// https://llvm.org/docs/LibFuzzer.html

#define MG_ENABLE_SOCKET 0

#define MG_ENABLE_LOG 0

#define MG_ENABLE_LINES 1

#define MG_ENABLE_TCPIP 1

#define MG_IO_SIZE (32 * 1024 * 1024)  // Big IO size for fast resizes

#include "mongoose.c"

#include "driver_mock.c"

#ifdef __cplusplus

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *, size_t);

#else

int LLVMFuzzerTestOneInput(const uint8_t *, size_t);

#endif

static void fn(struct mg_connection *c, int ev, void *ev_data) {

  struct mg_http_serve_opts opts = {.root_dir = "."};

  if (ev == MG_EV_HTTP_MSG) {

    mg_http_serve_dir(c, (struct mg_http_message *) ev_data, &opts);

  }

}

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

  mg_log_set(MG_LL_INFO);

  struct mg_dns_message dm;

  mg_dns_parse(data, size, &dm);

  mg_dns_parse(NULL, 0, &dm);

  struct mg_http_message hm;

  if (mg_http_parse((const char *) data, size, &hm) > 0) {

    mg_crc32(0, hm.method.buf, hm.method.len);

    mg_crc32(0, hm.uri.buf, hm.uri.len);

    mg_crc32(0, hm.uri.buf, hm.uri.len);

    for (size_t i = 0; i < sizeof(hm.headers) / sizeof(hm.headers[0]); i++) {

      struct mg_str *k = &hm.headers[i].name, *v = &hm.headers[i].value;

      mg_crc32(0, k->buf, k->len);

      mg_crc32(0, v->buf, v->len);

    }

  }

  mg_http_parse(NULL, 0, &hm);

  struct mg_str body = mg_str_n((const char *) data, size);

  char tmp[256];

  mg_http_get_var(&body, "key", tmp, sizeof(tmp));

  mg_http_get_var(&body, "key", NULL, 0);

  mg_url_decode((char *) data, size, tmp, sizeof(tmp), 1);

  mg_url_decode((char *) data, size, tmp, 1, 1);

  mg_url_decode(NULL, 0, tmp, 1, 1);

  struct mg_mqtt_message mm;

  if (mg_mqtt_parse(data, size, 0, &mm) == MQTT_OK) {

    mg_crc32(0, mm.topic.buf, mm.topic.len);

    mg_crc32(0, mm.data.buf, mm.data.len);

    mg_crc32(0, mm.dgram.buf, mm.dgram.len);

  }

  mg_mqtt_parse(NULL, 0, 0, &mm);

  if (mg_mqtt_parse(data, size, 5, &mm) == MQTT_OK) {

    mg_crc32(0, mm.topic.buf, mm.topic.len);

    mg_crc32(0, mm.data.buf, mm.data.len);

    mg_crc32(0, mm.dgram.buf, mm.dgram.len);

    {

      struct mg_mqtt_prop prop;

      size_t ofs = 0;

      while ((ofs = mg_mqtt_next_prop(&mm, &prop, ofs)) > 0) {

          mg_crc32(0, prop.key.buf, prop.key.len);

          mg_crc32(0, prop.val.buf, prop.val.len);

      }

    }

  }

  mg_mqtt_parse(NULL, 0, 5, &mm);

  mg_sntp_parse(data, size);

  mg_sntp_parse(NULL, 0);

  char buf[size * 4 / 3 + 5];  // At least 4 chars and nul termination

  mg_base64_decode((char *) data, size, buf, sizeof(buf));

  mg_base64_decode(NULL, 0, buf, sizeof(buf));

  mg_base64_encode(data, size, buf, sizeof(buf));

  mg_base64_encode(NULL, 0, buf, sizeof(buf));

  mg_match(mg_str_n((char *) data, size), mg_str_n((char *) data, size), NULL);

  struct mg_str entry, s = mg_str_n((char *) data, size);

  while (mg_span(s, &entry, &s, ',')) entry.len = 0;

  int n;

  mg_json_get(mg_str_n((char *) data, size), "$", &n);

  mg_json_get(mg_str_n((char *) data, size), "$.a.b", &n);

  mg_json_get(mg_str_n((char *) data, size), "$[0]", &n);

  // Test built-in TCP/IP stack

  if (size > 0) {

    struct mg_tcpip_if mif = {.ip = 1,

                              .mask = 255,

                              .gw = 1,

                              .gw_ready = true,

                              .state = MG_TCPIP_STATE_READY,

#if MG_ENABLE_IPV6

                              .ip6[0] = 1;

                              .prefix[0] = 1;

                              .prefix_len = 64;

                              .gw6[0] = 1;

                              .gw6_ready = true;

                              .state6 = MG_TCPIP_STATE_READY;  // so mg_send() works and RS stops

#endif

                              .driver = &mg_tcpip_driver_mock};

    struct mg_mgr mgr;

    mg_mgr_init(&mgr);

    mg_tcpip_init(&mgr, &mif);

