WiFiUDP only emit a packet on flush if not ended (earlephilhower#2618)

earlephilhower · web-flow · commit bda12cd7e7ff · 2024-11-17T08:58:44.000-08:00
A flush() on a packet that's already been sent should be a no-op, not send a 0-byte UDP packet. Track when an outgoing packet is dirty and only endPacket()/transmit it when so. Fixes earlephilhower#2617
diff --git a/libraries/WiFi/src/WiFiUdp.cpp b/libraries/WiFi/src/WiFiUdp.cpp
@@ -38,7 +38,7 @@ template<>
 WiFiUDP* SList<WiFiUDP>::_s_first = 0;
 
 /* Constructor */
-WiFiUDP::WiFiUDP() : _ctx(0), _multicast(false) {
+WiFiUDP::WiFiUDP() : _ctx(0), _multicast(false), _dirty(false) {
     WiFiUDP::_add(this);
 }
 
@@ -49,6 +49,7 @@ WiFiUDP::WiFiUDP(const WiFiUDP& other) {
     }
     WiFiUDP::_add(this);
     _multicast = other._multicast;
+    _dirty = other._dirty;
 }
 
 WiFiUDP& WiFiUDP::operator=(const WiFiUDP& rhs) {
@@ -149,6 +150,7 @@ int WiFiUDP::beginPacket(IPAddress ip, uint16_t port) {
         _ctx->setMulticastInterface(IP_ADDR_ANY);
         _ctx->setMulticastTTL(255);
     }
+    _dirty = false;
     return ret;
 
 }
@@ -164,13 +166,15 @@ int WiFiUDP::beginPacketMulticast(IPAddress multicastAddress, uint16_t port,
     }
     _ctx->setMulticastInterface(interfaceAddress);
     _ctx->setMulticastTTL(ttl);
+    _dirty = false;
     return 1;
 }
 
 int WiFiUDP::endPacket() {
     if (!_ctx) {
         return 0;
     }
+    _dirty = false;
 
     return (_ctx->send()) ? 1 : 0;
 }
@@ -183,7 +187,7 @@ size_t WiFiUDP::write(const uint8_t *buffer, size_t size) {
     if (!_ctx) {
         return 0;
     }
-
+    _dirty = true;
     return _ctx->append(reinterpret_cast<const char*>(buffer), size);
 }
 
@@ -224,7 +228,9 @@ int WiFiUDP::peek() {
 }
 
 void WiFiUDP::flush() {
-    endPacket();
+    if (_dirty) {
+        endPacket();
+    }
 }
 
 IPAddress WiFiUDP::remoteIP() {
diff --git a/libraries/WiFi/src/WiFiUdp.h b/libraries/WiFi/src/WiFiUdp.h
@@ -115,4 +115,5 @@ class WiFiUDP : public UDP, public SList<WiFiUDP> {
 
 private:
     bool _multicast;
+    bool _dirty;
 };

Original file line number	Diff line number	Diff line change
`@@ -38,7 +38,7 @@ template<>`
`38`	`38`	`WiFiUDP* SList<WiFiUDP>::_s_first = 0;`
`39`	`39`
`40`	`40`	`/* Constructor */`
`41`		`-WiFiUDP::WiFiUDP() : _ctx(0), _multicast(false) {`
	`41`	`+WiFiUDP::WiFiUDP() : _ctx(0), _multicast(false), _dirty(false) {`
`42`	`42`	`WiFiUDP::_add(this);`
`43`	`43`	`}`
`44`	`44`
`@@ -49,6 +49,7 @@ WiFiUDP::WiFiUDP(const WiFiUDP& other) {`
`49`	`49`	`}`
`50`	`50`	`WiFiUDP::_add(this);`
`51`	`51`	`_multicast = other._multicast;`
	`52`	`+ _dirty = other._dirty;`
`52`	`53`	`}`
`53`	`54`
`54`	`55`	`WiFiUDP& WiFiUDP::operator=(const WiFiUDP& rhs) {`
`@@ -149,6 +150,7 @@ int WiFiUDP::beginPacket(IPAddress ip, uint16_t port) {`
`149`	`150`	`_ctx->setMulticastInterface(IP_ADDR_ANY);`
`150`	`151`	`_ctx->setMulticastTTL(255);`
`151`	`152`	`}`
	`153`	`+ _dirty = false;`
`152`	`154`	`return ret;`
`153`	`155`
`154`	`156`	`}`
`@@ -164,13 +166,15 @@ int WiFiUDP::beginPacketMulticast(IPAddress multicastAddress, uint16_t port,`
`164`	`166`	`}`
`165`	`167`	`_ctx->setMulticastInterface(interfaceAddress);`
`166`	`168`	`_ctx->setMulticastTTL(ttl);`
	`169`	`+ _dirty = false;`
`167`	`170`	`return 1;`
`168`	`171`	`}`
`169`	`172`
`170`	`173`	`int WiFiUDP::endPacket() {`
`171`	`174`	`if (!_ctx) {`
`172`	`175`	`return 0;`
`173`	`176`	`}`
	`177`	`+ _dirty = false;`
`174`	`178`
`175`	`179`	`return (_ctx->send()) ? 1 : 0;`
`176`	`180`	`}`
`@@ -183,7 +187,7 @@ size_t WiFiUDP::write(const uint8_t *buffer, size_t size) {`
`183`	`187`	`if (!_ctx) {`
`184`	`188`	`return 0;`
`185`	`189`	`}`
`186`		`-`
	`190`	`+ _dirty = true;`
`187`	`191`	`return _ctx->append(reinterpret_cast<const char*>(buffer), size);`
`188`	`192`	`}`
`189`	`193`
`@@ -224,7 +228,9 @@ int WiFiUDP::peek() {`
`224`	`228`	`}`
`225`	`229`
`226`	`230`	`void WiFiUDP::flush() {`
`227`		`- endPacket();`
	`231`	`+ if (_dirty) {`
	`232`	`+ endPacket();`
	`233`	`+ }`
`228`	`234`	`}`
`229`	`235`
`230`	`236`	`IPAddress WiFiUDP::remoteIP() {`