[socket] Devirtualize socket abstraction layer (#14398)

esphome/components/api/api_server.h

@@ -257,7 +257,7 @@ class APIServer : public Component,
   }
   void socket_failed_(const LogString *msg);
   // Pointers and pointer-like types first (4 bytes each)
-  socket::Socket *socket_{nullptr};
+  socket::ListenSocket *socket_{nullptr};
 #ifdef USE_API_CLIENT_CONNECTED_TRIGGER
   Trigger<std::string, std::string> client_connected_trigger_;
 #endif

esphome/components/captive_portal/dns_server_esp32_idf.h

@@ -22,7 +22,7 @@ class DNSServer {
   }
   static constexpr size_t DNS_BUFFER_SIZE = 192;
 
-  socket::Socket *socket_{nullptr};
+  socket::ListenSocket *socket_{nullptr};
   network::IPAddress server_ip_;
   uint8_t buffer_[DNS_BUFFER_SIZE];
 };

esphome/components/esphome/ota/ota_esphome.h

@@ -84,7 +84,7 @@ class ESPHomeOTAComponent final : public ota::OTAComponent {
   std::unique_ptr<uint8_t[]> auth_buf_;
 #endif  // USE_OTA_PASSWORD
 
-  socket::Socket *server_{nullptr};
+  socket::ListenSocket *server_{nullptr};
   std::unique_ptr<socket::Socket> client_;
   std::unique_ptr<ota::OTABackend> backend_;
 

esphome/components/socket/bsd_sockets_impl.cpp

@@ -1,135 +1,81 @@
-#include "socket.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
+#include "socket.h"
 
 #ifdef USE_SOCKET_IMPL_BSD_SOCKETS
 
 #include <cstring>
 #include "esphome/core/application.h"
 
-#ifdef USE_ESP32
-#include <esp_idf_version.h>
-#include <lwip/sockets.h>
-#endif
-
 namespace esphome::socket {
 
-class BSDSocketImpl final : public Socket {
- public:
-  BSDSocketImpl(int fd, bool monitor_loop = false) {
-    this->fd_ = fd;
-    // Register new socket with the application for select() if monitoring requested
-    if (monitor_loop && this->fd_ >= 0) {
-      // Only set loop_monitored_ to true if registration succeeds
-      this->loop_monitored_ = App.register_socket_fd(this->fd_);
-    }
-  }
-  ~BSDSocketImpl() override {
-    if (!this->closed_) {
-      this->close();  // NOLINT(clang-analyzer-optin.cplusplus.VirtualCall)
-    }
-  }
-  int connect(const struct sockaddr *addr, socklen_t addrlen) override { return ::connect(this->fd_, addr, addrlen); }
-  std::unique_ptr<Socket> accept(struct sockaddr *addr, socklen_t *addrlen) override {
-    int fd = ::accept(this->fd_, addr, addrlen);
-    if (fd == -1)
-      return {};
-    return make_unique<BSDSocketImpl>(fd, false);
-  }
-  std::unique_ptr<Socket> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) override {
-    int fd = ::accept(this->fd_, addr, addrlen);
-    if (fd == -1)
-      return {};
-    return make_unique<BSDSocketImpl>(fd, true);
+BSDSocketImpl::BSDSocketImpl(int fd, bool monitor_loop) {
+  this->fd_ = fd;
+  // Register new socket with the application for select() if monitoring requested
+  if (monitor_loop && this->fd_ >= 0) {
+    // Only set loop_monitored_ to true if registration succeeds
+    this->loop_monitored_ = App.register_socket_fd(this->fd_);
   }
+}
 
-  int bind(const struct sockaddr *addr, socklen_t addrlen) override { return ::bind(this->fd_, addr, addrlen); }
-  int close() override {
-    if (!this->closed_) {
-      // Unregister from select() before closing if monitored
-      if (this->loop_monitored_) {
-        App.unregister_socket_fd(this->fd_);
-      }
-      int ret = ::close(this->fd_);
-      this->closed_ = true;
-      return ret;
+BSDSocketImpl::~BSDSocketImpl() {
+  if (!this->closed_) {
+    this->close();
+  }
+}
+
+int BSDSocketImpl::close() {
+  if (!this->closed_) {
+    // Unregister from select() before closing if monitored
+    if (this->loop_monitored_) {
+      App.unregister_socket_fd(this->fd_);
     }
+    int ret = ::close(this->fd_);
+    this->closed_ = true;
+    return ret;
+  }
+  return 0;
+}
+
+int BSDSocketImpl::setblocking(bool blocking) {
+  int fl = ::fcntl(this->fd_, F_GETFL, 0);
+  if (blocking) {
+    fl &= ~O_NONBLOCK;
+  } else {
+    fl |= O_NONBLOCK;
+  }
+  ::fcntl(this->fd_, F_SETFL, fl);
+  return 0;
+}
+
+bool BSDSocketImpl::ready() const { return socket_ready_fd(this->fd_, this->loop_monitored_); }
+
+size_t BSDSocketImpl::getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf) {
+  struct sockaddr_storage storage;
+  socklen_t len = sizeof(storage);
+  if (this->getpeername(reinterpret_cast<struct sockaddr *>(&storage), &len) != 0) {
+    buf[0] = '\0';
     return 0;
   }
-  int shutdown(int how) override { return ::shutdown(this->fd_, how); }
+  return format_sockaddr_to(reinterpret_cast<struct sockaddr *>(&storage), len, buf);
+}
 
