TCP Socket Port Check

    写了两个小程序，主要是用于linux和windows下TCP端口的检测，自带的telnet无法满足我批量检测的需要，在我眼里这类端口检测程序最为关键的是超时的限制，若端口不能却要老久才返回结果，有点不爽，在不改系统默认超时时间的前提上，引入socket的非阻塞模式达到超时限制的目的，下面是具体程序

1. windows下的tcp端口检测程序

简介：引入select模式作为超时限制

//TCP Port Check program in windows


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

#pragma comment(lib,"ws2_32.lib")


int main(int argc, char *argv[])
{
    SOCKET sockfd;    
    SOCKADDR_IN sockaddr;
    int port;
    unsigned long ip;
    WSADATA wsa;
    int timeout=2,ret;
    struct timeval tv;
    struct fd_set fs;
    unsigned long ul = 1;
    

    if(argc != 4)
    {
        printf("Usage: %s IP Port TimeOut
",argv[0]);
        return -1;
    }
    if((ip=inet_addr(argv[1]))==INADDR_NONE)
    {
        printf("IP Address Error
");
        return -1;
    }
    if((port=atoi(argv[2]))==0)
    {
        printf("Port Error
");
        return -1;
    }
    if((timeout=atoi(argv[3]))==0)
    {
        printf("Timeout Error
");
        return -1;
    }
    WSAStartup(MAKEWORD(1,1),&wsa);    //initialize Ws2_32.dll

    if((sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) <= 0)    //create a tcp socket
    {
        printf("Create socket fail!
");
        return -2;
    }
    //socket non-block mode set
    if((ret = ioctlsocket(sockfd, FIONBIO, (unsigned long*)&ul))==SOCKET_ERROR)
    {
        closesocket(sockfd);
        return -1;
    }
    sockaddr.sin_family = AF_INET;
    sockaddr.sin_port = htons(port);
    sockaddr.sin_addr.S_un.S_addr = inet_addr(argv[1]);

    //connect to target ip with port
    connect(sockfd, (SOCKADDR *)&sockaddr, sizeof(sockaddr));
    
    tv.tv_sec = timeout;
    tv.tv_usec = 0;
    FD_ZERO(&fs);
    FD_SET(sockfd,&fs);  
    ret = select(sockfd+1,NULL,&fs,NULL,&tv);
    if(ret<0)
    {
        printf("Select Error
");
        closesocket(sockfd);
        return -1;
    }
    else if(ret == 0)
    {
        printf(" %s %d Connect fail!
",argv[1],port);
        closesocket(sockfd);
        return -1;
    }
    else
    {
        printf(" %s %d Connected success!
",argv[1],port);
        closesocket(sockfd);
    }
    WSACleanup(); //clean up Ws2_32.dll 
    return 0;
}

2. Linux下TCP端口检测程序

#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <time.h>
#include <errno.h>
int main(int argc, char *argv[])
{
        int sockfd=socket(AF_INET,SOCK_STREAM,0);
        struct sockaddr_in client;
        char ip[20];
        int port;
        int timeout;
        struct timeval tv;
        if(argc != 4)
        {
                printf("Usage : %s ip port timeout
", argv[0]);
                exit(1);
        }
        strcpy(ip, argv[1]);
        port = atoi(argv[2]);
        timeout = atoi(argv[3]);
        
        bzero(&client, sizeof(struct sockaddr_in));
        client.sin_family = AF_INET;
        client.sin_addr.s_addr = inet_addr(ip);
        client.sin_port = htons(port);

        tv.tv_sec = 5;
        tv.tv_usec = 0;

        //set timeout with setsockopt
        if(setsockopt(sockfd,SOL_SOCKET,SO_RCVTIMEO,(char*)&tv, sizeof(tv))<0)
        {
            perror("setsockopt failed
");
            exit(1);
        }

        if(setsockopt(sockfd,SOL_SOCKET,SO_SNDTIMEO,(char*)&tv, sizeof(tv))<0)
        {
            perror("setsockopt failed
");
            exit(1);
        }
        if(!connect(sockfd,(struct sockaddr*)&client,sizeof(struct sockaddr_in)))
        {
                printf("connect ok
");

        }else{
                printf("connect fail
");
        }
    close(sockfd);
        return 0;
}

3. 总结

    代码不难，关键是能提高效率，有时候简单的东西反而更好，继续努力