    // Make a copy of the random data, in order to modify it

    void *pkt = malloc(size);

    struct eth *eth = (struct eth *) pkt;

    memcpy(pkt, data, size);

    if (size > sizeof(*eth)) {

      static size_t i;

      // eth_types[] exists in l2_eth.c

      memcpy(eth->dst, mif.mac, 6);  // Set valid destination MAC

      // send all handled eth types, then 2 random ones

      if (i >= (sizeof(eth_types) / sizeof(eth_types[0]) + 2)) i = 0;

      if (i < (sizeof(eth_types) / sizeof(eth_types[0]))) eth->type = mg_htons(eth_types[i++]);

      // build proper layer-3 datagrams, to be able to exercise layers above

      if (eth->type == mg_htons(0x800) && size > (sizeof(*eth) + sizeof(struct ip))) {             // IPv4

        static size_t j;

        uint8_t ip_protos[] = {1, 6, 17}; // ICMP, TCP, UDP

        struct ip *ip4 = (struct ip *) (eth + 1);

        ip4->ver = (ip4->ver & ~0xf0) | (4 << 4);

        // send all handled IP protos, then 2 random ones

        if (j >= (sizeof(ip_protos) / sizeof(ip_protos[0]) + 2)) j = 0;

        if (j < (sizeof(ip_protos) / sizeof(ip_protos[0]))) ip4->proto = (ip_protos[j++]);

        if (ip4->proto == 1) { // ICMP

        } else if (ip4->proto == 6) { // TCP

        } else if (ip4->proto == 17) { // UDP

          if (size > (sizeof(*eth) + sizeof(struct ip) + sizeof(struct udp))) {

            static size_t k;

            uint16_t udp_ports[] = {67, 68}; // DHCP server and client

            struct udp *udp = (struct udp *) (ip4 + 1);

            // send all handled UDP ports, then 2 random ones

            if (k >= (sizeof(udp_ports) / sizeof(udp_ports[0]) + 2)) k = 0;

            if (k < (sizeof(udp_ports) / sizeof(udp_ports[0]))) udp->dport = mg_htons(udp_ports[k++]);

          }

        }

      } else if (eth->type == mg_htons(0x806)) {      // ARP

      } else if (eth->type == mg_htons(0x86dd) && size > (sizeof(*eth) + sizeof(struct ip6))) {     // IPv6

        static size_t j;

        uint8_t ip6_protos[] = {6, 17, 58}; // TCP, UDP, ICMPv6

        struct ip6 *ip6 = (struct ip6 *) (eth + 1);

        ip6->ver = (ip6->ver & ~0xf0) | (6 << 4);

        // send all handled IPv6 "next headers", then 2 random ones

        if (j >= (sizeof(ip6_protos) / sizeof(ip6_protos[0]) + 2)) j = 0;

        if (j < (sizeof(ip6_protos) / sizeof(ip6_protos[0]))) ip6->next = (ip6_protos[j++]);

        if (ip6->next == 6) { // TCP

        } else if (ip6->next == 17) { // UDP

        } else if (ip6->next == 58) { // ICMPv6

          if (size >= (sizeof(*eth) + sizeof(struct ip6) + sizeof(struct icmp6))) {

            static size_t k;

            uint8_t icmp6_types[] = {128, 134, 135, 136}; // Echo Request, RA, NS, NA

            struct icmp6 *icmp6 = (struct icmp6 *) (ip6 + 1);

            // send all handled ICMPv6 types, then 2 random ones

            if (k >= (sizeof(icmp6_types) / sizeof(icmp6_types[0]) + 2)) k = 0;

            if (k < (sizeof(icmp6_types) / sizeof(icmp6_types[0]))) icmp6->type = icmp6_types[k++];

          }

        }

      }

    }

#if defined(MAIN)

    printf("Sending to net_builtin:\n");

    mg_hexdump(pkt, size);

#endif

    mg_tcpip_rx(&mif, pkt, size);

    // Test HTTP serving (via our built-in TCP/IP stack)

    const char *url = "http://localhost:12345";

    struct mg_connection *c = mg_http_connect(&mgr, url, fn, NULL);

    mg_iobuf_add(&c->recv, 0, data, size);

    c->pfn(c, MG_EV_READ, NULL); // manually invoke protocol event handler

    free(pkt);

    mg_mgr_free(&mgr);

  }

  return 0;

}

#if defined(MAIN)

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

  int res = EXIT_FAILURE;

  if (argc > 1) {

    struct mg_str data = mg_file_read(&mg_fs_posix, argv[1]);

    if (data.buf != NULL) {

      LLVMFuzzerTestOneInput((uint8_t *) data.buf, data.len);

      res = EXIT_SUCCESS;

    }

    free(data.buf);

  }

  return res;

}

#endif