Nanocoap small CoAP library

CoAP library optimized for minimal resource usage.

nanocoap provides a granular, low-level interface for writing CoAP messages via RIOT’s sock networking API.

Server Operation

See the nanocoap_server example, which is built on the nanocoap_sock.h::nanocoap_server() function. A server must define an array of coap_resource_t resources for which it responds. See the declarations of coap_resources and coap_resources_numof. The array contents must be ordered by the resource path, specifically the ASCII encoding of the path characters (digit and capital precede lower case). nanocoap provides the COAP_WELL_KNOWN_CORE_DEFAULT_HANDLER entry for /.well-known/core.

Handler functions

For each resource, you must implement a nanocoap.h::coap_handler_t handler function. nanocoap provides functions to help implement the handler. If the handler is called via nanocoap_sock.h::nanocoap_server(), the response buffer provided to the handler reuses the buffer for the request. So, your handler must read the request thoroughly before writing the response.

To read the request, use the coap_get_xxx() functions to read the header and options. Use the coap_opt_get_xxx() functions to read an option generically by data type. If the pkt payload_len attribute is a positive value, start to read it at the payload pointer attribute.

If a response does not require specific CoAP options, use nanocoap.h::coap_reply_simple(). If there is a payload, it writes a Content-Format option with the provided value.

For a response with additional CoAP options, start by calling nanocoap.h::coap_build_reply(). Then choose either the minimal API or the struct-based API to write the rest of the response. See the instructions in the section Write Options and Payload below.

Handler functions

For each resource, you must implement a nanocoap.h::coap_handler_t handler function. nanocoap provides functions to help implement the handler. If the handler is called via nanocoap_sock.h::nanocoap_server(), the response buffer provided to the handler reuses the buffer for the request. So, your handler must read the request thoroughly before writing the response.

To read the request, use the coap_get_xxx() functions to read the header and options. Use the coap_opt_get_xxx() functions to read an option generically by data type. If the pkt payload_len attribute is a positive value, start to read it at the payload pointer attribute.

If a response does not require specific CoAP options, use nanocoap.h::coap_reply_simple(). If there is a payload, it writes a Content-Format option with the provided value.

For a response with additional CoAP options, start by calling nanocoap.h::coap_build_reply(). Then choose either the minimal API or the struct-based API to write the rest of the response. See the instructions in the section Write Options and Payload below.

Client Operation

Choose either the minimal API or the struct-based API to write a request. Follow the instructions in the section Write Options and Payload below.

To send the message and await the response, see nanocoap_sock.h::nanocoap_request() as well as nanocoap_sock.h::nanocoap_get(), which additionally copies the response payload to a user supplied buffer. Finally, read the response as described above in the server Handler functions section for reading a request.

Write Options and Payload

For both server responses and client requests, CoAP uses an Option mechanism to encode message metadata that is not required for each message. For example, the resource URI path is required only for a request, and is encoded as the Uri-Path option.

nanocoap provides two APIs for writing CoAP options:

  • minimal API requires only a reference to the buffer for the message. However, the caller must provide the last option number written as well as the buffer position.
  • struct-based API uses a coap_pkt_t struct to conveniently track each option as it is written and prepare for any payload.

You must use one API exclusively for a given message. For either API, the caller must write options in order by option number (see “CoAP option numbers” in CoAP defines).

Minimal API

Before starting, ensure the CoAP header has been initialized with nanocoap.h::coap_build_hdr(). For a response, nanocoap.h::coap_build_reply() includes a call to nanocoap.h::coap_build_hdr(). Use the returned length to track the next position in the buffer to write and remaining length.

Next, use the coap_opt_put_xxx() and coap_put_xxx() functions to write each option. These functions require the position in the buffer to start writing, and return the number of bytes written.

If there is a payload, append a payload marker (0xFF). Then write the payload to within the maximum length remaining in the buffer.

