Common Socket Error Troubleshooting
The following summarizes common error logs in ESP-IDF Socket, their corresponding causes, and possible solutions.
Example: transport_base: poll_read select error 113, errno = Software caused connection abort, fd = 56
Error Message Analysis:
poll_read select error 113
errno = 113 (Software caused connection abort)
fd = 56
Possible Causes:
113 is usually due to TCP keepalive heartbeat timeout, retransmission timeout causing abnormal link disconnection.
Solutions:
Check for abnormal logs on the server side.
Ensure stable network connection.
Implement heartbeat mechanism at the application layer to avoid disconnection due to long periods of no data communication.
Note
When analyzing TCP flow abnormal issues, you can use the debug patch script to print TCP sequence number and other information to help locate the problem.
Usage: Enter the ESP-IDF main directory in the terminal and execute the command python <path to at_net_debug.py> to apply this patch. After applying the patch, subsequent ESP logs will include TCP sequence number (seq) and acknowledgment number (ack) and other debugging information.
Common errno and their analysis
Errno Definition |
Corresponding Value |
Corresponding ERR |
Corresponding Explanation |
Cause |
Localization Measures |
|---|---|---|---|---|---|
ENOMEM |
12 |
ERR_MEM |
Out of memory error |
Failed to allocate memory or mailbox is full, msg sending failed |
Print remaining memory and minimum memory, check if there is insufficient memory |
ENOBUFS |
105 |
ERR_BUF |
Buffer error |
1. Insufficient space, the header length has exceeded the allocated length
2. socket failed to allocate netconn
3. option len too long
|
Add log for positioning |
EWOULDBLOCK |
11 |
ERR_TIMEOUT / ERR_WOULDBLOCK |
Timeout / Operation would block |
1. Timeout – Receive Timeout (SO_RCVTIMEO set)
2. Operation would block – too fast send/receive calls under non-blocking
3. Operation would block – Send timeout (SO_SNDTIMEO set)
|
Add print at ERR_TIMEOUT; after nonblocking, connection/sending/receiving are immediately returned, the application layer should handle it well |
EHOSTUNREACH |
118 |
ERR_RTE |
Routing problem |
Can’t find the outgoing route (netif) |
Add log for positioning, check if there is a satisfying routing interface for the destination IP |
EINPROGRESS |
119 |
ERR_INPROGRESS |
Operation in progress |
The operation is in progress, non-blocking mode connect will encounter, DNS query will also encounter |
Normal errno |
EINVAL |
22 |
ERR_VAL |
Illegal value |
Parameter error (parameters set by option, fd passed in by select/poll) |
Check if there is a problem with the parameters of the function call |
EADDRINUSE |
112 |
ERR_USE |
Address in use |
The address or port is already bound when binding |
Check if the bound address or port is already bound, can be solved with SO_REUSEADDR |
EALREADY |
120 |
ERR_ALREADY |
Already connecting |
The socket is already connecting or is in the listen state, and the application layer calls connect or listen again |
Check the code logic |
EISCONN |
127 |
ERR_ISCONN |
Conn already established |
The socket is already in Connected |
Check the code logic |
ENOTCONN |
128 |
ERR_CONN / ERR_CLSD |
Not connected / Connection closed |
The socket is in an unconnected state or the other end has disconnected FIN |
Generally, the other end has disconnected, and we are still using this socket to send data, confirm by capturing packets |
ECONNABORTED |
113 |
ERR_ABRT |
Connection aborted |
The connection is disconnected due to an error state or the other party’s reason, or the TCP timer times out, removing the connection (generally this end disconnects the connection) |
Add log for positioning |
ECONNRESET |
104 |
ERR_RST |
Connection reset |
Received RST sent by the other end |
Confirm by capturing packets |
EIO |
5 |
ERR_ARG |
Illegal argument |
Input parameter error |
Check the operation that caused this problem, add log for positioning |
EBADF |
9 |
Bad file number |
The socket is already invalid |
Add log for positioning |
|
ENOPROTOOPT |
109 |
Protocol not available |
The protocol is not supported, generally the option of getsockopt/setsockopt is not supported |
Locate whether the option is supported |
|
1 |
ERR_IF |
Low-level netif error |
netif interface error |
Generally, the underlying interface is NULL, such as the interface index passed in when joining a multicast group, and the underlying query is NULL. |
Summary
Through the errno code, the root cause of the socket problem can be quickly located.
Combined with log analysis, error handling can be optimized to improve system stability.
Use getsockopt() to read SO_ERROR to get more error information.
Hope this information can help troubleshoot ESP-IDF Socket related issues.