text: /* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  
  /* coap-client -- simple CoAP client
   *
   * Copyright (C) 2010--2019 Olaf Bergmann <bergmann@tzi.org> and others
   *
   * This file is part of the CoAP library libcoap. Please see README for terms of
   * use.
   */
  
  #include <string.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <ctype.h>
  #include <signal.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #ifdef _WIN32
  #define strcasecmp _stricmp
  #define strncasecmp _strnicmp
  #define fileno _fileno
  #include "getopt.c"
  #if !defined(S_ISDIR)
  #define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
  #endif
  static char* strndup(const char* s1, size_t n)
  {
    char* copy = (char*)malloc(n + 1);
    if (copy) {
      memcpy(copy, s1, n);
      copy[n] = 0;
    }
    return copy;
  };
  #else
  #include <unistd.h>
  #include <sys/select.h>
  #include <sys/socket.h>
  #include <netinet/in.h>
  #include <arpa/inet.h>
  #include <netdb.h>
  #endif
  
  #include <coap2/coap.h>
  
  #define MAX_USER 128 /* Maximum length of a user name (i.e., PSK
                        * identity) in bytes. */
  #define MAX_KEY   64 /* Maximum length of a key (i.e., PSK) in bytes. */
  
  int flags = 0;
  
  static unsigned char _token_data[8];
  coap_binary_t the_token = { 0, _token_data };
  
  #define FLAGS_BLOCK 0x01
  
  static coap_optlist_t *optlist = NULL;
  /* Request URI.
   * TODO: associate the resources with transaction id and make it expireable */
  static coap_uri_t uri;
  static coap_uri_t proxy = { {0, NULL}, 0, {0, NULL}, {0, NULL}, 0 };
  static int proxy_scheme_option = 0;
  static int uri_host_option = 0;
  static unsigned int ping_seconds = 0;
  
  /* reading is done when this flag is set */
  static int ready = 0;
  
  /* processing a block response when this flag is set */
  static int doing_getting_block = 0;
  static int single_block_requested = 0;
  static uint32_t block_mode = COAP_BLOCK_USE_LIBCOAP;
  
  static coap_string_t output_file = { 0, NULL };   /* output file name */
  static FILE *file = NULL;               /* output file stream */
  
  static coap_string_t payload = { 0, NULL };       /* optional payload to send */
  
  static int reliable = 0;
  
  static int add_nl = 0;
  
  unsigned char msgtype = COAP_MESSAGE_CON; /* usually, requests are sent confirmable */
  
  static char *cert_file = NULL; /* certificate and optional private key in PEM,
                                    or PKCS11 URI*/
  static char *key_file = NULL; /* private key in PEM, DER or PKCS11 URI */
  static char *pkcs11_pin = NULL; /* PKCS11 pin to unlock access to token */
  static char *ca_file = NULL;   /* CA for cert_file - for cert checking in PEM,
                                    DER or PKCS11 URI */
  static char *root_ca_file = NULL; /* List of trusted Root CAs in PEM */
  static int is_rpk_not_cert = 0; /* Cert is RPK if set */
  static uint8_t *cert_mem = NULL; /* certificate and private key in PEM_BUF */
  static uint8_t *key_mem = NULL; /* private key in PEM_BUF */
  static uint8_t *ca_mem = NULL;   /* CA for cert checking in PEM_BUF */
  static size_t cert_mem_len = 0;
  static size_t key_mem_len = 0;
  static size_t ca_mem_len = 0;
  static int verify_peer_cert = 1; /* PKI granularity - by default set */
  
  typedef struct ih_def_t {
    char* hint_match;
    coap_bin_const_t *new_identity;
    coap_bin_const_t *new_key;
  } ih_def_t;
  
  typedef struct valid_ihs_t {
    size_t count;
    ih_def_t *ih_list;
  } valid_ihs_t;
  
  static valid_ihs_t valid_ihs = {0, NULL};
  
  typedef unsigned char method_t;
  method_t method = 1;                    /* the method we are using in our requests */
  
  coap_block_t block = { .num = 0, .m = 0, .szx = 6 };
  uint16_t last_block1_mid = 0;
  
  
  unsigned int wait_seconds = 90;                /* default timeout in seconds */
  unsigned int wait_ms = 0;
  int wait_ms_reset = 0;
  int obs_started = 0;
  unsigned int obs_seconds = 30;          /* default observe time */
  unsigned int obs_ms = 0;                /* timeout for current subscription */
  int obs_ms_reset = 0;
  int doing_observe = 0;
  
  #ifndef min
  #define min(a,b) ((a) < (b) ? (a) : (b))
  #endif
  
  static int quit = 0;
  
  /* SIGINT handler: set quit to 1 for graceful termination */
  static void
  handle_sigint(int signum COAP_UNUSED) {
    quit = 1;
  }
  
  static int
  append_to_output(const uint8_t *data, size_t len) {
    size_t written;
  
    if (!file) {
      if (!output_file.s || (output_file.length && output_file.s[0] == '-'))
        file = stdout;
      else {
        if (!(file = fopen((char *)output_file.s, "w"))) {
          perror("fopen");
          return -1;
        }
      }
    }
  
    do {
      written = fwrite(data, 1, len, file);
      len -= written;
      data += written;
    } while ( written && len );
    fflush(file);
  
    return 0;
  }
  
  static void
  close_output(void) {
    if (file) {
  
      /* add a newline before closing if no option '-o' was specified */
      if (!output_file.s)
        fwrite("\n", 1, 1, file);
  
      fflush(file);
      fclose(file);
    }
  }
  
  static void
  free_xmit_data(coap_session_t *session COAP_UNUSED, void *app_ptr) {
    coap_free(app_ptr);
    return;
  }
  
  static coap_pdu_t *
  coap_new_request(coap_context_t *ctx,
                   coap_session_t *session,
                   method_t m,
                   coap_optlist_t **options,
                   unsigned char *data,
                   size_t length) {
    coap_pdu_t *pdu;
    (void)ctx;
  
    if (!(pdu = coap_new_pdu(msgtype, m, session)))
      return NULL;
  
    if ( !coap_add_token(pdu, the_token.length, the_token.s)) {
      coap_log(LOG_DEBUG, "cannot add token to request\n");
    }
  
    if (options)
      coap_add_optlist_pdu(pdu, options);
  
    if (length) {
      /* Let the underlying libcoap decide how this data should be sent */
      coap_add_data_large_request(session, pdu, length, data,
                                  free_xmit_data, data);
    }
  
    return pdu;
  }
  
  static int
  resolve_address(const coap_str_const_t *server, struct sockaddr *dst) {
  
    struct addrinfo *res, *ainfo;
    struct addrinfo hints;
    static char addrstr[256];
    int error, len=-1;
  
    memset(addrstr, 0, sizeof(addrstr));
    if (server->length)
      memcpy(addrstr, server->s, server->length);
    else
      memcpy(addrstr, "localhost", 9);
  
    memset ((char *)&hints, 0, sizeof(hints));
    hints.ai_socktype = SOCK_DGRAM;
    hints.ai_family = AF_UNSPEC;
  
    error = getaddrinfo(addrstr, NULL, &hints, &res);
  
    if (error != 0) {
      fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(error));
      return error;
    }
  
    for (ainfo = res; ainfo != NULL; ainfo = ainfo->ai_next) {
      switch (ainfo->ai_family) {
      case AF_INET6:
      case AF_INET:
        len = (int)ainfo->ai_addrlen;
        memcpy(dst, ainfo->ai_addr, len);
        goto finish;
      default:
        ;
      }
    }
  
   finish:
    freeaddrinfo(res);
    return len;
  }
  
  #define HANDLE_BLOCK1(Pdu)                                        \
    ((method == COAP_REQUEST_PUT || method == COAP_REQUEST_POST) && \
     ((flags & FLAGS_BLOCK) == 0) &&                                \
     ((Pdu)->hdr->code == COAP_RESPONSE_CODE_CREATED ||                \
      (Pdu)->hdr->code == COAP_RESPONSE_CODE_CHANGED))
  
