Fix data race.

bot/dispatcher.go

@@ -7,15 +7,19 @@ package bot
 import (
 	"log"
 	"strings"
+	"sync"
 
 	cfg "github.com/arachnist/gorepost/config"
 	"github.com/arachnist/gorepost/irc"
 )
 
 var callbacks = make(map[string]map[string]func(func(irc.Message), irc.Message))
+var callbackLock sync.RWMutex
 
 // addCallback registers callbacks that can be later dispatched by Dispatcher
 func addCallback(command, name string, callback func(func(irc.Message), irc.Message)) {
+	callbackLock.Lock()
+	defer callbackLock.Unlock()
 	log.Println("adding callback", command, name)
 	if _, ok := callbacks[command]; !ok {
 		callbacks[command] = make(map[string]func(func(irc.Message), irc.Message))
@@ -33,6 +37,8 @@ func Dispatcher(output func(irc.Message), input irc.Message) {
 		return
 	}
 
+	callbackLock.RLock()
+	defer callbackLock.RUnlock()
 	if callbacks[input.Command] != nil {
 		if len(cfg.LookupStringMap(input.Context, "WhitelistedPlugins")) > 0 {
 			for i, f := range callbacks[input.Command] {