tcp_transport: Add TCP transport connection errors

Transport's error_handle is used to capture different types of errors
including esp_err_t from esp-tls and socket/system errors.
This change adds the following error codes for TCP transport:
* connection closed by a FIN flag (clean closure from server)
* DNS resolution problem
* connection timeout
These errors are already defined in esp-tls component and since this
component will be used in the future for both TCP and SSL transport, we
currently report these issues in transport::error_handle::esp_tls_last_error
of standard esp error type (esp_err_t)

Closes espressif/esp-mqtt#182

components/esp-tls/esp_tls.h

@@ -18,6 +18,7 @@
 #include <sys/socket.h>
 #include <fcntl.h>
 #include "esp_err.h"
+#include "esp_tls_errors.h"
 #ifdef CONFIG_ESP_TLS_USING_MBEDTLS
 #include "mbedtls/platform.h"
 #include "mbedtls/net_sockets.h"
@@ -36,71 +37,6 @@
 extern "C" {
 #endif
 
-#define ESP_ERR_ESP_TLS_BASE           0x8000             /*!< Starting number of ESP-TLS error codes */
-#define ESP_ERR_ESP_TLS_CANNOT_RESOLVE_HOSTNAME           (ESP_ERR_ESP_TLS_BASE + 0x01)  /*!< Error if hostname couldn't be resolved upon tls connection */
-#define ESP_ERR_ESP_TLS_CANNOT_CREATE_SOCKET              (ESP_ERR_ESP_TLS_BASE + 0x02)  /*!< Failed to create socket */
-#define ESP_ERR_ESP_TLS_UNSUPPORTED_PROTOCOL_FAMILY       (ESP_ERR_ESP_TLS_BASE + 0x03)  /*!< Unsupported protocol family */
-#define ESP_ERR_ESP_TLS_FAILED_CONNECT_TO_HOST            (ESP_ERR_ESP_TLS_BASE + 0x04)  /*!< Failed to connect to host */
-#define ESP_ERR_ESP_TLS_SOCKET_SETOPT_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x05)  /*!< failed to set socket option */
-#define ESP_ERR_MBEDTLS_CERT_PARTLY_OK                    (ESP_ERR_ESP_TLS_BASE + 0x06)  /*!< mbedtls parse certificates was partly successful */
-#define ESP_ERR_MBEDTLS_CTR_DRBG_SEED_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x07)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_SSL_SET_HOSTNAME_FAILED           (ESP_ERR_ESP_TLS_BASE + 0x08)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_SSL_CONFIG_DEFAULTS_FAILED        (ESP_ERR_ESP_TLS_BASE + 0x09)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_SSL_CONF_ALPN_PROTOCOLS_FAILED    (ESP_ERR_ESP_TLS_BASE + 0x0A)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_X509_CRT_PARSE_FAILED             (ESP_ERR_ESP_TLS_BASE + 0x0B)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_SSL_CONF_OWN_CERT_FAILED          (ESP_ERR_ESP_TLS_BASE + 0x0C)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_SSL_SETUP_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x0D)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_SSL_WRITE_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x0E)  /*!< mbedtls api returned error */
-#define ESP_ERR_MBEDTLS_PK_PARSE_KEY_FAILED               (ESP_ERR_ESP_TLS_BASE + 0x0F)  /*!< mbedtls api returned failed  */
-#define ESP_ERR_MBEDTLS_SSL_HANDSHAKE_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x10)  /*!< mbedtls api returned failed  */
-#define ESP_ERR_MBEDTLS_SSL_CONF_PSK_FAILED               (ESP_ERR_ESP_TLS_BASE + 0x11)  /*!< mbedtls api returned failed  */
