Tailor to Ubiquiti UniFi UPS units

README.md

@@ -1,4 +1,34 @@
-Package nut implements the Network UPS Tools network protocol.
+# uni-nut
+This is a subset of [go-nut](https://github.com/dominikh/go-nut) meant specifically for connecting to and monitoring variables on Ubiquiti UniFi UPS NUT servers.
 
-This package only implements those functions necessary for the
-nut_exporter; it is therefore not complete.
+Ubiquiti UPS units seem to use a somewhat non-standard format for responses from the in-built NUT server. Because of this, many existing NUT clients (including the module this project was forked off of) fail to function with Ubiquiti UPS units.
+
+## Usage
+1. Enable the NUT server on your Ubiquiti UniFi-connected UPS unit.
+    - Do **NOT** enable the "Login Credential" option!
+2. This module can now be used to get variables from your UPS's NUT server as follows:
+```go
+package main
+
+import (
+	"fmt"
+
+	nut "github.com/rwinkhart/uni-nut"
+)
+
+func main() {
+	host := "IP:PORT"
+	upsID := "UPS-ID"
+	client, err := nut.Dial(host)
+	if err != nil {
+		panic(err)
+	}
+	err = client.GetListVar(upsID)
+	if err != nil {
+		panic(err)
+	}
+	for key, value := range nut.NutKeyValMap {
+		fmt.Println(key + ": " + value)
+	}
+}
+```

nut.go

@@ -1,15 +1,9 @@
-// Package nut implements the Network UPS Tools network protocol.
-//
-// This package only implements those functions necessary for the
-// nut_exporter; it is therefore not complete.
 package nut
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
 	"net"
-	"strconv"
 	"strings"
 )
 
@@ -19,6 +13,9 @@ type Client struct {
 	br   *bufio.Reader
 }
 
+// Global map to be updated by GetListVar and read by the importing program.
+var NutKeyValMap = make(map[string]string)
+
 // Dial dials a NUT server using TCP. If the address does not contain
 // a port number, it will default to 3493.
 func Dial(addr string) (*Client, error) {
@@ -31,12 +28,7 @@ func Dial(addr string) (*Client, error) {
 	if err != nil {
 		return nil, err
 	}
-	return NewClient(conn), nil
-}
-
-// NewClient wraps an existing net.Conn.
-func NewClient(conn net.Conn) *Client {
-	return &Client{conn, bufio.NewReader(conn)}
+	return newClient(conn), nil
 }
 
 // Close closes the connection.
@@ -44,80 +36,34 @@ func (c *Client) Close() error {
 	return c.conn.Close()
 }
 
-func (c *Client) list(typ string) ([]string, error) {
-	cmd := "LIST " + typ
+func (c *Client) GetListVar(upsID string) error {
+	cmd := "LIST VAR \"" + upsID + "\""
 	if err := c.write(cmd); err != nil {
-		return nil, err
+		return err
 	}
 	l, err := c.read()
 	if err != nil {
-		return nil, err
+		return err
 	}
 	expected := "BEGIN " + cmd
 	if l != expected {
-		return nil, fmt.Errorf("expected %q, got %q", expected, l)
+		return fmt.Errorf("pre-loop error: expected %q, got %q", expected, l)
 	}
 
-	var lines []string
-	expected = typ + " "
 	for {
-		l, err := c.read()
-		if err != nil {
-			return nil, err
-		}
-		if l == "END "+cmd {
+		l, _ := c.read()
+		if !strings.HasPrefix(l, "VAR \""+upsID+"\" ") {
 			break
 		}
-		if !strings.HasPrefix(l, expected) {
-			return nil, fmt.Errorf("expected %q, got %q", expected, l)
-		}
-		l = l[len(expected):]
-		lines = append(lines, l)
+		lSplit := strings.Split(l, " ")
+		NutKeyValMap[strings.Trim(lSplit[2], "\"")] = strings.Trim(strings.Join(lSplit[3:], " "), "\"")
 	}
-	return lines, nil
+	return nil
 }
 
-// UPSs returns a list of all UPSs on the server.
-func (c *Client) UPSs() ([]string, error) {
-	lines, err := c.list("UPS")
-	if err != nil {
-		return nil, err
-	}
-
-	var upss []string
-	for _, l := range lines {
-		idx := strings.IndexByte(l, ' ')
-		if idx == -1 {
-			return nil, errors.New("protocol error")
-		}
-		ups := l[:idx]
-		upss = append(upss, ups)
-	}
-	return upss, nil
-}
-
-// Variables returns all variables and their values for a UPS.
-func (c *Client) Variables(ups string) (map[string]string, error) {
-	lines, err := c.list("VAR " + ups)
-	if err != nil {
-		return nil, err
-	}
-	vars := map[string]string{}
-	for _, l := range lines {
-		idx := strings.IndexByte(l, ' ')
-		if idx == -1 {
-			return nil, errors.New("protocol error")
-		}
-		k := l[:idx]
-		v := l[idx+1:]
-		v, err = strconv.Unquote(v)
-		if err != nil {
-			return nil, err
-		}
-
-		vars[k] = v
-	}
-	return vars, nil
+// newClient wraps an existing net.Conn.
+func newClient(conn net.Conn) *Client {
+	return &Client{conn, bufio.NewReader(conn)}
 }
 
 func (c *Client) write(s string) error {