simple echo server

echo.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
//

#define LISTEN_SIZ 10
#define BUF_SIZ 1024
#define PORT 8888


int main(int argc, char **argv){
    int sockfd, connfd;
    int r, tmp;
    int port;
    size_t salen;
    struct sockaddr_in servaddr;
    struct sockaddr_in cliaddr;
    char buf[BUF_SIZ];

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        printf("bad socket().\n");
        exit(sockfd);
    }
    tmp = 1;
    setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &tmp, sizeof(tmp));

    port = PORT;

    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(port);

    r = bind(sockfd, (struct sockaddr*) &servaddr, sizeof(servaddr));
    if (r < 0) {
        printf("bad bind(). %s\n", strerror(errno));
        exit(r);
    } 

    r = listen(sockfd, LISTEN_SIZ);
    if (r < 0) {
        printf("bad listen().\n");
        exit(r);
    }


    salen = sizeof(struct sockaddr_in);
    for(;;) {
        printf("waiting connection...\n");
        connfd = accept(sockfd, (struct sockaddr*)&cliaddr, &salen);
        if (connfd < 0) {
            printf("bad accept().");
            exit(connfd);
        }

        memset(buf, 0, BUF_SIZ);
        while((r = read(connfd, buf, BUF_SIZ))>0) {
            if (r < 0) {
                printf("bad readn()");
            }
            buf[r] = '\0';
            printf("> %d: %s", r, buf);
            write(connfd, buf, r);
            printf("> send: %s", buf);
            memset(buf, 0, BUF_SIZ);
        }

        close(connfd);
    }
}