fix #269 see below

/**
 * Generate a short suffix used to disambiguate channels that might have the same "name" entered by the human but different PSKs.
 * The ideas is that the PSK changing should be visible to the user so that they see they probably messed up and that's why they
their nodes
 * aren't talking to each other.
 *
 * This string is of the form "#name-XY".
 *
 * Where X is a letter from A to Z (base26), and formed by xoring all the bytes of the PSK together.
 * Y is not yet used but should eventually indicate 'speed/range' of the link
 *
 * This function will also need to be implemented in GUI apps that talk to the radio.
 *
 * https://github.com/meshtastic/Meshtastic-device/issues/269
 */
const char *getChannelName();

src/graphics/Screen.cpp

@@ -25,13 +25,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "GPS.h"
 #include "MeshService.h"
 #include "NodeDB.h"
+#include "Screen.h"
+#include "configs.h"
 #include "configuration.h"
 #include "graphics/images.h"
 #include "main.h"
 #include "mesh-pb-constants.h"
-#include "Screen.h"
 #include "utils.h"
-#include "configs.h"
 
 using namespace meshtastic; /** @todo remove */
 
@@ -208,25 +208,20 @@ static void drawNodes(OLEDDisplay *display, int16_t x, int16_t y, NodeStatus *no
 // Draw GPS status summary
 static void drawGPS(OLEDDisplay *display, int16_t x, int16_t y, const GPSStatus *gps)
 {
-    if (!gps->getIsConnected()) 
-    {
+    if (!gps->getIsConnected()) {
         display->drawString(x, y - 2, "No GPS");
         return;
     }
     display->drawFastImage(x, y, 6, 8, gps->getHasLock() ? imgPositionSolid : imgPositionEmpty);
-    if (!gps->getHasLock()) 
-    {
+    if (!gps->getHasLock()) {
         display->drawString(x + 8, y - 2, "No sats");
         return;
-    } 
-    else 
-    {
+    } else {
         char satsString[3];
         uint8_t bar[2] = {0};
 
         // Draw DOP signal bars
-        for(int i = 0; i < 5; i++)
-        {
+        for (int i = 0; i < 5; i++) {
             if (gps->getDOP() <= dopThresholds[i])
                 bar[0] = ~((1 << (5 - i)) - 1);
             else
@@ -390,7 +385,6 @@ static void drawNodeHeading(OLEDDisplay *display, int16_t compassX, int16_t comp
     float arrowOffsetX = 0.2f, arrowOffsetY = 0.2f;
     Point leftArrow(tip.x - arrowOffsetX, tip.y - arrowOffsetY), rightArrow(tip.x + arrowOffsetX, tip.y - arrowOffsetY);
 
-
     Point *arrowPoints[] = {&tip, &tail, &leftArrow, &rightArrow};
 
     for (int i = 0; i < 4; i++) {
@@ -440,8 +434,7 @@ static void drawNodeInfo(OLEDDisplay *display, OLEDDisplayUiState *state, int16_
         displayedNodeNum = n->num;
 
         // We just changed to a new node screen, ask that node for updated state if it's older than 2 minutes
-        if(sinceLastSeen(n) > 120)
-        {
+        if (sinceLastSeen(n) > 120) {
             service.sendNetworkPing(displayedNodeNum, true);
         }
     }
@@ -477,14 +470,12 @@ static void drawNodeInfo(OLEDDisplay *display, OLEDDisplayUiState *state, int16_
     int16_t compassX = x + SCREEN_WIDTH - COMPASS_DIAM / 2 - 5, compassY = y + SCREEN_HEIGHT / 2;
     bool hasNodeHeading = false;
 
-    if(ourNode && hasPosition(ourNode))
-    {
+    if (ourNode && hasPosition(ourNode)) {
         Position &op = ourNode->position;
         float myHeading = estimatedHeading(DegD(op.latitude_i), DegD(op.longitude_i));
         drawCompassHeading(display, compassX, compassY, myHeading);
 
-        if(hasPosition(node)) 
-        { 
+        if (hasPosition(node)) {
             // display direction toward node
             hasNodeHeading = true;
             Position &p = node->position;
@@ -508,7 +499,6 @@ static void drawNodeInfo(OLEDDisplay *display, OLEDDisplayUiState *state, int16_
         display->drawString(compassX - FONT_HEIGHT / 4, compassY - FONT_HEIGHT / 2, "?");
     display->drawCircle(compassX, compassY, COMPASS_DIAM / 2);
 