-#define ESP_ERR_ESP_TLS_CONNECTION_TIMEOUT                (ESP_ERR_ESP_TLS_BASE + 0x12)  /*!< new connection in esp_tls_low_level_conn connection timeouted */
-#define ESP_ERR_WOLFSSL_SSL_SET_HOSTNAME_FAILED           (ESP_ERR_ESP_TLS_BASE + 0x13)  /*!< wolfSSL api returned error */
-#define ESP_ERR_WOLFSSL_SSL_CONF_ALPN_PROTOCOLS_FAILED    (ESP_ERR_ESP_TLS_BASE + 0x14)  /*!< wolfSSL api returned error */
-#define ESP_ERR_WOLFSSL_CERT_VERIFY_SETUP_FAILED          (ESP_ERR_ESP_TLS_BASE + 0x15)  /*!< wolfSSL api returned error */
-#define ESP_ERR_WOLFSSL_KEY_VERIFY_SETUP_FAILED           (ESP_ERR_ESP_TLS_BASE + 0x16)  /*!< wolfSSL api returned error */
-#define ESP_ERR_WOLFSSL_SSL_HANDSHAKE_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x17)  /*!< wolfSSL api returned failed  */
-#define ESP_ERR_WOLFSSL_CTX_SETUP_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x18)  /*!< wolfSSL api returned failed */
-#define ESP_ERR_WOLFSSL_SSL_SETUP_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x19)  /*!< wolfSSL api returned failed */
-#define ESP_ERR_WOLFSSL_SSL_WRITE_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x1A)  /*!< wolfSSL api returned failed */
-
-#define ESP_ERR_ESP_TLS_SE_FAILED                         (ESP_ERR_ESP_TLS_BASE + 0x1B)  /*< esp-tls use Secure Element returned failed */
-#ifdef CONFIG_ESP_TLS_USING_MBEDTLS
-#define ESP_TLS_ERR_SSL_WANT_READ                          MBEDTLS_ERR_SSL_WANT_READ
-#define ESP_TLS_ERR_SSL_WANT_WRITE                         MBEDTLS_ERR_SSL_WANT_WRITE
-#define ESP_TLS_ERR_SSL_TIMEOUT                            MBEDTLS_ERR_SSL_TIMEOUT
-#elif CONFIG_ESP_TLS_USING_WOLFSSL /* CONFIG_ESP_TLS_USING_MBEDTLS */
-#define ESP_TLS_ERR_SSL_WANT_READ                          WOLFSSL_ERROR_WANT_READ
-#define ESP_TLS_ERR_SSL_WANT_WRITE                         WOLFSSL_ERROR_WANT_WRITE
-#define ESP_TLS_ERR_SSL_TIMEOUT                            WOLFSSL_CBIO_ERR_TIMEOUT
-#endif /*CONFIG_ESP_TLS_USING_WOLFSSL */
-
-/**
-* Definition of different types/sources of error codes reported
-* from different components
-*/
-typedef enum {
-    ESP_TLS_ERR_TYPE_UNKNOWN = 0,
-    ESP_TLS_ERR_TYPE_SYSTEM,                /*!< System error -- errno */
-    ESP_TLS_ERR_TYPE_MBEDTLS,               /*!< Error code from mbedTLS library */
-    ESP_TLS_ERR_TYPE_MBEDTLS_CERT_FLAGS,    /*!< Certificate flags defined in mbedTLS */
-    ESP_TLS_ERR_TYPE_ESP,                   /*!< ESP-IDF error type -- esp_err_t  */
-    ESP_TLS_ERR_TYPE_WOLFSSL,               /*!< Error code from wolfSSL library */
-    ESP_TLS_ERR_TYPE_WOLFSSL_CERT_FLAGS,    /*!< Certificate flags defined in wolfSSL */
-    ESP_TLS_ERR_TYPE_MAX,                   /*!< Last err type -- invalid entry */
-} esp_tls_error_type_t;
-
-typedef struct esp_tls_last_error* esp_tls_error_handle_t;
-
-/**
-*  @brief Error structure containing relevant errors in case tls error occurred
-*/
-typedef struct esp_tls_last_error {
-    esp_err_t last_error;               /*!< error code (based on ESP_ERR_ESP_TLS_BASE) of the last occurred error */
-    int       esp_tls_error_code;       /*!< esp_tls error code from last esp_tls failed api */
-    int       esp_tls_flags;            /*!< last certification verification flags */
-} esp_tls_last_error_t;
-
 /**
  *  @brief ESP-TLS Connection State
  */

