/* Copyright 2021 Google LLC

Licensed under the Apache License, Version 2.0 (the "License");

you may not use this file except in compliance with the License.

You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software

distributed under the License is distributed on an "AS IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and

limitations under the License.

*/

#include <stdio.h>

#include <errno.h>

#include <stdlib.h>

#include <stdint.h>

#include <unistd.h>

#include <string.h>

#include <stddef.h>

#include <pthread.h>

#include <arpa/inet.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <netinet/tcp.h>

#include <modbus.h>

#include "unit-test.h"

#define PORT 8080

#define kMinInputLength 9

#define kMaxInputLength MODBUS_RTU_MAX_ADU_LENGTH

struct Fuzzer{

    uint16_t    port;    

    char*       file;

    FILE*       inFile;

    uint64_t    size;

    uint8_t*    buffer;

    pthread_t   thread;

    int         socket;

};

typedef struct Fuzzer Fuzzer;

int server(Fuzzer *fuzzer);

void *client(void *args){ 

    Fuzzer *fuzzer = (Fuzzer*)args;

    int sockfd;

    struct sockaddr_in serv_addr;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    serv_addr.sin_family = AF_INET;

    serv_addr.sin_port = htons(fuzzer->port);

    serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    while(1){/* Try until connect*/

        if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0){

            continue;

        }else{

            break;

        }

    }

    send(sockfd,fuzzer->buffer,fuzzer->size,0);

    close(sockfd);

    pthread_exit(NULL);

}

extern int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

    if (size < kMinInputLength || size > kMaxInputLength){

        return 0;

    }

    Fuzzer *fuzzer = (Fuzzer*)malloc(sizeof(Fuzzer));

    fuzzer->port = PORT;

    fuzzer->size = size;

    fuzzer->buffer = data;

    pthread_create(&fuzzer->thread, NULL,client,fuzzer);

    server(fuzzer);

    pthread_join(fuzzer->thread, NULL); /* Avoid UAF*/

    free(fuzzer);

    return 0;

}

int server(Fuzzer *fuzzer)

{

    int s = -1;

    modbus_t *ctx;

    modbus_mapping_t *mb_mapping;

    int rc;

    int i;

    uint8_t *query;

    ctx = modbus_new_tcp("127.0.0.1", fuzzer->port);

    query = malloc(MODBUS_TCP_MAX_ADU_LENGTH);

    mb_mapping = modbus_mapping_new_start_address(

        UT_BITS_ADDRESS, UT_BITS_NB,

        UT_INPUT_BITS_ADDRESS, UT_INPUT_BITS_NB,

        UT_REGISTERS_ADDRESS, UT_REGISTERS_NB_MAX,

        UT_INPUT_REGISTERS_ADDRESS, UT_INPUT_REGISTERS_NB);

    if (mb_mapping == NULL) {

        fprintf(stderr, "Failed to allocate the mapping: %s\n",

                modbus_strerror(errno));

        modbus_free(ctx);

        return -1;

    }

    /* Initialize input values that's can be only done server side. */

    modbus_set_bits_from_bytes(mb_mapping->tab_input_bits, 0, UT_INPUT_BITS_NB,

                               UT_INPUT_BITS_TAB);

    /* Initialize values of INPUT REGISTERS */

    for (i=0; i < UT_INPUT_REGISTERS_NB; i++) {

        mb_mapping->tab_input_registers[i] = UT_INPUT_REGISTERS_TAB[i];

    }

    s = modbus_tcp_listen(ctx, 1);

    modbus_tcp_accept(ctx, &s);

    rc = modbus_receive(ctx, query);

    if (s != -1) {

        close(s);

    }

    modbus_mapping_free(mb_mapping);

    free(query);

    /* For RTU */

    modbus_close(ctx);

    modbus_free(ctx);

    return rc;

}