-  int getpeername(struct sockaddr *addr, socklen_t *addrlen) override {
-    return ::getpeername(this->fd_, addr, addrlen);
-  }
-  int getsockname(struct sockaddr *addr, socklen_t *addrlen) override {
-    return ::getsockname(this->fd_, addr, addrlen);
-  }
-  int getsockopt(int level, int optname, void *optval, socklen_t *optlen) override {
-    return ::getsockopt(this->fd_, level, optname, optval, optlen);
-  }
-  int setsockopt(int level, int optname, const void *optval, socklen_t optlen) override {
-    return ::setsockopt(this->fd_, level, optname, optval, optlen);
-  }
-  int listen(int backlog) override { return ::listen(this->fd_, backlog); }
-  ssize_t read(void *buf, size_t len) override {
-#ifdef USE_ESP32
-    return ::lwip_read(this->fd_, buf, len);
-#else
-    return ::read(this->fd_, buf, len);
-#endif
-  }
-  ssize_t recvfrom(void *buf, size_t len, sockaddr *addr, socklen_t *addr_len) override {
-#if defined(USE_ESP32) || defined(USE_HOST)
-    return ::recvfrom(this->fd_, buf, len, 0, addr, addr_len);
-#else
-    return ::lwip_recvfrom(this->fd_, buf, len, 0, addr, addr_len);
-#endif
-  }
-  ssize_t readv(const struct iovec *iov, int iovcnt) override {
-#if defined(USE_ESP32)
-    return ::lwip_readv(this->fd_, iov, iovcnt);
-#else
-    return ::readv(this->fd_, iov, iovcnt);
-#endif
-  }
-  ssize_t write(const void *buf, size_t len) override {
-#ifdef USE_ESP32
-    return ::lwip_write(this->fd_, buf, len);
-#else
-    return ::write(this->fd_, buf, len);
-#endif
-  }
-  ssize_t send(void *buf, size_t len, int flags) { return ::send(this->fd_, buf, len, flags); }
-  ssize_t writev(const struct iovec *iov, int iovcnt) override {
-#if defined(USE_ESP32)
-    return ::lwip_writev(this->fd_, iov, iovcnt);
-#else
-    return ::writev(this->fd_, iov, iovcnt);
-#endif
-  }
-
-  ssize_t sendto(const void *buf, size_t len, int flags, const struct sockaddr *to, socklen_t tolen) override {
-    return ::sendto(this->fd_, buf, len, flags, to, tolen);  // NOLINT(readability-suspicious-call-argument)
-  }
-
-  int setblocking(bool blocking) override {
-    int fl = ::fcntl(this->fd_, F_GETFL, 0);
-    if (blocking) {
-      fl &= ~O_NONBLOCK;
-    } else {
-      fl |= O_NONBLOCK;
-    }
-    ::fcntl(this->fd_, F_SETFL, fl);
+size_t BSDSocketImpl::getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf) {
+  struct sockaddr_storage storage;
+  socklen_t len = sizeof(storage);
+  if (this->getsockname(reinterpret_cast<struct sockaddr *>(&storage), &len) != 0) {
+    buf[0] = '\0';
     return 0;
   }
-};
+  return format_sockaddr_to(reinterpret_cast<struct sockaddr *>(&storage), len, buf);
+}
 
 // Helper to create a socket with optional monitoring
-static std::unique_ptr<Socket> create_socket(int domain, int type, int protocol, bool loop_monitored = false) {
+static std::unique_ptr<BSDSocketImpl> create_socket(int domain, int type, int protocol, bool loop_monitored = false) {
   int ret = ::socket(domain, type, protocol);
   if (ret == -1)
     return nullptr;
-  return std::unique_ptr<Socket>{new BSDSocketImpl(ret, loop_monitored)};
+  return make_unique<BSDSocketImpl>(ret, loop_monitored);
 }
 
 std::unique_ptr<Socket> socket(int domain, int type, int protocol) {
@@ -140,6 +86,14 @@ std::unique_ptr<Socket> socket_loop_monitored(int domain, int type, int protocol
   return create_socket(domain, type, protocol, true);
 }
 
+std::unique_ptr<ListenSocket> socket_listen(int domain, int type, int protocol) {
+  return create_socket(domain, type, protocol, false);
+}
+
+std::unique_ptr<ListenSocket> socket_listen_loop_monitored(int domain, int type, int protocol) {
+  return create_socket(domain, type, protocol, true);
+}
+
 }  // namespace esphome::socket
 
