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【python爬虫】16.爬虫知识点总结复习

树下的老石头 2023-09-09 阅读 17
tcp/ip

目录

1--TCP/IP协议栈

2--TCP服务器端默认函数调用顺序

3--TCP客户端的默认函数调用顺序

4--Linux实现迭代回声服务器端/客户端

5--Windows实现迭代回声服务器端/客户端

6--TCP原理

7--Windows实现计算器服务器端/客户端

1--TCP/IP协议栈

2--TCP服务器端默认函数调用顺序

#include <sys/socket.h>

int listen(int sock, int backlog); // 成功时返回 0, 失败时返回 -1;

// sock 表示希望进入等待连接请求状态的Socket的文件描述符
// backlog 表示连接请求等待队列的长度，即最多可以使多少个连接请求进入队列
#include <sys/socket.h>

int accept(int sock, struct sockaddr* addr, socklen_t* addrlen);
// 成功时返回创建的Socket的文件描述符，失败时返回-1

3--TCP客户端的默认函数调用顺序

#include <sys/socket.h>

int connect(int sock, struct sockaddr* servaddr, socklen_t addrlen);

// sock 表示客户端socket的文件描述符
// servaddr 保存了目标服务器端地址信息
// addrlen 第二个结构体参数 servaddr 的地址变量长度，以字节为单位

4--Linux实现迭代回声服务器端/客户端

服务器端：

// gcc echo_server.c -o echo_server
// ./echo_server 9190

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

#define BUF_SIZE 1024
void error_handling(char *message){
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

int main(int argc, char *argv[]){
    int serv_sock, clnt_sock;
    char message[BUF_SIZE];
    int str_len, i;

    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t clnt_adr_sz;

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

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if(serv_sock == -1){
        error_handling("socket() 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++){
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_adr, &clnt_adr_sz);
        if(clnt_sock == -1){
            error_handling("accept() error");
        }
        else{
            printf("Connected client %d \n", i+1);
        }

        while((str_len = read(clnt_sock, message, BUF_SIZE)) != 0){
            write(clnt_sock, message, str_len);
        }

        close(clnt_sock);
    }
    close(serv_sock);
    return 0;
}

客户端：

// gcc echo_client.c -o echo_client
// ./echo_client 127.0.0.1 9190

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

#define BUF_SIZE 1024

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

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

    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(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_adr.sin_port = htons(atoi(argv[2]));

    if(connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1){
        error_handling("connect() error!");
    }
    else{
        puts("Connected.......");
    }

    while(1){
        fputs("Input message(Q to quit): ", stdout);
        fgets(message, BUF_SIZE, stdin);

        if(!strcmp(message, "q\n") || !strcmp(message, "Q\n")){
            break;
        }

        write(sock, message, strlen(message));
        str_len = read(sock, message, BUF_SIZE-1);
        message[str_len] = 0;
        printf("Message from server: %s", message);
    }

    close(sock);
    return 0;
}

运行结果：

5--Windows实现迭代回声服务器端/客户端

服务器端：

// gcc echo_server_win.c -o echo_server_win -lwsock32
// echo_server_win 9190

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>

#define BUF_SIZE 1024

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

int main(int argc, char *argv[]){
    WSADATA wsaData;
    SOCKET hServSock, hClntSock;
    char message[BUF_SIZE];
    int strLen, i;

    SOCKADDR_IN servAdr, clntAdr;
    int clntAdrSize;

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

    if(WSAStartup(MAKEWORD(2, 2), &wsaData) != 0){
        ErrorHandling("WSAStartup() error!");
    }

    hServSock = socket(PF_INET, SOCK_STREAM, 0);
    if(hServSock == INVALID_SOCKET){
        ErrorHandling("socket() error");
    }

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

    if(bind(hServSock, (SOCKADDR*)&servAdr, sizeof(servAdr)) == SOCKET_ERROR){
        ErrorHandling("bind() error");
    }

    if(listen(hServSock, 5) == SOCKET_ERROR){
        ErrorHandling("listen() error");
    }

    clntAdrSize = sizeof(clntAdr);

    for(int i = 0; i < 5; i++){
        hClntSock = accept(hServSock, (SOCKADDR*)&clntAdr, &clntAdrSize);
        if(hClntSock == -1){
            ErrorHandling("accept() error");
        }
        else{
            printf("Connected client %d \n", i + 1);
        }
        while((strLen = recv(hClntSock, message, BUF_SIZE, 0)) != 0){
            send(hClntSock, message, strLen, 0);
        }
        closesocket(hClntSock);
    }
    closesocket(hServSock);
    WSACleanup();
    return 0;
}

客户端：

// gcc echo_client_win.c -o echo_client_win -lwsock32
// echo_client_win 127.0.0.1 9190