Struct-based API

As with the minimal API, first ensure the CoAP header has been initialized with nanocoap.h::coap_build_hdr(). Then use nanocoap.h::coap_pkt_init() to initialize the coap_pkt_t struct.

Next, use the coap_opt_add_xxx() functions to write each option, like nanocoap.h::coap_opt_add_uint(). When all options have been added, call nanocoap.h::coap_opt_finish().

Finally, write any message payload at the coap_pkt_t payload pointer attribute. The payload_len attribute provides the available length in the buffer. The option functions keep these values current as they are used.

Minimal API

Before starting, ensure the CoAP header has been initialized with nanocoap.h::coap_build_hdr(). For a response, nanocoap.h::coap_build_reply() includes a call to nanocoap.h::coap_build_hdr(). Use the returned length to track the next position in the buffer to write and remaining length.

Next, use the coap_opt_put_xxx() and coap_put_xxx() functions to write each option. These functions require the position in the buffer to start writing, and return the number of bytes written.

If there is a payload, append a payload marker (0xFF). Then write the payload to within the maximum length remaining in the buffer.

Struct-based API

As with the minimal API, first ensure the CoAP header has been initialized with nanocoap.h::coap_build_hdr(). Then use nanocoap.h::coap_pkt_init() to initialize the coap_pkt_t struct.

Next, use the coap_opt_add_xxx() functions to write each option, like nanocoap.h::coap_opt_add_uint(). When all options have been added, call nanocoap.h::coap_opt_finish().

Finally, write any message payload at the coap_pkt_t payload pointer attribute. The payload_len attribute provides the available length in the buffer. The option functions keep these values current as they are used.

Create a Block-wise Response (Block2)

Block-wise is a CoAP extension (RFC 7959) to divide a large payload across multiple physical packets. This section describes how to write a block-wise payload for a response, and is known as Block2. (Block1 is for a block-wise payload in a request.) See _riot_board_handler() in the nanocoap_server example for an example handler implementation.

Start with nanocoap.h::coap_block2_init() to read the client request and initialize a coap_slicer_t struct with the size and location for this slice of the overall payload. Then write the block2 option in the response with nanocoap.h::coap_opt_put_block2(). The option includes an indicator (“more”) that a slice completes the overall payload transfer. You may not know the value for more at this point, but you must initialize the space in the packet for the option before writing the payload. The option is rewritten later.

Next, use the coap_blockwise_put_xxx() functions to write the payload content. These functions use the coap_block_slicer_t to enable or disable actually writing the content, depending on the current position within the overall payload transfer.

Finally, use the convenience function nanocoap.h::coap_block2_build_reply(), which finalizes the packet and calls nanocoap.h::coap_block2_finish() internally to update the block2 option.

COAP_GET
1
(0x1)
COAP_POST
1
(0x2)
COAP_PUT
1
(0x4)
COAP_DELETE
1
(0x8)
NANOCOAP_NOPTS_MAX
1
(16)
NANOCOAP_URI_MAX
1
(64)
NANOCOAP_BLOCK_SIZE_EXP_MAX

Maximum size for a blockwise transfer as power of 2. 

1
(6)
COAP_OPT_FINISH_NONE

no special handling required 

1
(0x0000)
COAP_OPT_FINISH_PAYLOAD

expect a payload to follow 

1
(0x0001)
msp430_types.h::ssize_t(* coap_handler_t()

Resource handler type.

const coap_resource_t coap_resources()

Global CoAP resource list.

const unsigned coap_resources_numof

Number of entries in global CoAP resource list.

int coap_parse(coap_pkt_t * pkt, uint8_t * buf, msp430_types.h::size_t len)

Parse a CoAP PDU.

This function parses a raw CoAP PDU from buf with size len and fills the structure pointed to by pkt. pkt must point to a preallocated coap_pkt_t structure.