components/esp-tls/esp_tls_errors.h

@@ -0,0 +1,96 @@
+// Copyright 2021 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef _ESP_TLS_ERRORS_H_
+#define _ESP_TLS_ERRORS_H_
+
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define ESP_ERR_ESP_TLS_BASE           0x8000             /*!< Starting number of ESP-TLS error codes */
+#define ESP_ERR_ESP_TLS_CANNOT_RESOLVE_HOSTNAME           (ESP_ERR_ESP_TLS_BASE + 0x01)  /*!< Error if hostname couldn't be resolved upon tls connection */
+#define ESP_ERR_ESP_TLS_CANNOT_CREATE_SOCKET              (ESP_ERR_ESP_TLS_BASE + 0x02)  /*!< Failed to create socket */
+#define ESP_ERR_ESP_TLS_UNSUPPORTED_PROTOCOL_FAMILY       (ESP_ERR_ESP_TLS_BASE + 0x03)  /*!< Unsupported protocol family */
+#define ESP_ERR_ESP_TLS_FAILED_CONNECT_TO_HOST            (ESP_ERR_ESP_TLS_BASE + 0x04)  /*!< Failed to connect to host */
+#define ESP_ERR_ESP_TLS_SOCKET_SETOPT_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x05)  /*!< failed to set socket option */
+#define ESP_ERR_MBEDTLS_CERT_PARTLY_OK                    (ESP_ERR_ESP_TLS_BASE + 0x06)  /*!< mbedtls parse certificates was partly successful */
+#define ESP_ERR_MBEDTLS_CTR_DRBG_SEED_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x07)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_SSL_SET_HOSTNAME_FAILED           (ESP_ERR_ESP_TLS_BASE + 0x08)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_SSL_CONFIG_DEFAULTS_FAILED        (ESP_ERR_ESP_TLS_BASE + 0x09)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_SSL_CONF_ALPN_PROTOCOLS_FAILED    (ESP_ERR_ESP_TLS_BASE + 0x0A)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_X509_CRT_PARSE_FAILED             (ESP_ERR_ESP_TLS_BASE + 0x0B)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_SSL_CONF_OWN_CERT_FAILED          (ESP_ERR_ESP_TLS_BASE + 0x0C)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_SSL_SETUP_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x0D)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_SSL_WRITE_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x0E)  /*!< mbedtls api returned error */
+#define ESP_ERR_MBEDTLS_PK_PARSE_KEY_FAILED               (ESP_ERR_ESP_TLS_BASE + 0x0F)  /*!< mbedtls api returned failed  */
+#define ESP_ERR_MBEDTLS_SSL_HANDSHAKE_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x10)  /*!< mbedtls api returned failed  */
+#define ESP_ERR_MBEDTLS_SSL_CONF_PSK_FAILED               (ESP_ERR_ESP_TLS_BASE + 0x11)  /*!< mbedtls api returned failed  */
+#define ESP_ERR_ESP_TLS_CONNECTION_TIMEOUT                (ESP_ERR_ESP_TLS_BASE + 0x12)  /*!< new connection in esp_tls_low_level_conn connection timeouted */
+#define ESP_ERR_WOLFSSL_SSL_SET_HOSTNAME_FAILED           (ESP_ERR_ESP_TLS_BASE + 0x13)  /*!< wolfSSL api returned error */
+#define ESP_ERR_WOLFSSL_SSL_CONF_ALPN_PROTOCOLS_FAILED    (ESP_ERR_ESP_TLS_BASE + 0x14)  /*!< wolfSSL api returned error */
+#define ESP_ERR_WOLFSSL_CERT_VERIFY_SETUP_FAILED          (ESP_ERR_ESP_TLS_BASE + 0x15)  /*!< wolfSSL api returned error */
+#define ESP_ERR_WOLFSSL_KEY_VERIFY_SETUP_FAILED           (ESP_ERR_ESP_TLS_BASE + 0x16)  /*!< wolfSSL api returned error */
