[udp] Add UDP packet interface link

Each packet is one UDP datagram, using the settings of the udp component.
The udp component now reports whether a packet was sent, and an ENOMEM
refusal from lwIP is logged at verbose level as the packet can be sent
again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CODEOWNERS

@@ -680,6 +680,7 @@ esphome/components/uart/packet_transport/* @clydebarrow
 esphome/components/uart_mux/* @kbx81
 esphome/components/uart_tcp/* @Bascht74
 esphome/components/udp/* @clydebarrow
+esphome/components/udp/packet_interface/* @clydebarrow
 esphome/components/ufire_ec/* @pvizeli
 esphome/components/ufire_ise/* @pvizeli
 esphome/components/ufm01/* @ljungqvist

esphome/components/udp/packet_interface/__init__.py

@@ -0,0 +1,32 @@
+import esphome.codegen as cg
+from esphome.components import packet_interface
+from esphome.components.packet_interface import (
+    new_packet_interface,
+    packet_interface_schema,
+)
+from esphome.types import ConfigType
+
+from .. import CONF_UDP_ID, UDP_SCHEMA, udp_ns
+
+CODEOWNERS = ["@clydebarrow"]
+
+DEPENDENCIES = ["udp"]
+
+# Size of the receive buffer in udp_component.h
+MAX_PACKET_SIZE = 508
+
+UdpPacketInterface = udp_ns.class_(
+    "UdpPacketInterface",
+    packet_interface.PacketInterface,
+)
+
+CONFIG_SCHEMA = packet_interface_schema(
+    UdpPacketInterface, MAX_PACKET_SIZE, MAX_PACKET_SIZE
+).extend(UDP_SCHEMA)
+
+
+async def to_code(config: ConfigType) -> None:
+    udp_var = await cg.get_variable(config[CONF_UDP_ID])
+    cg.add(udp_var.set_should_listen())
+    cg.add(udp_var.set_should_broadcast())
+    await new_packet_interface(config, udp_var)

esphome/components/udp/packet_interface/udp_packet_interface.cpp

@@ -0,0 +1,37 @@
+#include "udp_packet_interface.h"
+#ifdef USE_NETWORK
+#include <array>
+#include "esphome/components/network/util.h"
+#include "esphome/core/log.h"
+
+namespace esphome::udp {
+
+using packet_interface::PacketBuffer;
+using packet_interface::PacketMetaData;
+
+ESPHOME_LOG_TAG(TAG, "udp.packet_interface");
+
+void UdpPacketInterface::setup() {
+  this->parent_->add_listener([this](std::span<const uint8_t> buf) {
+    this->on_receive_from_interface_(PacketBuffer(buf.data(), buf.size()), {});
+  });
+}
+
+bool UdpPacketInterface::send_to_interface(const PacketBuffer &data, const PacketMetaData &meta_data) {
+  if (!network::is_connected())
+    return false;
+  if (data.is_contiguous()) {
+    auto span = data.as_span();
+    return this->parent_->send_packet(span.data(), span.size());
+  }
+  if (data.size() > MAX_PACKET_SIZE) {
+    ESP_LOGW(TAG, "Packet of %zu bytes is larger than %zu", data.size(), MAX_PACKET_SIZE);
+    return false;
+  }
+  std::array<uint8_t, MAX_PACKET_SIZE> buf;
+  size_t len = data.copy_to(buf.data(), buf.size());
+  return this->parent_->send_packet(buf.data(), len);
+}
+
+}  // namespace esphome::udp
+#endif

esphome/components/udp/packet_interface/udp_packet_interface.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "esphome/core/defines.h"
+
+// udp_component.h declares nothing without USE_NETWORK
+#ifdef USE_NETWORK
+#include "esphome/components/packet_interface/packet_interface.h"
+#include "../udp_component.h"
+
+namespace esphome::udp {
+
+class UdpPacketInterface : public packet_interface::PacketInterface {
+ public:
+  explicit UdpPacketInterface(UDPComponent *udp_component) : parent_(udp_component) {}
+
+  void setup() override;
+  bool send_to_interface(const packet_interface::PacketBuffer &data,
+                         const packet_interface::PacketMetaData &meta_data) override;
+
+ protected:
+  UDPComponent *parent_;
+};
+}  // namespace esphome::udp
+#endif

esphome/components/udp/packet_transport/udp_transport.cpp

@@ -1,12 +1,9 @@
-#include "esphome/core/log.h"
 #include "esphome/core/application.h"
 #include "esphome/components/network/util.h"
 #include "udp_transport.h"
 
 namespace esphome::udp {
 
-ESPHOME_LOG_TAG(TAG, "udp_transport");
-
 bool UDPTransport::should_send() { return network::is_connected(); }
 void UDPTransport::setup() {
   PacketTransport::setup();

esphome/components/udp/udp_component.cpp

@@ -205,18 +205,20 @@ void UDPComponent::set_poll_warning_(PollStep step, const LogString *what) {
 }
 
 void UDPComponent::loop() {
-  if (this->should_listen_) {
-    std::array<uint8_t, MAX_PACKET_SIZE> buf;
-    for (;;) {
-      if (!this->listen_socket_->ready())
-        break;
-      auto len = this->listen_socket_->read(buf.data(), buf.size());
-      if (len <= 0)
-        break;
-      size_t packet_len = static_cast<size_t>(len);
-      ESP_LOGV(TAG, "Received packet of length %zu", packet_len);
-      this->packet_listeners_.call(std::span<const uint8_t>(buf.data(), packet_len));
-    }
+  if (!this->should_listen_) {
+    this->disable_loop();
+    return;
+  }
+  std::array<uint8_t, MAX_PACKET_SIZE> buf;
+  for (;;) {
+    if (!this->listen_socket_->ready())
+      break;
+    auto len = this->listen_socket_->read(buf.data(), buf.size());
+    if (len <= 0)
+      break;
+    size_t packet_len = static_cast<size_t>(len);
+    ESP_LOGV(TAG, "Received packet of length %zu", packet_len);
+    this->packet_listeners_.call(std::span<const uint8_t>(buf.data(), packet_len));
   }
 }
 
