0623 socket 的connect 如何增加time out 屬性

將socket 設定為noblock 即可
即增加下方藍色字體部分

自製範例：

//利用socket 測試是否已經連上線

#include <sys/socket.h>

#include <netinet/tcp.h>

#include <netinet/in.h>

#include <unistd.h>

#include <netdb.h>       // for gethostbyname()

int checkRobotLinkState()

{

    return robotLink_state;

}

void startRobotLinkFun()

{

    robotLink_state=robotlink_conning;

    threadcv.notify_one(); //啟動thread

    

}

void robotSocketLink()

{

    int sock,ret;

    struct sockaddr_in server;

    struct hostent* entp = NULL;

    log("00.Construct Client... start init socket\n");

    // Create socket

    if( (sock = socket(PF_INET, SOCK_STREAM, 0))<0 )

    {

        log("socket() failed with error \n");

        robotLink_state= robotlink_ER1;

        return;

    }

    log("01.socket init...check TCP/IP\n");

    

    // Disable Nagel's algorithm for lower latency

    int yes = 1;

    if(setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &yes,

                  sizeof(int)) == -1)

    {

        log("failed to enable TCP_NODELAY - setsockopt failed");

        robotLink_state= robotlink_ER2;

        return;

    }

    log("02.TCP/IP Ready...wait check IP\n");

    // Construct server address

    memset(&server, 0, sizeof(server));

    server.sin_family = AF_INET;

    server.sin_port = htons(6665);

    

    // Get host by name

    entp = gethostbyname("192.168.30.1");

    if (entp == NULL)

    {

        log("gethostbyname() failed with error \n");

        robotLink_state= robotlink_ER3;

        return;

    }

    //BOB ADD 設定socket 為nonblock 避免time out 過久

    fcntl(sock, F_SETFL, O_NONBLOCK);

    fd_set set;

    FD_ZERO(&set);

    FD_SET(sock, &set);

    

    log("03.check robot IP OK...wait connect\n");

    assert(entp->h_length <= sizeof (server.sin_addr));

    memcpy(&(server.sin_addr), entp->h_addr_list[0], entp->h_length);

    

    // Connect

     ret = connect(sock, (struct sockaddr*)&server, sizeof(server));

    if (ret < 0)

    {

        if ( errno != EINPROGRESS )

        {

            printf("connect call on [%s:%d] failed! \n", "192.168.30.1", 6665);

            robotLink_state= robotlink_ER4;

            return;

            

        }

    }

    log("04.connect start...select...\n");

    struct timeval  timeout;

    timeout.tv_sec = 3; //搜尋3秒

    timeout.tv_usec = 0;

    int status = select(sock+1, &set, NULL, NULL, &timeout);

    if(status==1)

    {

        robotLink_state= robotlink_LinkOK;

        log("end. connect OK \n");

        

    }

    else

    {

        robotLink_state= robotlink_ER5;

        log("05. select time out(3 sec.) \n");

    }

}

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網路 成功範例如下
http://stackoverflow.com/questions/14254061/setting-time-out-for-connect-function-tcp-socket-programming-in-c-breaks-recv

int sock;

struct sockaddr_in addr;

int connectWithServer

{

    int status;

    struct timeval  timeout;

    timeout.tv_sec = 10;

    timeout.tv_usec = 0;

    addr.sin_port = htons(port);

    sock = socket (AF_INET,SOCK_STREAM,0);

    inet_pton(AF_INET,serverIP,&addr.sin_addr);

    fd_set set;

    FD_ZERO(&set);

    FD_SET(sock, &set);

    fcntl(sock, F_SETFL, O_NONBLOCK);

    if ( (status = connect(sock, (struct sockaddr*)&addr, sizeof(addr))) == -1)

    {

        if ( errno != EINPROGRESS )

            return status;

    }

    status = select(sock+1, NULL, &set, NULL, &timeout);

    return status;

}

long int receiveResponse (void *response , unsigned int length)

{

    socklen_t sockLen = sizeof(struct sockaddr);

    long int received = recvfrom(sock, response, length, 0,(struct sockaddr *)&addr,  &sockLen);

    printf("Received %ld bytes...  err %d\n",received, errno);

    return received;

}