socklib.c

// 자주 쓰는 것들을 모아서 파일을 만듦.

// 서버에서는 make server socker, 클라이언트에서는 connect to server 만 하면 소켓을 만들고 연결 할 수 있게 해줌.

#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<time.h>
#include<strings.h>

#define   HOSTLEN  256
#define  BACKLOG  1

int make_server_socket_q(int , int );

int make_server_socket(int portnum)
{
    return make_server_socket_q(portnum, BACKLOG);
}
int make_server_socket_q(int portnum, int backlog)
{
    struct  sockaddr_in   saddr;    /* build our address here */
    struct hostent*  hp;                 /* this is part of our           */
    char   hostname[HOSTLEN];     /* address                            */
    int      sock_id;        /* the socket                        */

    sock_id = socket(PF_INET, SOCK_STREAM, 0);  /* get a socket  */
    if ( sock_id == -1 )
        return -1;

    /** build address and bind it to socket **/

    bzero((void *)&saddr, sizeof(saddr));     /* clear out struct     */
    gethostname(hostname, HOSTLEN);     /* where am I ?         */
    hp = gethostbyname(hostname);             /* get info about host  */
                                                                     /* fill in host part    */
    bcopy( (void *)hp->h_addr, (void *)&saddr.sin_addr, hp->h_length);
    saddr.sin_port = htons(portnum);            /* fill in socket port  */
    saddr.sin_family = AF_INET ;                /* fill in addr family  */
    if ( bind(sock_id, (struct sockaddr *)&saddr, sizeof(saddr)) != 0 )
        return -1;
}

int connect_to_server(char *host, int portnum)
{
    int                               sock;
    struct sockaddr_in  servadd;    /* the number to call */
    struct hostent           *hp;                /* used to get number */

    /** Step 1: Get a socket **/
    sock = socket( AF_INET, SOCK_STREAM, 0 );    /* get a line   */
    if ( sock == -1 )
        return -1;

    /** Step 2: connect to server **/
    bzero( &servadd, sizeof(servadd) );    /* zero the address     */
    hp = gethostbyname( host );    /* lookup host's ip #   */
    if (hp == NULL)
        return -1;
    bcopy(hp->h_addr, (struct sockaddr *)&servadd.sin_addr, hp->h_length);
    servadd.sin_port = htons(portnum);    /* fill in port number  */
    servadd.sin_family = AF_INET ;              /* fill in socket type  */

    if ( connect(sock,(struct sockaddr *)&servadd, sizeof(servadd)) !=0)
        return -1;

    return sock;
}