#define _CRT_SECURE_NO_DEPRECATE

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

#define USERPASS "pentest:midterm"

// VS2005: cl /GS- /MD htpasswd.c
// gcc: rename _snprintf -> snprintf

int verbose = 0;

static char authbuf[512];
static int authenticated = 0;

int authenticate(char *username, char *password){
    _snprintf(authbuf, sizeof(authbuf)+1, "%s:%s", username, password);

    if (!authenticated) {
        // If the user is not already authenticated, try and authenticate them now
        authenticated = !strncmp(authbuf, USERPASS, strlen(USERPASS));
    }

    return authenticated;
}

void debugprint(char* str)
{
    char debugbuf[522];

    _snprintf(debugbuf, strlen(str)+10, "DEBUG: %s\n", str);
    fprintf(stderr, debugbuf);
}

void debug(char *username, char *password)
{
    char pass[512];
    char user[512];

    strncpy(user, username, sizeof(user));
    strncpy(pass, password, sizeof(pass));

    debugprint(user);
    debugprint(pass);
}

void update_file(char *new, char *outfile)
{
    char s_buffer[512];
    unsigned char f;

    f = strlen(new);
    if(f > sizeof(s_buffer)-10){
            fprintf(stderr, "new username too long!\n");
            exit(1);
    }
    strcpy(s_buffer, new);

    fprintf(stdout, "Username: %s added to %s!\n", s_buffer, outfile);
}

void usage(void)
{
    fprintf(stderr,"Usage: adduser [options]\n");
    fprintf(stderr,"Options\n");
    fprintf(stderr,"  -v          verbose\n");
    fprintf(stderr,"  -u<username>    Your username\n");
    fprintf(stderr,"  -p<password>    Your password\n");
    fprintf(stderr,"  -f<filename>    htpasswd file to update\n");
    fprintf(stderr,"  -n<newusername>    New username to add to htpasswd file\n");
    exit (8);
}

int main(int argc, char *argv[])
{
    char *username = NULL, *password = NULL, *outfile = NULL, *newuser = NULL;

    __asm int 3

    /* loop for each option.
     *  Stop if we run out of arguments
     *  or we get an argument without a dash.
     */
    while ((argc > 1) && (argv[1][0] == '-')) {
        /* argv[1][1] is the actual option character. */
        switch (argv[1][1]) {
        case 'v':
            verbose = 1;
            printf("DEBUG: verbose set\n");
            break;
            /* -f<name>  output file
             *    [0] is the dash
             *    [1] is the "f"
             *    [2] starts the name */
        case 'f':
            outfile = &argv[1][2];
            break;
        case 'u':
            username = &argv[1][2];
            break;
        case 'p':
            password = &argv[1][2];
            break;
        case 'n':
            newuser = &argv[1][2];
            break;
        default:
            fprintf(stderr,"Bad option %s\n", argv[1]);
            usage();
        }

        /* move the argument list up one
        * move the count down one
        */
        ++argv;
        --argc;
    }

    if (!username || !password || !outfile || !newuser) {
        usage();
    }

    if(verbose)
        debug(username, password);

    if(authenticate(username, password)) {
        fprintf(stdout, "You correctly authenticated!\nAdding new user to %s...\n", outfile);
        update_file(newuser, outfile);
    }

    return 0;
}