  static inline int
  check_token(coap_pdu_t *received) {
    coap_bin_const_t token = coap_pdu_get_token(received);
  
    return token.length == the_token.length &&
      memcmp(token.s, the_token.s, the_token.length) == 0;
  }
  
  static int
  event_handler(coap_context_t *ctx COAP_UNUSED,
                coap_event_t event,
                coap_session_t *session COAP_UNUSED) {
  
    switch(event) {
    case COAP_EVENT_DTLS_CLOSED:
    case COAP_EVENT_TCP_CLOSED:
    case COAP_EVENT_SESSION_CLOSED:
      quit = 1;
      break;
    default:
      break;
    }
    return 0;
  }
  
  static void
  nack_handler(coap_context_t *context COAP_UNUSED,
               coap_session_t *session COAP_UNUSED,
               coap_pdu_t *sent COAP_UNUSED,
               coap_nack_reason_t reason,
               const coap_mid_t id COAP_UNUSED) {
  
    switch(reason) {
    case COAP_NACK_TOO_MANY_RETRIES:
    case COAP_NACK_NOT_DELIVERABLE:
    case COAP_NACK_RST:
    case COAP_NACK_TLS_FAILED:
      quit = 1;
      break;
    case COAP_NACK_ICMP_ISSUE:
    default:
      ;
    }
    return;
  }
  
  /*
   * Response handler used for coap_send_large() responses
   */
  static coap_response_t
  message_handler(coap_context_t *ctx COAP_UNUSED,
                  coap_session_t *session COAP_UNUSED,
                  coap_pdu_t *sent,
                  coap_pdu_t *received,
                  const coap_mid_t id COAP_UNUSED) {
  
    coap_opt_t *block_opt;
    coap_opt_iterator_t opt_iter;
    size_t len;
    const uint8_t *databuf;
    size_t offset;
    size_t total;
    coap_pdu_code_t rcv_code = coap_pdu_get_code(received);
    coap_pdu_type_t rcv_type = coap_pdu_get_type(received);
  
    coap_log(LOG_DEBUG, "** process incoming %d.%02d response:\n",
             COAP_RESPONSE_CLASS(rcv_code), rcv_code & 0x1F);
    if (coap_get_log_level() < LOG_DEBUG)
      coap_show_pdu(LOG_INFO, received);
  
    /* check if this is a response to our original request */
    if (!check_token(received)) {
      /* drop if this was just some message, or send RST in case of notification */
      if (!sent && (rcv_type == COAP_MESSAGE_CON ||
                    rcv_type == COAP_MESSAGE_NON)) {
        /* Cause a CoAP RST to be sent */
        return COAP_RESPONSE_FAIL;
      }
      return COAP_RESPONSE_OK;
    }
  
    if (rcv_type == COAP_MESSAGE_RST) {
      coap_log(LOG_INFO, "got RST\n");
      return COAP_RESPONSE_OK;
    }
  
    /* output the received data, if any */
    if (COAP_RESPONSE_CLASS(rcv_code) == 2) {
  
      /* set obs timer if we have successfully subscribed a resource */
      if (doing_observe && !obs_started &&
          coap_check_option(received, COAP_OPTION_OBSERVE, &opt_iter)) {
        coap_log(LOG_DEBUG,
                 "observation relationship established, set timeout to %d\n",
                 obs_seconds);
        obs_started = 1;
        obs_ms = obs_seconds * 1000;
        obs_ms_reset = 1;
      }
  
      if (coap_get_data_large(received, &len, &databuf, &offset, &total)) {
        append_to_output(databuf, len);
        if ((len + offset == total) && add_nl)
          append_to_output((const uint8_t*)"\n", 1);
      }
  
      /* Check if Block2 option is set */
      block_opt = coap_check_option(received, COAP_OPTION_BLOCK2, &opt_iter);
      if (!single_block_requested && block_opt) { /* handle Block2 */
  
        /* TODO: check if we are looking at the correct block number */
        if (coap_opt_block_num(block_opt) == 0) {
          /* See if observe is set in first response */
          ready = doing_observe ? coap_check_option(received,
                                    COAP_OPTION_OBSERVE, &opt_iter) == NULL : 1;
        }
        if(COAP_OPT_BLOCK_MORE(block_opt)) {
          wait_ms = wait_seconds * 1000;
          wait_ms_reset = 1;
          doing_getting_block = 1;
        }
        else {
          doing_getting_block = 0;
        }
        return COAP_RESPONSE_OK;
      }
    } else {      /* no 2.05 */
      /* check if an error was signaled and output payload if so */
      if (COAP_RESPONSE_CLASS(rcv_code) >= 4) {
        fprintf(stderr, "%d.%02d", COAP_RESPONSE_CLASS(rcv_code),
                rcv_code & 0x1F);
        if (coap_get_data_large(received, &len, &databuf, &offset, &total)) {
          fprintf(stderr, " ");
          while(len--) {
            fprintf(stderr, "%c", isprint(*databuf) ? *databuf : '.');
            databuf++;
          }
        }
        fprintf(stderr, "\n");
      }
  
    }
  
    /* our job is done, we can exit at any time */
    ready = doing_observe ? coap_check_option(received,
                                    COAP_OPTION_OBSERVE, &opt_iter) == NULL : 1;
    return COAP_RESPONSE_OK;
  }
  
  static void
  usage( const char *program, const char *version) {
    const char *p;
    char buffer[64];
    coap_tls_version_t *tls_version = coap_get_tls_library_version();
    const char *lib_version = coap_package_version();
  
    p = strrchr( program, '/' );
    if ( p )
      program = ++p;
  