@@ -239,9 +241,10 @@ void UDPComponent::dump_config() {
                 YESNO(this->should_broadcast_), YESNO(this->should_listen_));
 }
 
-void UDPComponent::send_packet(const uint8_t *data, size_t size) {
+bool UDPComponent::send_packet(const uint8_t *data, size_t size) {
   if (this->is_failed())
-    return;  // a send socket may be missing
+    return false;  // a send socket may be missing
+  bool sent = true;
   for (const auto &entry : this->sockaddrs_) {
 #ifdef USE_UDP_IPV6_SEND
     const bool v6 = entry.sa.sa_family == AF_INET6;
@@ -256,11 +259,23 @@ void UDPComponent::send_packet(const uint8_t *data, size_t size) {
     socket::UDPSendSocket *sock = this->broadcast_socket_.get();
     socklen_t sockaddr_size = sizeof(sockaddr_in);
 #endif
+    if (sock == nullptr) {
+      ESP_LOGW(TAG, "Broadcast socket not initialized");
+      return false;
+    }
     auto result = sock->sendto(data, size, 0, &entry.sa, sockaddr_size);
     if (result < 0) {
-      ESP_LOGW(TAG, "sendto() error %d", errno);
+      // lwIP refuses a packet with ENOMEM while the destination's ARP lookup is pending and its queue is full;
+      // the packet can be sent again later
+      if (errno == ENOMEM) {
+        ESP_LOGV(TAG, "sendto() out of memory");
+      } else {
+        ESP_LOGW(TAG, "sendto() error %d", errno);
+      }
+      sent = false;
     }
   }
+  return sent;
 }
 }  // namespace esphome::udp
 

esphome/components/udp/udp_component.h

@@ -35,8 +35,9 @@ class UDPComponent final : public Component {
   void setup() override;
   void loop() override;
   void dump_config() override;
-  void send_packet(const uint8_t *data, size_t size);
-  void send_packet(const std::vector<uint8_t> &buf) { this->send_packet(buf.data(), buf.size()); }
+  /// Returns false if the packet could not be sent to every destination.
+  bool send_packet(const uint8_t *data, size_t size);
+  bool send_packet(const std::vector<uint8_t> &buf) { return this->send_packet(buf.data(), buf.size()); }
   float get_setup_priority() const override { return setup_priority::AFTER_WIFI; };
 
  protected:
@@ -53,7 +54,7 @@ class UDPComponent final : public Component {
   bool network_poll_();
   void set_poll_warning_(PollStep step, const LogString *what);
 
-  CallbackManager<void(std::span<const uint8_t>)> packet_listeners_{};
+  LazyCallbackManager<void(std::span<const uint8_t>)> packet_listeners_{};
   std::unique_ptr<socket::UDPSendSocket> broadcast_socket_ = nullptr;
   std::unique_ptr<socket::UDPSocket> listen_socket_ = nullptr;
 #ifdef USE_UDP_IPV6_SEND

tests/components/packet_interface/common.yaml

@@ -1,7 +1,17 @@
+wifi:
+  ssid: MySSID
+  password: password1
+
+udp:
+  - id: packet_interface_udp
+
 packet_interface:
   - platform: uart
     id: packet_interface_uart
     max_packet_size: 256
+  - platform: udp
+    id: packet_interface_network
+    udp_id: packet_interface_udp
 
 sensor:
   - platform: template
@@ -13,3 +23,7 @@ packet_transport:
     packet_interface: packet_interface_uart
     sensors:
       - packet_interface_sensor
+  - platform: packet_interface
+    packet_interface: packet_interface_network
+    sensors:
+      - packet_interface_sensor

tests/components/packet_transport/common.yaml

@@ -3,12 +3,14 @@ wifi:
   password: password1
 
 udp:
-  listen_address: 239.0.60.53
-  addresses: ["239.0.60.53"]
+  - id: transport_udp_component
+    listen_address: 239.0.60.53
+    addresses: ["239.0.60.53"]
 
 packet_transport:
   - platform: udp
     id: transport_udp
+    udp_id: transport_udp_component
     update_interval: 5s
     encryption: "our key goes here"
     rolling_code_enable: true

tests/unit_tests/test_packet_interface.py

@@ -6,12 +6,14 @@ from esphome import config_validation as cv
 from esphome.components import packet_interface
 from esphome.components.packet_interface import CONF_MAX_PACKET_SIZE
 from esphome.components.uart import packet_interface as uart_packet_interface
+from esphome.components.udp import packet_interface as udp_packet_interface
 
 
 @pytest.mark.parametrize(
     ("schema", "default", "limit"),
     [
         (uart_packet_interface.CONFIG_SCHEMA, 508, 4096),
+        (udp_packet_interface.CONFIG_SCHEMA, 508, 508),
     ],
 )
 def test_platform_max_packet_size(