/omg-coap

CoAP implementation in Go with observe support.

Primary LanguageGoMIT LicenseMIT

coap

import "github.com/cloudwalkio/omg-coap"

CoAP Client and Server in Go

[![Build Status](https://drone.io/github.com/cloudwalkio/omg-coap/status.png)](https://drone.io/github.com/cloudwalkio/omg-coap/latest)

Index

Constants

const (
	// ResponseTimeout is the amount of time to wait for a
	// response.
	ResponseTimeout = time.Second * 1
	// ResponseRandomFactor is a multiplier for response backoff.
	ResponseRandomFactor = 1.5
	// MaxRetransmit is the maximum number of times a message will
	// be retransmitted.
	MaxRetransmit = 0
	// Print debug messages
	Verbose = false
)
const (
	// Confirmable messages require acknowledgements.
	Confirmable = COAPType(0)
	// NonConfirmable messages do not require acknowledgements.
	NonConfirmable = COAPType(1)
	// Acknowledgement is a message type indicating a response to
	// a confirmable message.
	Acknowledgement = COAPType(2)
	// Reset indicates a permanent negative acknowledgement.
	Reset = COAPType(3)
)
const (
	IfMatch       = OptionID(1)
	URIHost       = OptionID(3)
	ETag          = OptionID(4)
	IfNoneMatch   = OptionID(5)
	Observe       = OptionID(6)
	URIPort       = OptionID(7)
	LocationPath  = OptionID(8)
	URIPath       = OptionID(11)
	ContentFormat = OptionID(12)
	MaxAge        = OptionID(14)
	URIQuery      = OptionID(15)
	Accept        = OptionID(17)
	LocationQuery = OptionID(20)
	ProxyURI      = OptionID(35)
	ProxyScheme   = OptionID(39)
	Size1         = OptionID(60)
)
const (
	TextPlain     = MediaType(0)  // text/plain;charset=utf-8
	AppLinkFormat = MediaType(40) // application/link-format
	AppXML        = MediaType(41) // application/xml
	AppOctets     = MediaType(42) // application/octet-stream
	AppExi        = MediaType(47) // application/exi
	AppJSON       = MediaType(50) // application/json
)

Content types.

Variables

var (
	ErrInvalidTokenLen   = errors.New("invalid token length")
	ErrOptionTooLong     = errors.New("option is too long")
	ErrOptionGapTooLarge = errors.New("option gap too large")
)

Message encoding errors.

var DefaultServeMux = NewServeMux()
var DefaultServer = new(Server)

func Handle

func Handle(pattern string, handler Handler)

func HandleFunc

func HandleFunc(pattern string, handler func(r *RemoteAddr, m *Message) *Message)

func ListenAndServe

func ListenAndServe(addr string, handler Handler) error

Bind to the given address and serve requests forever.

func Notify

func Notify(resource string, m *Message)

Notify observers of resource.

func Serve

func Serve(l *net.UDPConn, handler Handler) error

func StringToTime

func StringToTime(s string) (uint32, error)

StringToTime translates the RRSIG's incep. and expir. times from string values like "20110403154150" to an 32 bit integer. It takes serial arithmetic (RFC 1982) into observe option.

func TimeToString

func TimeToString(t uint32) string

TimeToString translates the RRSIG's incep. and expir. times to the string representation used when printing the record. It takes serial arithmetic (RFC 1982) into observe option.

func Transmit

func Transmit(r *RemoteAddr, m Message) error

Unicast message to remote address

func TransmitToObserver

func TransmitToObserver(resource, id string, m *Message) (done chan bool)

Transmit to an observer

type COAPCode

type COAPCode uint8

COAPCode is the type used for both request and response codes.

const (
	GET    COAPCode = 1
	POST   COAPCode = 2
	PUT    COAPCode = 3
	DELETE COAPCode = 4
	// deprecated
	SUBSCRIBE COAPCode = 5
)

Request Codes

const (
	Created               COAPCode = 65
	Deleted               COAPCode = 66
	Valid                 COAPCode = 67
	Changed               COAPCode = 68
	Content               COAPCode = 69
	BadRequest            COAPCode = 128
	Unauthorized          COAPCode = 129
	BadOption             COAPCode = 130
	Forbidden             COAPCode = 131
	NotFound              COAPCode = 132
	MethodNotAllowed      COAPCode = 133
	NotAcceptable         COAPCode = 134
	PreconditionFailed    COAPCode = 140
	RequestEntityTooLarge COAPCode = 141
	UnsupportedMediaType  COAPCode = 143
	InternalServerError   COAPCode = 160
	NotImplemented        COAPCode = 161
	BadGateway            COAPCode = 162
	ServiceUnavailable    COAPCode = 163
	GatewayTimeout        COAPCode = 164
	ProxyingNotSupported  COAPCode = 165
)