    fprintf( stderr, "%s v%s -- a small CoAP implementation\n"
       "Copyright (C) 2010-2021 Olaf Bergmann <bergmann@tzi.org> and others\n\n"
       "%s\n"
       "%s\n"
      , program, version, lib_version,
      coap_string_tls_version(buffer, sizeof(buffer)));
    switch (tls_version->type) {
    case COAP_TLS_LIBRARY_NOTLS:
      break;
    case COAP_TLS_LIBRARY_TINYDTLS:
      fprintf(stderr, "(DTLS and no TLS support; PSK and RPK support)\n");
      break;
    case COAP_TLS_LIBRARY_OPENSSL:
      fprintf(stderr, "(DTLS and TLS support; PSK, PKI and no RPK support)\n");
      break;
    case COAP_TLS_LIBRARY_GNUTLS:
      if (tls_version->version >= 0x030606)
        fprintf(stderr, "(DTLS and TLS support; PSK, PKI and RPK support)\n");
      else
        fprintf(stderr, "(DTLS and TLS support; PSK, PKI and no RPK support)\n");
      break;
    case COAP_TLS_LIBRARY_MBEDTLS:
      fprintf(stderr, "(DTLS and no TLS support; PSK, PKI and no RPK support)\n");
      break;
    default:
      break;
    }
    fprintf(stderr, "\n"
       "Usage: %s [-a addr] [-b [num,]size] [-e text] [-f file] [-l loss]\n"
       "\t\t[-m method] [-o file] [-p port] [-r] [-s duration] [-t type]\n"
       "\t\t[-v num] [-w] [-A type] [-B seconds] [-H hoplimit] [-K interval]\n"
       "\t\t[-N] [-O num,text] [-P scheme://address[:port]] [-T token] [-U]\n"
       "\t\t[[-h match_hint_file] [-k key] [-u user]]\n"
       "\t\t[[-c certfile] [-j keyfile] [-n] [-C cafile]\n"
       "\t\t[-J pkcs11_pin] [-M raw_pk] [-R trust_casfile]\n"
       "\t\t[-S match_pki_sni_file]] URI\n"
       "\tURI can be an absolute URI or a URI prefixed with scheme and host\n\n"
       "General Options\n"
       "\t-a addr\t\tThe local interface address to use\n"
       "\t-b [num,]size\tBlock size to be used in GET/PUT/POST requests\n"
       "\t       \t\t(value must be a multiple of 16 not larger than 1024)\n"
       "\t       \t\tIf num is present, the request chain will start at\n"
       "\t       \t\tblock num\n"
       "\t-e text\t\tInclude text as payload (use percent-encoding for\n"
       "\t       \t\tnon-ASCII characters)\n"
       "\t-f file\t\tFile to send with PUT/POST (use '-' for STDIN)\n"
       "\t-l list\t\tFail to send some datagrams specified by a comma\n"
       "\t       \t\tseparated list of numbers or number ranges\n"
       "\t       \t\t(for debugging only)\n"
       "\t-l loss%%\tRandomly fail to send datagrams with the specified\n"
       "\t       \t\tprobability - 100%% all datagrams, 0%% no datagrams\n"
       "\t-m method\tRequest method (get|put|post|delete|fetch|patch|ipatch),\n"
       "\t       \t\tdefault is 'get'\n"
       "\t-o file\t\tOutput received data to this file (use '-' for STDOUT)\n"
       "\t-p port\t\tListen on specified port\n"
       "\t-r     \t\tUse reliable protocol (TCP or TLS); requires TCP support\n"
       "\t-s duration\tSubscribe to / Observe resource for given duration\n"
       "\t       \t\tin seconds\n"
       "\t-t type\t\tContent format for given resource for PUT/POST\n"
       "\t-v num \t\tVerbosity level (default 3, maximum is 9). Above 7,\n"
       "\t       \t\tthere is increased verbosity in GnuTLS logging\n"
       "\t-w     \t\tAppend a newline to received data\n"
       "\t-A type\t\tAccepted media type\n"
       "\t-B seconds\tBreak operation after waiting given seconds\n"
       "\t       \t\t(default is %d)\n"
       "\t-H hoplimit\tSet the Hop Limit count to hoplimit for proxies. Must\n"
       "\t       \t\thave a value between 1 and 255 inclusive.\n"
       "\t       \t\tDefault is '16'\n"
       "\t-K interval\tSend a ping after interval seconds of inactivity\n"
       "\t-L value\tSum of one or more COAP_BLOCK_* flag valuess for block\n"
       "\t       \t\thandling methods. Default is 1 (COAP_BLOCK_USE_LIBCOAP)\n"
       "\t       \t\t(Sum of one or more of 1,2,4 and 8)\n"
       "\t-N     \t\tSend NON-confirmable message\n"
       "\t-O num,text\tAdd option num with contents text to request. If the\n"
       "\t       \t\ttext begins with 0x, then the hex text (two [0-9a-f] per\n"
       "\t       \t\tbyte) is converted to binary data\n"
       "\t-P scheme://address[:port]\tScheme, address and optional port to\n"
       "\t       \t\tdefine how to connect to a CoAP proxy (automatically adds\n"
       "\t       \t\tProxy-Uri option to request) to forward the request to.\n"
       "\t       \t\tScheme is one of coap, coaps, coap+tcp and coaps+tcp\n"
       "\t-T token\tDefine the initial starting token\n"
       "\t-U     \t\tNever include Uri-Host or Uri-Port options\n"
       ,program, wait_seconds);
    fprintf( stderr,
       "PSK Options (if supported by underlying (D)TLS library)\n"
       "\t-h match_hint_file\n"
       "\t       \t\tThis is a file that contains one or more lines of\n"
       "\t       \t\treceived Identity Hints to match to use different\n"
       "\t       \t\tuser identity and associated pre-shared key (PSK) (comma\n"
       "\t       \t\tseparated) instead of the '-k key' and '-u user'\n"
       "\t       \t\toptions. E.g., per line\n"
       "\t       \t\t hint_to_match,use_user,with_key\n"
       "\t       \t\tNote: -k and -u still need to be defined for the default\n"
       "\t       \t\tin case there is no match\n"
       "\t-k key \t\tPre-shared key for the specified user identity\n"
       "\t-u user\t\tUser identity to send for pre-shared key mode\n"
       "PKI Options (if supported by underlying (D)TLS library)\n"
       "\tNote: If any one of '-c certfile', '-j keyfile' or '-C cafile' is in\n"
       "\tPKCS11 URI naming format (pkcs11: prefix), then any remaining non\n"
       "\tPKCS11 URI file definitions have to be in DER, not PEM, format.\n"
       "\tOtherwise all of '-c certfile', '-j keyfile' or '-C cafile' are in\n"
       "\tPEM format.\n\n"
       "\t-c certfile\tPEM file or PKCS11 URI for the certificate. The private\n"
       "\t       \t\tkey can also be in the PEM file, or has the same PKCS11\n"
       "\t       \t\tURI. If not, the private key is defined by '-j keyfile'\n"
       "\t-j keyfile\tPEM file or PKCS11 URI for the private key for the\n"
       "\t       \t\tcertificate in '-c certfile' if the parameter is\n"
       "\t       \t\tdifferent from certfile in '-c certfile'\n"
       "\t-n     \t\tDisable remote peer certificate checking\n"
       "\t-C cafile\tPEM file or PKCS11 URI for the CA certificate that was\n"
       "\t       \t\tused to sign the server certfile. Ideally the client\n"
       "\t       \t\tcertificate should be signed by the same CA so that\n"
       "\t       \t\tmutual authentication can take place. The contents of\n"
       "\t       \t\tcafile are added to the trusted store of root CAs.\n"
       "\t       \t\tUsing the -C or -R options will trigger the\n"
       "\t       \t\tvalidation of the server certificate unless overridden\n"
       "\t       \t\tby the -n option\n"
       "\t-J pkcs11_pin\tThe user pin to unlock access to the PKCS11 token\n"
       "\t-M rpk_file\tRaw Public Key (RPK) PEM file or PKCS11 URI that\n"
       "\t       \t\tcontains both PUBLIC KEY and PRIVATE KEY or just\n"
       "\t       \t\tEC PRIVATE KEY. (GnuTLS and TinyDTLS(PEM) support only).\n"
       "\t       \t\t'-C cafile' or '-R trust_casfile' are not required\n"
       "\t-R trust_casfile\tPEM file containing the set of trusted root CAs\n"
       "\t       \t\tthat are to be used to validate the server certificate.\n"
       "\t       \t\tAlternatively, this can point to a directory containing\n"
       "\t       \t\ta set of CA PEM files.\n"
       "\t       \t\tUsing '-R trust_casfile' disables common CA mutual\n"
       "\t       \t\tauthentication which can only be done by using\n"
       "\t       \t\t'-C cafile'.\n"
       "\t       \t\tUsing the -C or -R options will will trigger the\n"
       "\t       \t\tvalidation of the server certificate unless overridden\n"
       "\t       \t\tby the -n option\n"
       );
    fprintf( stderr,
       "Examples:\n"
       "\tcoap-client -m get coap://[::1]/\n"
       "\tcoap-client -m get coap://[::1]/.well-known/core\n"
       "\tcoap-client -m get coap+tcp://[::1]/.well-known/core\n"
       "\tcoap-client -m get coaps://[::1]/.well-known/core\n"
       "\tcoap-client -m get coaps+tcp://[::1]/.well-known/core\n"
       "\tcoap-client -m get -T cafe coap://[::1]/time\n"
       "\techo -n 1000 | coap-client -m put -T cafe coap://[::1]/time -f -\n"
       );
  }
  
  typedef struct {
    unsigned char code;
    const char *media_type;
  } content_type_t;
  
  static void
  cmdline_content_type(char *arg, uint16_t key) {
    static content_type_t content_types[] = {
      {  0, "plain" },
      {  0, "text/plain" },
      { 40, "link" },
      { 40, "link-format" },
      { 40, "application/link-format" },
      { 41, "xml" },
      { 41, "application/xml" },
      { 42, "binary" },
      { 42, "octet-stream" },
      { 42, "application/octet-stream" },
      { 47, "exi" },
      { 47, "application/exi" },
      { 50, "json" },
      { 50, "application/json" },
      { 60, "cbor" },
      { 60, "application/cbor" },
      { 255, NULL }
    };
    coap_optlist_t *node;
    unsigned char i;
    uint16_t value;
    uint8_t buf[2];
  