Parameters

pkt:structure to parse into
buf:pointer to raw packet data
len:length of packet at buf

Return values

  • 0 on success
  • <0 on error
msp430_types.h::ssize_t coap_build_reply(coap_pkt_t * pkt, unsigned code, uint8_t * rbuf, unsigned rlen, unsigned payload_len)

Build reply to CoAP request.

This function can be used to create a reply to any CoAP request packet. It will create the reply packet header based on parameters from the request (e.g., id, token). Passing a non-zero payload_len will ensure the payload fits into the buffer along with the header.

Parameters

pkt:packet to reply to
code:reply code (e.g., COAP_CODE_204)
rbuf:buffer to write reply to
rlen:size of rbuf
payload_len:length of payload

Return values

  • size of reply packet on success
  • <0 on error
msp430_types.h::ssize_t coap_reply_simple(coap_pkt_t * pkt, unsigned code, uint8_t * buf, msp430_types.h::size_t len, unsigned ct, const uint8_t * payload, uint8_t payload_len)

Create CoAP reply (convenience function)

This is a simple wrapper that allows for building CoAP replies for simple use-cases.

The reply will be written to buf. Is payload and payload_len non-zero, the payload will be copied into the resulting reply packet.

Parameters

pkt:packet to reply to
code:reply code (e.g., COAP_CODE_204)
buf:buffer to write reply to
len:size of buf
ct:content type of payload
payload:ptr to payload
payload_len:length of payload

Return values

  • size of reply packet on success
  • <0 on error
msp430_types.h::ssize_t coap_handle_req(coap_pkt_t * pkt, uint8_t * resp_buf, unsigned resp_buf_len)

Handle incoming CoAP request.

This function will find the correct handler, call it and write the reply into resp_buf.

Parameters

pkt:pointer to (parsed) CoAP packet
resp_buf:buffer for response
resp_buf_len:size of response buffer

Return values

  • size of reply packet on success
  • <0 on error
msp430_types.h::ssize_t coap_build_hdr(coap_hdr_t * hdr, unsigned type, uint8_t * token, msp430_types.h::size_t token_len, unsigned code, uint16_t id)

Builds a CoAP header.

Caller must ensure hdr can hold the header and the full token!

Parameters

hdr:hdr to fill
type:CoAP packet type (e.g., COAP_TYPE_CON, …)
token:token
token_len:length of token
code:CoAP code (e.g., COAP_CODE_204, …)
id:CoAP request id

Return values

  • length of resulting header
void coap_pkt_init(coap_pkt_t * pkt, uint8_t * buf, msp430_types.h::size_t len, msp430_types.h::size_t header_len)

Initialize a packet struct, to build a message buffer.

Parameters

pkt:pkt to initialize
buf:buffer to write for pkt, with CoAP header already initialized
len:length of buf
header_len:length of header in buf, including token

msp430_types.h::size_t coap_put_option(uint8_t * buf, uint16_t lastonum, uint16_t onum, uint8_t * odata, msp430_types.h::size_t olen)

Insert a CoAP option into buffer.

This function writes a CoAP option with nr. onum to buf. It handles calculating the option delta (from lastonum), encoding the length from olen and copying the option data from odata.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 for first option
onum:number of option
odata:ptr to raw option data (or NULL)
olen:length of odata (if any)

Return values

  • amount of bytes written to buf
msp430_types.h::size_t coap_put_option_ct(uint8_t * buf, uint16_t lastonum, uint16_t content_type)

Insert content type option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 if first option
content_type:content type to set

Return values

  • amount of bytes written to buf
msp430_types.h::size_t coap_opt_put_string(uint8_t * buf, uint16_t lastonum, uint16_t optnum, const char * string, char separator)

Encode the given string as multi-part option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 if first option
optnum:option number to use
string:string to encode as option
separator:character used in string to separate parts

Return values

  • number of bytes written to buf
msp430_types.h::size_t coap_opt_put_uri_path(uint8_t * buf, uint16_t lastonum, const char * uri)

Convenience function for inserting URI_PATH option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 if first option
uri:ptr to source URI

