src/fuzz/fuzz-dhcp-server.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  Copyright 2018 Jonathan Rudenberg

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include "fuzz.h"

#include "sd-dhcp-server.c"

/* stub out network so that the server doesn't send */
ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen) {
        return len;
}

ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags) {
        return 0;
}

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
        _cleanup_(sd_dhcp_server_unrefp) sd_dhcp_server *server = NULL;
        struct in_addr address = {.s_addr = htobe32(UINT32_C(10) << 24 | UINT32_C(1))};
        static const uint8_t chaddr[] = {3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3};
        uint8_t *client_id;
        DHCPLease *lease;
        int pool_offset;

        if (size < sizeof(DHCPMessage))
                return 0;

        assert_se(sd_dhcp_server_new(&server, 1) >= 0);
        server->fd = open("/dev/null", O_RDWR|O_CLOEXEC|O_NOCTTY);
        assert_se(server->fd >= 0);
        assert_se(sd_dhcp_server_configure_pool(server, &address, 24, 0, 0) >= 0);

        /* add a lease to the pool to expose additional code paths */
        client_id = malloc(2);
        assert_se(client_id);
        client_id[0] = 2;
        client_id[1] = 2;
        lease = new0(DHCPLease, 1);
        assert_se(lease);
        lease->client_id.length = 2;
        lease->client_id.data = client_id;
        lease->address = htobe32(UINT32_C(10) << 24 | UINT32_C(2));
        lease->gateway = htobe32(UINT32_C(10) << 24 | UINT32_C(1));
        lease->expiration = UINT64_MAX;
        memcpy(lease->chaddr, chaddr, 16);
        pool_offset = get_pool_offset(server, lease->address);
        server->bound_leases[pool_offset] = lease;
        assert_se(hashmap_put(server->leases_by_client_id, &lease->client_id, lease) >= 0);

        (void) dhcp_server_handle_message(server, (DHCPMessage*)data, size);

        return 0;
}