    if (isdigit((int)arg[0])) {
      value = atoi(arg);
    } else {
      for (i=0;
           content_types[i].media_type &&
             strncmp(arg, content_types[i].media_type, strlen(arg)) != 0 ;
           ++i)
        ;
  
      if (content_types[i].media_type) {
        value = content_types[i].code;
      } else {
        coap_log(LOG_WARNING, "W: unknown content-format '%s'\n",arg);
        return;
      }
    }
  
    node = coap_new_optlist(key, coap_encode_var_safe(buf, sizeof(buf), value), buf);
    if (node) {
      coap_insert_optlist(&optlist, node);
    }
  }
  
  static int
  cmdline_hop_limit(char *arg) {
    coap_optlist_t *node;
    uint32_t value;
    uint8_t buf[4];
  
    value = strtol(arg, NULL, 10);
    if (value < 1 || value > 255) {
      return 0;
    }
    node = coap_new_optlist(COAP_OPTION_HOP_LIMIT, coap_encode_var_safe(buf, sizeof(buf), value), buf);
    if (node) {
      coap_insert_optlist(&optlist, node);
    }
    return 1;
  }
  
  
  static uint16_t
  get_default_port(const coap_uri_t *u) {
    return coap_uri_scheme_is_secure(u) ? COAPS_DEFAULT_PORT : COAP_DEFAULT_PORT;
  }
  
  /**
   * Sets global URI options according to the URI passed as @p arg.
   * This function returns 0 on success or -1 on error.
   *
   * @param arg             The URI string.
   * @param create_uri_opts Flags that indicate whether Uri-Host and
   *                        Uri-Port should be suppressed.
   * @return 0 on success, -1 otherwise
   */
  static int
  cmdline_uri(char *arg, int create_uri_opts) {
    unsigned char portbuf[2];
  #define BUFSIZE 100
    unsigned char _buf[BUFSIZE];
    unsigned char *buf = _buf;
    size_t buflen;
    int res;
  
    if (!proxy_scheme_option && proxy.host.length) {
      /* create Proxy-Uri from argument */
      size_t len = strlen(arg);
      if (len > 1034) {
        coap_log(LOG_ERR, "Absolute URI length must be <= 1034 bytes for a proxy\n");
        return -1;
      }
  
      coap_insert_optlist(&optlist,
                  coap_new_optlist(COAP_OPTION_PROXY_URI,
                  len,
                  (unsigned char *)arg));
  
    } else {      /* split arg into Uri-* options */
      if (coap_split_uri((unsigned char *)arg, strlen(arg), &uri) < 0) {
        coap_log(LOG_ERR, "invalid CoAP URI\n");
        return -1;
      }
  
      if (uri.scheme==COAP_URI_SCHEME_COAPS && !reliable && !coap_dtls_is_supported()) {
        coap_log(LOG_EMERG,
                 "coaps URI scheme not supported in this version of libcoap\n");
        return -1;
      }
  
      if ((uri.scheme==COAP_URI_SCHEME_COAPS_TCP || (uri.scheme==COAP_URI_SCHEME_COAPS && reliable)) && !coap_tls_is_supported()) {
        coap_log(LOG_EMERG,
              "coaps+tcp URI scheme not supported in this version of libcoap\n");
        return -1;
      }
  
      if (uri.scheme==COAP_URI_SCHEME_COAP_TCP && !coap_tcp_is_supported()) {
        /* coaps+tcp caught above */
        coap_log(LOG_EMERG,
              "coap+tcp URI scheme not supported in this version of libcoap\n");
        return -1;
      }
  
      if (uri.port != get_default_port(&uri) && create_uri_opts) {
        coap_insert_optlist(&optlist,
                    coap_new_optlist(COAP_OPTION_URI_PORT,
                                     coap_encode_var_safe(portbuf, sizeof(portbuf),
                                                          (uri.port & 0xffff)),
                    portbuf));
      }
  
      if (uri.path.length) {
        buflen = BUFSIZE;
        if (uri.path.length > BUFSIZE)
          coap_log(LOG_WARNING, "URI path will be truncated (max buffer %d)\n", BUFSIZE);
        res = coap_split_path(uri.path.s, uri.path.length, buf, &buflen);
  
        while (res--) {
          coap_insert_optlist(&optlist,
                      coap_new_optlist(COAP_OPTION_URI_PATH,
                      coap_opt_length(buf),
                      coap_opt_value(buf)));
  
          buf += coap_opt_size(buf);
        }
      }
  
      if (uri.query.length) {
        buflen = BUFSIZE;
        buf = _buf;
        res = coap_split_query(uri.query.s, uri.query.length, buf, &buflen);
  
        while (res--) {
          coap_insert_optlist(&optlist,
                      coap_new_optlist(COAP_OPTION_URI_QUERY,
                      coap_opt_length(buf),
                      coap_opt_value(buf)));
  
          buf += coap_opt_size(buf);
        }
      }
    }
  
    return 0;
  }
  
  static int
  cmdline_blocksize(char *arg) {
    uint16_t size;
  
    again:
    size = 0;
    while(*arg && *arg != ',')
      size = size * 10 + (*arg++ - '0');
  
    if (*arg == ',') {
      arg++;
      block.num = size;
      if (size != 0) {
        /* Random access selection - only handle single response */
        single_block_requested = 1;
      }
      goto again;
    }
  
    if (size)
      block.szx = (coap_fls(size >> 4) - 1) & 0x07;
  
    flags |= FLAGS_BLOCK;
    return 1;
  }
  
  /* Called after processing the options from the commandline to set
   * Block1 or Block2 depending on method. */
  static void
  set_blocksize(void) {
    static unsigned char buf[4];        /* hack: temporarily take encoded bytes */
    uint16_t opt;
    unsigned int opt_length;
  
    if (method != COAP_REQUEST_DELETE) {
      if (method == COAP_REQUEST_GET || method == COAP_REQUEST_FETCH) {
        opt = COAP_OPTION_BLOCK2;
      }
      else {
        opt = COAP_OPTION_BLOCK1;
      }
  
      block.m = (opt == COAP_OPTION_BLOCK1) &&
        ((1ull << (block.szx + 4)) < payload.length);
  
      opt_length = coap_encode_var_safe(buf, sizeof(buf),
            (block.num << 4 | block.m << 3 | block.szx));
  
      coap_insert_optlist(&optlist, coap_new_optlist(opt, opt_length, buf));
    }
  }
  
  static void
  cmdline_subscribe(char *arg) {
    uint8_t buf[4];
  
    obs_seconds = atoi(arg);
    coap_insert_optlist(&optlist,
                        coap_new_optlist(COAP_OPTION_OBSERVE,
                          coap_encode_var_safe(buf, sizeof(buf),
                          COAP_OBSERVE_ESTABLISH), buf)
                        );
    doing_observe = 1;
  }
  
  static int
  cmdline_proxy(char *arg) {
    if (coap_split_uri((unsigned char *)arg, strlen(arg), &proxy) < 0 ||
        proxy.path.length != 0 || proxy.query.length != 0) {
      coap_log(LOG_ERR, "invalid CoAP Proxy definition\n");
      return 0;
    }
    return 1;
  }
  
  static inline void
  cmdline_token(char *arg) {
    the_token.length = min(sizeof(_token_data), strlen(arg));
    if (the_token.length > 0) {
      memcpy((char *)the_token.s, arg, the_token.length);
    }
  }
  
  /**
   * Utility function to convert a hex digit to its corresponding
   * numerical value.
   *
   * param c  The hex digit to convert. Must be in [0-9A-Fa-f].
   *
   * return The numerical representation of @p c.
   */
  static uint8_t
  hex2char(char c) {
    assert(isxdigit(c));
    if ('a' <= c && c <= 'f')
      return c - 'a' + 10;
    else if ('A' <= c && c <= 'F')
      return c - 'A' + 10;
    else
      return c - '0';
  }
  
