/* Modified version of yesterday's discussion section code, which is in turn
 * derived from Beej's guide -- see there for more explanation:
 *  http://beej.us/guide/bgnet/output/html/multipage/clientserver.html
 *
 * 
 * This verison demonstrates what happens when the client abruptly
 * closes a connection, and how to deal with it.
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <pthread.h>


#define PORT "31338"  // the port users will be connecting to

#define BACKLOG 10     // how many pending connections queue will hold

#define BUFFER_LEN 100


// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
    if (sa->sa_family == AF_INET) {
        return &(((struct sockaddr_in*)sa)->sin_addr);
    }

    return &(((struct sockaddr_in6*)sa)->sin6_addr);
}

int main(void)
{
    // Ignore SIGPIPE
    // signal(SIGPIPE, SIG_IGN);
    
    int sockfd, new_fd;  // listen on sock_fd, new connection on new_fd
    struct addrinfo hints, *servinfo, *p;
    struct sockaddr_storage their_addr; // connector's address information
    socklen_t sin_size;
    int yes=1;
    char s[INET6_ADDRSTRLEN];
    int rv;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE; // use my IP

    if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // loop through all the results and bind to the first we can
    for(p = servinfo; p != NULL; p = p->ai_next) {
        if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
            perror("server: socket");
            continue;
        }

        if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {
            perror("setsockopt");
            exit(1);
        }

        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
            close(sockfd);
            perror("server: bind");
            continue;
        }

        break;
    }

    if (p == NULL)  {
        fprintf(stderr, "server: failed to bind\n");
        return 2;
    }

    freeaddrinfo(servinfo); // all done with this structure

    if (listen(sockfd, BACKLOG) == -1) {
        perror("listen");
        exit(1);
    }


    while (1) {  // main accept() loop
        sin_size = sizeof(their_addr);
        printf("server: waiting for connections...\n");
        new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
        if (new_fd == -1) {
            perror("accept");
            continue;
        }

        inet_ntop(their_addr.ss_family,
                  get_in_addr((struct sockaddr *)&their_addr), s, sizeof(s));
        printf("Boy oh boy!  I got a connection from %s\n", s);

        int res = 0;
        while(res >= 0) {
            char* str = "Hi there!\n";
            res = write(new_fd, str, strlen(str));
            printf("Write returned %d\n", res);
            sleep(1);
        }
    }

    return 0;
}