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>

#define BUF_SIZE 1024

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

int main(int argc, char *argv[]){
    WSADATA wsaData;
    SOCKET hSocket;
    char message[BUF_SIZE];
    int strLen;
    SOCKADDR_IN servAdr;

    if(argc != 3){
        printf("Usage: %s <IP> <port>\n", argv[0]);
        exit(1);
    }

    if(WSAStartup(MAKEWORD(2, 2), &wsaData) != 0){
        ErrorHandling("WSAStartup() error!");
    }

    hSocket = socket(PF_INET, SOCK_STREAM, 0);
    if(hSocket == INVALID_SOCKET){
        ErrorHandling("socket() error");
    }

    memset(&servAdr, 0, sizeof(servAdr));
    servAdr.sin_family = AF_INET;
    servAdr.sin_addr.s_addr = inet_addr(argv[1]);
    servAdr.sin_port = htons(atoi(argv[2]));

    if(connect(hSocket, (SOCKADDR*)&servAdr, sizeof(servAdr)) == SOCKET_ERROR){
        ErrorHandling("connect() error!");
    }
    else{
        puts("Connected........");
    }

    while(1){
        fputs("Input message(Q to quit): ", stdout);
        fgets(message, BUF_SIZE, stdin);

        if(!strcmp(message, "q\n") || !strcmp(message, "Q\n")){
            break;
        }

        send(hSocket, message, strlen(message), 0);
        strLen = recv(hSocket, message, BUF_SIZE - 1, 0);
        message[strLen] = 0;
        printf("Message from server: %s", message);
    }
    closesocket(hSocket);
    WSACleanup();
    return 0;
}

测试结果：

6--TCP原理

7--Windows实现计算器服务器端/客户端

服务器端：

// gcc op_server_win.c -o op_server_win -lwsock32
// op_server_win 9190

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>

#define BUF_SIZE 1024
#define OPSZ 4

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

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;
}

int main(int argc, char* argv[]){
    WSADATA wsaData;
    SOCKET hServSock, hClntSock;
    char opinfo[BUF_SIZE];
    int result, opndCnt, i;
    int recvCnt, recvLen;
    SOCKADDR_IN servAdr, clntAdr;
    int clntAdrSize;
    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    if(WSAStartup(MAKEWORD(2, 2), &wsaData) != 0){
        ErrorHandling("WSAStartup() error!");
    }

    hServSock = socket(PF_INET, SOCK_STREAM, 0);
    if(hServSock == INVALID_SOCKET){
        ErrorHandling("socket() error!");
    }

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

    if(bind(hServSock, (SOCKADDR*)&servAdr, sizeof(servAdr)) == SOCKET_ERROR){
        ErrorHandling("bind() error");
    }

    if(listen(hServSock, 5) == SOCKET_ERROR){
        ErrorHandling("listen() error");
    }

    clntAdrSize = sizeof(clntAdr);

    for(int i = 0; i < 5; i++){
        opndCnt = 0;
        hClntSock = accept(hServSock, (SOCKADDR*)&clntAdr, &clntAdrSize);
        recv(hClntSock, (char*)&opndCnt, 1, 0); // recv one byte

        recvLen = 0;
        while((opndCnt * OPSZ + 1) > recvLen){
            recvCnt = recv(hClntSock, &opinfo[recvLen], BUF_SIZE - 1, 0);
            recvLen += recvCnt;
        }

        result = calculate(opndCnt, (int*)opinfo, opinfo[recvLen - 1]);
        send(hClntSock, (char*)&result, sizeof(result), 0);
        closesocket(hClntSock);
    }

    closesocket(hServSock);
    WSACleanup();
    return 0;
}

客户端：

// gcc op_client_win.c -o op_client_win -lwsock32
// op_client_win 127.0.0.1 9190

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>

#define BUF_SIZE 1024
#define RLT_SIZE 4
#define OPSZ 4

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

int main(int argc, char* argv[]){
    WSADATA wsaData;
    SOCKET hSocket;
    char opmsg[BUF_SIZE];
    int result, opndCnt, i;
    SOCKADDR_IN servAdr;
    if(argc != 3){
        printf("Usage : %s <IP> <port>\n", argv[0]);
        exit(1);
    }

    if(WSAStartup(MAKEWORD(2, 2), &wsaData) != 0){
        ErrorHandling("WSAStartup() error!");
    }

    hSocket = socket(PF_INET, SOCK_STREAM, 0);
    if(hSocket == INVALID_SOCKET){
        ErrorHandling("socket() error!");
    }

    memset(&servAdr, 0, sizeof(servAdr));
    servAdr.sin_family = AF_INET;
    servAdr.sin_addr.s_addr = inet_addr(argv[1]);
    servAdr.sin_port = htons(atoi(argv[2]));

    if(connect(hSocket, (SOCKADDR*)&servAdr, sizeof(servAdr)) == SOCKET_ERROR){
        ErrorHandling("connect() error!");
    }
    else{
        puts("Connected........");
    }

    fputs("Operand count: ", stdout);
    scanf("%d", &opndCnt);
    opmsg[0] = (char)opndCnt; // one byte

    for(i = 0; i < opndCnt; i++){
        printf("Operand %d: ", i + 1);
        scanf("%d", (int*)&opmsg[i*OPSZ + 1]);
    }

    fgetc(stdin);
    fputs("Operator: ", stdout);
    scanf("%c", &opmsg[opndCnt * OPSZ + 1]); // one byte
    send(hSocket, opmsg, opndCnt * OPSZ + 2, 0);
    recv(hSocket, (char*)&result, RLT_SIZE, 0);

    printf("Operation result: %d \n", result);
    closesocket(hSocket);
    WSACleanup();
    return 0;
}

运行结果：

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