  /**
   * Converts the sequence of hex digits in src to a sequence of bytes.
   *
   * This function returns the number of bytes that have been written to
   * @p dst.
   *
   * param[in]  src  The null-terminated hex string to convert.
   * param[out] dst  Conversion result.
   *
   * return The length of @p dst.
   */
  static size_t
  convert_hex_string(const char *src, uint8_t *dst) {
    uint8_t *p = dst;
    while (isxdigit((int)src[0]) && isxdigit((int)src[1])) {
      *p++ = (hex2char(src[0]) << 4) + hex2char(src[1]);
      src += 2;
    }
    if (src[0] != '\0') { /* error in hex input */
      coap_log(LOG_WARNING, "invalid hex string in option '%s'\n", src);
    }
    return p - dst;
  }
  
  static void
  cmdline_option(char *arg) {
    unsigned int num = 0;
  
    while (*arg && *arg != ',') {
      num = num * 10 + (*arg - '0');
      ++arg;
    }
    if (*arg == ',')
      ++arg;
  
     /* read hex string when arg starts with "0x" */
    if (arg[0] == '0' && arg[1] == 'x') {
      /* As the command line option is part of our environment we can do
       * the conversion in place. */
      size_t len = convert_hex_string(arg + 2, (uint8_t *)arg);
  
      /* On success, 2 * len + 2 == strlen(arg) */
      coap_insert_optlist(&optlist,
                          coap_new_optlist(num, len, (unsigned char *)arg));
    } else { /* null-terminated character string */
      coap_insert_optlist(&optlist,
                          coap_new_optlist(num, strlen(arg), (unsigned char *)arg));
    }
    if (num == COAP_OPTION_PROXY_SCHEME) {
      proxy_scheme_option = 1;
      if (strcasecmp(arg, "coaps+tcp") == 0) {
        proxy.scheme = COAP_URI_SCHEME_COAPS_TCP;
        proxy.port = COAPS_DEFAULT_PORT;
      }
      else if (strcasecmp(arg, "coap+tcp") == 0) {
        proxy.scheme = COAP_URI_SCHEME_COAP_TCP;
        proxy.port = COAP_DEFAULT_PORT;
      }
      else if (strcasecmp(arg, "coaps") == 0) {
        proxy.scheme = COAP_URI_SCHEME_COAPS;
        proxy.port = COAPS_DEFAULT_PORT;
      }
      else if (strcasecmp(arg, "coap") == 0) {
        proxy.scheme = COAP_URI_SCHEME_COAP;
        proxy.port = COAP_DEFAULT_PORT;
      }
      else {
        coap_log(LOG_WARNING, "%s is not a supported CoAP Proxy-Scheme\n", arg);
      }
    }
    if (num == COAP_OPTION_URI_HOST) {
      uri_host_option = 1;
    }
  }
  
  /**
   * Calculates decimal value from hexadecimal ASCII character given in
   * @p c. The caller must ensure that @p c actually represents a valid
   * heaxdecimal character, e.g. with isxdigit(3).
   *
   * @hideinitializer
   */
  #define hexchar_to_dec(c) ((c) & 0x40 ? ((c) & 0x0F) + 9 : ((c) & 0x0F))
  
  /**
   * Decodes percent-encoded characters while copying the string @p seg
   * of size @p length to @p buf. The caller of this function must
   * ensure that the percent-encodings are correct (i.e. the character
   * '%' is always followed by two hex digits. and that @p buf provides
   * sufficient space to hold the result. This function is supposed to
   * be called by make_decoded_option() only.
   *
   * @param seg     The segment to decode and copy.
   * @param length  Length of @p seg.
   * @param buf     The result buffer.
   */
  static void
  decode_segment(const uint8_t *seg, size_t length, unsigned char *buf) {
  
    while (length--) {
  
      if (*seg == '%') {
        *buf = (hexchar_to_dec(seg[1]) << 4) + hexchar_to_dec(seg[2]);
  
        seg += 2; length -= 2;
      } else {
        *buf = *seg;
      }
  
      ++buf; ++seg;
    }
  }
  
  /**
   * Runs through the given path (or query) segment and checks if
   * percent-encodings are correct. This function returns @c -1 on error
   * or the length of @p s when decoded.
   */
  static int
  check_segment(const uint8_t *s, size_t length) {
  
    int n = 0;
  
    while (length) {
      if (*s == '%') {
        if (length < 2 || !(isxdigit(s[1]) && isxdigit(s[2])))
          return -1;
  
        s += 2;
        length -= 2;
      }
  
      ++s; ++n; --length;
    }
  
    return n;
  }
  
  static int
  cmdline_input(char *text, coap_string_t *buf) {
    int len;
    len = check_segment((unsigned char *)text, strlen(text));
  
    if (len < 0)
      return 0;
  
    buf->s = (unsigned char *)coap_malloc(len);
    if (!buf->s)
      return 0;
  
    buf->length = len;
    decode_segment((unsigned char *)text, strlen(text), buf->s);
    return 1;
  }
  
  static int
  cmdline_input_from_file(char *filename, coap_string_t *buf) {
    FILE *inputfile = NULL;
    ssize_t len;
    int result = 1;
    struct stat statbuf;
  
    if (!filename || !buf)
      return 0;
  
    if (filename[0] == '-' && !filename[1]) { /* read from stdin */
      buf->length = 20000;
      buf->s = (unsigned char *)coap_malloc(buf->length);
      if (!buf->s)
        return 0;
  
      inputfile = stdin;
    } else {
      /* read from specified input file */
      inputfile = fopen(filename, "r");
      if ( !inputfile ) {
        perror("cmdline_input_from_file: fopen");
        return 0;
      }
  
      if (fstat(fileno(inputfile), &statbuf) < 0) {
        perror("cmdline_input_from_file: stat");
        fclose(inputfile);
        return 0;
      }
  
      buf->length = statbuf.st_size;
      buf->s = (unsigned char *)coap_malloc(buf->length);
      if (!buf->s) {
        fclose(inputfile);
        return 0;
      }
    }
  
    len = fread(buf->s, 1, buf->length, inputfile);
  
    if (len < 0 || ((size_t)len < buf->length)) {
      if (ferror(inputfile) != 0) {
        perror("cmdline_input_from_file: fread");
        coap_free(buf->s);
        buf->length = 0;
        buf->s = NULL;
        result = 0;
      } else {
        buf->length = len;
      }
    }
  
    if (inputfile != stdin)
      fclose(inputfile);
  
    return result;
  }
  
  static method_t
  cmdline_method(char *arg) {
    static const char *methods[] =
      { 0, "get", "post", "put", "delete", "fetch", "patch", "ipatch", 0};
    unsigned char i;
  
    for (i=1; methods[i] && strcasecmp(arg,methods[i]) != 0 ; ++i)
      ;
  
    return i;     /* note that we do not prevent illegal methods */
  }
  
  static ssize_t
  cmdline_read_user(char *arg, unsigned char **buf, size_t maxlen) {
    size_t len = strnlen(arg, maxlen);
    if (len) {
      *buf = (unsigned char *)arg;
      /* len is the size or less, so 0 terminate to maxlen */
      (*buf)[len] = '\000';
    }
    /* 0 length Identity is valid */
    return len;
  }
  
  static ssize_t
  cmdline_read_key(char *arg, unsigned char **buf, size_t maxlen) {
    size_t len = strnlen(arg, maxlen);
    if (len) {
      *buf = (unsigned char *)arg;
      return len;
    }
    /* Need at least one byte for the pre-shared key */
    coap_log( LOG_CRIT, "Invalid Pre-Shared Key specified\n" );
    return -1;
  }
  
  static int cmdline_read_hint_check(const char *arg) {
    FILE *fp = fopen(arg, "r");
    static char tmpbuf[256];
    if (fp == NULL) {
      coap_log(LOG_ERR, "Hint file: %s: Unable to open\n", arg);
      return 0;
    }
    while (fgets(tmpbuf, sizeof(tmpbuf), fp) != NULL) {
      char *cp = tmpbuf;
      char *tcp = strchr(cp, '\n');
  
      if (tmpbuf[0] == '#')
        continue;
      if (tcp)
        *tcp = '\000';
  
      tcp = strchr(cp, ',');
      if (tcp) {
        ih_def_t *new_ih_list;
        new_ih_list = realloc(valid_ihs.ih_list,
                            (valid_ihs.count + 1)*sizeof (valid_ihs.ih_list[0]));
        if (new_ih_list == NULL) {
          break;
        }
        valid_ihs.ih_list = new_ih_list;
        valid_ihs.ih_list[valid_ihs.count].hint_match = strndup(cp, tcp-cp);
        cp = tcp+1;
        tcp = strchr(cp, ',');
        if (tcp) {
          valid_ihs.ih_list[valid_ihs.count].new_identity =
                                 coap_new_bin_const((const uint8_t *)cp, tcp-cp);
          cp = tcp+1;
          valid_ihs.ih_list[valid_ihs.count].new_key =
                             coap_new_bin_const((const uint8_t *)cp, strlen(cp));
          valid_ihs.count++;
        }
        else {
          /* Badly formatted */
          free(valid_ihs.ih_list[valid_ihs.count].hint_match);
        }
      }
    }
    fclose(fp);
    return valid_ihs.count > 0;
  }
  
  static uint8_t *read_file_mem(const char* filename, size_t *length) {
    FILE *f;
    uint8_t *buf;
    struct stat statbuf;
  
