README

wsrpc

Module github.com/jrick/wsrpc provides a partial implementation of a JSON-RPC 2.0 websocket client. Inspired by net/rpc, clients call methods by their name with arguments and return values marshaled by encoding/json. The client may be used to create convenience calls with types specific to an application.

Receiving notifications is supported but it is up to the caller to unmarshal the JSON-RPC parameters into meaningful data.

This module currently does not implement JSON-RPC 2.0 request batching or keyed request parameters when performing calls.

CLI

A command line tool is provided to perform individual websocket JSON-RPCs against a server.

A JSON array must be used to pass parameters in a method call.

$ wsrpc -h
usage: wsrpc address [flags] method [arg]
  -c string
        Root certificate PEM file
  -p string
        Password
  -u string
        User
$ wsrpc wss://dcrd0.i.zettaport.com:9109/ws -c dcrd0.pem -u jrick -p sekrit getinfo
{
  "version": 1050000,
  "protocolversion": 6,
  "blocks": 324795,
  "timeoffset": 0,
  "connections": 65,
  "proxy": "",
  "difficulty": 19920803496.64989,
  "testnet": false,
  "relayfee": 0.0001,
  "errors": ""
}
$ wsrpc wss://dcrd0.i.zettaport.com:9109/ws -c dcrd0.pem -u jrick -p sekrit getblockhash '[324795]'
"0000000000000000235b1210221d412c428237175dbb0aef202277d1706b9312"

The wsrpc-agent tool can be optionally used to manage persistent connections. Usage of the agent is similar to ssh-agent. The agent can exec a command, running only so long as the command continues to run, or by daemonizing and using eval to set the environment of the Bourne shell:

$ wsrpc-agent -h
usage (exec):   wsrpc-agent cmd [args...]
usage (daemon): eval $(wsrpc-agent)

Once running, wsrpc will use the WSRPCAGENT_SOCK and WSRPCAGENT_AUTH environment variables to perform IPC with the agent. TLS and RPC authentication flags only apply to the initial connection.

$ eval `wsrpc-agent`
Agent listening on /tmp/wsrpc732266934/agent.19981
$ wsrpc wss://dcrd0.i.zettaport.com:9109/ws -c dcrd0.pem -u jrick -p sekrit getblockhash '[324795]'
"0000000000000000235b1210221d412c428237175dbb0aef202277d1706b9312"
$ wsrpc wss://dcrd0.i.zettaport.com:9109/ws getblockhash '[324795]'
"0000000000000000235b1210221d412c428237175dbb0aef202277d1706b9312"

License

wsrpc is licensed under the permissive ISC License.

Documentation

Overview

Package wsrpc provides a partial implementation of a JSON-RPC 2.0 websocket client. Inspired by net/rpc, clients call methods by their name with arguments and return values marshaled by encoding/json. The client may be used to create convenience calls with types specific to an application.

Receiving notifications is supported but it is up to the caller to unmarshal the JSON-RPC parameters into meaningful data.

This package currently does not implement JSON-RPC 2.0 request batching or keyed request parameters when performing calls.

Index

• type Client
  • func Dial(ctx context.Context, addr string, opts ...Option) (*Client, error)
  • func (c *Client) Address() string
  • func (c *Client) Call(ctx context.Context, method string, result interface{}, args ...interface{}) (err error)
  • func (c *Client) Close() error
  • func (c *Client) Err() error
• type DialFunc
• type Error
  • func (e *Error) Error() string
• type Notification
• type Notifier
• type Option
  • func WithBasicAuth(user, pass string) Option
  • func WithDial(dial DialFunc) Option
  • func WithNotifier(n Notifier) Option
  • func WithTLSConfig(tls *tls.Config) Option

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client implements JSON-RPC calls and notifications over a websocket.

func Dial

func Dial(ctx context.Context, addr string, opts ...Option) (*Client, error)

Dial establishes an RPC client connection to the server described by addr. Addr must be the URL of the websocket, e.g., "wss://[::1]:9109/ws".

func (*Client) Address

func (c *Client) Address() string

Address returns the dialed network address.

func (*Client) Call

func (c *Client) Call(ctx context.Context, method string, result interface{}, args ...interface{}) (err error)

Call performs the JSON-RPC described by method with positional parameters passed through args. Result should point to an object to unmarshal the result, or equal nil to discard the result.

func (*Client) Close

func (c *Client) Close() error

Close closes the underlying websocket connection.

func (*Client) Err

func (c *Client) Err() error

Err blocks until the client has shutdown and returns the final error.

type DialFunc

type DialFunc func(network, address string) (net.Conn, error)

DialFunc dials a network connection. Custom dialers may utilize a proxy or set connection timeouts.

type Error

type Error struct {
	Code    int64           `json:"code"`
	Message string          `json:"message"`
	Data    json.RawMessage `json:"data,omitempty"`
}

Error represents a JSON-RPC error object.

func (*Error) Error

func (e *Error) Error() string

type Notification

type Notification struct {
	Method string
	Params json.RawMessage
}

Notification represents a JSON-RPC notification. Method defines the type of notification and Params describes the arguments (positional or keyed) if any were included in the Request object.

type Notifier

type Notifier chan Notification

Notifier is a channel of received JSON-RPC notifications. Notifications are sent in the order received. Notifier is closed after the client connection is broken. Notifications may be read from the channel after client disconnect if there is enough backpressure.

type Option

type Option func(*options)

Option modifies the behavior of Dial.

func WithBasicAuth

func WithBasicAuth(user, pass string) Option

WithBasicAuth enables basic access authentication using the user and password.

func WithDial

func WithDial(dial DialFunc) Option

WithDial specifies a custom dial function.

func WithNotifier

func WithNotifier(n Notifier) Option

WithNotifier specifies a channel to read received JSON-RPC notifications. The channel is closed when no futher notifications will be sent. Notifications may be read from the channel after the client has closed.

func WithTLSConfig

func WithTLSConfig(tls *tls.Config) Option

WithTLSConfig specifies a TLS config when connecting to a secure websocket (wss) server. If unspecified, the default TLS config will be used.