clientudp.c

UDP client and server!!!

    /****************udpclient.c********************/


    #include <stdio.h>

    #include <stdlib.h>

    #include <string.h>

    #include <sys/types.h>

    #include <sys/socket.h>

    #include <netinet/in.h>

    #include <arpa/inet.h>

    #include <netdb.h>

     

    /* Host name of my system, change accordingly */

    /* Put the server hostname that run the UDP server program */

    /* This will be used as default UDP server for client connection */

    #define SERVER "posluzivac:-)"

    /* Server's port number */

    #define SERVPORT 3333

    /* Pass in 1 argument (argv[1]) which is either the */

    /* address or host name of the server, or */

    /* set the server name in the #define SERVER above. */

     

    int main(int argc, char *argv[])

    {

    /* Variable and structure definitions. */

    int sd, rc;

    struct sockaddr_in serveraddr, clientaddr;

    int serveraddrlen = sizeof(serveraddr);

    char server[255];

    char buffer[100];

    char *bufptr = buffer;

    int buflen = sizeof(buffer);

    struct hostent *hostp;

    memset(buffer, 0x00, sizeof(buffer));

    /* 36 characters + terminating NULL */

    //memcpy(buffer, "Hello!!!", 37);

     

    /* The socket() function returns a socket */

    /* descriptor representing an endpoint. */

    /* The statement also identifies that the */

    /* INET (Internet Protocol) address family */

    /* with the UDP transport (SOCK_DGRAM) will */

    /* be used for this socket. */

    /******************************************/

    /* get a socket descriptor */

    if((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)

    {

    perror("UDP Client - socket() error");

    /* Just exit lol! */

    exit(-1);

    }

    else

    printf("UDP Client - socket() is OK!\n");

     

    /* If the hostname/IP of the server is supplied */

    /* Or if(argc = 2) */

    if(argc > 1)

    strcpy(server, argv[1]);

    else

    {

    /*Use default hostname or IP*/

    printf("UDP Client - Usage %s <Server hostname or IP>\n", argv[0]);

    printf("UDP Client - Using default hostname/IP!\n");

     

    strcpy(server, SERVER);

    }

     

    memset(&serveraddr, 0x00, sizeof(struct sockaddr_in));

    serveraddr.sin_family = AF_INET;

    serveraddr.sin_port = htons(SERVPORT);

     

    if((serveraddr.sin_addr.s_addr = inet_addr(server)) == (unsigned long)INADDR_NONE)

    {

    /* Use the gethostbyname() function to retrieve */

    /* the address of the host server if the system */

    /* passed the host name of the server as a parameter. */

    /************************************************/

    /* get server address */

    hostp = gethostbyname(server);

    if(hostp == (struct hostent *)NULL)

    {

    printf("HOST NOT FOUND --> ");

    /* h_errno is usually defined */

    /* in netdb.h */

    printf("h_errno = %d\n", h_errno);

    exit(-1);

    }

    else

    {

    printf("UDP Client - gethostname() of the server is OK... \n");

    printf("Connected to UDP server %s on port %d.\n", server, SERVPORT);

    }

    memcpy(&serveraddr.sin_addr, hostp->h_addr, sizeof(serveraddr.sin_addr));

    }

     

    /* Use the sendto() function to send the data */

    /* to the server. */

    /************************************************/

    /* This example does not use flags that control */

    /* the transmission of the data. */

    /************************************************/

    /* send request to server */
    do{
    printf("Unesite string za slanje ka UDP serveru: ");    
    gets(buffer);        
    rc = sendto(sd, bufptr, buflen, 0, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
        
    if(rc < 0)

    {

    perror("UDP Client - sendto() error");

    close(sd);

    exit(-1);

    }

    else

    printf("UDP Client - sendto() is OK!\n");

     

    printf("Waiting a reply from UDP server...\n");

     

    /* Use the recvfrom() function to receive the */

    /* data back from the server. */

    /************************************************/

    /* This example does not use flags that control */

    /* the reception of the data. */

    /************************************************/

    /* Read server reply. */

    /* Note: serveraddr is reset on the recvfrom() function. */

    rc = recvfrom(sd, bufptr, buflen, 0, (struct sockaddr *)&serveraddr, &serveraddrlen);

     

    if(rc < 0)

    {

    perror("UDP Client - recvfrom() error");

    close(sd);

    exit(-1);

    }

    else

    {

    printf("UDP client received the following: \"%s\" message\n", bufptr);

    printf(" from port %d, address %s\n", ntohs(serveraddr.sin_port), inet_ntoa(serveraddr.sin_addr));

    }

    }while(strcmp(buffer,"quit") != 0);  

    /* When the data has been received, close() */

    /* the socket descriptor. */

    /********************************************/

    /* close() the socket descriptor. */

    close(sd);

    exit(0);

    }