-
     // Must be after distStr is populated
     drawColumns(display, x, y, fields);
 }
@@ -779,7 +769,7 @@ void DebugInfo::drawFrame(OLEDDisplay *display, OLEDDisplayUiState *state, int16
     char channelStr[20];
     {
         concurrency::LockGuard guard(&lock);
-        snprintf(channelStr, sizeof(channelStr), "#%s", channelName.c_str());
+        snprintf(channelStr, sizeof(channelStr), "%s", channelName.c_str());
 
         // Display power status
         if (powerStatus->getHasBattery())
@@ -827,8 +817,7 @@ void Screen::adjustBrightness()
 int Screen::handleStatusUpdate(const meshtastic::Status *arg)
 {
     // DEBUG_MSG("Screen got status update %d\n", arg->getStatusType());
-    switch(arg->getStatusType())
-    {
+    switch (arg->getStatusType()) {
     case STATUS_TYPE_NODE:
         if (nodeDB.updateTextMessage || nodeStatus->getLastNumTotal() != nodeStatus->getNumTotal())
             setFrames();

src/main.cpp

@@ -364,7 +364,7 @@ void loop()
 #endif
 
     // Update the screen last, after we've figured out what to show.
-    screen.debug_info()->setChannelNameStatus(channelSettings.name);
+    screen.debug_info()->setChannelNameStatus(getChannelName());
     // screen.debug()->setPowerStatus(powerStatus);
 
     // No GPS lock yet, let the OS put the main CPU in low power mode for 100ms (or until another interrupt comes in)

src/mesh/NodeDB.cpp

@@ -66,6 +66,33 @@ static uint8_t ourMacAddr[6];
  */
 NodeNum displayedNodeNum;
 
+/**
+ * Generate a short suffix used to disambiguate channels that might have the same "name" entered by the human but different PSKs.
+ * The ideas is that the PSK changing should be visible to the user so that they see they probably messed up and that's why they
+their nodes
+ * aren't talking to each other.
+ *
+ * This string is of the form "#name-XY".
+ *
+ * Where X is a letter from A to Z (base26), and formed by xoring all the bytes of the PSK together.
+ * Y is not yet used but should eventually indicate 'speed/range' of the link
+ *
+ * This function will also need to be implemented in GUI apps that talk to the radio.
+ *
+ * https://github.com/meshtastic/Meshtastic-device/issues/269
+ */
+const char *getChannelName()
+{
+    static char buf[32];
+
+    uint8_t code = 0;
+    for (int i = 0; i < sizeof(channelSettings.psk.size); i++)
+        code ^= channelSettings.psk.bytes[i];
+
+    snprintf(buf, sizeof(buf), "#%s-%c", channelSettings.name, 'A' + (code % 26));
+    return buf;
+}
+
 NodeDB::NodeDB() : nodes(devicestate.node_db), numNodes(&devicestate.node_db_count) {}
 
 void NodeDB::resetRadioConfig()

src/mesh/NodeDB.h

@@ -1,12 +1,12 @@
 #pragma once
 
+#include "Observer.h"
 #include <Arduino.h>
 #include <assert.h>
-#include "Observer.h"
 
 #include "MeshTypes.h"
-#include "mesh-pb-constants.h"
 #include "NodeStatus.h"
+#include "mesh-pb-constants.h"
 
 extern DeviceState devicestate;
 extern MyNodeInfo &myNodeInfo;
@@ -95,7 +95,8 @@ class NodeDB
     NodeInfo *getOrCreateNode(NodeNum n);
 
     /// Notify observers of changes to the DB
-    void notifyObservers(bool forceUpdate = false) {
+    void notifyObservers(bool forceUpdate = false)
+    {
         // Notify observers of the current node state
         const meshtastic::NodeStatus status = meshtastic::NodeStatus(getNumOnlineNodes(), getNumNodes(), forceUpdate);
         newStatus.notifyObservers(&status);
@@ -115,3 +116,20 @@ class NodeDB
 extern NodeNum displayedNodeNum;
 
 extern NodeDB nodeDB;
+
+/**
+ * Generate a short suffix used to disambiguate channels that might have the same "name" entered by the human but different PSKs.
+ * The ideas is that the PSK changing should be visible to the user so that they see they probably messed up and that's why they
+their nodes
+ * aren't talking to each other.
+ *
+ * This string is of the form "#name-XY".
+ *
+ * Where X is a letter from A to Z (base26), and formed by xoring all the bytes of the PSK together.
+ * Y is not yet used but should eventually indicate 'speed/range' of the link
+ *
+ * This function will also need to be implemented in GUI apps that talk to the radio.
+ *
+ * https://github.com/meshtastic/Meshtastic-device/issues/269
+ */
+const char *getChannelName();

src/mesh/RadioInterface.cpp

@@ -115,6 +115,8 @@ unsigned long hash(char *str)
     return hash;
 }
 
+
+
 #define POWER_DEFAULT 17
 
 /**