Optimized and fixed degraded GetBulk responses

examples/ESP32_SNMP/ESP32_SNMP.ino

@@ -49,13 +49,22 @@ TimestampCallback* timestampCallbackOID;
 
 char staticString[] = "This value will never change";
 
+/* Versioned sysDescr served on .1.3.6.1.2.1.1.1.0 — the handler keeps the pointer,
+   so this must be a static buffer, not a local. Lets `snmpget` confirm the exact
+   library build running on the chip during hardware testing. */
+static char sysDescrBuf[64];
+
 // Setup an SNMPTrap for later use
 SNMPTrap* settableNumberTrap = new SNMPTrap("public", SNMP_VERSION_2C);
 char _changingStringBuf[25];
 char* changingString = _changingStringBuf;
 
 void setup(){
     Serial.begin(115200);
+
+    // Hardware-test banner: confirm the flashed library version in the serial monitor
+    Serial.printf("SNMP_Agent v%s\n", snmp.getVersion());
+
     WiFi.begin(ssid, password);
     // WiFi.begin(ssid);
     Serial.println("");
@@ -81,6 +90,11 @@ void setup(){
     stuff[2] = 24;
     stuff[3] = 67;
 
+    // RFC1213 sysDescr: serves the library version, queryable from the SNMP terminal:
+    //   snmpget -v 2c -c public <IP> .1.3.6.1.2.1.1.1.0
+    snprintf(sysDescrBuf, sizeof(sysDescrBuf), "ESP32_SNMP demo (SNMP_Agent v%s)", snmp.getVersion());
+    snmp.addReadOnlyStaticStringHandler(".1.3.6.1.2.1.1.1.0", sysDescrBuf);
+
     // add 'callback' for an OID - pointer to an integer
     changingNumberOID = snmp.addIntegerHandler(".1.3.6.1.4.1.5.0", &changingNumber);
 

examples/SNMP_Sensor/SNMP_Sensor.ino

@@ -85,7 +85,10 @@ const char* oidSysName = ".1.3.6.1.2.1.1.5.0";     // OctetString SysName
 const char* oidSysLocation = ".1.3.6.1.2.1.1.6.0"; // OctetString SysLocation
 const char* oidSysServices = ".1.3.6.1.2.1.1.7.0"; // Integer sysServices
 
-char sysDescr[] = "SNMP Agent";
+/* Versioned sysDescr served on .1.3.6.1.2.1.1.1.0 — filled in setup() with the
+   running library version so `snmpget` confirms the exact build during hardware
+   testing. 64 B leaves room for the version string; handler keeps the pointer. */
+static char sysDescr[64] = "SNMP Agent";
 char sysObjectID[] = "";
 uint32_t sysUptime = 0;
 char sysContactValue[255];
@@ -194,6 +197,10 @@ void printFile(const char* filename);
 void setup()
 {
     Serial.begin(115200);
+
+    // Hardware-test banner: confirm the flashed library version in the serial monitor
+    Serial.printf("SNMP_Agent v%s\n", snmp.getVersion());
+
     if (!FS_BEGIN())
     {
         Serial.println("LittleFS Mount Failed");
@@ -217,6 +224,10 @@ void setup()
     snmp.setUDP(&udp);
     snmp.begin();
 
+    // Fill sysDescr (.1.3.6.1.2.1.1.1.0) with the version string, queryable from the
+    // SNMP terminal: snmpget -v 2c -c public <IP> .1.3.6.1.2.1.1.1.0
+    snprintf(sysDescr, sizeof(sysDescr), "SNMP_Sensor demo (SNMP_Agent v%s)", snmp.getVersion());
+
     addRFC1213MIBHandler();      // RFC1213-MIB (System)
     addENTITYMIBHandler();       // ENTITY-MIB
     addENTITYSENSORMIBHandler(); // ENTITY-SENSOR-MIB

library.properties

@@ -1,5 +1,5 @@
 name=SNMP_Agent
-version=3.1.5
+version=3.1.23
 author=Aidan Cyr <cyraidan@gmail.com>
 maintainer=Aidan Cyr <cyraidan@gmail.com>
 sentence=SNMP Agent: An fully compliant SNMPv2c Agent for esp32 for acting as an SNMP client device.