+#define ESP_ERR_WOLFSSL_SSL_HANDSHAKE_FAILED              (ESP_ERR_ESP_TLS_BASE + 0x17)  /*!< wolfSSL api returned failed  */
+#define ESP_ERR_WOLFSSL_CTX_SETUP_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x18)  /*!< wolfSSL api returned failed */
+#define ESP_ERR_WOLFSSL_SSL_SETUP_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x19)  /*!< wolfSSL api returned failed */
+#define ESP_ERR_WOLFSSL_SSL_WRITE_FAILED                  (ESP_ERR_ESP_TLS_BASE + 0x1A)  /*!< wolfSSL api returned failed */
+
+#define ESP_ERR_ESP_TLS_SE_FAILED                         (ESP_ERR_ESP_TLS_BASE + 0x1B)  /*< esp-tls use Secure Element returned failed */
+#define ESP_ERR_ESP_TLS_TCP_CLOSED_FIN                    (ESP_ERR_ESP_TLS_BASE + 0x1C)  /*< esp-tls's TPC transport connection has benn closed (in a clean way) */
+
+#ifdef CONFIG_ESP_TLS_USING_MBEDTLS
+#define ESP_TLS_ERR_SSL_WANT_READ                          MBEDTLS_ERR_SSL_WANT_READ
+#define ESP_TLS_ERR_SSL_WANT_WRITE                         MBEDTLS_ERR_SSL_WANT_WRITE
+#define ESP_TLS_ERR_SSL_TIMEOUT                            MBEDTLS_ERR_SSL_TIMEOUT
+#elif CONFIG_ESP_TLS_USING_WOLFSSL /* CONFIG_ESP_TLS_USING_MBEDTLS */
+#define ESP_TLS_ERR_SSL_WANT_READ                          WOLFSSL_ERROR_WANT_READ
+#define ESP_TLS_ERR_SSL_WANT_WRITE                         WOLFSSL_ERROR_WANT_WRITE
+#define ESP_TLS_ERR_SSL_TIMEOUT                            WOLFSSL_CBIO_ERR_TIMEOUT
+#endif /*CONFIG_ESP_TLS_USING_WOLFSSL */
+
+/**
+* Definition of different types/sources of error codes reported
+* from different components
+*/
+typedef enum {
+    ESP_TLS_ERR_TYPE_UNKNOWN = 0,
+    ESP_TLS_ERR_TYPE_SYSTEM,                /*!< System error -- errno */
+    ESP_TLS_ERR_TYPE_MBEDTLS,               /*!< Error code from mbedTLS library */
+    ESP_TLS_ERR_TYPE_MBEDTLS_CERT_FLAGS,    /*!< Certificate flags defined in mbedTLS */
+    ESP_TLS_ERR_TYPE_ESP,                   /*!< ESP-IDF error type -- esp_err_t  */
+    ESP_TLS_ERR_TYPE_WOLFSSL,               /*!< Error code from wolfSSL library */
+    ESP_TLS_ERR_TYPE_WOLFSSL_CERT_FLAGS,    /*!< Certificate flags defined in wolfSSL */
+    ESP_TLS_ERR_TYPE_TCP_CONNECTION,        /*!< Errors related to TCP layer, extending errno */
+    ESP_TLS_ERR_TYPE_MAX,                   /*!< Last err type -- invalid entry */
+} esp_tls_error_type_t;
+
+typedef struct esp_tls_last_error* esp_tls_error_handle_t;
+
+/**
+*  @brief Error structure containing relevant errors in case tls error occurred
+*/
+typedef struct esp_tls_last_error {
+    esp_err_t last_error;               /*!< error code (based on ESP_ERR_ESP_TLS_BASE) of the last occurred error */
+    int       esp_tls_error_code;       /*!< esp_tls error code from last esp_tls failed api */
+    int       esp_tls_flags;            /*!< last certification verification flags */
+} esp_tls_last_error_t;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif //_ESP_TLS_ERRORS_H_

components/tcp_transport/private_include/esp_transport_internal.h

@@ -44,6 +44,29 @@ struct esp_transport_item_t {
     STAILQ_ENTRY(esp_transport_item_t) next;
 };
 
