ossp/firewall-rules/checkPacket.c

#include "parser.c"
#include <stdio.h>
#include <stdlib.h>

#define TRUE 1
#define FALSE 0

int check_rules(struct Rule **rules, size_t num_rules, struct IP *ip,
                Port *port) {
    for (size_t i = 0; i < num_rules; i += 1) {
        struct Rule *r = rules[i];

        int ip_matches = FALSE;
        int port_matches = FALSE;

        if ((r->ip.end != NULL && compare_ip(ip, &r->ip.start) > -1 &&
             compare_ip(ip, r->ip.end) < 1) ||
            compare_ip(ip, &r->ip.start) == 0) {
            ip_matches = TRUE;
        }

        if ((r->port.end != NULL && akpa_numcmp(*port, r->port.start) > -1 &&
             akpa_numcmp(*port, *r->port.end) < 1) ||
            akpa_numcmp(*port, r->port.start) == 0) {
            port_matches = TRUE;
        }

        if (ip_matches == TRUE && port_matches == TRUE) {
            return TRUE;
        }
    }

    return FALSE;
}

int main(int argc, char *argv[]) {
    if (argc < 4) {
        fprintf(stderr, "Usage: %s FILENAME IP_ADDR PORT\n", argv[0]);
        return 1;
    }

    size_t num_parsed_rules;
    struct Rule **parsed_rules = parse_file(argv[1], &num_parsed_rules);

    if (parsed_rules == NULL) {
        return 1;
    }

    struct IP *ip = (struct IP *)malloc(sizeof(struct IP));
    if (parse_ip(argv[2], ip) == NULL) {
        fprintf(stderr, "Failed to parse IP\n");
        return 1;
    }

    Port *port = (Port *)malloc(sizeof(Port));
    if (parse_port(argv[3], port) == NULL) {
        fprintf(stderr, "Failed to parse port\n");
        return 1;
    }

    printf("Packet from ");
    print_ip(ip);
    printf(" and port %d ", *port);
    if (check_rules(parsed_rules, num_parsed_rules, ip, port)) {
        printf("accepted\n");
    } else {
        printf("rejected\n");
    }

    for (int i = 0; i < num_parsed_rules; i += 1) {
        free_rule(parsed_rules[i]);
    }

    free(ip);
    free(port);

    return 0;
}