Implement dns.lookupAll() and use for net.connect() #4169
Conversation
| @@ -97,27 +107,45 @@ exports.lookup = function(domain, family, callback) { | |||
| return {}; | |||
| } | |||
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| var callbackAddr = function(address, fam){ | |||
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I see no fundamental flaws in your PR but I'm somewhat undecided if trying addresses sequentially is a good thing. In a worst case scenario none of the addresses are reachable/usable but all of a sudden your net.connect() calls takes ten times as long to finish. In the past, we've always recommended that people (most likely library authors) handle this manually because there's no 'one size fits all' solution. |
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Also, this needs tests. :-) |
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Thanks Ben for the feedback. I've updated my PR with a refactored dns.lookupAll(), changed lookup() to just wrap lookupAll() and pulled out the option parsing. I'll take a look at some tests for lookupAll(), but the existing tests for lookup() will now apply here too. |
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Also, in response to the "...we've recommended that people handle this manually..." - the main issue I'm trying to resolve is with node's own net.connect() which does a dns.lookup() and only tries to connect to the first IP (no matter which address family it belongs to). On a machine with only IPv4, this will fail if that first IP is an IPv6 address (even if that host does have an IPv4 address) and similarly for a machine with only IPv6 if the first IP is an IPv4 address; this is horribly broken, so the extra delay is a lesser of two evils. |
This fixes errors from an IPv4-only or IPv6-only host connecting to the opposite address family; this used to throw an EHOSTUNREACH or ENETUNREACH because the host didn't have a route to that address family.
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Can one of the admins verify this patch? |
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I'm wondering what the status of this is? Issue #4168 is a blocker on my current project. |
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At this point, it's likely best to close this. There is work underway to refactor dns support entirely within io.js. That work would be picked up in the converged stream and this would need to be updated significantly. @tomlanyon ... I know it's been a while, but is this still something you want to pursue? If yes, the PR would need to be updated significantly. If not, we should likely go ahead and close. |
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Happy for this to be closed. I suggest that lookups in whatever DNS changes occur in io.js need to implement support for trying A and AAAA records, trying multiple records - potentially concurrently (happy eyeballs). |
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Noted! Closing |
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I only read the title of this PR just now, so this could be something different, but |
In hope that this fixes #4168, this implements dns.lookupAll() to return all A/AAAA RRs for a hostname retrieved from getaddrinfo() and subsequently sets net.connect() to use this when connecting to remote hosts. This requires re-working of some of the other net connection code to retry with another host on failure and to setup a new TCP socket handle for each so hopefully it's all OK still.
This is my first node hacking; be gentle!