Fix #2192 - honor addr%scopeid ipv6 notation

[cpq]

No description provided.

[comburent]

Apologies for chiming in late, the % has to be percent-encoded as @scaprile already pointed out in #2192 (comment).

Looking at the ASSERT(…) additions to the test/unit_test.c this doesn't seem to be what's happening here.

[cpq]

@comburent could you provide a couple of examples please?

[comburent]

@comburent could you provide a couple of examples please?

Sure, here are some examples:

http://[fe80::1%251]:8000  => zone-id is 1.
http://[2001:db8:1234%25255]:8000  => zone-id is 255.

These are described in RFC6874 if you're interested in further information.
Curiously they also make this suggestion:

It is desirable for all browsers to recognise a ZoneID preceded by a
percent-encoded "%". In the spirit of "be liberal with what you
accept", we also suggest that URI parsers accept bare "%" signs when
possible (i.e., a "%" not followed by two valid and meaningful
hexadecimal characters). This would make it possible for a user to
copy and paste a string such as "fe80::a%en1" from the output of a
"ping" command and have it work. On the other hand, "%ee1" would
need to be manually rewritten to "fe80::a%25ee1" to avoid any risk of
misinterpretation.

Though this doesn't matter since this applies for interface names which we agreed to leave them out in #2192 (comment).

[comburent]

^^ ping @cpq

[cpq]

Uh, sorry, missed a notification for this.

So, basically, the current logic is bad since we treat the %xx scope_id suffix as-is, like %31 gives scope_id == 31
Whereas we must treat it as a URL-encoded value, thus %31 should give scope_id == 1 (1 has ASCII code 0x31).

Can you confirm please?

[comburent]

So, basically, the current logic is bad since we treat the %xx scope_id suffix as-is, like %31 gives scope_id == 31 (…)

Yes.

(…) Whereas we must treat it as a URL-encoded value, thus %31 should give scope_id == 1 (1 has ASCII code 0x31).

No since URL-encoded %31 would decode as a bare 1. (e.g. 2001:db8::432%31 URL-decodes to 2001:db8::4321 which we clearly see that there's no scope-id here, it's just a different way of typing the same thing)

The % character itself is what needs to be percent-encoded, so the URL-encoded %25xx should give xx as scope-id. (e.g. %251 is URL-decoded to %1 which means that scope_id == 1, as shown in the examples at #2395 (comment))