src/BERDecode.cpp

@@ -21,17 +21,34 @@
     ASNPool::Slot ASNPool::slots[SNMP_POOL_ASN_OBJECTS] = {};
 #endif
 int ASNPool::usedCount = 0;
+int ASNPool::permCount = 0;
+int ASNPool::usedCountPeak = 0;
 
 void ASNPool::release(BER_CONTAINER* p){
     if(!p) return;
 #ifndef SNMP_POOLS_IN_BSS
     if(!_poolsReady) { delete p; return; }
 #endif
-    p->~BER_CONTAINER();
+    /* Double-release guard: without it, a double-destroyed object re-runs its
+     * destructor AND decrements usedCount twice. The counter then under-reports
+     * occupancy, rawAlloc() reuses a slot that still holds a live object, and
+     * live OIDs get corrupted — the root cause of degraded GetBulk responses
+     * and the "agent goes deaf" incidents (HARDWARE_TEST_REPORT.md §2/§9). */
     for(int i = 0; i < SNMP_POOL_ASN_OBJECTS; i++){
         if(static_cast<void*>(slots[i].storage) == static_cast<void*>(p)){
+            if(!slots[i].occupied){
+                /* Slot already free: second release of the same object.
+                 * Do NOT run the destructor again, do NOT decrement.
+                 * One-shot alarm when DEBUG>0: a caller is destroying twice. */
+                if(!slots[i].doubleReleaseWarned){
+                    slots[i].doubleReleaseWarned = true;
+                    SNMP_LOGE("ASNPool: DOUBLE RELEASE of slot %d detected (caller destroying an object twice)\n", i);
+                }
+                return;
+            }
+            p->~BER_CONTAINER();
             slots[i].occupied = false;
-            if(usedCount > 0) usedCount--;
+            usedCount--;
             return;
         }
     }
@@ -242,24 +259,6 @@ const char* OIDType::string() {
     return _valueStr;
 }
 
-void SortableOIDType::generateSortingMap(uint32_t outMap[SNMP_MAX_OID_SUBIDENTIFIERS], int* outLen) const {
-    int count = 0;
-
-    const uint8_t* ptr = this->data;
-
-    ptr += 1;
-    int i = this->dataLen - 1;
-
-    while(i > 0 && count < SNMP_MAX_OID_SUBIDENTIFIERS){
-        long item;
-        size_t len = decode_ber_longform_integer(ptr, &item, i);
-        ptr += len; i -= len;
-        outMap[count++] = (uint32_t)item;
-    }
-
-    *outLen = count;
-}
-
 int NullType::fromBuffer(const uint8_t *, size_t){
     _length = 0;
     return 2;

src/BEREncode.cpp

@@ -183,6 +183,26 @@ bool OIDType::generateInternalData() {
     return true;
 }
 
+void OIDType::_init_from_cstr(const char* value, size_t len) noexcept {
+    memcpy(this->_valueStr, value, len);
+    this->_valueStr[len] = '\0';
+    this->dataLen = 0;
+    this->valid = this->generateInternalData();
+}
+
+void OIDType::_init_from_cstr_with_data(const char* value, size_t len, const uint8_t* srcData, int srcLen, bool valid_) noexcept {
+    memcpy(this->_valueStr, value, len);
+    this->_valueStr[len] = '\0';
+    if(srcLen > 0 && srcData) {
+        if(srcLen > (int)sizeof(this->data)) srcLen = (int)sizeof(this->data);
+        this->dataLen = srcLen;
+        memcpy(this->data, srcData, (size_t)srcLen);
+    } else {
+        this->dataLen = 0;
+    }
+    this->valid = valid_;
+}
+
 static inline void shift_arr_right(uint8_t* ptr, int num_length_bytes, size_t length){
     for(int l = length+num_length_bytes-1; l-num_length_bytes >= 0; l--){
         ptr[l] = ptr[l-num_length_bytes];

src/SNMPPDUHandler.cpp

@@ -3,6 +3,32 @@
 #include "include/BER.h"
 #include "include/ValueCallbacks.h"
 
