dns: getaddrinfo() differences between glibc and musl

[bnoordhuis]

getaddrinfo() without hints defaults to:

1. ai_flags = AI_ADDRCONFIG|AI_V4MAPPED with glibc, and
2. ai_flags = 0 with musl libc.

That means musl by default returns addresses that may be unreachable from the current machine whereas glibc won't.

And on the flip side, glibc will return IPv4-over-IPv6 addresses if no IPv6 address for that host exists whereas musl won't.

We should probably harmonize that one way or the other but what's the preferred behavior and why?

[cjihrig]

This would have to be a v2 thing, right?

As a side note, if I'm remembering correctly, Node.js had a number of issues reported around using AI_ADDRCONFIG|AI_V4MAPPED by default.

[bnoordhuis]

This would have to be a v2 thing, right?

Maybe. glibc's default seems more useful than musl's. We'd have to think through the implications but I wouldn't dismiss outright the idea of making AI_ADDRCONFIG|AI_V4MAPPED the default in v1.x.

if I'm remembering correctly, Node.js had a number of issues reported around using AI_ADDRCONFIG|AI_V4MAPPED by default.

Yes, although they weren't our bug, it was glibc's (and uclibc's, IIRC): nodejs/node#5436 (comment)

[santigimeno]

Maybe. glibc's default seems more useful than musl's. We'd have to think through the implications but I wouldn't dismiss outright the idea of making AI_ADDRCONFIG|AI_V4MAPPED the default in v1.x.

I tend to agree. If we're going to set a default I would go for glibc's and tbh it seems more like a bug on our side not having the same behavior across platform, so I would vote for doing this in v1.x

[saghul]

I tend to agree. If we're going to set a default I would go for glibc's and tbh it seems more like a bug on our side not having the same behavior across platform, so I would vote for doing this in v1.x

+1

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.