+/**
+ * @brief Internal error types for TCP connection issues not covered in socket's errno
+ */
+enum tcp_transport_errors {
+    ERR_TCP_TRANSPORT_CONNECTION_TIMEOUT,
+    ERR_TCP_TRANSPORT_CANNOT_RESOLVE_HOSTNAME,
+    ERR_TCP_TRANSPORT_CONNECTION_CLOSED_BY_FIN,
+    ERR_TCP_TRANSPORT_CONNECTION_FAILED,
+    ERR_TCP_TRANSPORT_SETOPT_FAILED,
+};
+
+/**
+ * @brief      Captures internal tcp connection error
+ *
+ * This is internally translated to esp-tls return codes of esp_err_t type, since the esp-tls
+ * will be used as TCP transport layer
+ *
+ * @param[in] t The transport handle
+ * @param[in] error Internal tcp-transport's error
+ *
+ */
+void capture_tcp_transport_error(esp_transport_handle_t t, enum tcp_transport_errors error);
+
 /**
  * @brief Returns underlying socket for the supplied transport handle
  *

components/tcp_transport/transport.c

@@ -23,6 +23,7 @@
 #include "esp_transport.h"
 #include "esp_transport_internal.h"
 #include "esp_transport_utils.h"
+#include "esp_tls_errors.h"
 
 static const char *TAG = "TRANSPORT";
 
@@ -298,6 +299,28 @@ int esp_transport_get_errno(esp_transport_handle_t t)
     return -1;
 }
 
+void capture_tcp_transport_error(esp_transport_handle_t t, enum tcp_transport_errors error)
+{
+    esp_tls_last_error_t *err_handle = esp_transport_get_error_handle(t);
+    switch (error) {
+        case ERR_TCP_TRANSPORT_CONNECTION_TIMEOUT:
+            err_handle->last_error = ESP_ERR_ESP_TLS_CONNECTION_TIMEOUT;
+            break;
+        case ERR_TCP_TRANSPORT_CANNOT_RESOLVE_HOSTNAME:
+            err_handle->last_error = ESP_ERR_ESP_TLS_CANNOT_RESOLVE_HOSTNAME;
+            break;
+        case ERR_TCP_TRANSPORT_CONNECTION_CLOSED_BY_FIN:
+            err_handle->last_error = ESP_ERR_ESP_TLS_TCP_CLOSED_FIN;
+            break;
+        case ERR_TCP_TRANSPORT_CONNECTION_FAILED:
+            err_handle->last_error = ESP_ERR_ESP_TLS_FAILED_CONNECT_TO_HOST;
+            break;
+        case ERR_TCP_TRANSPORT_SETOPT_FAILED:
+            err_handle->last_error = ESP_ERR_ESP_TLS_SOCKET_SETOPT_FAILED;
+            break;
+    }
+}
+
 void esp_transport_set_errors(esp_transport_handle_t t, const esp_tls_error_handle_t error_handle)
 {
     if (t && t->error_handle) {

components/tcp_transport/transport_ssl.c

@@ -166,6 +166,10 @@ static int ssl_read(esp_transport_handle_t t, char *buffer, int len, int timeout
         esp_transport_set_errors(t, ssl->tls->error_handle);
     }
     if (ret == 0) {
+        if (poll > 0) {
+            // no error, socket reads 0 while previously detected as readable -> connection has been closed cleanly
+            capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_CONNECTION_CLOSED_BY_FIN);
+        }
         ret = -1;
     }
     return ret;

components/tcp_transport/transport_tcp.c

@@ -26,13 +26,15 @@
 #include "esp_transport_utils.h"
 #include "esp_transport.h"
 #include "esp_transport_internal.h"
+#include "esp_tls_errors.h"
 
 static const char *TAG = "TRANS_TCP";
 
 typedef struct {
     int sock;
 } transport_tcp_t;
 
