sin_addr.s_addr = inet_addr(ip);
    client_addr.sin_port = htons(port);
    if (connect(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)) == -1)
    {
        error_handling("connect() error");
    }
    printf("Connected...");
    char buf[BUF_SIZE];
    while (1)
    {
        //获取输入，发送到服务端，并打印来自服务端的消息
        printf("Please input message(Q to quit): ");
        fgets(buf, BUF_SIZE,stdin);
        if (!strcmp(buf, "Q\n"))
        {
            break;
        }
        write(sock, buf, strlen(buf));
        int str_len = read(sock, buf, BUF_SIZE - 1);
        //手动字符串的结束位置
        buf[str_len] = 0;
        printf("Message from server: %s\n", buf);
    }
    close(sock);
}

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

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

#define BUF_SIZE 1024
#define OPSZ 4
void error_handling(char *message);
int calculate(int opnum, int opnds[], char oprator);

int main(int argc, char *argv[])
{
    int serv_sock, clnt_sock;
    char opinfo[BUF_SIZE];
    int result, opnd_cnt, i;
    int recv_cnt, recv_len;
    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t clnt_adr_sz;
    if (argc != 2)
    {
        printf("Usage: %s <port>\n", argv[0]);
        exit(0);
    }
    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1)
    {
        error_handling("sock() error");
    }
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi(argv[1]));
    if (bind(serv_sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1)
    {
        error_handling("bind() error");
    }
    if (listen(serv_sock, 5) == -1)
    {
        error_handling("listen() error");
    }
    clnt_adr_sz = sizeof(clnt_adr);
    for (i = 0; i < 5; i++)
    {
        opnd_cnt = 0;
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_adr, &clnt_adr_sz);
        read(clnt_sock, &opnd_cnt, 1);
        recv_len = 0;
        while ((opnd_cnt * OPSZ + 1) > recv_len)
        {
            recv_cnt = read(clnt_sock, &opinfo[recv_len], BUF_SIZE - 1);
            recv_len += recv_cnt;
        }
        result = calculate(opnd_cnt, (int*)opinfo, opinfo[recv_len - 1]);
        write(clnt_sock, (char *)&result, sizeof(result));
        close(clnt_sock);
    }
    close(serv_sock);
    return 0;
}

int calculate(int opnum, int opnds[], char op)
{
    int result = opnds[0], i;
    switch (op)
    {
    case '+':
        for ( i = 1; i < opnum; i++)
        {
            result += opnds[i];
        }
        break;
    case '-':
        for ( i = 1; i < opnum; i++)
        {
            result -= opnds[i];
        }
        break;
    case '*':
        for ( i = 1; i < opnum; i++)
        {
            result *= opnds[i];
        }
        break;
    }
    return result;
}

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

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

#define BUF_SIZE 1024
#define RLT_SIZE 4
#define OPSZ 4
void error_handling(char *message);

int main(int argc, char *argv[])
{
    if(argc != 3)
    {
        printf("Usage %s <IP> <port>\n", argv[0]);
        exit(1);
    }
    int sock = socket(PF_INET, SOCK_STREAM, 0);
    if(sock == -1)
    {
        error_handling("sock() error");
    }
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr(argv[1]);
    addr.sin_port = htons(atoi(argv[2]));

    if (connect(sock, (struct sockaddr*)&addr, sizeof(addr)) == -1)
    {
        error_handling("connect() error");
    }
    puts("Connected...");
    fputs("Operand count: ",stdout);
    int opnd_cnt;
    scanf("%d", &opnd_cnt);
    char opmsg[BUF_SIZE];
    opmsg[0] = (char)opnd_cnt;
    for (int i = 0; i < opnd_cnt; i++)
    {
        printf("Operand %d:", i + 1);
        scanf("%d",(int*)&opmsg[i * OPSZ + 1]);
    }
    //冲刷掉回车
    fgetc(stdin);
    fputs("Operator: ",stdout);
    scanf("%c", &opmsg[opnd_cnt * OPSZ + 1]);
    //将所有的输入一次发送到服务端
    write(sock, opmsg, opnd_cnt * OPSZ + 2);
    int result;
    read(sock, &result, RLT_SIZE);
    printf("Operation result: %d \n", result);
    close(sock);
    return 0;
    
    
}

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