Casey Liss

I'm out of my depth.

I'm trying to make a URL GET request to a service I'm discovering via Bonjour.

I have gotten a NWBrowser.Result, and I've gotten an NWEndpoint.

The endpoint is an IPv6 link local address.

How the hell do I make a URLRequest to this? I don't seem to be able to construct a URL from what I've got, but I suspect I'm holding it wrong.

Again, this is probably simple, but I'm way out of my depth here.

Aug 13, 2023 at 1:12amIvory for Mac
Show threadCasey LissAug 13, 2023

Wait, it seems the presence of “%en0" at the end may be the problem?

I can construct the URL without that, but actually connecting to that server with URLSession doesn't work.

(Worth noting it's HTTP not HTTPS; could ATS be stomping on me? If so, how would I know?)

Show threadCasey LissAug 13, 2023

Whoops. I didn't think of that. @_nd_ pointed out I need to percent-escape… the percent sign. That got me over the finish line. 🎉

https://fnordon.de/@_nd_/110881126508440982

Andreas Hartl (@[email protected])

@[email protected] my reading of https://datatracker.ietf.org/doc/html/rfc6874 is that you must percent-escape the %: http://[<IPv6address>%25<zoneID>]

Fnordon
Show threadChris Huck  Aug 13, 2023
@caseyliss @_nd_ This is classic case of the internet being awesome. There is almost always someone that not only knows the answer to your problem, but is also willing to share it.
Show threadalex.tmAug 13, 2023
@chrishuck @caseyliss @_nd_ As long as you have the reach for it to be seen of course. I think posting a question like this and expecting an accurate response wouldn’t work for the majority of social media users. (I’m not trying to bemoan anyone the visibility/notoriety they have earned, just pointing out that while this is a great result, it likely wouldn’t be the same for most other people.)
Show threadJim LutherAug 14, 2023
@chrishuck @caseyliss @_nd_ I knew the answer but I’m 11 hours behind reading my feed. RFC6874 explains how zone identifiers are represented in the authority component of a URL https://www.rfc-editor.org/rfc/rfc6874
RFC 6874: Representing IPv6 Zone Identifiers in Address Literals and Uniform Resource Identifiers

Show threadAndy GalletlyAug 13, 2023
@caseyliss @_nd_ “escape the percent sign” sounds like something from a self help book
Show threadAndrew LaurenceAug 13, 2023
@caseyliss whyyyy is there a reference to the NIC? 🧐🤔
Show threadOnlyMeAug 13, 2023
@atlauren @caseyliss That’s because all interfaces have an fe80:: address. So you need to let it know which interface that particular host is on
Show threadMarcoAug 14, 2023
Link local is a special case. Each segment of the network has its own independent link local space. Link locals also all share a prefix, fe80::/10. When you have interfaces connected to different segments they will be physically separated while seemingly within the same address space. Regular prefix-based routing doesn’t work. Instead, a “zone index” is added to differentiate each segment. Unix-like systems use the NIC name as an index (the standard requires just a number too)
Show threadjgjl 🇪🇺Aug 13, 2023
@caseyliss the “%en0” should only be needed for link-local addresses. All other address types should not need it.
Show threadCasey LissAug 13, 2023
@jgjl It is link local
Show threadjgjl 🇪🇺Aug 13, 2023
@caseyliss without the interface id the OS cannot determine which interface to use, since the link local prefix is the same on all interfaces. Hence, it makes sense that you don’t get a connection without it.
Show threadCasey LissAug 13, 2023
@jgjl Okay, fair enough. But now I need to construct a URL from it so I can issue a HTTP request
Show threadGreg ThompsonAug 13, 2023
@caseyliss If you can do the Http get in Safari with the url then I would think it HAS to be the Http call instead of HTTPS and the App Transport Security.
Show threadAndreas HartlAug 13, 2023

@caseyliss my reading of https://datatracker.ietf.org/doc/html/rfc6874 is that you must percent-escape the %:

http://[<IPv6address>%25<zoneID>]

RFC 6874: Representing IPv6 Zone Identifiers in Address Literals and Uniform Resource Identifiers

This document describes how the zone identifier of an IPv6 scoped address, defined as <zone_id> in the IPv6 Scoped Address Architecture (RFC 4007), can be represented in a literal IPv6 address and in a Uniform Resource Identifier that includes such a literal address. It updates the URI Generic Syntax specification (RFC 3986) accordingly.

