Server emitting errors and traceback on ECONNRESET when it should be a warning.

[ashleysommer]

Using versions:
Julia 1.6
HTTP.jl 0.9.14

It appears the intention of this code in Servers.jl is to throw a warning rather than an error when the connection is reset by the peer (ie, client closed the connection to our server).

However this is done by a check on the error code. And this code seems to change based on the architecture of the system running. On my system, ECONNRESET corresponds with e.code of -104.

See this list of search results for "connection reset by peer" in the linux source code:
https://github.com/torvalds/linux/search?p=1&q=%22connection+reset+by+peer%22&type=code

Notice lots of different errno.h files.

• For SPARC and ALPHA architectures, ECONNRESET is 54 (as per the code in Julia)
• For Generic architecture, ECONNERESET is 104 (this is what my system is, and probably 99% of users)
• For PARISC architecture, ECONNRESET is 232
• For MIPS architecture, ECONNRESET is 131

Note, when the TCP driver throws these exceptions, it makes them negative, so Julia must match on the negative value, eg -104.

I don't know why -4077 is in the code, it doesn't match any error number I could find, maybe thats the one windows uses?

Related to #547
Tangentially related to #657 (in the sense that an error is propagated in a non-actionable way)

[ashleysommer]

This comment on #547 also mentions their code is -104, and suggests the code can change between platforms.

[ashleysommer]

I just performed a local build of this library, with the -54 changed to -104 and it fixed some major server issues I was seeing due to propagation of that error.

[ashleysommer]

Ok, I'm now pretty sure the code -4077 is used on Windows, so makes sense to have that in there.
I don't know for certain, but I guess the -54 code is used on MacOS? Because I'm certain the devs of this library are not using SPARC or ALPHA based processors.

From what I can tell by looking at code overlaps, it should be pretty safe to just naively write e.code == -54 || e.code == -104 || e.code == -131 || e.code == -232 || e.code == -4077. In the places where those codes mean something else on a different system, it's in situations not related to TCP. Eg code 54 in Generic architecture is EXFULL (exchange full), used in email processing, would never be seen in this situation.