    *length = 0;
    if (!filename || !(f = fopen(filename, "r")))
      return NULL;
  
    if (fstat(fileno(f), &statbuf) == -1) {
      fclose(f);
      return NULL;
    }
  
    buf = coap_malloc(statbuf.st_size+1);
    if (!buf) {
      fclose(f);
      return NULL;
    }
  
    if (fread(buf, 1, statbuf.st_size, f) != (size_t)statbuf.st_size) {
      fclose(f);
      coap_free(buf);
      return NULL;
    }
    buf[statbuf.st_size] = '\000';
    *length = (size_t)(statbuf.st_size + 1);
    fclose(f);
    return buf;
  }
  
  static int
  verify_cn_callback(const char *cn,
                     const uint8_t *asn1_public_cert COAP_UNUSED,
                     size_t asn1_length COAP_UNUSED,
                     coap_session_t *session COAP_UNUSED,
                     unsigned depth,
                     int validated COAP_UNUSED,
                     void *arg COAP_UNUSED
  ) {
    coap_log(LOG_INFO, "CN '%s' presented by server (%s)\n",
             cn, depth ? "CA" : "Certificate");
    return 1;
  }
  
  static const coap_dtls_cpsk_info_t *
  verify_ih_callback(coap_str_const_t *hint,
                     coap_session_t *c_session COAP_UNUSED,
                     void *arg
  ) {
    coap_dtls_cpsk_info_t *psk_info = (coap_dtls_cpsk_info_t *)arg;
    char lhint[COAP_DTLS_HINT_LENGTH];
    static coap_dtls_cpsk_info_t psk_identity_info;
    size_t i;
  
    snprintf(lhint, sizeof(lhint), "%.*s", (int)hint->length, hint->s);
    coap_log(LOG_INFO, "Identity Hint '%s' provided\n", lhint);
  
    /* Test for hint to possibly change identity + key */
    for (i = 0; i < valid_ihs.count; i++) {
      if (strcmp(lhint, valid_ihs.ih_list[i].hint_match) == 0) {
        /* Preset */
        psk_identity_info = *psk_info;
        if (valid_ihs.ih_list[i].new_key) {
          psk_identity_info.key = *valid_ihs.ih_list[i].new_key;
        }
        if (valid_ihs.ih_list[i].new_identity) {
          psk_identity_info.identity = *valid_ihs.ih_list[i].new_identity;
        }
        coap_log(LOG_INFO, "Switching to using '%s' identity + '%s' key\n",
                 psk_identity_info.identity.s, psk_identity_info.key.s);
        return &psk_identity_info;
      }
    }
    /* Just use the defined key for now as passed in by arg */
    return psk_info;
  }
  
  static coap_dtls_pki_t *
  setup_pki(coap_context_t *ctx) {
    static coap_dtls_pki_t dtls_pki;
    static char client_sni[256];
  
    /* If general root CAs are defined */
    if (root_ca_file) {
      struct stat stbuf;
      if ((stat(root_ca_file, &stbuf) == 0) && S_ISDIR(stbuf.st_mode)) {
        coap_context_set_pki_root_cas(ctx, NULL, root_ca_file);
      } else {
        coap_context_set_pki_root_cas(ctx, root_ca_file, NULL);
      }
    }
  
    memset(client_sni, 0, sizeof(client_sni));
    memset (&dtls_pki, 0, sizeof(dtls_pki));
    dtls_pki.version = COAP_DTLS_PKI_SETUP_VERSION;
    if (ca_file || root_ca_file) {
      /*
       * Add in additional certificate checking.
       * This list of enabled can be tuned for the specific
       * requirements - see 'man coap_encryption'.
       *
       * Note: root_ca_file is setup separately using
       * coap_context_set_pki_root_cas(), but this is used to define what
       * checking actually takes place.
       */
      dtls_pki.verify_peer_cert        = verify_peer_cert;
      dtls_pki.check_common_ca         = !root_ca_file;
      dtls_pki.allow_self_signed       = 1;
      dtls_pki.allow_expired_certs     = 1;
      dtls_pki.cert_chain_validation   = 1;
      dtls_pki.cert_chain_verify_depth = 2;
      dtls_pki.check_cert_revocation   = 1;
      dtls_pki.allow_no_crl            = 1;
      dtls_pki.allow_expired_crl       = 1;
      dtls_pki.validate_cn_call_back   = verify_cn_callback;
      dtls_pki.cn_call_back_arg        = NULL;
      dtls_pki.validate_sni_call_back  = NULL;
      dtls_pki.sni_call_back_arg       = NULL;
    }
    if ((uri.host.length == 3 && memcmp(uri.host.s, "::1", 3) != 0) ||
        (uri.host.length == 9 && memcmp(uri.host.s, "127.0.0.1", 9) != 0))
      memcpy(client_sni, uri.host.s, min(uri.host.length, sizeof(client_sni)-1));
    else
      memcpy(client_sni, "localhost", 9);
  
    dtls_pki.is_rpk_not_cert = is_rpk_not_cert;
    dtls_pki.client_sni = client_sni;
    if ((key_file && strncasecmp (key_file, "pkcs11:", 7) == 0) ||
        (cert_file && strncasecmp (cert_file, "pkcs11:", 7) == 0) ||
        (ca_file && strncasecmp (ca_file, "pkcs11:", 7) == 0)) {
      dtls_pki.pki_key.key_type = COAP_PKI_KEY_PKCS11;
      dtls_pki.pki_key.key.pkcs11.public_cert = cert_file;
      dtls_pki.pki_key.key.pkcs11.private_key = key_file ?
                                                       key_file : cert_file;
      dtls_pki.pki_key.key.pkcs11.ca = ca_file;
      dtls_pki.pki_key.key.pkcs11.user_pin = pkcs11_pin;
    }
    else if (!is_rpk_not_cert) {
      dtls_pki.pki_key.key_type = COAP_PKI_KEY_PEM;
      dtls_pki.pki_key.key.pem.public_cert = cert_file;
      dtls_pki.pki_key.key.pem.private_key = key_file ? key_file : cert_file;
      dtls_pki.pki_key.key.pem.ca_file = ca_file;
    }
    else {
      /* Map file into memory */
      if (ca_mem == 0 && cert_mem == 0 && key_mem == 0) {
        ca_mem = read_file_mem(ca_file, &ca_mem_len);
        cert_mem = read_file_mem(cert_file, &cert_mem_len);
        key_mem = read_file_mem(key_file, &key_mem_len);
      }
      dtls_pki.pki_key.key_type = COAP_PKI_KEY_PEM_BUF;
      dtls_pki.pki_key.key.pem_buf.ca_cert = ca_mem;
      dtls_pki.pki_key.key.pem_buf.public_cert = cert_mem;
      dtls_pki.pki_key.key.pem_buf.private_key = key_mem ? key_mem : cert_mem;
      dtls_pki.pki_key.key.pem_buf.ca_cert_len = ca_mem_len;
      dtls_pki.pki_key.key.pem_buf.public_cert_len = cert_mem_len;
      dtls_pki.pki_key.key.pem_buf.private_key_len = key_mem ?
                                                      key_mem_len : cert_mem_len;
    }
    return &dtls_pki;
  }
  
