eapilib.go

//
// Copyright (c) 2015-2016, Arista Networks, Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//   * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
//   * Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the distribution.
//
//   * Neither the name of Arista Networks nor the names of its
//   contributors may be used to endorse or promote products derived from
//   this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ARISTA NETWORKS
// BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
// OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
// IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//

package goeapi

import (
	"bytes"
	"crypto/tls"
	"crypto/x509"
	"encoding/json"
	"fmt"
	"net"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"
)

// EapiConnectionEntity is an interface representing the ability to execute a
// single json transaction, obtaining the Response for a given Request.
type EapiConnectionEntity interface {
	Execute(commands []interface{}, encoding string) (*JSONRPCResponse, error)
	SetTimeout(to uint32)
	SetDisableKeepAlive(disableKeepAlive bool)
	Error() error
}

// EapiConnection represents the base object for implementing an EapiConnection
// type. This clase should not be instantiated directly
type EapiConnection struct {
	transport        string
	err              error
	url              string
	host             string
	port             int
	path             string
	auth             *url.Userinfo
	timeOut          uint32
	disableKeepAlive bool
}

// Execute the list of commands on the destination node. In the case of
// EapiConnection, this serves as a base model and is not fully implemented.
//
// Args:
//
//	commands ([]interface): list of commands to execute on remote node
//	encoding (string): The encoding to send along with the request
//	                    message to the destination node.  Valid values include
//	                    'json' or 'text'.  This argument will influence the
//	                    response encoding
//
// Returns:
//
//	pointer to JSONRPCResponse or error on failure
func (conn *EapiConnection) Execute(commands []interface{},
	encoding string) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No connection")
	}
	return &JSONRPCResponse{}, fmt.Errorf("Not Currently Implemented")
}

// Authentication Configures the user authentication for eAPI. This method
// configures the username and password combination to use for authenticating
// to eAPI.
//
// Args:
//
//	username (string): The username to use to authenticate the eAPI
//	                    connection with
//	password (string): The password in clear text to use to authenticate
//	                    the eAPI connection with
func (conn *EapiConnection) Authentication(username string, passwd string) {
	username = strings.Replace(username, "\n", "", -1)
	passwd = strings.Replace(passwd, "\n", "", -1)
	conn.auth = url.UserPassword(username, passwd)
}

// getURL helper method to prebuild url for http/s
func (conn *EapiConnection) getURL() string {
	if conn == nil {
		return ""
	}
	var parsedURL url.URL
	if conn.transport == "https_certs" {
		parsedURL = url.URL{
			Scheme: "https", // As conn.transport is "https_certs"
			Host:   conn.host + ":" + strconv.Itoa(conn.port),
			Path:   "/command-api",
		}
	} else {
		parsedURL = url.URL{
			Scheme: conn.transport,
			User:   conn.auth,
			Host:   conn.host + ":" + strconv.Itoa(conn.port),
			Path:   "/command-api",
		}
	}
	return parsedURL.String()
}

// Error returns the current error for Connection
func (conn *EapiConnection) Error() error {
	if conn == nil {
		return nil
	}
	return conn.err
}

// SetError sets error for Connection
func (conn *EapiConnection) SetError(e error) {
	if conn == nil {
		return
	}
	conn.err = e
}

// ClearError clears any error for Connection
func (conn *EapiConnection) ClearError() {
	if conn == nil {
		return
	}
	conn.err = nil
}

// SetTimeout sets timeout value for Connection
func (conn *EapiConnection) SetTimeout(timeOut uint32) {
	var val uint32
	if conn == nil {
		return
	}

	if timeOut > 65535 {
		val = 60
	} else {
		val = timeOut
	}
	conn.timeOut = val
}

// SetDisableKeepAlive sets disablekeepalive value for Connection
func (conn *EapiConnection) SetDisableKeepAlive(disableKeepAlive bool) {
	conn.disableKeepAlive = disableKeepAlive
}

// buildJSONRequest builds a JSON request given a list of commands, encoding
// type of either json or text, and request id. The command list input is made
// up of a list of interface{} types. This is so associative entries and list
// entries both can be used. Returns []byte of the built JSON request.
// Successful call returns err == nil.
func buildJSONRequest(commands []interface{},
	encoding string, reqid string) ([]byte, error) {
	p := Parameters{1, commands, encoding}

	req := Request{"2.0", "runCmds", p, reqid}
	data, err := json.Marshal(req)
	//debugJSON(data)
	return data, err
}