 #endif  // USE_SOCKET_IMPL_BSD_SOCKETS

esphome/components/socket/bsd_sockets_impl.h

@@ -0,0 +1,114 @@
+#pragma once
+#include "esphome/core/defines.h"
+
+#ifdef USE_SOCKET_IMPL_BSD_SOCKETS
+
+#include <memory>
+#include <span>
+
+#include "esphome/core/helpers.h"
+#include "headers.h"
+
+#ifdef USE_ESP32
+#include <lwip/sockets.h>
+#endif
+
+namespace esphome::socket {
+
+class BSDSocketImpl {
+ public:
+  BSDSocketImpl(int fd, bool monitor_loop = false);
+  ~BSDSocketImpl();
+  BSDSocketImpl(const BSDSocketImpl &) = delete;
+  BSDSocketImpl &operator=(const BSDSocketImpl &) = delete;
+
+  int connect(const struct sockaddr *addr, socklen_t addrlen) { return ::connect(this->fd_, addr, addrlen); }
+  std::unique_ptr<BSDSocketImpl> accept(struct sockaddr *addr, socklen_t *addrlen) {
+    int fd = ::accept(this->fd_, addr, addrlen);
+    if (fd == -1)
+      return {};
+    return make_unique<BSDSocketImpl>(fd, false);
+  }
+  std::unique_ptr<BSDSocketImpl> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) {
+    int fd = ::accept(this->fd_, addr, addrlen);
+    if (fd == -1)
+      return {};
+    return make_unique<BSDSocketImpl>(fd, true);
+  }
+
+  int bind(const struct sockaddr *addr, socklen_t addrlen) { return ::bind(this->fd_, addr, addrlen); }
+  int close();
+  int shutdown(int how) { return ::shutdown(this->fd_, how); }
+
+  int getpeername(struct sockaddr *addr, socklen_t *addrlen) { return ::getpeername(this->fd_, addr, addrlen); }
+  int getsockname(struct sockaddr *addr, socklen_t *addrlen) { return ::getsockname(this->fd_, addr, addrlen); }
+
+  /// Format peer address into a fixed-size buffer (no heap allocation)
+  size_t getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf);
+  /// Format local address into a fixed-size buffer (no heap allocation)
+  size_t getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf);
+
+  int getsockopt(int level, int optname, void *optval, socklen_t *optlen) {
+    return ::getsockopt(this->fd_, level, optname, optval, optlen);
+  }
+  int setsockopt(int level, int optname, const void *optval, socklen_t optlen) {
+    return ::setsockopt(this->fd_, level, optname, optval, optlen);
+  }
+  int listen(int backlog) { return ::listen(this->fd_, backlog); }
+  ssize_t read(void *buf, size_t len) {
+#ifdef USE_ESP32
+    return ::lwip_read(this->fd_, buf, len);
+#else
+    return ::read(this->fd_, buf, len);
+#endif
+  }
+  ssize_t recvfrom(void *buf, size_t len, sockaddr *addr, socklen_t *addr_len) {
+#if defined(USE_ESP32) || defined(USE_HOST)
+    return ::recvfrom(this->fd_, buf, len, 0, addr, addr_len);
+#else
+    return ::lwip_recvfrom(this->fd_, buf, len, 0, addr, addr_len);
+#endif
+  }
+  ssize_t readv(const struct iovec *iov, int iovcnt) {
+#if defined(USE_ESP32)
+    return ::lwip_readv(this->fd_, iov, iovcnt);
+#else
+    return ::readv(this->fd_, iov, iovcnt);
+#endif
+  }
+  ssize_t write(const void *buf, size_t len) {
+#ifdef USE_ESP32
+    return ::lwip_write(this->fd_, buf, len);
+#else
+    return ::write(this->fd_, buf, len);
+#endif
+  }
+  ssize_t send(void *buf, size_t len, int flags) { return ::send(this->fd_, buf, len, flags); }
+  ssize_t writev(const struct iovec *iov, int iovcnt) {
+#if defined(USE_ESP32)
+    return ::lwip_writev(this->fd_, iov, iovcnt);
+#else
+    return ::writev(this->fd_, iov, iovcnt);
+#endif
+  }
+
+  ssize_t sendto(const void *buf, size_t len, int flags, const struct sockaddr *to, socklen_t tolen) {
+    return ::sendto(this->fd_, buf, len, flags, to, tolen);  // NOLINT(readability-suspicious-call-argument)
+  }
+
+  int setblocking(bool blocking);
+  int loop() { return 0; }
+
+  bool ready() const;
+
+  int get_fd() const { return this->fd_; }
+
+ protected:
+  int fd_{-1};
+  bool closed_{false};
+  bool loop_monitored_{false};
+};
+
+}  // namespace esphome::socket
+
+#endif  // USE_SOCKET_IMPL_BSD_SOCKETS

esphome/components/socket/headers.h

@@ -183,3 +183,20 @@ using socklen_t = uint32_t;
 #endif
 
 #endif  // USE_SOCKET_IMPL_BSD_SOCKETS
+
+#if defined(USE_SOCKET_IMPL_LWIP_TCP) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS) || defined(USE_SOCKET_IMPL_BSD_SOCKETS)
+
+namespace esphome::socket {
+
+// Maximum length for formatted socket address string (IP address without port)
+// IPv4: "255.255.255.255" = 15 chars + null = 16
+// IPv6: full address = 45 chars + null = 46
+#if USE_NETWORK_IPV6
+static constexpr size_t SOCKADDR_STR_LEN = 46;  // INET6_ADDRSTRLEN
+#else
+static constexpr size_t SOCKADDR_STR_LEN = 16;  // INET_ADDRSTRLEN
+#endif
+
+}  // namespace esphome::socket
+
+#endif

