Handle returnValue and add rc/rsn to socket trace - #548
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1000TurquoisePogs wants to merge 3 commits into
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Handle returnValue and add rc/rsn to socket trace#5481000TurquoisePogs wants to merge 3 commits into
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Signed-off-by: 1000TurquoisePogs <sgrady@rocketsoftware.com>
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The socket trace claimed to print the hostent address but printed *((int*)hostEntPtr) -- the first four bytes of the struct, which is half of its name pointer, under a label saying otherwise. On z/OS that is the high half, so for storage below the bar it printed zero whether the lookup succeeded or failed. Anyone who switched socketTrace on to diagnose a resolution problem was reading a number that meant nothing. %p prints what the label promises and does not follow the pointer, which also removes a dereference that ran before anything established the pointer was usable. hostEntPtr is now initialised. BPXGHN leaves Hostent_ptr alone when the lookup fails, so it held whatever the stack contained; getV4HostEntByName returns it directly, so callers were handed that. Verified with MemorySanitizer against the real function: staging reports use-of-uninitialized-value on a failed lookup with tracing off and on, and neither reports it after this change. Signed-off-by: JoeNemo <joe.devlin@gmail.com>
hostent->length is the width of one address -- 4 for IPv4 -- not how many addresses came back, so using it as a loop bound reads up to four entries regardless of how many exist. AddressSanitizer reports a stack-buffer-overflow on a host that resolves to an empty list: the array holds only its terminator and the loop reads three entries past it. addrList is null-terminated, so the terminator is the bound. Selecting the first address is unchanged: verified identical for one address, several addresses, an empty list, and a list whose first non-null entry is late. The trace now prints the address that was found, dotted-quad and hex, rather than the pointer holding it -- which is what someone turning socketTrace on to diagnose a lookup wants to see. It walks the whole list, since knowing a name resolved to more than one address is part of the diagnosis. Dropped an unused local. Signed-off-by: JoeNemo <joe.devlin@gmail.com>
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I don't think this code is called. But your intent for this PR was valid and I can't remove a public API mid-release. But I needed to do some fixes for things that were latent memory errors, not introduced by your change.
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To trace zowe/zss#794, I need to see rc/rsn that aren't handled thus far.
This PR prints them in socketTrace
But also, I saw the TBD message about that none of them are even inspected. I added handling of returnValue.