Return values

  • amount of bytes written to buf
msp430_types.h::size_t coap_opt_put_uri_query(uint8_t * buf, uint16_t lastonum, const char * uri)

Convenience function for inserting URI_QUERY option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 if first option
uri:ptr to source URI

Return values

  • amount of bytes written to buf
msp430_types.h::size_t coap_opt_put_location_path(uint8_t * buf, uint16_t lastonum, const char * location)

Convenience function for inserting LOCATION_PATH option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 if first option
location:ptr to string holding the location

Return values

  • amount of bytes written to buf
msp430_types.h::size_t coap_opt_put_location_query(uint8_t * buf, uint16_t lastonum, const char * location)

Convenience function for inserting LOCATION_QUERY option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), or 0 if first option
location:ptr to string holding the location

Return values

  • amount of bytes written to buf
int coap_get_blockopt(coap_pkt_t * pkt, uint16_t option, uint32_t * blknum, unsigned * szx)

Generic block option getter.

Parameters

pkt:pkt to work on
option:actual block option number to get
blknum:block number
szx:SZX value

Return values

  • -1 if option not found
  • 0 if more flag is not set
  • 1 if more flag is set
int coap_get_block1(coap_pkt_t * pkt, coap_block1_t * block1)

Block1 option getter.

This function gets a CoAP packet’s block1 option and parses it into a helper structure.

If no block1 option is present in pkt, the values in block1 will be initialized with zero. That implies both block1->offset and block1->more are also valid in that case, as packet with offset==0 and more==0 means it contains all the payload for the corresponding request.

Parameters

pkt:pkt to work on
block1:ptr to preallocated coap_block1_t structure

Return values

  • 0 if block1 option not present
  • 1 if structure has been filled
int coap_get_block2(coap_pkt_t * pkt, coap_block1_t * block2)

Block2 option getter.

Parameters

pkt:pkt to work on
block2:ptr to preallocated coap_block1_t structure

Return values

  • 0 if block2 option not present
  • 1 if structure has been filled
msp430_types.h::size_t coap_put_option_block1(uint8_t * buf, uint16_t lastonum, unsigned blknum, unsigned szx, int more)

Insert block1 option into buffer.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), must be < 27
blknum:block number
szx:SXZ value
more:more flag (1 or 0)

Return values

  • amount of bytes written to buf
msp430_types.h::size_t coap_put_block1_ok(uint8_t * pkt_pos, coap_block1_t * block1, uint16_t lastonum)

Insert block1 option into buffer (from coap_block1_t)

This function is wrapper around nanocoap.h::coap_put_option_block1(), taking its arguments from a coap_block1_t struct.

It will write option Nr. 27 (COAP_OPT_BLOCK1).

It is safe to be called when block1 was generated for a non-blockwise request.

Parameters

pkt_pos:buffer to write to
block1:ptr to block1 struct (created by nanocoap.h::coap_get_block1())
lastonum:last option number (must be < 27)

Return values

  • amount of bytes written to pkt_pos
msp430_types.h::ssize_t coap_opt_add_string(coap_pkt_t * pkt, uint16_t optnum, const char * string, char separator)

Encode the given string as option(s) into pkt.

Use separator to split string into multiple options.

Parameters

pkt:pkt referencing target buffer
optnum:option number to use
string:string to encode as option
separator:character used in string to separate parts

Return values

  • number of bytes written to buffer
  • -ENOSPC if no available options
msp430_types.h::ssize_t coap_opt_add_uint(coap_pkt_t * pkt, uint16_t optnum, uint32_t value)

Encode the given uint option into pkt.

Parameters

pkt:pkt referencing target buffer
optnum:option number to use
value:uint to encode

Return values

  • number of bytes written to buffer
  • <0 reserved for error but not implemented yet
msp430_types.h::ssize_t coap_opt_finish(coap_pkt_t * pkt, uint16_t flags)

Finalizes options as required and prepares for payload.

