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

char inbuff[1024];

void DoAttack(int PortNo);
void Attack(FILE *outfile);

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

    char * studStr, *portStr;
    int studLen, portLen;
    int studNo, portNo;
    int i;

    if (argc != 2){
        fprintf(stderr, "usage %s portno\n", argv[0]);
        exit(1);
    }

    portStr = argv[1];
    if ((portLen = strlen(portStr)) < 1){
        fprintf(stderr, "%s: port number must be 1 or more digits\n", argv[0]);
        exit(1);
    }
    for (i = 0; i < portLen; i++){
        if(!isdigit(portStr[i])){
            fprintf(stderr, "%s: port number must be all digits\n", argv[0]);
            exit(1);
        }
    }
    portNo = atoi(portStr);

    fprintf(stderr, "Port Number  %d\n", portNo);

    DoAttack(portNo);

    exit(0);
}

void  DoAttack(int portNo) {
    int server_sockfd;
    int serverlen;

    struct sockaddr_in server_address;

    FILE * outf;
    FILE * inf;
    struct hostent *h;


    server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if((h=gethostbyname("localhost"))==NULL){
        fprintf(stderr,"Host Name Error...");
        exit(1);
    }

    server_address.sin_family = AF_INET;
    memcpy((char *) &server_address.sin_addr.s_addr, h->h_addr_list[0], h->h_length);
    /* server_address.sin_addr.s_addr = htonl(INADDR_ANY); */
    server_address.sin_port = htons(portNo);

    if(connect(server_sockfd,(struct sockaddr*)&server_address,sizeof(struct sockaddr))==-1){
        fprintf(stderr,"Connection out...");
        exit(1);
    }

    outf = fdopen(server_sockfd, "w");

    // add log message here
    Attack(outf);

    inf = fdopen(server_sockfd, "r");
    if (inf == NULL){
        fprintf(stderr,"could not open socket for read");
        exit(1);
    }
    do {
        inbuff[0] = '\0';
        fgets(inbuff,1024,inf);
        if (inbuff[0]){
            fputs(inbuff,stdout);
        }
    } while (!feof(inf));
    fclose(outf);
    fclose(inf);
    return;
}

char compromise[130] = {
    'h','e','l','l','o',' ','t','h','e','r','e','\n'
};

void Attack(FILE *outfile){
    fprintf(outfile,compromise);
    fflush(outfile);
}