Iot sdk thesis

Resolving the UNIX dependency: 
To make this function compatible on SODAQ SARA, the 
following changes had to be made: 
•
Remove the parameters that depend on UNIX libraries 
•
Pass 
int sock 
to compensate for deleted address parameters
•
Compare socket field from the passed DTLS connection structure with the socket 
passed as parameter
dtls_connection_t * connection_find(dtls_connection_t * connList, 
int
sock) 
{ 
dtls_connection_t * connP; 
connP = connList; 
while
(connP != 
nullptr
){ 
{ 
/* Compare the passed socket parameter with the socket field in the passed 
connection parameter, return the currently loaded connection if they 
match*/
if
(connP->sock == sock) 
{ 
return
connP; 
} 
connP = connP->next; 
} 
return
connP; 
} 
/* -----------------------------------------------------------------------------*/

---

63 
So, in this chapter, we saw how the UNIX-specific dependencies in tinydtls library have 
been removed using SODAQ NB-IoT API and other logically equivalent adjustments and 
substitutions. 
3.3.4
 
Integration to Wakaama and other changes 
In section 3.3.1, we talked about making tinydtls library compatible with the Arduino-
like SODAQ SARA board. In this section, we explain the changes or additions required to be 
made to rest of the Wakaama to integrate the now compatible tinydtls library. 
A LWM2M DTLS client has to have an exclusive pair of pre-shared key (PSK) and 
PSK ID, to be uniquely identifiable to the LWM2M server. We define
char * pskId 
and 
char 
* psk 
as the private members of 
class ArduinoClient
as shown in the code snippet below. 
We also have to define the unique client name. It has been defined alongside network-specific 
parameters. 

---

64 
class
ArduinoClient { 
public:
/* 
Other variables and functions 
*/
private:
/* 
Other variables 
*/ 
const
char
* serverIP = 
"23.97.187.154"
; 
// Eclipse Leshan Server
#ifdef WITH_TINYDTLS 
/*DTLS Credentials, psk must be in HEX format */
char
* pskId = (
char
*) 
"SODAQWakaamaDTLS"
; 
char
* psk = (
char
*) 
"abcd"
; 
/*A buffer to parse the DTLS credentials */
uint16_t
pskLen = strlen(psk)/
2
; 
char
* pskBuffer = (
char
*) lwm2m_malloc(pskLen); 
/*DTLS remote port*/
const
char
* serverPort = 
"5684"
;
#else 
//non-DTLS remote port
const
char
* serverPort = 
"5683"
;
#endif 
/* 
Other variables 
*/
}; 
/* In main.cpp, defined as global variables */
#define WITH_TINYDTLS
const
char
* apn = 
"u.iot.mt.gr.hu"
; 
const
char
* cdp = 
NULL
; 
const
uint8_t
cid = 
1
;
const
uint8_t
band = 
20
;
const
char
* forceOperator = 
"21630"
; 
#ifdef WITH_TINYDTLS
const
char
* lwm2mEndpoint = 
"SODAQWakaamaDTLS"
; 
#else
const
char
* lwm2mEndpoint = 
"NO-DTLS-Client"
; 
#endif
Whenever the Wakaama client with a set of credentials tries to establish a DTLS 
connection with LWM2M server, the server verifies the credentials by checking them against 
the stored configurations of the credentials. If the verification is successful, the certificate 
transfer is initiated. 

---

65 
So, the credentials have to be added to the server before we ask the client to connect. 
For the thesis, I used Eclipse Leshan as a LWM2M server.