Parameters

pkt:pkt to update
flags:see COAP_OPT_FINISH… macros

Return values

  • total number of bytes written to buffer
msp430_types.h::size_t coap_opt_put_block2(uint8_t * buf, uint16_t lastonum, coap_block_slicer_t * slicer, bool more)

Insert block2 option into buffer.

When calling this function to initialize a packet with a block2 option, the more flag must be set to prevent the creation of an option with a length too small to contain the size bit.

Parameters

buf:buffer to write to
lastonum:number of previous option (for delta calculation), must be < 23
slicer:coap blockwise slicer helper struct
more:more flag (1 or 0)

Return values

  • amount of bytes written to buf
unsigned coap_get_content_type(coap_pkt_t * pkt)

Get content type from packet.

Parameters

pkt:packet to work on

Return values

  • the packet’s content type value if included, COAP_FORMAT_NONE otherwise
msp430_types.h::ssize_t coap_opt_get_string(const coap_pkt_t * pkt, uint16_t optnum, uint8_t * target, msp430_types.h::size_t max_len, char separator)

Read a full option as null terminated string into the target buffer.

This function is for reading and concatenating string based, multi-part CoAP options like COAP_OPT_URI_PATH or COAP_OPT_LOCATION_PATH. It will write all parts of the given option into the target buffer, separating the parts using the given separator. The resulting string is \0 terminated.

Parameters

pkt:packet to read from
optnum:absolute option number
target:target buffer
max_len:size of target
separator:character used for separating the option parts

Return values

  • -ENOSPC if the complete option does not fit into target
  • nr of bytes written to target (including ‘\0’)
msp430_types.h::ssize_t coap_get_uri_path(const coap_pkt_t * pkt, uint8_t * target)

Convenience function for getting the packet’s URI_PATH.

This function decodes the pkt’s URI option into a “/”-separated and ‘\0’-terminated string.

Caller must ensure target can hold at least NANOCOAP_URI_MAX bytes!

Parameters

pkt:pkt to work on
target:buffer for target URI

Return values

  • -ENOSPC if URI option is larger than NANOCOAP_URI_MAX
  • nr of bytes written to target (including ‘\0’)
msp430_types.h::ssize_t coap_get_uri_query(const coap_pkt_t * pkt, uint8_t * target)

Convenience function for getting the packet’s URI_QUERY option.

This function decodes the pkt’s URI_QUERY option into a “&”-separated and ‘\0’-terminated string.

Caller must ensure target can hold at least NANOCOAP_URI_MAX bytes!

Parameters

pkt:pkt to work on
target:buffer for target URI

Return values

  • -ENOSPC if URI option is larger than NANOCOAP_URI_MAX
  • nr of bytes written to target (including ‘\0’)
msp430_types.h::ssize_t coap_get_location_path(const coap_pkt_t * pkt, uint8_t * target, msp430_types.h::size_t max_len)

Convenience function for getting the packet’s LOCATION_PATH option.

This function decodes the pkt’s LOCATION_PATH option into a ‘/’-separated and ‘\0’-terminated string.

Caller must ensure target can hold at least 2 bytes!

Parameters

pkt:pkt to work on
target:buffer for location path
max_len:size of target in bytes

Return values

  • -ENOSPC if URI option is larger than max_len
  • nr of bytes written to target (including ‘\0’)
msp430_types.h::ssize_t coap_get_location_query(const coap_pkt_t * pkt, uint8_t * target, msp430_types.h::size_t max_len)

Convenience function for getting the packet’s LOCATION_QUERY option.

This function decodes the pkt’s LOCATION_PATH option into a ‘&’-separated and ‘\0’-terminated string.

Caller must ensure target can hold at least 2 bytes!

Parameters

pkt:pkt to work on
target:buffer for location path
max_len:size of target in bytes

Return values

  • -ENOSPC if URI option is larger than max_len
  • nr of bytes written to target (including ‘\0’)
void coap_block2_init(coap_pkt_t * pkt, coap_block_slicer_t * slicer)

Initialize a block2 slicer struct for writing the payload.