IETF Datatracker
Show threadCasey LissAug 13, 2023
@_nd_ nailed it. Thank you!!!
Show threadSören GadeAug 13, 2023

@caseyliss Not an expert on IPv6, but in general for running on iOS devices you'll need the “Privacy - Local Network Usage Description” and the ATS setting to allow insecure requests to (that or all) domains. For the second reason you should get an error message. For the first not so much

From experience, I would also recommend testing on the final device (assuming an iPhone for example) because the Network framework can behave differently in small but meaningful ways depending on the platform.

Show threadGreg ThompsonAug 13, 2023

@caseyliss In a browser you would enter an IPV6 address like this: https://[XXXXXIPV6ADDRESS]/index.html

Obviously replace XXXXXIPV6ADDRESS with your IPV6 address. Notice the [] in the URL.

Show threadCasey LissAug 13, 2023

@gc_headtech Tried that. Didn't work.

(Again, VERY likely I'm holding it wrong)

Show threadGreg ThompsonAug 13, 2023
@caseyliss Does it work in safari?
Show threadGreg ThompsonAug 13, 2023
@caseyliss also foudn this: https://developer.apple.com/forums/thread/711196 It appears that this should work in 16.
"According to RFC 2732 Section 2, IPv6 addresses must be enclosed in [ and ] when it’s part of an URL. In this particular case, the host should be ipv6URLComponents.host = “[2001:0000:3238:dfe1:0063:0000:0000:fefb]”.”
URLComponent does not accept IPv6 … | Apple Developer Forums

Show threadMichael CookAug 13, 2023
@gc_headtech you have to do that? I guess I’ve never seen an IPv6 address in a URL before. Didn’t know that.
Show threadKarl SwansonAug 13, 2023
@caseyliss does the device you are connecting from have an IPv6 address?
Show threadCasey LissAug 13, 2023
@karlcswanson I believe so, yes
Show threadJon MaddoxAug 13, 2023
@caseyliss can’t you just resolve the bonjour signal to get an ip and port, then make the request on thr endpoint with what we swift provides for http requests?
Show threadCasey LissAug 13, 2023
@maddox I did. It’s IPV6 link local. Which URL doesn’t understand
Show threadJon MaddoxAug 13, 2023
@caseyliss turn off ipv6 on your router. Like the solution has been for 20 years 😂
Show threadEric LindvallAug 13, 2023
@maddox @caseyliss 👎🏻
Show threadCasey LissAug 13, 2023
@maddox 😑
Show threadCasey LissAug 13, 2023
@maddox in summary this is all your fault.
Show threadEric LindvallAug 13, 2023
@caseyliss is the link local endpoint the _only_ endpoint that is returned?
Show threadCasey LissAug 13, 2023
@lindvall as far as I can tell, yes; the ATV definitely has an ipv4 address though.
Show threadrickAug 13, 2023
@caseyliss I am going to guess that this is Bonjour's fault simply because nothing that uses Bonjour has ever been reliable. I'm guessing that nothing that uses Bonjour can be made to be reliable. Simply using both wifi and Ethernet on the same device seems to completely destroy it.
Show threadMaxwellAug 13, 2023
@caseyliss is it a NWEndpoint.hostPort? Are you advertising it or is it another app you are working with? You can set the required local endpoint to be 127.0.0.1 (or maybe even a Unix socket but who knows if that works)
Show threadCasey LissAug 13, 2023

@maxtown yes, it’s hostPort.

Trying to consume another app’s services.

Show threadMaxwellAug 13, 2023

@caseyliss huh that sucks. If you pass it into getaddrinfo do you get another address that does work with URLRequest? Like 127.0.0.1?

https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/getaddrinfo.3.html

Mac OS X Manual Page For getaddrinfo(3)

HTML versions of the iOS man pages.

Show threadSörenAug 13, 2023
@caseyliss are you not getting an mDNS hostname?
Show threadN4RSE - JimAug 14, 2023
@caseyliss at one point in my life escape sequences were the bane of my existence. I’m now retired and my own escape sequence.
Show threadChancerubbageAug 14, 2023

@caseyliss they still call it bonjour? I thought that was one of the ‘features’ they touted then forgot about 25 years ago.

But that ‘bump to share contacts’ iOS feature was around iPhone 4 iPhone 6 days too, and they are touting that as a new iOS 17 feature.

For a successful company, Apple sure does seem to forget a lot, has a right hand not knowing what the left hand is doing vibe.

Show threadKyle McMahonAug 14, 2023

@caseyliss Strictly speaking, you're discouraged from resolving the address out of an NWEndpoint yourself; it can change. You open an NWConnection with the NWEndpoint directly and it resolves the address internally.

https://developer.apple.com/forums/thread/122638

But how you make an HTTP request over an NWConnection, I do not know. Different network layers.

Get IP & Port from NWBrowser | Apple Developer Forums