// SocketEapiConnection represents the EapiConnection for handling Socket
// level transactions
type SocketEapiConnection struct {
	EapiConnection
}

const defaultUnixSocket = "/var/run/command-api.sock"

// NewSocketEapiConnection initializes a SocketEapiConnection.
//
// Args:
//
//	transport (string): The transport to use to create the instance.
//	host (string): The IP addres or DNS host name of the connection device.
//	username(string): The username to pass to the device to authenticate
//	                  the eAPI connection.
//	password(string): The password to pass to the device to authenticate
//	                  the eAPI connection. The default value is ''
//	port(int): The TCP port of the endpoint for the eAPI connection.
//
// Returns:
//
//	Newly created SocketEapiConnection
func NewSocketEapiConnection(transport string, host string, username string,
	password string, port int) EapiConnectionEntity {
	conn := EapiConnection{transport: transport, host: host, port: port, timeOut: 60}
	return &SocketEapiConnection{conn}
}

// send the eAPI request to the destination node
//
// This method is responsible for sending an eAPI request to the
// destination node and returning a response based on the JSONRPCResponse
// object.  eAPI responds to request messages with either a success
// message or failure message. On successful decode of the Response,
// a JSONRPCResponse type is returned. Otherwise err is returned.
func (conn *SocketEapiConnection) send(data []byte) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No Connection")
	}

	timeOut := time.Duration(time.Duration(conn.timeOut) * time.Second)

	// We create our fake URL. Post() will be checking the format, but it ignores
	// the fqhn. Also we replace the Dial func with our own fakeDial() to create
	// the socket connection. By doing this, we can leverage the
	// client.Post/Get methods to compose our headers, etc..
	//
	fakeURL := "http://localhost/command-api"
	var fakeDial = func(proto, addr string) (conn net.Conn, err error) {
		return net.Dial("unix", defaultUnixSocket)
	}

	client := &http.Client{
		Timeout: timeOut,
		Transport: &http.Transport{
			Dial: fakeDial,
		},
	}

	resp, err := client.Post(fakeURL, "application/json", bytes.NewReader(data))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}

	defer func() {
		if cerr := resp.Body.Close(); cerr != nil {
			err = cerr
			conn.SetError(err)
		}
	}()

	jsonRsp, err := decodeEapiResponse(resp)
	if err != nil {
		conn.SetError(err)
		return jsonRsp, err
	}
	return jsonRsp, nil
}

// Execute the list of commands on the destination node
//
// This method takes a list of commands and sends them to the
// destination node, returning the results. It is assumed that the
// list of commands (type []interface{}) has been properly built and
// enable mode passwd is set if needed. On success, a reference
// to JSONRPCResponse is returned...otherwise err is set.
//
// Args:
//
//	commands ([]interface): list of commands to execute on remote node
//	encoding (string): The encoding to send along with the request
//	                    message to the destination node.  Valid values include
//	                    'json' or 'text'.  This argument will influence the
//	                    response encoding
//
// Returns:
//
//	pointer to JSONRPCResponse or error on failure
func (conn *SocketEapiConnection) Execute(commands []interface{},
	encoding string) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No connection")
	}
	conn.ClearError()
	data, err := buildJSONRequest(commands, encoding, strconv.Itoa(os.Getpid()))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}
	return conn.send(data)
}

// HTTPLocalEapiConnection is an EapiConnection suited for local HTTP connection
type HTTPLocalEapiConnection struct {
	EapiConnection
}

// UseDefaultPortNum recommends the underlying api to use default value for
// Port Number.
const UseDefaultPortNum = -1

// DefaultHTTPLocalPort uses 8080
const DefaultHTTPLocalPort = 8080

// NewHTTPLocalEapiConnection initializes a HTTPLocalEapiConnection.
//
// Args:
//
//	transport (string): The transport to use to create the instance.
//	host (string): The IP addres or DNS host name of the connection device.
//	username(string): The username to pass to the device to authenticate
//	                  the eAPI connection.
//	password(string): The password to pass to the device to authenticate
//	                  the eAPI connection. The default value is ''
//	port(int): The TCP port of the endpoint for the eAPI connection.
//
// Returns:
//
//	Newly created SocketEapiConnection
func NewHTTPLocalEapiConnection(transport string, host string, username string,
	password string, port int) EapiConnectionEntity {
	if port == UseDefaultPortNum {
		port = DefaultHTTPLocalPort
	}
	conn := EapiConnection{transport: transport, host: host, port: port, timeOut: 60}
	return &HTTPLocalEapiConnection{conn}
}