  static coap_dtls_cpsk_t *
  setup_psk(
    const uint8_t *identity,
    size_t identity_len,
    const uint8_t *key,
    size_t key_len
  ) {
    static coap_dtls_cpsk_t dtls_psk;
    static char client_sni[256];
  
    memset(client_sni, 0, sizeof(client_sni));
    memset (&dtls_psk, 0, sizeof(dtls_psk));
    dtls_psk.version = COAP_DTLS_CPSK_SETUP_VERSION;
    dtls_psk.validate_ih_call_back = verify_ih_callback;
    dtls_psk.ih_call_back_arg = &dtls_psk.psk_info;
    if (uri.host.length)
      memcpy(client_sni, uri.host.s,
             min(uri.host.length, sizeof(client_sni) - 1));
    else
      memcpy(client_sni, "localhost", 9);
    dtls_psk.client_sni = client_sni;
    dtls_psk.psk_info.identity.s = identity;
    dtls_psk.psk_info.identity.length = identity_len;
    dtls_psk.psk_info.key.s = key;
    dtls_psk.psk_info.key.length = key_len;
    return &dtls_psk;
  }
  
  #ifdef _WIN32
  #define S_ISDIR(x) (((x) & S_IFMT) == S_IFDIR)
  #endif
  
  static coap_session_t*
  open_session(
    coap_context_t *ctx,
    coap_proto_t proto,
    coap_address_t *bind_addr,
    coap_address_t *dst,
    const uint8_t *identity,
    size_t identity_len,
    const uint8_t *key,
    size_t key_len
  ) {
    coap_session_t *session;
  
    if (proto == COAP_PROTO_DTLS || proto == COAP_PROTO_TLS) {
      /* Encrypted session */
      if (root_ca_file || ca_file || cert_file) {
        /* Setup PKI session */
        coap_dtls_pki_t *dtls_pki = setup_pki(ctx);
        session = coap_new_client_session_pki(ctx, bind_addr, dst, proto, dtls_pki);
      }
      else if (identity || key) {
        /* Setup PSK session */
        coap_dtls_cpsk_t *dtls_psk = setup_psk(identity, identity_len,
                                                 key, key_len);
        session = coap_new_client_session_psk2(ctx, bind_addr, dst, proto,
                                             dtls_psk);
      }
      else {
        /* No PKI or PSK defined, as encrypted, use PKI */
        coap_dtls_pki_t *dtls_pki = setup_pki(ctx);
        session = coap_new_client_session_pki(ctx, bind_addr, dst, proto, dtls_pki);
      }
    }
    else {
      /* Non-encrypted session */
      session = coap_new_client_session(ctx, bind_addr, dst, proto);
    }
    return session;
  }
  
  static coap_session_t *
  get_session(
    coap_context_t *ctx,
    const char *local_addr,
    const char *local_port,
    coap_proto_t proto,
    coap_address_t *dst,
    const uint8_t *identity,
    size_t identity_len,
    const uint8_t *key,
    size_t key_len
  ) {
    coap_session_t *session = NULL;
  
    if ( local_addr ) {
      int s;
      struct addrinfo hints;
      struct addrinfo *result = NULL, *rp;
  
      memset( &hints, 0, sizeof( struct addrinfo ) );
      hints.ai_family = AF_UNSPEC;    /* Allow IPv4 or IPv6 */
      hints.ai_socktype = COAP_PROTO_RELIABLE(proto) ? SOCK_STREAM : SOCK_DGRAM; /* Coap uses UDP */
      hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST | AI_NUMERICSERV | AI_ALL;
  
      s = getaddrinfo( local_addr, local_port, &hints, &result );
      if ( s != 0 ) {
        fprintf( stderr, "getaddrinfo: %s\n", gai_strerror( s ) );
        return NULL;
      }
  
      /* iterate through results until success */
      for ( rp = result; rp != NULL; rp = rp->ai_next ) {
        coap_address_t bind_addr;
        if ( rp->ai_addrlen <= (socklen_t)sizeof( bind_addr.addr ) ) {
          coap_address_init( &bind_addr );
          bind_addr.size = (socklen_t)rp->ai_addrlen;
          memcpy( &bind_addr.addr, rp->ai_addr, rp->ai_addrlen );
          session = open_session(ctx, proto, &bind_addr, dst,
                                 identity, identity_len, key, key_len);
          if ( session )
            break;
        }
      }
      freeaddrinfo( result );
    } else {
      session = open_session(ctx, proto, NULL, dst,
                                 identity, identity_len, key, key_len);
    }
    return session;
  }
  
  int
  main(int argc, char **argv) {
    coap_context_t  *ctx = NULL;
    coap_session_t *session = NULL;
    coap_address_t dst;
    static char addr[INET6_ADDRSTRLEN];
    void *addrptr = NULL;
    int result = -1;
    coap_pdu_t  *pdu;
    static coap_str_const_t server;
    uint16_t port = COAP_DEFAULT_PORT;
    char port_str[NI_MAXSERV] = "0";
    char node_str[NI_MAXHOST] = "";
    int opt, res;
    coap_log_t log_level = LOG_WARNING;
    unsigned char *user = NULL, *key = NULL;
    ssize_t user_length = -1, key_length = 0;
    int create_uri_opts = 1;
    size_t i;
    coap_uri_scheme_t scheme;
  #ifndef _WIN32
    struct sigaction sa;
  #endif
  
    while ((opt = getopt(argc, argv, "a:b:c:e:f:h:j:k:l:m:no:p:rs:t:u:v:wA:B:C:H:J:K:L:M:NO:P:R:T:U")) != -1) {
      switch (opt) {
      case 'a':
        strncpy(node_str, optarg, NI_MAXHOST - 1);
        node_str[NI_MAXHOST - 1] = '\0';
        break;
      case 'b':
        cmdline_blocksize(optarg);
        break;
      case 'B':
        wait_seconds = atoi(optarg);
        break;
      case 'c':
        cert_file = optarg;
        break;
      case 'C':
        ca_file = optarg;
        break;
      case 'R':
        root_ca_file = optarg;
        break;
      case 'e':
        if (!cmdline_input(optarg, &payload))
          payload.length = 0;
        break;
      case 'f':
        if (!cmdline_input_from_file(optarg, &payload))
          payload.length = 0;
        break;
      case 'j' :
        key_file = optarg;
        break;
      case 'J' :
        pkcs11_pin = optarg;
        break;
      case 'k':
        key_length = cmdline_read_key(optarg, &key, MAX_KEY);
        break;
      case 'L':
        block_mode = strtoul(optarg, NULL, 0);
        if (!(block_mode & COAP_BLOCK_USE_LIBCOAP)) {
          fprintf(stderr, "Block mode must include COAP_BLOCK_USE_LIBCOAP (1)\n");
          exit(-1);
        }
        break;
      case 'p':
        strncpy(port_str, optarg, NI_MAXSERV - 1);
        port_str[NI_MAXSERV - 1] = '\0';
        break;
      case 'm':
        method = cmdline_method(optarg);
        break;
      case 'w':
        add_nl = 1;
        break;
      case 'N':
        msgtype = COAP_MESSAGE_NON;
        break;
      case 's':
        cmdline_subscribe(optarg);
        break;
      case 'o':
        output_file.length = strlen(optarg);
        output_file.s = (unsigned char *)coap_malloc(output_file.length + 1);
  