+/* Every `asn_new<T>()` returns a RAW POINTER into the static ASNPool
+ * (placement-new slots).  When such a raw pointer is bound to a function
+ * parameter of type `const std::shared_ptr<BER_CONTAINER>&`, C++
+ * implicitly constructs a TEMPORARY shared_ptr using the DEFAULT
+ * `delete T` deleter — which immediately calls `delete` on a pool slot
+ * address at scope exit → Undefined Behavior.  On ESP-01 this corrupted
+ * pool metadata silently (no exception triggered since the double-free
+ * happened on a slot not currently in the free-list), causing
+ * SNMPResponse encode path to fail to build even a single VarBind →
+ * ZERO UDP TX bytes sent, agent DEAF despite UDP RX confirmed.
+ *
+ * FIX: wrap every `asn_new<T>()` passed into a `shared_ptr<T>` context
+ * with `pool_asn_sp(...)` below.  It constructs a shared_ptr whose
+ * custom deleter calls `asn_delete` instead of `operator delete`. */
+namespace {
+    struct pool_asn_deleter {
+        void operator()(BER_CONTAINER* p) const noexcept { asn_delete(p); }
+    };
+}
+template <typename T>
+static inline std::shared_ptr<BER_CONTAINER> pool_asn_sp(T* raw_pool_ptr) noexcept {
+    static_assert(std::is_base_of<BER_CONTAINER, T>::value,
+                  "pool_asn_sp only accepts BER_CONTAINER-derived pointers");
+    return std::shared_ptr<BER_CONTAINER>(static_cast<BER_CONTAINER*>(raw_pool_ptr), pool_asn_deleter());
+}
+
 template<typename... Args>
 static inline bool appendResponseVarBind(VarBind out[], int &outCount, Args&&... args){
     if(outCount >= SNMP_MAX_VARBINDS) return false;
@@ -22,9 +48,9 @@ bool handleGetRequestPDU(ValueCallback* const *callbacks, int callbacksCount, co
             SNMP_LOGD("Couldn't find callback\n");
 #if 1
             if(isGetNextRequest){
-                appendResponseVarBind(outResponseList, outResponseCount, requestVarBind, asn_new<ImplicitNullType>(ENDOFMIBVIEW));
+                appendResponseVarBind(outResponseList, outResponseCount, requestVarBind, pool_asn_sp(asn_new<ImplicitNullType>(ENDOFMIBVIEW)));
             } else {
-                appendResponseVarBind(outResponseList, outResponseCount, requestVarBind, asn_new<ImplicitNullType>(NOSUCHOBJECT));
+                appendResponseVarBind(outResponseList, outResponseCount, requestVarBind, pool_asn_sp(asn_new<ImplicitNullType>(NOSUCHOBJECT)));
             }
 
 #else
@@ -104,7 +130,7 @@ bool handleGetBulkRequestPDU(ValueCallback* const *callbacks, int callbacksCount
             const VarBind& requestVarBind = varbindList[i];
             ValueCallback* callback = ValueCallback::findCallback(callbacks, callbacksCount, requestVarBind.oid, true);
             if(!callback){
-                appendResponseVarBind(outResponseList, outResponseCount, requestVarBind, asn_new<ImplicitNullType>(ENDOFMIBVIEW));
+                appendResponseVarBind(outResponseList, outResponseCount, requestVarBind, pool_asn_sp(asn_new<ImplicitNullType>(ENDOFMIBVIEW)));
                 continue;
             }
 
@@ -130,7 +156,7 @@ bool handleGetBulkRequestPDU(ValueCallback* const *callbacks, int callbacksCount
                 SNMP_LOGD("finding next callback for OID: %s\n", oid->string());
                 ValueCallback* callback = ValueCallback::findCallback(callbacks, callbacksCount, oid, true, foundAt, &foundAt);
                 if(!callback){
-                    appendResponseVarBind(outResponseList, outResponseCount, oid, asn_new<ImplicitNullType>(ENDOFMIBVIEW));
+                    appendResponseVarBind(outResponseList, outResponseCount, oid, pool_asn_sp(asn_new<ImplicitNullType>(ENDOFMIBVIEW)));
                     oid = nullptr;
                     break;
                 }