wtf is this?

wtf.c

// create a mail server without include any library
// compile: gcc -o wtf wtf.c
// run: ./wtf

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

#define MAX_MSG 1000

int main(int argc, char *argv[])
{
    int sd, newSd, cliLen, n;
    struct sockaddr_in cliAddr, servAddr;
    char line[MAX_MSG];

    // create socket
    sd = socket(AF_INET, SOCK_STREAM, 0);
    if (sd < 0)
    {
        perror("cannot open socket ");
        exit(1);
    }

    // bind socket to port
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servAddr.sin_port = htons(atoi(argv[1]));
    if (bind(sd, (struct sockaddr *) &servAddr, sizeof(servAddr)) < 0)
    {
        perror("cannot bind port ");
        exit(1);
    }

    listen(sd, 5);

    while (1)
    {
        printf("%s: waiting for data on port TCP %u ... ", argv[0], atoi(argv[1]));

        cliLen = sizeof(cliAddr);
        newSd = accept(sd, (struct sockaddr *) &cliAddr, &cliLen);
        if (newSd < 0)
        {
            perror("cannot accept connection ");
            exit(1);
        }

        // init line
        memset(line, 0x0, MAX_MSG);

        while (n = recv(newSd, line, MAX_MSG, 0))
        {
            line[n] = '\0';
            printf("%s", line);
            fflush(stdout);
        }

        printf("Server: got from %s:TCP%d : %s", inet_ntoa(cliAddr.sin_addr), ntohs(cliAddr.sin_port), line);
        close(newSd);
    }
}