Adding a checksum to ICCC messages (#45)

ICCC/HTTPConnector.go

@@ -9,8 +9,8 @@ import (
 	"net/url"
 )
 
-// The HTTP handler for the local ICCC commands. Will used in case, that another server
-// want to utelise an command from this server.
+// The HTTP handler for the local ICCC listeners. Will used in case, that another server
+// want to utelise an listener from this server.
 func ICCCHandler(response http.ResponseWriter, request *http.Request) {
 
 	// Cannot parse the form?
@@ -23,9 +23,9 @@ func ICCCHandler(response http.ResponseWriter, request *http.Request) {
 	// Read the data out of the request:
 	messageData := map[string][]string(request.PostForm)
 
-	// The data must contain at least three fields (command, channel & communication password)
+	// The data must contain at least three fields (command, channel & checksum)
 	if len(messageData) < 3 {
-		Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityCritical, LM.ImpactCritical, LM.MessageNameNETWORK, `The ICCC message contains not enough data: At least the channel, command and password is required!`)
+		Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityCritical, LM.ImpactCritical, LM.MessageNameNETWORK, `The ICCC message contains not enough data: At least the channel, command and checksum is required!`)
 		http.NotFound(response, request)
 		return
 	}
@@ -33,11 +33,17 @@ func ICCCHandler(response http.ResponseWriter, request *http.Request) {
 	// Read the meta data:
 	channel := messageData[`channel`][0]
 	command := messageData[`command`][0]
-	password := messageData[`InternalCommPassword`][0]
+	receivedChecksum := messageData[`checksum`][0]
 
-	// Check the password:
-	if password != Tools.InternalCommPassword() {
-		Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelSECURITY, LM.SeverityCritical, LM.ImpactNone, LM.MessageNamePASSWORD, `Received a ICCC message with wrong password!`, request.RemoteAddr)
+	// Remove the checksum as preparation for the re-hash:
+	delete(messageData, `checksum`)
+
+	// Re-hash the received message:
+	receivedMessageHash := signMessage(messageData).Get(`checksum`)
+
+	// Check the checksums:
+	if receivedChecksum != receivedMessageHash {
+		Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelSECURITY, LM.SeverityCritical, LM.ImpactNone, LM.MessageNamePASSWORD, `Received a ICCC message with wrong checksum!`, request.RemoteAddr, fmt.Sprintf("channel=%s", channel), fmt.Sprintf("command=%s", command))
 		http.NotFound(response, request)
 		return
 	}

ICCC/Send.go

@@ -4,7 +4,6 @@ import (
 	"github.com/SommerEngineering/Ocean/ICCC/Scheme"
 	"github.com/SommerEngineering/Ocean/Log"
 	LM "github.com/SommerEngineering/Ocean/Log/Meta"
-	"github.com/SommerEngineering/Ocean/Tools"
 	"io/ioutil"
 	"net/http"
 	"net/url"
@@ -12,11 +11,9 @@ import (
 
 // Send a message to a listener.
 func sendMessage(listener Scheme.Listener, data map[string][]string) (result map[string][]string) {
-	// Convert the data and encode it:
-	valuesHTTP := url.Values(data)
 
-	// Add the communication password:
-	valuesHTTP.Add(`InternalCommPassword`, Tools.InternalCommPassword())
+	// Lets sign the data:
+	valuesHTTP := signMessage(data)
 
 	// Try to deliver the message:
 	if response, err := http.PostForm(`http://`+listener.IPAddressPort+`/ICCC`, valuesHTTP); err != nil {

ICCC/SignMessage.go

@@ -0,0 +1,47 @@
+package ICCC
+
+import (
+	"crypto/sha512"
+	"fmt"
+	"github.com/SommerEngineering/Ocean/Tools"
+	"net/url"
+	"sort"
+)
+
+// Sign a message to secure it.
+func signMessage(data map[string][]string) (result url.Values) {
+	// Create the hash generator:
+	hash := sha512.New()
+
+	// To the start, we hash the password:
+	fmt.Fprintf(hash, "%s", Tools.InternalCommPassword())
+
+	// Because the order of a map is random, we have to sort
+	// the keys beforehand. Next, we can use the ordered keys
+	// to access the data:
+	keys := []string{}
+
+	// Get all keys:
+	for key := range data {
+		keys = append(keys, key)
+	}
+
+	// Sort the keys:
+	sort.Strings(keys)
+
+	// Now, loop over all the data:
+	for _, key := range keys {
+		// Get the value:
+		value := data[key]
+
+		// Hash each key and value:
+		fmt.Fprintf(hash, "key=%s :: value=%s\n", key, value)
+	}
+
+	// Create the result:
+	result = url.Values(data)
+
+	// Append the sign:
+	result.Add(`checksum`, fmt.Sprintf("%x", hash.Sum(nil)))
+	return
+}