        if (!output_file.s) {
          fprintf(stderr, "cannot set output file: insufficient memory\n");
          exit(-1);
        } else {
          /* copy filename including trailing zero */
          memcpy(output_file.s, optarg, output_file.length + 1);
        }
        break;
      case 'A':
        cmdline_content_type(optarg, COAP_OPTION_ACCEPT);
        break;
      case 't':
        cmdline_content_type(optarg, COAP_OPTION_CONTENT_TYPE);
        break;
      case 'M':
        cert_file = optarg;
        is_rpk_not_cert = 1;
        verify_peer_cert = 0; /* This does not work for RPK */
        break;
      case 'O':
        cmdline_option(optarg);
        break;
      case 'P':
        if (!cmdline_proxy(optarg)) {
          fprintf(stderr, "error specifying proxy address\n");
          exit(-1);
        }
        break;
      case 'T':
        cmdline_token(optarg);
        break;
      case 'u':
        user_length = cmdline_read_user(optarg, &user, MAX_USER);
        break;
      case 'U':
        create_uri_opts = 0;
        break;
      case 'v':
        log_level = strtol(optarg, NULL, 10);
        break;
      case 'l':
        if (!coap_debug_set_packet_loss(optarg)) {
          usage(argv[0], LIBCOAP_PACKAGE_VERSION);
          exit(1);
        }
        break;
      case 'r':
        reliable = coap_tcp_is_supported();
        break;
      case 'K':
        ping_seconds = atoi(optarg);
        break;
      case 'h':
        if (!cmdline_read_hint_check(optarg)) {
          usage(argv[0], LIBCOAP_PACKAGE_VERSION);
          exit(1);
        }
        break;
      case 'H':
        if (!cmdline_hop_limit(optarg))
          fprintf(stderr, "Hop Limit has to be > 0 and < 256\n");
        break;
      case 'n':
        verify_peer_cert = 0;
        break;
      default:
        usage( argv[0], LIBCOAP_PACKAGE_VERSION );
        exit( 1 );
      }
    }
  
    coap_startup();
    coap_dtls_set_log_level(log_level);
    coap_set_log_level(log_level);
  
    if (optind < argc) {
      if (cmdline_uri(argv[optind], create_uri_opts) < 0) {
        exit(1);
      }
    } else {
      usage( argv[0], LIBCOAP_PACKAGE_VERSION );
      exit( 1 );
    }
  
    if (key_length < 0) {
      coap_log( LOG_CRIT, "Invalid pre-shared key specified\n" );
      goto finish;
    }
  
    if (proxy.host.length) {
      server = proxy.host;
      port = proxy.port;
      scheme = proxy.scheme;
    } else {
      server = uri.host;
      port = proxy_scheme_option ? proxy.port : uri.port;
      scheme = proxy_scheme_option ? proxy.scheme : uri.scheme;
    }
  
    /* resolve destination address where server should be sent */
    res = resolve_address(&server, &dst.addr.sa);
  
    if (res < 0) {
      fprintf(stderr, "failed to resolve address\n");
      exit(-1);
    }
  
    ctx = coap_new_context( NULL );
    if ( !ctx ) {
      coap_log( LOG_EMERG, "cannot create context\n" );
      goto finish;
    }
  
    coap_context_set_keepalive(ctx, ping_seconds);
    coap_context_set_block_mode(ctx, block_mode);
  
    dst.size = res;
    dst.addr.sin.sin_port = htons( port );
  
    session = get_session(
      ctx,
      node_str[0] ? node_str : NULL, port_str,
      scheme==COAP_URI_SCHEME_COAP_TCP ? COAP_PROTO_TCP :
      scheme==COAP_URI_SCHEME_COAPS_TCP ? COAP_PROTO_TLS :
      (reliable ?
          scheme==COAP_URI_SCHEME_COAPS ? COAP_PROTO_TLS : COAP_PROTO_TCP
        : scheme==COAP_URI_SCHEME_COAPS ? COAP_PROTO_DTLS : COAP_PROTO_UDP),
      &dst,
      user_length >= 0 ? user : NULL,
      user_length >= 0 ? user_length : 0,
      key_length > 0 ? key : NULL,
      key_length > 0 ? key_length : 0
    );
  
    if ( !session ) {
      coap_log( LOG_EMERG, "cannot create client session\n" );
      goto finish;
    }
    coap_session_init_token(session, the_token.length, the_token.s);
  
    /* add Uri-Host if server address differs from uri.host */
  
    switch (dst.addr.sa.sa_family) {
    case AF_INET:
      addrptr = &dst.addr.sin.sin_addr;
      /* create context for IPv4 */
      break;
    case AF_INET6:
      addrptr = &dst.addr.sin6.sin6_addr;
      break;
    default:
      ;
    }
  
    coap_register_option(ctx, COAP_OPTION_BLOCK2);
    coap_register_response_handler(ctx, message_handler);
    coap_register_event_handler(ctx, event_handler);
    coap_register_nack_handler(ctx, nack_handler);
  
    /* construct CoAP message */
  
    if (!uri_host_option && (!proxy.host.length && addrptr
        && (inet_ntop(dst.addr.sa.sa_family, addrptr, addr, sizeof(addr)) != 0)
        && (strlen(addr) != uri.host.length
        || memcmp(addr, uri.host.s, uri.host.length) != 0)
        && create_uri_opts)) {
          /* add Uri-Host */
  
          coap_insert_optlist(&optlist,
                      coap_new_optlist(COAP_OPTION_URI_HOST,
                      uri.host.length,
                      uri.host.s));
    }
  
    /* set block option if requested at commandline */
    if (flags & FLAGS_BLOCK)
      set_blocksize();
  
    if (! (pdu = coap_new_request(ctx, session, method, &optlist, payload.s, payload.length))) {
      goto finish;
    }
  
    coap_log(LOG_DEBUG, "sending CoAP request:\n");
    if (coap_get_log_level() < LOG_DEBUG)
      coap_show_pdu(LOG_INFO, pdu);
  
    coap_send_large(session, pdu);
  
    wait_ms = wait_seconds * 1000;
    coap_log(LOG_DEBUG, "timeout is set to %u seconds\n", wait_seconds);
  
  #ifdef _WIN32
    signal(SIGINT, handle_sigint);
  #else
    memset (&sa, 0, sizeof(sa));
    sigemptyset(&sa.sa_mask);
    sa.sa_handler = handle_sigint;
    sa.sa_flags = 0;
    sigaction (SIGINT, &sa, NULL);
    sigaction (SIGTERM, &sa, NULL);
    /* So we do not exit on a SIGPIPE */
    sa.sa_handler = SIG_IGN;
    sigaction (SIGPIPE, &sa, NULL);
  #endif
  
    while (!quit && !(ready && !doing_getting_block && coap_can_exit(ctx)) ) {
  
      result = coap_io_process( ctx, wait_ms == 0 ?
                                   obs_ms : obs_ms == 0 ?
                                   min(wait_ms, 1000) : min( wait_ms, obs_ms ) );
  
      if ( result >= 0 ) {
        if ( wait_ms > 0 && !wait_ms_reset ) {
          if ( (unsigned)result >= wait_ms ) {
            coap_log(LOG_INFO, "timeout\n");
            break;
          } else {
            wait_ms -= result;
          }
        }
        if ( obs_ms > 0 && !obs_ms_reset ) {
          if ( (unsigned)result >= obs_ms ) {
            coap_log(LOG_DEBUG, "clear observation relationship\n" );
            coap_cancel_observe(session, &the_token, msgtype);
            doing_observe = 0;
            quit = 1;
  
            /* make sure that the obs timer does not fire again */
            obs_ms = 0;
            obs_seconds = 0;
          } else {
            obs_ms -= result;
          }
        }
        wait_ms_reset = 0;
        obs_ms_reset = 0;
      }
    }
  
    result = 0;
  
   finish:
  
    coap_free(ca_mem);
    coap_free(cert_mem);
    coap_free(key_mem);
    for (i = 0; i < valid_ihs.count; i++) {
      free(valid_ihs.ih_list[i].hint_match);
      coap_delete_bin_const(valid_ihs.ih_list[i].new_identity);
      coap_delete_bin_const(valid_ihs.ih_list[i].new_key);
    }
    if (valid_ihs.count)
      free(valid_ihs.ih_list);
    coap_delete_optlist(optlist);
    coap_session_release( session );
    coap_free_context( ctx );
    coap_cleanup();
    close_output();
  
    return result;
  }
  