esphome/components/socket/lwip_raw_tcp_impl.h

@@ -0,0 +1,200 @@
+#pragma once
+#include "esphome/core/defines.h"
+
+#ifdef USE_SOCKET_IMPL_LWIP_TCP
+
+#include <array>
+#include <cerrno>
+#include <cstring>
+#include <memory>
+#include <span>
+
+#include "esphome/core/helpers.h"
+#include "headers.h"
+#include "lwip/ip.h"
+#include "lwip/netif.h"
+#include "lwip/opt.h"
+#include "lwip/tcp.h"
+
+namespace esphome::socket {
+
+// Forward declaration
+class LWIPRawImpl;
+
+/// Non-virtual common base for LWIP raw TCP sockets.
+/// Provides shared fields and methods for both connected and listening sockets.
+/// No virtual methods — pure code sharing.
+class LWIPRawCommon {
+ public:
+  LWIPRawCommon(sa_family_t family, struct tcp_pcb *pcb) : pcb_(pcb), family_(family) {}
+  ~LWIPRawCommon();
+  LWIPRawCommon(const LWIPRawCommon &) = delete;
+  LWIPRawCommon &operator=(const LWIPRawCommon &) = delete;
+
+  int bind(const struct sockaddr *name, socklen_t addrlen);
+  int close();
+  int shutdown(int how);
+
+  int getpeername(struct sockaddr *name, socklen_t *addrlen);
+  int getsockname(struct sockaddr *name, socklen_t *addrlen);
+
+  /// Format peer address into a fixed-size buffer (no heap allocation)
+  size_t getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf);
+  /// Format local address into a fixed-size buffer (no heap allocation)
+  size_t getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf);
+
+  int getsockopt(int level, int optname, void *optval, socklen_t *optlen);
+  int setsockopt(int level, int optname, const void *optval, socklen_t optlen);
+
+  int get_fd() const { return -1; }
+
+ protected:
+  int ip2sockaddr_(ip_addr_t *ip, uint16_t port, struct sockaddr *name, socklen_t *addrlen);
+
+  // Member ordering optimized to minimize padding on 32-bit systems
+  struct tcp_pcb *pcb_;
+  // don't use lwip nodelay flag, it sometimes causes reconnect
+  // instead use it for determining whether to call lwip_output
+  bool nodelay_ = false;
+  sa_family_t family_ = 0;
+};
+
+/// Connected socket implementation for LWIP raw TCP.
+/// No virtual methods — callers always use the concrete type.
+class LWIPRawImpl : public LWIPRawCommon {
+ public:
+  using LWIPRawCommon::LWIPRawCommon;
+  ~LWIPRawImpl();
+
+  void init();
+
+  // Non-listening sockets return error
+  std::unique_ptr<LWIPRawImpl> accept(struct sockaddr *, socklen_t *) {
+    errno = EINVAL;
+    return nullptr;
+  }
+  std::unique_ptr<LWIPRawImpl> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) {
+    return this->accept(addr, addrlen);
+  }
+  // Regular sockets can't be converted to listening - this shouldn't happen
+  // as listen() should only be called on sockets created for listening
+  int listen(int) {
+    errno = EOPNOTSUPP;
+    return -1;
+  }
+  ssize_t read(void *buf, size_t len);
+  ssize_t readv(const struct iovec *iov, int iovcnt);
+  ssize_t recvfrom(void *, size_t, sockaddr *, socklen_t *) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  ssize_t write(const void *buf, size_t len);
+  ssize_t writev(const struct iovec *iov, int iovcnt);
+  ssize_t sendto(const void *, size_t, int, const struct sockaddr *, socklen_t) {
+    // return ::sendto(fd_, buf, len, flags, to, tolen);
+    errno = ENOSYS;
+    return -1;
+  }
+  bool ready() const { return this->rx_buf_ != nullptr || this->rx_closed_ || this->pcb_ == nullptr; }
+
+  int setblocking(bool blocking) {
+    if (this->pcb_ == nullptr) {
+      errno = ECONNRESET;
+      return -1;
+    }
+    if (blocking) {
+      // blocking operation not supported
+      errno = EINVAL;
+      return -1;
+    }
+    return 0;
+  }
+  int loop() { return 0; }
+
+  err_t recv_fn(struct pbuf *pb, err_t err);
+
+  static void s_err_fn(void *arg, err_t err);
+  static err_t s_recv_fn(void *arg, struct tcp_pcb *pcb, struct pbuf *pb, err_t err);
+
+ protected:
+  ssize_t internal_write_(const void *buf, size_t len);
+  int internal_output_();
+
+  pbuf *rx_buf_ = nullptr;
+  size_t rx_buf_offset_ = 0;
+  bool rx_closed_ = false;
+};
+
+/// Listening socket implementation for LWIP raw TCP.
+/// Separate from LWIPRawImpl — no virtual dispatch needed.
+class LWIPRawListenImpl : public LWIPRawCommon {
+ public:
+  using LWIPRawCommon::LWIPRawCommon;
+  ~LWIPRawListenImpl();
+
+  void init();
+
+  bool ready() const { return this->accepted_socket_count_ > 0; }
+
+  std::unique_ptr<LWIPRawImpl> accept(struct sockaddr *addr, socklen_t *addrlen);
+  std::unique_ptr<LWIPRawImpl> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) {
+    return this->accept(addr, addrlen);
+  }
+  int listen(int backlog);
+
+  // Listening sockets don't do I/O
+  ssize_t read(void *, size_t) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  ssize_t write(const void *, size_t) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  ssize_t readv(const struct iovec *, int) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  ssize_t writev(const struct iovec *, int) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  ssize_t recvfrom(void *, size_t, sockaddr *, socklen_t *) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  ssize_t sendto(const void *, size_t, int, const struct sockaddr *, socklen_t) {
+    errno = ENOTSUP;
+    return -1;
+  }
+  int setblocking(bool) { return 0; }
+  int loop() { return 0; }
+
+  static void s_err_fn(void *arg, err_t err);
+
+ private:
+  err_t accept_fn_(struct tcp_pcb *newpcb, err_t err);
+  static err_t s_accept_fn(void *arg, struct tcp_pcb *newpcb, err_t err);
+
+  // Accept queue - holds incoming connections briefly until the event loop calls accept()
+  // This is NOT a connection pool - just a temporary queue between LWIP callbacks and the main loop
+  // 3 slots is plenty since connections are pulled out quickly by the event loop
+  //
+  // Memory analysis: std::array<3> vs original std::queue implementation:
+  // - std::queue uses std::deque internally which on 32-bit systems needs:
+  //   24 bytes (deque object) + 32+ bytes (map array) + heap allocations
+  //   Total: ~56+ bytes minimum, plus heap fragmentation
+  // - std::array<3>: 12 bytes fixed (3 pointers × 4 bytes)
+  // Saves ~44+ bytes RAM per listening socket + avoids ALL heap allocations
+  // Used on ESP8266 and RP2040 (platforms using LWIP_TCP implementation)
+  //
+  // By using a separate listening socket class, regular connected sockets save
+  // 16 bytes (12 bytes array + 1 byte count + 3 bytes padding) of memory overhead on 32-bit systems
+  static constexpr size_t MAX_ACCEPTED_SOCKETS = 3;
+  std::array<std::unique_ptr<LWIPRawImpl>, MAX_ACCEPTED_SOCKETS> accepted_sockets_;
+  uint8_t accepted_socket_count_ = 0;  // Number of sockets currently in queue
+};
+
+}  // namespace esphome::socket
+
+#endif  // USE_SOCKET_IMPL_LWIP_TCP

esphome/components/socket/lwip_sockets_impl.cpp

@@ -1,6 +1,6 @@
-#include "socket.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
+#include "socket.h"
 