This function determines the size of the response payload based on the size requested by the client in pkt.

Parameters

pkt:packet to work on
slicer:Preallocated slicer struct to fill

void coap_block2_finish(coap_block_slicer_t * slicer)

Finish a block2 response.

This function finalizes the block2 response header

Checks whether the more bit should be set in the block2 option and sets/clears it if required. Doesn’t return the number of bytes as this overwrites bytes in the packet, it doesn’t add new bytes to the packet.

Parameters

slicer:Preallocated slicer struct to use

msp430_types.h::ssize_t coap_block2_build_reply(coap_pkt_t * pkt, unsigned code, uint8_t * rbuf, unsigned rlen, unsigned payload_len, coap_block_slicer_t * slicer)

Build reply to CoAP block2 request.

This function can be used to create a reply to a CoAP block2 request packet. In addition to nanocoap.h::coap_build_reply(), this function checks the block2 option and returns an error message to the client if necessary.

Parameters

pkt:packet to reply to
code:reply code (e.g., COAP_CODE_204)
rbuf:buffer to write reply to
rlen:size of rbuf
payload_len:length of payload
slicer:slicer to use

Return values

  • size of reply packet on success
  • <0 on error
msp430_types.h::size_t coap_blockwise_put_char(coap_block_slicer_t * slicer, uint8_t * bufpos, char c)

Add a single character to a block2 reply.

This function is used to add single characters to a CoAP block2 reply. It checks whether the character should be added to the buffer and ignores it when the character is outside the current block2 request.

Parameters

slicer:slicer to use
bufpos:pointer to the current payload buffer position
c:character to write

Return values

  • Number of bytes writen to bufpos
msp430_types.h::size_t coap_blockwise_put_bytes(coap_block_slicer_t * slicer, uint8_t * bufpos, const uint8_t * c, msp430_types.h::size_t len)

Add a byte array to a block2 reply.

This function is used to add an array of bytes to a CoAP block2 reply. it checks which parts of the string should be added to the reply and ignores parts that are outside the current block2 request.

Parameters

slicer:slicer to use
bufpos:pointer to the current payload buffer position
c:byte array to copy
len:length of the byte array

Return values

  • Number of bytes writen to bufpos
unsigned coap_szx2size(unsigned szx)

Helper to decode SZX value to size in bytes.

Parameters

szx:SZX value to decode

Return values

  • SZX value decoded to bytes
unsigned coap_get_ver(coap_pkt_t * pkt)

Get the CoAP version number.

Parameters

pkt:CoAP packet

Return values

  • CoAP version number
unsigned coap_get_type(coap_pkt_t * pkt)

Get the message type.

Parameters

pkt:CoAP packet

Return values

  • COAP_TYPE_CON
  • COAP_TYPE_NON
  • COAP_TYPE_ACK
  • COAP_TYPE_RST
unsigned coap_get_token_len(coap_pkt_t * pkt)

Get a message’s token length [in byte].

Parameters

pkt:CoAP packet

Return values

  • length of token in the given message (0-8 byte)
unsigned coap_get_code_class(coap_pkt_t * pkt)

Get a message’s code class (3 most significant bits of code)

Parameters

pkt:CoAP packet

Return values

  • message code class
unsigned coap_get_code_detail(coap_pkt_t * pkt)

Get a message’s code detail (5 least significant bits of code)

Parameters

pkt:CoAP packet

Return values

  • message code detail
unsigned coap_get_code_raw(coap_pkt_t * pkt)

Get a message’s raw code (class + detail)

Parameters

pkt:CoAP packet

Return values

  • raw message code
unsigned coap_get_code(coap_pkt_t * pkt)

Get a message’s code in decimal format ((class * 100) + detail)

Parameters

pkt:CoAP packet

Return values

  • message code in decimal format
unsigned coap_get_id(coap_pkt_t * pkt)

Get the message ID of the given CoAP packet.