+
 static int resolve_dns(const char *host, struct sockaddr_in *ip)
 {
     const struct addrinfo hints = {
@@ -91,6 +93,7 @@ static int tcp_connect(esp_transport_handle_t t, const char *host, int port, int
     //if stream_host is not ip address, resolve it AF_INET,servername,&serveraddr.sin_addr
     if (inet_pton(AF_INET, host, &remote_ip.sin_addr) != 1) {
         if (resolve_dns(host, &remote_ip) < 0) {
+            capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_CANNOT_RESOLVE_HOSTNAME);
             return -1;
         }
     }
@@ -120,10 +123,12 @@ static int tcp_connect(esp_transport_handle_t t, const char *host, int port, int
     int flags;
     if ((flags = fcntl(tcp->sock, F_GETFL, NULL)) < 0) {
         ESP_LOGE(TAG, "[sock=%d] get file flags error: %s", tcp->sock, strerror(errno));
+        capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_SETOPT_FAILED);
         goto error;
     }
     if (fcntl(tcp->sock, F_SETFL, flags |= O_NONBLOCK) < 0) {
         ESP_LOGE(TAG, "[sock=%d] set nonblocking error: %s", tcp->sock, strerror(errno));
+        capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_SETOPT_FAILED);
         goto error;
     }
 
@@ -146,19 +151,21 @@ static int tcp_connect(esp_transport_handle_t t, const char *host, int port, int
             }
             else if (res == 0) {
                 ESP_LOGE(TAG, "[sock=%d] select() timeout", tcp->sock);
-                esp_transport_capture_errno(t, EINPROGRESS);    // errno=EINPROGRESS indicates connection timeout
+                capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_CONNECTION_TIMEOUT);
                 goto error;
             } else {
                 int sockerr;
                 socklen_t len = (socklen_t)sizeof(int);
 
                 if (getsockopt(tcp->sock, SOL_SOCKET, SO_ERROR, (void*)(&sockerr), &len) < 0) {
                     ESP_LOGE(TAG, "[sock=%d] getsockopt() error: %s", tcp->sock, strerror(errno));
+                    capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_SETOPT_FAILED);
                     goto error;
                 }
                 else if (sockerr) {
                     esp_transport_capture_errno(t, sockerr);
                     ESP_LOGE(TAG, "[sock=%d] delayed connect error: %s", tcp->sock, strerror(sockerr));
+                    capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_CONNECTION_FAILED);
                     goto error;
                 }
             }
@@ -170,10 +177,12 @@ static int tcp_connect(esp_transport_handle_t t, const char *host, int port, int
     // Reset socket to blocking
     if ((flags = fcntl(tcp->sock, F_GETFL, NULL)) < 0) {
         ESP_LOGE(TAG, "[sock=%d] get file flags error: %s", tcp->sock, strerror(errno));
+        capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_SETOPT_FAILED);
         goto error;
     }
     if (fcntl(tcp->sock, F_SETFL, flags & ~O_NONBLOCK) < 0) {
         ESP_LOGE(TAG, "[sock=%d] reset blocking error: %s", tcp->sock, strerror(errno));
+        capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_SETOPT_FAILED);
         goto error;
     }
     return tcp->sock;
@@ -202,6 +211,10 @@ static int tcp_read(esp_transport_handle_t t, char *buffer, int len, int timeout
     }
     int read_len = read(tcp->sock, buffer, len);
     if (read_len == 0) {
+        if (poll > 0) {
+            // no error, socket reads 0 while previously detected as readable -> connection has been closed cleanly
+            capture_tcp_transport_error(t, ERR_TCP_TRANSPORT_CONNECTION_CLOSED_BY_FIN);
+        }
         return -1;
     }
     return read_len;