 #ifdef USE_SOCKET_IMPL_LWIP_SOCKETS
 
@@ -9,94 +9,73 @@
 
 namespace esphome::socket {
 
-class LwIPSocketImpl final : public Socket {
- public:
-  LwIPSocketImpl(int fd, bool monitor_loop = false) {
-    this->fd_ = fd;
-    // Register new socket with the application for select() if monitoring requested
-    if (monitor_loop && this->fd_ >= 0) {
-      // Only set loop_monitored_ to true if registration succeeds
-      this->loop_monitored_ = App.register_socket_fd(this->fd_);
-    }
-  }
-  ~LwIPSocketImpl() override {
-    if (!this->closed_) {
-      this->close();  // NOLINT(clang-analyzer-optin.cplusplus.VirtualCall)
-    }
-  }
-  int connect(const struct sockaddr *addr, socklen_t addrlen) override {
-    return lwip_connect(this->fd_, addr, addrlen);
-  }
-  std::unique_ptr<Socket> accept(struct sockaddr *addr, socklen_t *addrlen) override {
-    int fd = lwip_accept(this->fd_, addr, addrlen);
-    if (fd == -1)
-      return {};
-    return make_unique<LwIPSocketImpl>(fd, false);
-  }
-  std::unique_ptr<Socket> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) override {
-    int fd = lwip_accept(this->fd_, addr, addrlen);
-    if (fd == -1)
-      return {};
-    return make_unique<LwIPSocketImpl>(fd, true);
+LwIPSocketImpl::LwIPSocketImpl(int fd, bool monitor_loop) {
+  this->fd_ = fd;
+  // Register new socket with the application for select() if monitoring requested
+  if (monitor_loop && this->fd_ >= 0) {
+    // Only set loop_monitored_ to true if registration succeeds
+    this->loop_monitored_ = App.register_socket_fd(this->fd_);
   }
+}
 
-  int bind(const struct sockaddr *addr, socklen_t addrlen) override { return lwip_bind(this->fd_, addr, addrlen); }
-  int close() override {
-    if (!this->closed_) {
-      // Unregister from select() before closing if monitored
-      if (this->loop_monitored_) {
-        App.unregister_socket_fd(this->fd_);
-      }
-      int ret = lwip_close(this->fd_);
-      this->closed_ = true;
-      return ret;
+LwIPSocketImpl::~LwIPSocketImpl() {
+  if (!this->closed_) {
+    this->close();
+  }
+}
+
+int LwIPSocketImpl::close() {
+  if (!this->closed_) {
+    // Unregister from select() before closing if monitored
+    if (this->loop_monitored_) {
+      App.unregister_socket_fd(this->fd_);
     }
+    int ret = lwip_close(this->fd_);
+    this->closed_ = true;
+    return ret;
+  }
+  return 0;
+}
+
+int LwIPSocketImpl::setblocking(bool blocking) {
+  int fl = lwip_fcntl(this->fd_, F_GETFL, 0);
+  if (blocking) {
+    fl &= ~O_NONBLOCK;
+  } else {
+    fl |= O_NONBLOCK;
+  }
+  lwip_fcntl(this->fd_, F_SETFL, fl);
+  return 0;
+}
+
+bool LwIPSocketImpl::ready() const { return socket_ready_fd(this->fd_, this->loop_monitored_); }
+
+size_t LwIPSocketImpl::getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf) {
+  struct sockaddr_storage storage;
+  socklen_t len = sizeof(storage);
+  if (this->getpeername(reinterpret_cast<struct sockaddr *>(&storage), &len) != 0) {
+    buf[0] = '\0';
     return 0;
   }
-  int shutdown(int how) override { return lwip_shutdown(this->fd_, how); }
+  return format_sockaddr_to(reinterpret_cast<struct sockaddr *>(&storage), len, buf);
+}
 
-  int getpeername(struct sockaddr *addr, socklen_t *addrlen) override {
-    return lwip_getpeername(this->fd_, addr, addrlen);
-  }
-  int getsockname(struct sockaddr *addr, socklen_t *addrlen) override {
-    return lwip_getsockname(this->fd_, addr, addrlen);
-  }
-  int getsockopt(int level, int optname, void *optval, socklen_t *optlen) override {
-    return lwip_getsockopt(this->fd_, level, optname, optval, optlen);
-  }
-  int setsockopt(int level, int optname, const void *optval, socklen_t optlen) override {
-    return lwip_setsockopt(this->fd_, level, optname, optval, optlen);
-  }
-  int listen(int backlog) override { return lwip_listen(this->fd_, backlog); }
-  ssize_t read(void *buf, size_t len) override { return lwip_read(this->fd_, buf, len); }
-  ssize_t recvfrom(void *buf, size_t len, sockaddr *addr, socklen_t *addr_len) override {
-    return lwip_recvfrom(this->fd_, buf, len, 0, addr, addr_len);
-  }
-  ssize_t readv(const struct iovec *iov, int iovcnt) override { return lwip_readv(this->fd_, iov, iovcnt); }
-  ssize_t write(const void *buf, size_t len) override { return lwip_write(this->fd_, buf, len); }
-  ssize_t send(void *buf, size_t len, int flags) { return lwip_send(this->fd_, buf, len, flags); }
-  ssize_t writev(const struct iovec *iov, int iovcnt) override { return lwip_writev(this->fd_, iov, iovcnt); }
-  ssize_t sendto(const void *buf, size_t len, int flags, const struct sockaddr *to, socklen_t tolen) override {
-    return lwip_sendto(this->fd_, buf, len, flags, to, tolen);
-  }
-  int setblocking(bool blocking) override {
-    int fl = lwip_fcntl(this->fd_, F_GETFL, 0);
-    if (blocking) {
-      fl &= ~O_NONBLOCK;
-    } else {
-      fl |= O_NONBLOCK;
-    }
-    lwip_fcntl(this->fd_, F_SETFL, fl);
+size_t LwIPSocketImpl::getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf) {
+  struct sockaddr_storage storage;
+  socklen_t len = sizeof(storage);
+  if (this->getsockname(reinterpret_cast<struct sockaddr *>(&storage), &len) != 0) {
+    buf[0] = '\0';
     return 0;
   }
-};
+  return format_sockaddr_to(reinterpret_cast<struct sockaddr *>(&storage), len, buf);
+}
 
