Re: getsockopt truncating values to 256 bytes ?

At first glance that looks to be what's happening (presuming my rusty C is right) and I can duplicate with your script on my mac. This is probably something you should open an issue for (see perlbug); my guess is that hard-coded 256 should really be changed to maybe sizeof(struct tcp_info) (but again, rusty).

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Re^2: getsockopt truncating values to 256 bytes ? by Yaribz (Beadle) on May 20, 2022 at 15:54 UTC
I can duplicate with your script on my mac Thanks for taking time to reproduce. This is probably something you should open an issue for I was hoping I was wrong and missed something, but I guess I should indeed... I just opened this issue. my guess is that hard-coded 256 should really be changed to maybe sizeof(struct tcp_info) As far as I understand this code is responsible for all getsockopt calls, not just the calls for the TCP_INFO structure (for example on macOS one can also retrieve the TCP_CONNECTION_INFO structure using getsockopt...). So unless we are sure the TCP_INFO structure will always be the largest one, it would require checking the size of the requested structure, i.e. translating the getsockopt macro name to the actual C structure name to be able to compute the length, which seems quite complicated... I guess adding an optional parameter to the getsockopt function to allow the calling code to override the default 256 max size would be ok though. Or the ugly way: simply doubling current limit and hoping all structures retrievable with getsockopt will always have a size below 512 ;)	[reply]

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Re^2: getsockopt truncating values to 256 bytes ?
by Yaribz (Beadle) on May 20, 2022 at 15:54 UTC

I can duplicate with your script on my mac

Thanks for taking time to reproduce.

This is probably something you should open an issue for

I was hoping I was wrong and missed something, but I guess I should indeed... I just opened this issue.

my guess is that hard-coded 256 should really be changed to maybe sizeof(struct tcp_info)

As far as I understand this code is responsible for all getsockopt calls, not just the calls for the TCP_INFO structure (for example on macOS one can also retrieve the TCP_CONNECTION_INFO structure using getsockopt...). So unless we are sure the TCP_INFO structure will always be the largest one, it would require checking the size of the requested structure, i.e. translating the getsockopt macro name to the actual C structure name to be able to compute the length, which seems quite complicated...

I guess adding an optional parameter to the getsockopt function to allow the calling code to override the default 256 max size would be ok though.
Or the ugly way: simply doubling current limit and hoping all structures retrievable with getsockopt will always have a size below 512 ;)

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