/*
NAME:       UDP.ECHO.CLIENT
SYNOPSIS:    UDPClient hostid portnumber 
DESCRIPTION:    The program creates a datagram socket in the inet 
                domain, gets messsages typed by a user
                and sends them to echoserver running on hostid
                Then it waits for a reply from  the echoserver
                and shows it back to the user, with a message
                indicating if there is an error during the round trip. 
*/
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <stdio.h>
#include <errno.h>
#include <sys/time.h>
#include <stdlib.h>
#include <string.h>

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/file.h>

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>

#define BUF_SIZE 500
#define MAXHOSTNAME 80

int main(int argc, char * argv[])
{   
    struct addrinfo hints, *result, *rp;
    struct addrinfo hints_local, *result_local;
    int sfd, s, s2, rc;
    struct sockaddr_storage peer_addr;
    socklen_t peer_addr_len;
    ssize_t nread;
    char buf[BUF_SIZE];
    char ThisHost[MAXHOSTNAME];

    if (argc < 2) {
        fprintf(stderr, "Usage: %s host port \n", argv[0]);
        exit(EXIT_FAILURE);
    }         

    gethostname(ThisHost, MAXHOSTNAME);
    /*Obtain address(es) matching localhost/localport*/
    memset(&hints_local, 0, sizeof(hints_local));
    hints_local.ai_family = AF_INET; //IPv4
    hints_local.ai_socktype = SOCK_DGRAM; //UDP
    hints_local.ai_flags = AI_PASSIVE;

    if (getaddrinfo(ThisHost, argv[2], &hints_local, &result_local) != 0)
    {
        fprintf(stderr, "getaddrinfo error\n");
        exit(EXIT_FAILURE);
    }



    printf("----EchoClient running at host NAME: %s\n", ThisHost);
    printf("(EchoClient INET ADDRESS is: %s )\n", inet_ntoa(((struct sockaddr_in*)result_local->ai_addr)->sin_addr));

    /*Obtain address(es) matching host/port*/
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET; //IPv4
    hints.ai_socktype = SOCK_DGRAM; //UDP
    hints.ai_flags = AI_PASSIVE;


    if (getaddrinfo(argv[1], argv[2], &hints, &result) != 0)
    {
        fprintf(stderr, "getaddrinfo error\n");
        exit(EXIT_FAILURE);
    }

    



    /* getaddrinfo() returns a list of address structures.
              Try each address until we successfully connect(2).
              If socket(2) (or connect(2)) fails, we (close the socket
              and) try the next address. */

    for (rp = result; rp != NULL; rp = rp->ai_next) {
        sfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
        if (sfd == -1)
            continue;

        if (connect(sfd, rp->ai_addr, rp->ai_addrlen) != -1)
            break;                  /* Success */

        close(sfd);
    }
    
    freeaddrinfo(result);           /* No longer needed */

    if (rp == NULL) {               /* No address succeeded */
        fprintf(stderr, "Could not connect\n");
        exit(EXIT_FAILURE);
    
    
    }
      
    /* Send remaining command-line arguments as separate
       datagrams, and read responses from server. */

    printf("----EchoServer running at host NAME: %s\n", argv[1]);


    printf("(EchoServer INET ADDRESS is: %s )\n", inet_ntoa(((struct sockaddr_in*)rp->ai_addr)->sin_addr));


    for (;;) {
        printf("\nType anything followed by RETURN, or type CTRL-D to exit\n");

        /* +1 for terminating null byte */
        rc=read(0,buf, sizeof(buf)-1);
        buf[rc] = '\0';
        if (rc == 0) break;

        peer_addr_len = sizeof(peer_addr);

        if (write(sfd, buf, rc) != rc) {
            fprintf(stderr, "partial/failed write\n");
            exit(EXIT_FAILURE);
        }
        nread = recvfrom(sfd, buf, BUF_SIZE, 0, (struct sockaddr *)&peer_addr, &peer_addr_len);

        buf[nread]='\0';
        if (nread == 1)
        {
         continue; //Ignore failed request
        }
        if (nread == -1) {
            perror("read");
            exit(EXIT_FAILURE);
        }
        char host[NI_MAXHOST], service[NI_MAXSERV];

        s2 = getnameinfo((struct sockaddr *)&peer_addr, peer_addr_len, host, NI_MAXHOST, service, NI_MAXSERV, NI_NUMERICSERV);

        if (s2 == 0)
        {
         printf("Received: %s from %s:%s\n", buf, host, service);
        }
        else
        fprintf(stderr, "getnameinfo: %s\n", gai_strerror(s));
    }
    exit(EXIT_SUCCESS);
   
}