Response Codes

func (COAPCode) String

func (c COAPCode) String() string

type COAPType

type COAPType uint8

COAPType represents the message type.

func (COAPType) String

func (t COAPType) String() string

type Conn

type Conn struct {
}

Conn is a CoAP client connection.

func Dial

func Dial(n, addr string) (*Conn, error)

Dial connects a CoAP client.

func (*Conn) Receive

func (c *Conn) Receive() (*Message, error)

Receive a message.

func (*Conn) Send

func (c *Conn) Send(req Message) (*Message, error)

Send a message. Get a response if there is one.

type Handler

type Handler interface {
	// Handle the message and optionally return a response message.
	ServeCOAP(r *RemoteAddr, m *Message) *Message
}

Handler is a type that handles CoAP messages.

type HandlerFunc

type HandlerFunc func(r *RemoteAddr, m *Message) *Message

func (HandlerFunc) ServeCOAP

func (f HandlerFunc) ServeCOAP(r *RemoteAddr, m *Message) *Message

type MediaType

type MediaType byte

MediaType specifies the content type of a message.

type Message

type Message struct {
	Type      COAPType
	Code      COAPCode
	MessageID uint16

	Token, Payload []byte
}

Message is a CoAP message.

func Receive

func Receive(l *net.UDPConn, buf []byte) (Message, error)

Receive a message.

func ReceiveTimeout

func ReceiveTimeout(l *net.UDPConn, rt time.Duration, buf []byte) (Message, error)

Receive a message with timeout.

func (*Message) AddOption

func (m *Message) AddOption(opId OptionID, val interface{})

AddOption adds an option.

func (Message) IsConfirmable

func (m Message) IsConfirmable() bool

IsConfirmable returns true if this message is confirmable.

func (Message) IsObserver

func (m Message) IsObserver() bool

IsObserver returns true if this message is for observe.

func (Message) Option

func (m Message) Option(o OptionID) interface{}

Option gets the first value for the given option ID.

func (Message) Options

func (m Message) Options(o OptionID) []interface{}

Get all the values for the given option.

func (Message) Path

func (m Message) Path() []string

Path gets the Path set on this message if any.

func (Message) PathString

func (m Message) PathString() string

PathString gets a path as a / separated string.

func (*Message) RemoveOption

func (m *Message) RemoveOption(opId OptionID)

RemoveOption removes all references to an option

func (*Message) SetOption

func (m *Message) SetOption(opId OptionID, val interface{})

SetOption sets an option, discarding any previous value

func (*Message) SetPath

func (m *Message) SetPath(s []string)

SetPath updates or adds a LocationPath attribute on this message.

func (*Message) SetPathString

func (m *Message) SetPathString(s string)

SetPathString sets a path by a / separated string.

type OptionID

type OptionID uint8

Option IDs.

type RemoteAddr

type RemoteAddr struct {
	*net.UDPAddr
}

type ServeMux

type ServeMux struct {
}

ServeMux provides mappings from a common endpoint to handlers by request path.

func NewServeMux

func NewServeMux() *ServeMux

NewServeMux creates a new ServeMux.

func (*ServeMux) Handle

func (mux *ServeMux) Handle(pattern string, handler Handler)

Handle configures a handler for the given path.

func (*ServeMux) HandleFunc

func (mux *ServeMux) HandleFunc(pattern string, handler func(r *RemoteAddr, m *Message) *Message)

HandleFunc configures a handler for the given path.

func (*ServeMux) ServeCOAP

func (mux *ServeMux) ServeCOAP(r *RemoteAddr, m *Message) *Message

ServeCOAP handles a single COAP message. The message arrives from the given listener having originated from the given UDPAddr.

type Server

type Server struct {
	Addr           string        // UDP address to listen on, ":coap" if empty
	Handler        Handler       // handler to invoke, coap.ServeMux if nil
	ReadTimeout    time.Duration // maximum duration before timing out read of the request
	WriteTimeout   time.Duration // maximum duration before timing out write of the response
	MaxHeaderBytes int           // maximum size of request headers, DefaultMaxHeaderBytes if 0
}

func (*Server) ListenAndServe

func (srv *Server) ListenAndServe() error

func (*Server) Serve

func (srv *Server) Serve(l *net.UDPConn) error