[TW#15973] select() FD_GET/FD_SET macros are incorrectly defined

[karawin]

On SDK v3.0-dev-942-g2e8441df-dirty
Sockets are allocated from 4096.
This break the FD_xxxx and far from FD_SETSIZE
So no select() can work.

Why this change?

[igrr]

LwIP sockets start at LWIP_SOCKET_OFFSET, and FD_SET/FD_GET macros take this into account when operating on fd sets: LWIP_SOCKET_OFFSET is subtracted from fd number, and the resulting value as used as bit offset in fd set.

Previously, LWIP_SOCKET_OFFSET was always zero. With the latest changes, LWIP_SOCKET_OFFSET is defined to lwip_socket_offset global variable. When LwIP is initialized, the value of lwip_socket_offset is determined dynamically.

It is unlikely, but if you happen to do operations on fd sets before LwIP is initialized, you may get incorrect behavior. Otherwise, lwip_socket_offset should be taken into account correctly.

Perhaps you could share the code which you are having an issue with?

[karawin]

The code is at https://github.com/karawin/Ka-Radio32
main/servers.c

It works well on esp8266 and worked well in esp32 before the last release.

How can i know if lwip_socket_offset is initialized?

[karawin]

Something is wrong in FD_XXXX because
I (8999) servers: telnetServer_sock socket: 4096, errno: 0
I (9009) servers: Webserver socket: 4097, errno: 0
...
V (54889) servers: Activity 1, max_fd: 4097
V (54889) servers: Server web accept, socket: 4097.
V (54909) servers: telnetServer_sock accept. Socket: 4096
Two FD_ISSET for one activity. And i am sure that the telnetServer_soc socket is not awaked.

		if (FD_ISSET(telnetServer_sock, &readfds)) 
		{
			FD_CLR(telnetServer_sock , &readfds); 
			ESP_LOGV(TAG,"telnetServer_sock accept. Socket: %d",telnetServer_sock);	 				
			if ((telnetClient_sock = accept(telnetServer_sock, (struct sockaddr *) &tenetclient_addr, &telnetSin_size)) < 0) 
			{
				ESP_LOGE(TAG,strsTELNET,"accept",errno);
				close(telnetClient_sock);
				vTaskDelay(50);					
			} else

[karawin]

It seems that i am not able to include the right FD_XXXX in lwip/sockets.h
And no error msg
`
/* FD_SET used for lwip_select /
#ifndef FD_SET
#undef FD_SETSIZE
/ Make FD_SETSIZE match NUM_SOCKETS in socket.c /
#define FD_SETSIZE MEMP_NUM_NETCONN
#define FDSETSAFESET(n, code) do {
if (n >= LWIP_SOCKET_OFFSET && ((n) - LWIP_SOCKET_OFFSET < MEMP_NUM_NETCONN) && (((int)(n) - LWIP_SOCKET_OFFSET) >= 0)) {
code; }} while(0)
#define FDSETSAFEGET(n, code) (n >= LWIP_SOCKET_OFFSET && ((n) - LWIP_SOCKET_OFFSET < MEMP_NUM_NETCONN) && (((int)(n) - LWIP_SOCKET_OFFSET) >= 0) ?
(code) : 0)
#define FD_SET(n, p) FDSETSAFESET(n, (p)->fd_bits[((n)-LWIP_SOCKET_OFFSET)/8] |= (1 << (((n)-LWIP_SOCKET_OFFSET) & 7)))
#define FD_CLR(n, p) FDSETSAFESET(n, (p)->fd_bits[((n)-LWIP_SOCKET_OFFSET)/8] &= ~(1 << (((n)-LWIP_SOCKET_OFFSET) & 7)))
#define FD_ISSET(n,p) FDSETSAFEGET(n, (p)->fd_bits[((n)-LWIP_SOCKET_OFFSET)/8] & (1 << (((n)-LWIP_SOCKET_OFFSET) & 7)))
#define FD_ZERO(p) memset((void)(p), 0, sizeof(*(p)))

typedef struct fd_set
{
unsigned char fd_bits [(FD_SETSIZE+7)/8];
} fd_set;

#elif LWIP_SOCKET_OFFSET
#error LWIP_SOCKET_OFFSET does not work with external FD_SET!
#endif /* FD_SET */
`

[karawin]

Succeeded with these modifications in lwip/sockets.h
Not clean. Please fix it.

/* FD_SET used for lwip_select */
//#ifndef FD_SET
#ifdef LWIP_SOCKET_OFFSET
#undef FD_SET
#undef FD_CLR
#undef FD_ISSET
#undef FD_ZERO
#undef _types_fd_set
#undef fd_set

[projectgus]

Thanks for reporting this @karawin.

There was a second set of FD_SET/etc macros in newlib sys/types.h that were unexpectedly overriding the LWIP ones. This is why the workaround you have is working as well.

A fix to the newlib header is on the way, in the mean time the workaround you have will fix the problem.

[karawin]

Great, Thanks