 // Helper to create a socket with optional monitoring
-static std::unique_ptr<Socket> create_socket(int domain, int type, int protocol, bool loop_monitored = false) {
+static std::unique_ptr<LwIPSocketImpl> create_socket(int domain, int type, int protocol, bool loop_monitored = false) {
   int ret = lwip_socket(domain, type, protocol);
   if (ret == -1)
     return nullptr;
-  return std::unique_ptr<Socket>{new LwIPSocketImpl(ret, loop_monitored)};
+  return make_unique<LwIPSocketImpl>(ret, loop_monitored);
 }
 
 std::unique_ptr<Socket> socket(int domain, int type, int protocol) {
@@ -107,6 +86,14 @@ std::unique_ptr<Socket> socket_loop_monitored(int domain, int type, int protocol
   return create_socket(domain, type, protocol, true);
 }
 
+std::unique_ptr<ListenSocket> socket_listen(int domain, int type, int protocol) {
+  return create_socket(domain, type, protocol, false);
+}
+
+std::unique_ptr<ListenSocket> socket_listen_loop_monitored(int domain, int type, int protocol) {
+  return create_socket(domain, type, protocol, true);
+}
+
 }  // namespace esphome::socket
 
 #endif  // USE_SOCKET_IMPL_LWIP_SOCKETS

esphome/components/socket/lwip_sockets_impl.h

@@ -0,0 +1,80 @@
+#pragma once
+#include "esphome/core/defines.h"
+
+#ifdef USE_SOCKET_IMPL_LWIP_SOCKETS
+
+#include <memory>
+#include <span>
+
+#include "esphome/core/helpers.h"
+#include "headers.h"
+
+namespace esphome::socket {
+
+class LwIPSocketImpl {
+ public:
+  LwIPSocketImpl(int fd, bool monitor_loop = false);
+  ~LwIPSocketImpl();
+  LwIPSocketImpl(const LwIPSocketImpl &) = delete;
+  LwIPSocketImpl &operator=(const LwIPSocketImpl &) = delete;
+
+  int connect(const struct sockaddr *addr, socklen_t addrlen) { return lwip_connect(this->fd_, addr, addrlen); }
+  std::unique_ptr<LwIPSocketImpl> accept(struct sockaddr *addr, socklen_t *addrlen) {
+    int fd = lwip_accept(this->fd_, addr, addrlen);
+    if (fd == -1)
+      return {};
+    return make_unique<LwIPSocketImpl>(fd, false);
+  }
+  std::unique_ptr<LwIPSocketImpl> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) {
+    int fd = lwip_accept(this->fd_, addr, addrlen);
+    if (fd == -1)
+      return {};
+    return make_unique<LwIPSocketImpl>(fd, true);
+  }
+
+  int bind(const struct sockaddr *addr, socklen_t addrlen) { return lwip_bind(this->fd_, addr, addrlen); }
+  int close();
+  int shutdown(int how) { return lwip_shutdown(this->fd_, how); }
+
+  int getpeername(struct sockaddr *addr, socklen_t *addrlen) { return lwip_getpeername(this->fd_, addr, addrlen); }
+  int getsockname(struct sockaddr *addr, socklen_t *addrlen) { return lwip_getsockname(this->fd_, addr, addrlen); }
+
+  /// Format peer address into a fixed-size buffer (no heap allocation)
+  size_t getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf);
+  /// Format local address into a fixed-size buffer (no heap allocation)
+  size_t getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf);
+
+  int getsockopt(int level, int optname, void *optval, socklen_t *optlen) {
+    return lwip_getsockopt(this->fd_, level, optname, optval, optlen);
+  }
+  int setsockopt(int level, int optname, const void *optval, socklen_t optlen) {
+    return lwip_setsockopt(this->fd_, level, optname, optval, optlen);
+  }
+  int listen(int backlog) { return lwip_listen(this->fd_, backlog); }
+  ssize_t read(void *buf, size_t len) { return lwip_read(this->fd_, buf, len); }
+  ssize_t recvfrom(void *buf, size_t len, sockaddr *addr, socklen_t *addr_len) {
+    return lwip_recvfrom(this->fd_, buf, len, 0, addr, addr_len);
+  }
+  ssize_t readv(const struct iovec *iov, int iovcnt) { return lwip_readv(this->fd_, iov, iovcnt); }
+  ssize_t write(const void *buf, size_t len) { return lwip_write(this->fd_, buf, len); }
+  ssize_t send(void *buf, size_t len, int flags) { return lwip_send(this->fd_, buf, len, flags); }
+  ssize_t writev(const struct iovec *iov, int iovcnt) { return lwip_writev(this->fd_, iov, iovcnt); }
+  ssize_t sendto(const void *buf, size_t len, int flags, const struct sockaddr *to, socklen_t tolen) {
+    return lwip_sendto(this->fd_, buf, len, flags, to, tolen);
+  }
+  int setblocking(bool blocking);
+  int loop() { return 0; }
+
+  bool ready() const;
+
+  int get_fd() const { return this->fd_; }
+
+ protected:
+  int fd_{-1};
+  bool closed_{false};
+  bool loop_monitored_{false};
+};
+
+}  // namespace esphome::socket
+
+#endif  // USE_SOCKET_IMPL_LWIP_SOCKETS