// send the eAPI request to the destination node
//
// This method is responsible for sending an eAPI request to the
// destination node and returning a response based on the JSONRPCResponse
// object.  eAPI responds to request messages with either a success
// message or failure message. On successful decode of the Response,
// a JSONRPCResponse type is returned. Otherwise err is returned.
//
// Args:
//
//	data ([]byte): data to be sent
//
// Returns:
//
//	ptr to JSONRPCResponse on success. Otherwise error will be returned.
func (conn *HTTPLocalEapiConnection) send(data []byte) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No Connection")
	}
	return &JSONRPCResponse{}, fmt.Errorf("Not Currently Implemented")
}

// Execute the list of commands
//
// This method takes a list of commands and sends them to the
// destination node, returning the results. It is assumed that the
// list of commands (type []interface{}) has been properly built and
// enable mode passwd is set if needed. On success, a reference
// to JSONRPCResponse is returned...otherwise err is set.
//
// Args:
//
//	commands ([]interface): list of commands to execute on remote node
//	encoding (string): The encoding to send along with the request
//	                    message to the destination node.  Valid values include
//	                    'json' or 'text'.  This argument will influence the
//	                    response encoding
//
// Returns:
//
//	pointer to JSONRPCResponse or error on failure
func (conn *HTTPLocalEapiConnection) Execute(commands []interface{},
	encoding string) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No connection")
	}
	conn.ClearError()
	data, err := buildJSONRequest(commands, encoding, strconv.Itoa(os.Getpid()))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}
	return conn.send(data)
}

// HTTPEapiConnection is an EapiConnection suited for HTTP connection
type HTTPEapiConnection struct {
	EapiConnection
}

// DefaultHTTPPort uses 80
const DefaultHTTPPort = 80

// NewHTTPEapiConnection initializes a HttpEapiConnection.
//
// Args:
//
//	transport (string): The transport to use to create the instance.
//	host (string): The IP addres or DNS host name of the connection device.
//	username(string): The username to pass to the device to authenticate
//	                  the eAPI connection.
//	password(string): The password to pass to the device to authenticate
//	                  the eAPI connection. The default value is ''
//	port(int): The TCP port of the endpoint for the eAPI connection.
//
// Returns:
//
//	Newly created HTTPEapiConnection
func NewHTTPEapiConnection(transport string, host string, username string,
	password string, port int) EapiConnectionEntity {
	if port == UseDefaultPortNum {
		port = DefaultHTTPPort
	}
	conn := EapiConnection{transport: transport, host: host, port: port, timeOut: 60, disableKeepAlive: false}
	conn.Authentication(username, password)
	return &HTTPEapiConnection{conn}
}

// send the eAPI request to the destination node
//
// This method is responsible for sending an eAPI request to the
// destination node and returning a response based on the JSONRPCResponse
// object.  eAPI responds to request messages with either a success
// message or failure message. On successful decode of the Response,
// a JSONRPCResponse type is returned. Otherwise err is returned.
//
// Args:
//
//	data ([]byte): data to be sent
//
// Returns:
//
//	ptr to JSONRPCResponse on success. Otherwise error will be returned.
func (conn *HTTPEapiConnection) send(data []byte) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No Connection")
	}

	tr := &http.Transport{
		DisableKeepAlives: conn.disableKeepAlive,
	}

	timeOut := time.Duration(time.Duration(conn.timeOut) * time.Second)
	client := &http.Client{
		Timeout:   timeOut,
		Transport: tr,
	}
	url := conn.getURL()
	resp, err := client.Post(url, "application/json", bytes.NewReader(data))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}

	defer func() {
		if cerr := resp.Body.Close(); cerr != nil {
			err = cerr
			conn.SetError(err)
		}
	}()

	jsonRsp, err := decodeEapiResponse(resp)
	if err != nil {
		conn.SetError(err)
		return jsonRsp, err
	}
	return jsonRsp, nil
}

// Execute the list of commands on the destination node
//
// This method takes a list of commands and sends them to the
// destination node, returning the results. It is assumed that the
// list of commands (type []interface{}) has been properly built and
// enable mode passwd is set if needed. On success, a reference
// to JSONRPCResponse is returned...otherwise err is set.
//
// Args:
//
//	commands ([]interface): list of commands to execute on remote node
//	encoding (string): The encoding to send along with the request
//	                    message to the destination node.  Valid values include
//	                    'json' or 'text'.  This argument will influence the
//	                    response encoding
//
// Returns:
//
//	pointer to JSONRPCResponse or error on failure
func (conn *HTTPEapiConnection) Execute(commands []interface{},
	encoding string) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No connection")
	}
	conn.ClearError()
	data, err := buildJSONRequest(commands, encoding, strconv.Itoa(os.Getpid()))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}
	return conn.send(data)
}

