#include "unp.h"

void dg_echo(int, SA*, socklen_t);

int main(int argc, char* argv[])
{
    int     sockfd;
    struct  sockaddr_in servaddr, cliaddr;

    sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);

    Bind(sockfd, (SA *)&servaddr, sizeof(servaddr));
    dg_echo(sockfd, (SA *)&cliaddr, sizeof(cliaddr));
}

void dg_echo(int sockfd, SA *pcliaddr, socklen_t clien)
{
    int     n;
    socklen_t len;
    char msg[MAXLINE];
    char res[MAXLINE];
    char greeting[] = "This is from server: ";

    for(;;) {
        len = clien;

        n = Recvfrom(sockfd, msg, MAXLINE, 0, pcliaddr, &len);
        strcpy(res, "");
        strncat(res, greeting, strlen(greeting));
        strncat(res, msg, n);
        Sendto(sockfd, res, strlen(res), 0, pcliaddr, len);
    }
 }