esphome/components/socket/socket.cpp

@@ -8,10 +8,10 @@
 
 namespace esphome::socket {
 
-Socket::~Socket() {}
-
 #ifdef USE_SOCKET_SELECT_SUPPORT
-bool Socket::ready() const { return !this->loop_monitored_ || App.is_socket_ready_(this->fd_); }
+// Shared ready() implementation for fd-based socket implementations (BSD and LWIP sockets).
+// Checks if the Application's select() loop has marked this fd as ready.
+bool socket_ready_fd(int fd, bool loop_monitored) { return !loop_monitored || App.is_socket_ready_(fd); }
 #endif
 
 // Platform-specific inet_ntop wrappers
@@ -81,26 +81,6 @@ size_t format_sockaddr_to(const struct sockaddr *addr_ptr, socklen_t len, std::s
   return 0;
 }
 
-size_t Socket::getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf) {
-  struct sockaddr_storage storage;
-  socklen_t len = sizeof(storage);
-  if (this->getpeername(reinterpret_cast<struct sockaddr *>(&storage), &len) != 0) {
-    buf[0] = '\0';
-    return 0;
-  }
-  return format_sockaddr_to(reinterpret_cast<struct sockaddr *>(&storage), len, buf);
-}
-
-size_t Socket::getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf) {
-  struct sockaddr_storage storage;
-  socklen_t len = sizeof(storage);
-  if (this->getsockname(reinterpret_cast<struct sockaddr *>(&storage), &len) != 0) {
-    buf[0] = '\0';
-    return 0;
-  }
-  return format_sockaddr_to(reinterpret_cast<struct sockaddr *>(&storage), len, buf);
-}
-
 std::unique_ptr<Socket> socket_ip(int type, int protocol) {
 #if USE_NETWORK_IPV6
   return socket(AF_INET6, type, protocol);
@@ -109,11 +89,11 @@ std::unique_ptr<Socket> socket_ip(int type, int protocol) {
 #endif /* USE_NETWORK_IPV6 */
 }
 
-std::unique_ptr<Socket> socket_ip_loop_monitored(int type, int protocol) {
+std::unique_ptr<ListenSocket> socket_ip_loop_monitored(int type, int protocol) {
 #if USE_NETWORK_IPV6
-  return socket_loop_monitored(AF_INET6, type, protocol);
+  return socket_listen_loop_monitored(AF_INET6, type, protocol);
 #else
-  return socket_loop_monitored(AF_INET, type, protocol);
+  return socket_listen_loop_monitored(AF_INET, type, protocol);
 #endif /* USE_NETWORK_IPV6 */
 }
 

esphome/components/socket/socket.h

@@ -7,87 +7,41 @@
 #include "headers.h"
 
 #if defined(USE_SOCKET_IMPL_LWIP_TCP) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS) || defined(USE_SOCKET_IMPL_BSD_SOCKETS)
+
+// Include only the active implementation's header.
+// SOCKADDR_STR_LEN is defined in headers.h.
+#ifdef USE_SOCKET_IMPL_BSD_SOCKETS
+#include "bsd_sockets_impl.h"
+#elif defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
+#include "lwip_sockets_impl.h"
+#elif defined(USE_SOCKET_IMPL_LWIP_TCP)
+#include "lwip_raw_tcp_impl.h"
+#endif
+
 namespace esphome::socket {
 
-// Maximum length for formatted socket address string (IP address without port)
-// IPv4: "255.255.255.255" = 15 chars + null = 16
-// IPv6: full address = 45 chars + null = 46
-#if USE_NETWORK_IPV6
-static constexpr size_t SOCKADDR_STR_LEN = 46;  // INET6_ADDRSTRLEN
-#else
-static constexpr size_t SOCKADDR_STR_LEN = 16;  // INET_ADDRSTRLEN
+// Type aliases — only one implementation is active per build.
+// Socket is the concrete type for connected sockets.
+// ListenSocket is the concrete type for listening/server sockets.
+// On BSD and LWIP_SOCKETS, both aliases resolve to the same type.
+// On LWIP_TCP, they are different types (no virtual dispatch between them).
+#ifdef USE_SOCKET_IMPL_BSD_SOCKETS
+using Socket = BSDSocketImpl;
+using ListenSocket = BSDSocketImpl;
+#elif defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
+using Socket = LwIPSocketImpl;
+using ListenSocket = LwIPSocketImpl;
+#elif defined(USE_SOCKET_IMPL_LWIP_TCP)
+using Socket = LWIPRawImpl;
+using ListenSocket = LWIPRawListenImpl;
 #endif
 