// HTTPSEapiConnection is an EapiConnection suited for HTTP connection
type HTTPSEapiConnection struct {
	EapiConnection
	path                string
	enforceVerification bool
}

// DefaultHTTPSPort default port used by https
const DefaultHTTPSPort = 443

// DefaultHTTPSPath command path
const DefaultHTTPSPath = "/command-api"

// NewHTTPSEapiConnection initializes an HttpsEapiConnection.
//
// Args:
//
//	transport (string): The transport to use to create the instance.
//	host (string): The IP addres or DNS host name of the connection device.
//	username(string): The username to pass to the device to authenticate
//	                  the eAPI connection.
//	password(string): The password to pass to the device to authenticate
//	                  the eAPI connection. The default value is ''
//	port(int): The TCP port of the endpoint for the eAPI connection.
//
// Returns:
//
//	Newly created HTTPSEapiConnection
func NewHTTPSEapiConnection(transport string, host string, username string,
	password string, port int) EapiConnectionEntity {
	if port == UseDefaultPortNum {
		port = DefaultHTTPSPort
	}
	path := DefaultHTTPSPath

	conn := EapiConnection{transport: transport, host: host, port: port, timeOut: 60, disableKeepAlive: false}

	conn.Authentication(username, password)
	return &HTTPSEapiConnection{path: path, EapiConnection: conn}
}

// send the eAPI request to the destination node
//
// This method is responsible for sending an eAPI request to the
// destination node and returning a response based on the JSONRPCResponse
// object.  eAPI responds to request messages with either a success
// message or failure message. On successful decode of the Response,
// a JSONRPCResponse type is returned. Otherwise err is returned.
//
// Args:
//
//	data ([]byte): data to be sent
//
// Returns:
//
//	ptr to JSONRPCResponse on success. Otherwise error will be returned.
func (conn *HTTPSEapiConnection) send(data []byte) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No Connection")
	}
	timeOut := time.Duration(time.Duration(conn.timeOut) * time.Second)
	url := conn.getURL()
	suites := []uint16{}
	for _, suite := range tls.CipherSuites() {
		suites = append(suites, suite.ID)
	}
	for _, suite := range tls.InsecureCipherSuites() {
		suites = append(suites, suite.ID)
	}
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true,
			CipherSuites:       suites,
		},
		DisableKeepAlives: conn.disableKeepAlive,
	}
	client := &http.Client{
		Timeout:   timeOut,
		Transport: tr,
	}

	resp, err := client.Post(url, "application/json", bytes.NewReader(data))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}

	defer func() {
		if cerr := resp.Body.Close(); cerr != nil {
			err = cerr
			conn.SetError(err)
		}
	}()

	jsonRsp, err := decodeEapiResponse(resp)
	if err != nil {
		conn.SetError(err)
		return jsonRsp, err
	}
	return jsonRsp, nil
}

// Execute the list of commands on the destination node
//
// This method takes a list of commands and sends them to the
// destination node, returning the results. It is assumed that the
// list of commands (type []interface{}) has been properly built and
// enable mode passwd is set if needed. On success, a reference
// to JSONRPCResponse is returned...otherwise err is set.
//
// Args:
//
//	commands ([]interface): list of commands to execute on remote node
//	encoding (string): The encoding to send along with the request
//	                    message to the destination node.  Valid values include
//	                    'json' or 'text'.  This argument will influence the
//	                    response encoding
//
// Returns:
//
//	pointer to JSONRPCResponse or error on failure
func (conn *HTTPSEapiConnection) Execute(commands []interface{},
	encoding string) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No connection")
	}
	conn.ClearError()
	data, err := buildJSONRequest(commands, encoding, strconv.Itoa(os.Getpid()))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}
	return conn.send(data)
}

// disableCertificateVerification disables https verification
func (conn *HTTPSEapiConnection) disableCertificateVerification() {
	conn.enforceVerification = false
}

// enableCertificateVerification enables https verification
func (conn *HTTPSEapiConnection) enableCertificateVerification() {
	conn.enforceVerification = true
}

// HTTPSCertsEapiConnection is an EapiConnection suited for HTTPS connection
type HTTPSCertsEapiConnection struct {
	EapiConnection
	path       string // Request URL
	keyFile    string // Path to the Client Private Key file
	certFile   string // Path to the Client Certificate file
	caCertFile string // Path to the CA certificate file
}

