text: #define MBEDTLS_ALLOW_PRIVATE_ACCESS
  
  #include <string.h>
  #include <stdlib.h>
  #include <stdint.h>
  #include "common.h"
  #include "mbedtls/ssl.h"
  #include "test/certs.h"
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
  #include "mbedtls/entropy.h"
  #include "mbedtls/ctr_drbg.h"
  #include "mbedtls/timing.h"
  #include "mbedtls/ssl_cookie.h"
  
  
  #if defined(MBEDTLS_SSL_SRV_C) && \
      defined(MBEDTLS_ENTROPY_C) && \
      defined(MBEDTLS_CTR_DRBG_C) && \
      defined(MBEDTLS_TIMING_C)
  const char *pers = "fuzz_dtlsserver";
  const unsigned char client_ip[4] = {0x7F, 0, 0, 1};
  static int initialized = 0;
  #if defined(MBEDTLS_X509_CRT_PARSE_C) && defined(MBEDTLS_PEM_PARSE_C)
  static mbedtls_x509_crt srvcert;
  static mbedtls_pk_context pkey;
  #endif
  #endif
  #endif // MBEDTLS_SSL_PROTO_DTLS
  
  int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
  #if defined(MBEDTLS_SSL_PROTO_DTLS) && \
      defined(MBEDTLS_SSL_SRV_C) && \
      defined(MBEDTLS_ENTROPY_C) && \
      defined(MBEDTLS_CTR_DRBG_C) && \
      defined(MBEDTLS_TIMING_C)
      int ret;
      size_t len;
      mbedtls_ssl_context ssl;
      mbedtls_ssl_config conf;
      mbedtls_ctr_drbg_context ctr_drbg;
      mbedtls_entropy_context entropy;
      mbedtls_timing_delay_context timer;
      mbedtls_ssl_cookie_ctx cookie_ctx;
      unsigned char buf[4096];
      fuzzBufferOffset_t biomemfuzz;
  
      mbedtls_ctr_drbg_init( &ctr_drbg );
      mbedtls_entropy_init( &entropy );
  
      if( mbedtls_ctr_drbg_seed( &ctr_drbg, dummy_entropy, &entropy,
                                 ( const unsigned char * ) pers, strlen( pers ) ) != 0 )
          goto exit;
  
      if (initialized == 0) {
  #if defined(MBEDTLS_X509_CRT_PARSE_C) && defined(MBEDTLS_PEM_PARSE_C)
          mbedtls_x509_crt_init( &srvcert );
          mbedtls_pk_init( &pkey );
          if (mbedtls_x509_crt_parse( &srvcert, (const unsigned char *) mbedtls_test_srv_crt,
                                     mbedtls_test_srv_crt_len ) != 0)
              return 1;
          if (mbedtls_x509_crt_parse( &srvcert, (const unsigned char *) mbedtls_test_cas_pem,
                                     mbedtls_test_cas_pem_len ) != 0)
              return 1;
          if (mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_srv_key,
                                   mbedtls_test_srv_key_len, NULL, 0,
                                   dummy_random, &ctr_drbg ) != 0)
              return 1;
  #endif
          dummy_init();
  
          initialized = 1;
      }
      mbedtls_ssl_init( &ssl );
      mbedtls_ssl_config_init( &conf );
      mbedtls_ssl_cookie_init( &cookie_ctx );
  
      if( mbedtls_ssl_config_defaults( &conf,
                                      MBEDTLS_SSL_IS_SERVER,
                                      MBEDTLS_SSL_TRANSPORT_DATAGRAM,
                                      MBEDTLS_SSL_PRESET_DEFAULT ) != 0 )
          goto exit;
  
  
      srand(1);
      mbedtls_ssl_conf_rng( &conf, dummy_random, &ctr_drbg );
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C) && defined(MBEDTLS_PEM_PARSE_C)
      mbedtls_ssl_conf_ca_chain( &conf, srvcert.next, NULL );
      if( mbedtls_ssl_conf_own_cert( &conf, &srvcert, &pkey ) != 0 )
          goto exit;
  #endif
  
      if( mbedtls_ssl_cookie_setup( &cookie_ctx, dummy_random, &ctr_drbg ) != 0 )
          goto exit;
  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY)
      mbedtls_ssl_conf_dtls_cookies( &conf, mbedtls_ssl_cookie_write, mbedtls_ssl_cookie_check, &cookie_ctx );
  #endif /* defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) */
  
      if( mbedtls_ssl_setup( &ssl, &conf ) != 0 )
          goto exit;
  
      mbedtls_ssl_set_timer_cb( &ssl, &timer, mbedtls_timing_set_delay,
                               mbedtls_timing_get_delay );
  
      biomemfuzz.Data = Data;
      biomemfuzz.Size = Size;
      biomemfuzz.Offset = 0;
      mbedtls_ssl_set_bio( &ssl, &biomemfuzz, dummy_send, fuzz_recv, fuzz_recv_timeout );
      if( mbedtls_ssl_set_client_transport_id( &ssl, client_ip, sizeof(client_ip) ) != 0 )
          goto exit;
  
      ret = mbedtls_ssl_handshake( &ssl );
  
      if (ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED) {
          biomemfuzz.Offset = ssl.next_record_offset;
          mbedtls_ssl_session_reset( &ssl );
          mbedtls_ssl_set_bio( &ssl, &biomemfuzz, dummy_send, fuzz_recv, fuzz_recv_timeout );
          if( mbedtls_ssl_set_client_transport_id( &ssl, client_ip, sizeof(client_ip) ) != 0 )
              goto exit;
  
          ret = mbedtls_ssl_handshake( &ssl );
  
          if( ret == 0 )
          {
              //keep reading data from server until the end
              do
              {
                  len = sizeof( buf ) - 1;
                  ret = mbedtls_ssl_read( &ssl, buf, len );
                  if( ret == MBEDTLS_ERR_SSL_WANT_READ )
                      continue;
                  else if( ret <= 0 )
                      //EOF or error
                      break;
              }
              while( 1 );
          }
      }
  
  exit:
      mbedtls_ssl_cookie_free( &cookie_ctx );
      mbedtls_entropy_free( &entropy );
      mbedtls_ctr_drbg_free( &ctr_drbg );
      mbedtls_ssl_config_free( &conf );
      mbedtls_ssl_free( &ssl );
  
  #else
      (void) Data;
      (void) Size;
  #endif
      return 0;
  }
  