Parameters

pkt:CoAP packet

Return values

  • message ID
uint8_t * coap_hdr_data_ptr(coap_hdr_t * hdr)

Get the start of data after the header.

Parameters

hdr:Header of CoAP packet in contiguous memory

Return values

  • pointer to first byte after the header
unsigned coap_get_total_hdr_len(coap_pkt_t * pkt)

Get the total header length (4-byte header + token length)

Parameters

pkt:CoAP packet

Return values

  • total header length
uint8_t coap_code(unsigned cls, unsigned detail)

Encode given code class and code detail to raw code.

Parameters

cls:message code class
detail:message code detail

Return values

  • raw message code
void coap_hdr_set_code(coap_hdr_t * hdr, uint8_t code)

Write the given raw message code to given CoAP header.

Parameters

hdr:CoAP header to write to
code:raw message code

void coap_hdr_set_type(coap_hdr_t * hdr, unsigned type)

Set the message type for the given CoAP header.

Parameters

hdr:CoAP header to write
type:message type as integer value [0-3]

unsigned coap_method2flag(unsigned code)

Convert message code (request method) into a corresponding bit field.

Parameters

code:request code denoting the request method

Return values

  • bit field corresponding to the given request method
bool coap_has_observe(coap_pkt_t * pkt)

Identifies a packet containing an observe option.

Parameters

pkt:CoAP packet

Return values

  • true if observe value is set
  • false if not
void coap_clear_observe(coap_pkt_t * pkt)

Clears the observe option value from a packet.

Parameters

pkt:CoAP packet

uint32_t coap_get_observe(coap_pkt_t * pkt)

Get the value of the observe option from the given packet.

Parameters

pkt:CoAP packet

Return values

  • value of the observe option
msp430_types.h::ssize_t coap_well_known_core_default_handler(coap_pkt_t * pkt, uint8_t * buf, msp430_types.h::size_t len, void * context)

Reference to the default .well-known/core handler defined by the application.

COAP_FORMAT_NONE

Nanocoap-specific value to indicate no format specified. 

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(UINT16_MAX)
COAP_WELL_KNOWN_CORE_DEFAULT_HANDLER

Resource definition for the default .well-known/core handler. 

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{ \
        .path = "/.well-known/core", \
        .methods = COAP_GET, \
        .handler = coap_well_known_core_default_handler \
    }
struct coap_hdr_t

Raw CoAP PDU header structure.

uint8_t ver_t_tkl

version, token, token length

uint8_t code

CoAP code (e.g.m 205)

uint16_t id

Req/resp ID.

struct coap_optpos_t

CoAP option array entry.

uint16_t opt_num

full CoAP option number

uint16_t offset

offset in packet

struct coap_pkt_t

CoAP PDU parsing context structure.

coap_hdr_t * hdr

pointer to raw packet

uint8_t * token

pointer to token

uint8_t * payload

pointer to payload

uint16_t payload_len

length of payload

uint16_t options_len

length of options array

coap_optpos_t options()

option offset array

struct coap_resource_t

Type for CoAP resource entry.

const char * path

URI path of resource.

unsigned methods

OR’ed methods this resource allows.

nanocoap.h::coap_handler_t handler

ptr to resource handler

void * context

ptr to user defined context data

struct coap_block1_t

Block1 helper struct.

msp430_types.h::size_t offset

offset of received data

uint32_t blknum

block number

unsigned szx

szx value

int more

-1 for no option, 0 for last block, 1 for more blocks coming

struct coap_block_slicer_t

Blockwise transfer helper struct.

msp430_types.h::size_t start

Start offset of the current block.

msp430_types.h::size_t end

End offset of the current block.

msp430_types.h::size_t cur

Offset of the generated content.

uint8_t * opt

Pointer to the placed option.