From a4daa772c3186cdf9ba0283d937f49f48b11646a Mon Sep 17 00:00:00 2001
From: cyberman54 <cyberman@obh.snafu.de>
Date: Sun, 27 Dec 2020 00:36:23 +0100
Subject: [PATCH 1/2] generalize hash() function

---
 include/hash.h   | 2 +-
 src/hash.cpp     | 4 ++++
 src/macsniff.cpp | 2 +-
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/hash.h b/include/hash.h
index b86e7b2e..2caa6133 100644
--- a/include/hash.h
+++ b/include/hash.h
@@ -4,6 +4,6 @@
 #include <Arduino.h>
 #include <inttypes.h>
 
-uint32_t IRAM_ATTR rokkit(const char *data, int len);
+uint32_t IRAM_ATTR hash(const char *data, int len);
 
 #endif
\ No newline at end of file
diff --git a/src/hash.cpp b/src/hash.cpp
index e5d268f9..137e98a5 100644
--- a/src/hash.cpp
+++ b/src/hash.cpp
@@ -85,3 +85,7 @@ uint32_t IRAM_ATTR rokkit(const char *data, int len) {
 
   return hash;
 }
+
+uint32_t IRAM_ATTR hash(const char *data, int len) {
+  return rokkit(data, len);
+}
diff --git a/src/macsniff.cpp b/src/macsniff.cpp
index 6fefc07c..3e5e8210 100644
--- a/src/macsniff.cpp
+++ b/src/macsniff.cpp
@@ -141,7 +141,7 @@ uint16_t mac_analyze(MacBuffer_t MacBuffer) {
   snprintf(buff, sizeof(buff), "%08X",
            *mac + (uint32_t)salt); // convert unsigned 32-bit salted MAC
                                    // to 8 digit hex string
-  uint16_t hashedmac = rokkit(&buff[3], 5); // hash MAC 8 digit -> 5 digit
+  uint16_t hashedmac = hash(&buff[3], 5); // hash MAC 8 digit -> 5 digit
   auto newmac = macs.insert(hashedmac);     // add hashed MAC, if new unique
   bool added =
       newmac.second ? true : false; // true if hashed MAC is unique in container

From 1a2f9e04394c926b217767b9867e9193b7ebb887 Mon Sep 17 00:00:00 2001
From: cyberman54 <cyberman@obh.snafu.de>
Date: Sun, 27 Dec 2020 00:40:07 +0100
Subject: [PATCH 2/2] mqttclient.cpp: hash mqtt client name

---
 include/mqttclient.h | 2 +-
 src/mqttclient.cpp   | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/mqttclient.h b/include/mqttclient.h
index 6e351e2a..5e595cca 100644
--- a/include/mqttclient.h
+++ b/include/mqttclient.h
@@ -17,7 +17,7 @@
 #define MQTT_KEEPALIVE 10 // keep alive interval in seconds
 
 #ifndef MQTT_CLIENTNAME
-#define MQTT_CLIENTNAME clientId.c_str()
+#define MQTT_CLIENTNAME clientId
 #endif
 
 extern TaskHandle_t mqttTask;
diff --git a/src/mqttclient.cpp b/src/mqttclient.cpp
index 8e1d5aec..6dd5a89a 100644
--- a/src/mqttclient.cpp
+++ b/src/mqttclient.cpp
@@ -41,7 +41,10 @@ esp_err_t mqtt_init(void) {
 
 int mqtt_connect(const char *my_host, const uint16_t my_port) {
   IPAddress mqtt_server_ip;
-  static String clientId = "paxcounter-" + ETH.macAddress();
+  const uint16_t hashed = hash(&ETH.macAddress()[0], 4); // hash MAC to 4 digits
+  char clientId[16];
+  snprintf(clientId, 16, "paxcounter_%d", hashed);
+
   ESP_LOGI(TAG, "MQTT name is %s", MQTT_CLIENTNAME);
 
   // resolve server host name