// NewHTTPSCertsEapiConnection initializes an HTTPSCertsEapiConnection.
//
// Args:
//
//		transport (string): The transport to use to create the instance,
//							which is "https_certs"
//		host (string): The IP address or DNS host name of the connection device.
//		keyFile(string): The path to the Client's Private Key file which will be pass to the device
//		certFile(string): The path to the Client's Certificate which will be pass to the device
//		                  to authenticate the eAPI connection.
//		caCertFile(string): The path to the CA Certificate file which will be used to verify against's
//	        				switch's certificate.
//		port(int): The TCP port of the endpoint for the eAPI connection.
//
// Returns:
//
//	Newly created HTTPSCertsEapiConnection
func NewHTTPSCertsEapiConnection(transport, host, keyFile, certFile, caCertFile string, port int) EapiConnectionEntity {
	if port == UseDefaultPortNum {
		port = DefaultHTTPSPort
	}
	path := DefaultHTTPSPath

	conn := EapiConnection{transport: transport, host: host, port: port, timeOut: 60, disableKeepAlive: false}

	return &HTTPSCertsEapiConnection{path: path, EapiConnection: conn, keyFile: keyFile, certFile: certFile, caCertFile: caCertFile}
}

// send the eAPI request to the destination node
//
// This method is responsible for sending an eAPI request to the
// destination node and returning a response based on the JSONRPCResponse
// object.  eAPI responds to request messages with either a success
// message or failure message. On successful decode of the Response,
// a JSONRPCResponse type is returned. Otherwise err is returned.
//
// Args:
//
//	data ([]byte): data to be sent
//
// Returns:
//
//	ptr to JSONRPCResponse on success. Otherwise error will be returned.
func (conn *HTTPSCertsEapiConnection) send(data []byte) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No Connection")
	}
	timeOut := time.Duration(time.Duration(conn.timeOut) * time.Second)
	url := conn.getURL()

	cert, err := tls.LoadX509KeyPair(conn.certFile, conn.keyFile)
	if err != nil {
		conn.SetError(err)
		return nil, err
	}

	tlsConfig := &tls.Config{
		InsecureSkipVerify: true,
		Certificates:       []tls.Certificate{cert},
		RootCAs:            x509.NewCertPool(),
	}

	// Handle CA Certificate if provided
	if conn.caCertFile != "" {
		caCert, err := os.ReadFile(conn.caCertFile)
		if err != nil {
			conn.SetError(err)
			return nil, fmt.Errorf("failed to read CA certificate file: %v", err)
		}
		if ok := tlsConfig.RootCAs.AppendCertsFromPEM(caCert); !ok {
			conn.SetError(fmt.Errorf("failed to append CA certificate to pool"))
			return nil, fmt.Errorf("failed to append CA certificate to pool")
		}
	}

	tr := &http.Transport{
		TLSClientConfig:   tlsConfig,
		DisableKeepAlives: conn.disableKeepAlive,
	}
	client := &http.Client{
		Timeout:   timeOut,
		Transport: tr,
	}

	resp, err := client.Post(url, "application/json", bytes.NewReader(data))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}

	defer func() {
		if cerr := resp.Body.Close(); cerr != nil {
			err = cerr
			conn.SetError(err)
		}
	}()

	jsonRsp, err := decodeEapiResponse(resp)
	if err != nil {
		conn.SetError(err)
		return jsonRsp, err
	}
	return jsonRsp, nil
}

// Execute the list of commands on the destination node
//
// This method takes a list of commands and sends them to the
// destination node, returning the results. It is assumed that the
// list of commands (type []interface{}) has been properly built and
// enable mode passwd is set if needed. On success, a reference
// to JSONRPCResponse is returned...otherwise err is set.
//
// Args:
//
//	commands ([]interface): list of commands to execute on remote node
//	encoding (string): The encoding to send along with the request
//	                    message to the destination node.  Valid values include
//	                    'json' or 'text'.  This argument will influence the
//	                    response encoding
//
// Returns:
//
//	pointer to JSONRPCResponse or error on failure
func (conn *HTTPSCertsEapiConnection) Execute(commands []interface{},
	encoding string) (*JSONRPCResponse, error) {
	if conn == nil {
		return &JSONRPCResponse{}, fmt.Errorf("No connection")
	}
	conn.ClearError()
	data, err := buildJSONRequest(commands, encoding, strconv.Itoa(os.Getpid()))
	if err != nil {
		conn.SetError(err)
		return &JSONRPCResponse{}, err
	}
	return conn.send(data)
}