Determining Latency of Web Sites

This is a discussion on Determining Latency of Web Sites within the C Programming forums, part of the General Programming Boards category; I am writing a simple program that connects a socket to, say google, and then waits for a response. Basically, ...

  1. #1
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    Determining Latency of Web Sites

    I am writing a simple program that connects a socket to, say google, and then waits for a response. Basically, I am determining the latency of web sites over a 24 hour period. I am doing something wrong because my writes aren't working. I use port 80 and copy GET / http/1.0\r\n\r\n into a buffer and write it to google. My program seems to be sticking in the write process, and I have no ideas if the read will work or not. I am using AF_INET and SOCK_STREAM to create my socket file descriptors. Any ideas?

  2. #2
    End Of Line Hammer's Avatar
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    6,231
    Need to see some code. Also, read the FAQ thread in the Linux forum for various info.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  3. #3
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    Here is my code:

    Code:
    #include <string.h>
    #include <unistd.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <netdb.h>
    
    void error(char *msg)
    {
        perror(msg);
        exit(0);
    }
    
    int main(int argc, char *argv[])
    {
        int sockfd, portno, n;
        struct sockaddr_in serv_addr;
        struct hostent *server;
    
        char buffer[256];
        if (argc < 2) {
           fprintf(stderr,"usage %s hostname\n", argv[0]);
           exit(0);
        }
        portno = 80;
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0)
            error("ERROR opening socket");
        server = gethostbyname(argv[1]);
        if (server == NULL) {
            fprintf(stderr,"ERROR, no such host\n");
            exit(0);
        }
        bzero((char *) &serv_addr, sizeof(serv_addr));
        serv_addr.sin_family = AF_INET;
        bcopy((char *)server->h_addr,
             (char *)&serv_addr.sin_addr.s_addr,
             server->h_length);
        serv_addr.sin_port = htons(portno);
        if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0)
            error("ERROR connecting");
        strcpy(buffer, "GET / http/1.0\r\n\r\n");
        bzero(buffer,256);
        fgets(buffer,255,stdin);
        n = write(sockfd,buffer,strlen(buffer));
        if (n < 0)
             error("ERROR writing to socket");
        printf("wrote to site");
        bzero(buffer,256);
        n = read(sockfd,buffer,255);
        if (n < 0)
             error("ERROR reading from socket");
        printf("%s\n",buffer);
        return 0;
    }
    All I need is for google to get my request and send back one line. I am determining the latency over a 24 hour period.

  4. #4
    Guest Sebastiani's Avatar
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    Waterloo, Texas
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    5,699
    Start here:

    strcpy(buffer, "GET / http/1.0\r\n\r\n"); // copy.
    bzero(buffer,256); // erase?
    fgets(buffer,255,stdin); // fill?!!

    That won't work, now will it?

    Drop the last two statements and try again.
    Code:
    bool fun(bool value)
    {
        return std::pow(std::exp(1), std::complex<float>(0, 1) 
        * std::complex<float>(std::atan(1)*(1 << (value + 2))))
        .real() > 0;
    }

  5. #5
    Registered User
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    Thank you! Next time I will check my code a little closer before posting.

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