/* * Multithreaded Echo Servers on port 60000 for Transfer Control Protocol * */
#ifndef unix
#include <winsock2.h>
/* also include Ws2_32.lib library in linking options */
#include <process.h>
#else
!! this example shows only WIndows-based multithreading !!
#define closesocket close
#define SOCKET int
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
/* also include xnet library for linking; on command line add: -lxnet */
#include <pthread.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PROTOPORT       60000
                             /* default protocol port number        */
#define QLEN 5
                                   /* size of request queue        */
void service_client(SOCKET cli);

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

    struct  protoent *ptrp;  /* pointer to a protocol table entry   */
    struct  sockaddr_in sad; /* structure to hold server's address  */
    struct  sockaddr_in cad; /* structure to hold client's address  */
    SOCKET  sd, sd2;         /* socket descriptors                  */
    int     port;            /* protocol port number                */
    int     alen;            /* length of address                   */

#ifdef WIN32
    WSADATA wsaData;
    if(WSAStartup(0x0101, &wsaData)!=0)
    {
        fprintf(stderr, "Windows Socket Init failed: %d\n", GetLastError());
        exit(1);
    }
#endif

    memset((char *)&sad,0,sizeof(sad)); /* clear sockaddr structure */
        
    if (argc > 1) {                 /* if argument specified        */
        port = atoi(argv[1]);       /* convert argument to binary   */
    } else {
        port = PROTOPORT;           /* use default port number      */
    }

    if (port <= 0)                  /* test for illegal value       */
    {                               /* print error message and exit */
        fprintf(stderr,"bad port number %s\n",argv[1]);
        exit(1);
    }

    sad.sin_port = htons((u_short)port); /* set server port number  */
    sad.sin_family = AF_INET;         /* set family to Internet     */
    sad.sin_addr.s_addr = INADDR_ANY; /* set the local IP address   */
    
    /* Map TCP transport protocol name to protocol number */
    ptrp = getprotobyname("tcp");
    if ( ptrp == 0 ) {
        fprintf(stderr, "Cannot map \"tcp\" to protocol number");
        exit(1);
    }
    
    /* Create a socket */
    sd = socket(PF_INET, SOCK_STREAM, ptrp->p_proto);
    if (sd < 0) {
        fprintf(stderr, "Socket creation failed\n");
        exit(1);
    }
    
    /* Bind a local address to the socket */
    if (bind(sd, (struct sockaddr *)&sad, sizeof(sad)) < 0) {
        fprintf(stderr,"Bind failed\n");
        exit(1);
    }
    
    /* Specify size of request queue */
    if (listen(sd, QLEN) < 0) {
        fprintf(stderr,"Listen failed\n");
        exit(1);
    }
    
    /* Main server loop - accept and handle requests */
    while (1)
    {
        alen = sizeof(cad);
        sd2=accept(sd, (struct sockaddr *)&cad, &alen);
        if ( sd2 < 0) {
            fprintf(stderr, "Accept failed\n");
            exit(1);
        }
        
        _beginthread((void (*)(void *))service_client, 0, (void *)sd2);
    }

#ifdef WIN32
    WSACleanup();
#endif

    return(0);
}


void service_client(SOCKET cli)
{
    char    buf[65536];      /* buffer for string the echoing       */
    int     n;               /* number of characters received       */
    int     m;               /* number of characters sent back      */
    while (1)
    {
        n = recv(cli, buf, sizeof(buf), 0);
        
        if (n<0)
        {
            fprintf(stderr,"Err in receiving\n");
            break;
        }
        else if (n==0) {
            /* Remote closed the connection */
            break;
        }
        else if(n>0)
        {
            m = send(cli,buf,n,0);
            if(m<0){
                fprintf(stderr,"Error in sending\n");
                break;
            }
        }
    }
    closesocket(cli);
}