-class Socket {
- public:
-  Socket() = default;
-  virtual ~Socket();
-  Socket(const Socket &) = delete;
-  Socket &operator=(const Socket &) = delete;
-
-  virtual std::unique_ptr<Socket> accept(struct sockaddr *addr, socklen_t *addrlen) = 0;
-  /// Accept a connection and monitor it in the main loop
-  /// NOTE: This function is NOT thread-safe and must only be called from the main loop
-  virtual std::unique_ptr<Socket> accept_loop_monitored(struct sockaddr *addr, socklen_t *addrlen) {
-    return accept(addr, addrlen);  // Default implementation for backward compatibility
-  }
-  virtual int bind(const struct sockaddr *addr, socklen_t addrlen) = 0;
-  virtual int close() = 0;
-  // not supported yet:
-  // virtual int connect(const std::string &address) = 0;
-#if defined(USE_SOCKET_IMPL_LWIP_SOCKETS) || defined(USE_SOCKET_IMPL_BSD_SOCKETS)
-  virtual int connect(const struct sockaddr *addr, socklen_t addrlen) = 0;
-#endif
-  virtual int shutdown(int how) = 0;
-
-  virtual int getpeername(struct sockaddr *addr, socklen_t *addrlen) = 0;
-  virtual int getsockname(struct sockaddr *addr, socklen_t *addrlen) = 0;
-
-  /// Format peer address into a fixed-size buffer (no heap allocation)
-  /// Non-virtual wrapper around getpeername() - can be optimized away if unused
-  /// Returns number of characters written (excluding null terminator), or 0 on error
-  size_t getpeername_to(std::span<char, SOCKADDR_STR_LEN> buf);
-  /// Format local address into a fixed-size buffer (no heap allocation)
-  /// Non-virtual wrapper around getsockname() - can be optimized away if unused
-  size_t getsockname_to(std::span<char, SOCKADDR_STR_LEN> buf);
-  virtual int getsockopt(int level, int optname, void *optval, socklen_t *optlen) = 0;
-  virtual int setsockopt(int level, int optname, const void *optval, socklen_t optlen) = 0;
-  virtual int listen(int backlog) = 0;
-  virtual ssize_t read(void *buf, size_t len) = 0;
-  virtual ssize_t recvfrom(void *buf, size_t len, sockaddr *addr, socklen_t *addr_len) = 0;
-  virtual ssize_t readv(const struct iovec *iov, int iovcnt) = 0;
-  virtual ssize_t write(const void *buf, size_t len) = 0;
-  virtual ssize_t writev(const struct iovec *iov, int iovcnt) = 0;
-  virtual ssize_t sendto(const void *buf, size_t len, int flags, const struct sockaddr *to, socklen_t tolen) = 0;
-
-  virtual int setblocking(bool blocking) = 0;
-  virtual int loop() { return 0; };
-
-    /// Get the underlying file descriptor (returns -1 if not supported)
-    /// Non-virtual: only one socket implementation is active per build.
 #ifdef USE_SOCKET_SELECT_SUPPORT
-  int get_fd() const { return this->fd_; }
-#else
-  int get_fd() const { return -1; }
+/// Shared ready() helper for fd-based socket implementations.
+/// Checks if the Application's select() loop has marked this fd as ready.
+bool socket_ready_fd(int fd, bool loop_monitored);
 #endif
 
-  /// Check if socket has data ready to read. Must only be called from the main loop thread.
-  /// For select()-based sockets: non-virtual, checks Application's select() results
-  /// For LWIP raw TCP sockets: virtual, checks internal buffer state
-#ifdef USE_SOCKET_SELECT_SUPPORT
-  bool ready() const;
-#else
-  virtual bool ready() const { return true; }
-#endif
-
- protected:
-#ifdef USE_SOCKET_SELECT_SUPPORT
-  int fd_{-1};
-  bool closed_{false};
-  bool loop_monitored_{false};
-#endif
-};
-
 /// Create a socket of the given domain, type and protocol.
 std::unique_ptr<Socket> socket(int domain, int type, int protocol);
 /// Create a socket in the newest available IP domain (IPv6 or IPv4) of the given type and protocol.
@@ -100,7 +54,13 @@ std::unique_ptr<Socket> socket_ip(int type, int protocol);
 /// NOTE: On ESP platforms, FD_SETSIZE is typically 10, limiting the number of monitored sockets.
 /// File descriptors >= FD_SETSIZE will not be monitored and will log an error.
 std::unique_ptr<Socket> socket_loop_monitored(int domain, int type, int protocol);
-std::unique_ptr<Socket> socket_ip_loop_monitored(int type, int protocol);
+
+/// Create a listening socket of the given domain, type and protocol.
+std::unique_ptr<ListenSocket> socket_listen(int domain, int type, int protocol);
+/// Create a listening socket and monitor it for data in the main loop.
+std::unique_ptr<ListenSocket> socket_listen_loop_monitored(int domain, int type, int protocol);
+/// Create a listening socket in the newest available IP domain and monitor it.
+std::unique_ptr<ListenSocket> socket_ip_loop_monitored(int type, int protocol);
 
 /// Set a sockaddr to the specified address and port for the IP version used by socket_ip().
 /// @param addr Destination sockaddr structure

esphome/core/application.h

@@ -105,7 +105,10 @@
 #endif
 
 namespace esphome::socket {
-class Socket;
+#ifdef USE_SOCKET_SELECT_SUPPORT
+/// Shared ready() helper for fd-based socket implementations.
+bool socket_ready_fd(int fd, bool loop_monitored);  // NOLINT(readability-redundant-declaration)
+#endif
 }  // namespace esphome::socket
 
 // Forward declarations for friend access from codegen-generated setup()
@@ -520,7 +523,9 @@ class Application {
 
  protected:
   friend Component;
-  friend class socket::Socket;
+#ifdef USE_SOCKET_SELECT_SUPPORT
+  friend bool socket::socket_ready_fd(int fd, bool loop_monitored);
+#endif
   friend void ::setup();
   friend void ::original_setup();