hostip: on macOS avoid DoH when given a numerical IP address

[bagder]

USE_RESOLVE_ON_IPS (defined on macOS) means that addresses still need to
get "resolved" but not with DoH.

Reported-by: Viktor Szakats
Fixes #5454

[vszakats]

Thank you — there is an improvement! But it now falls into the same trap inside Curl_resolv_check() a few lines later. (respwait becomes 1 in Curl_getaddrinfo())

[bagder]

Ah right, I didn't consider the fact that it will do the name resolve in a separate thread and thus get the response back asynchronously and not immediately...

[vszakats]

Retried with your latest update and it's a success now (on macOS):

stderr

* Found bundle for host dns.cloudflare.com: 0x7ff6b5c0c010 [serially]
* Server doesn't support multiplex (yet)
*   Trying 2606:4700::6810:85e5:443...
* Hostname 'dns.cloudflare.com' was found in DNS cache
*   Trying 2606:4700::6810:85e5:443...
* Connected to dns.cloudflare.com (2606:4700::6810:85e5) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* Connected to dns.cloudflare.com (2606:4700::6810:85e5) port 443 (#1)
* ALPN, offering h2
* ALPN, offering http/1.1
* TLS 1.2 connection using TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
* Server certificate: cloudflare.com
* Server certificate: CloudFlare Inc ECC CA-2
* Server certificate: Baltimore CyberTrust Root
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x7ff6b601d600)
> POST /dns-query HTTP/2
Host: dns.cloudflare.com
accept: */*
content-type: application/dns-message
content-length: 41

* Connection state changed (MAX_CONCURRENT_STREAMS == 256)!
* We are completely uploaded and fine
* TLS 1.2 connection using TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
* Server certificate: cloudflare.com
* Server certificate: CloudFlare Inc ECC CA-2
* Server certificate: Baltimore CyberTrust Root
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x7ff6b6023200)
> POST /dns-query HTTP/2
Host: dns.cloudflare.com
accept: */*
content-type: application/dns-message
content-length: 41

* Connection state changed (MAX_CONCURRENT_STREAMS == 256)!
* We are completely uploaded and fine
< HTTP/2 200 
< date: Tue, 26 May 2020 13:19:32 GMT
< content-type: application/dns-message
< content-length: 98
< access-control-allow-origin: *
< cf-request-id: 02f2bc7a720000cea3a8b36200000001
< expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
< server: cloudflare
< cf-ray: 5997c9d71f55cea3-GVA
< 
* Connection #0 to host dns.cloudflare.com left intact
* a DOH request is completed, 1 to go
< HTTP/2 200 
< date: Tue, 26 May 2020 13:19:32 GMT
< content-type: application/dns-message
< content-length: 123
< access-control-allow-origin: *
< cf-request-id: 02f2bc7a790000ceabdf94a200000001
< expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
< server: cloudflare
< cf-ray: 5997c9d72f74ceab-GVA
< 
* Connection #1 to host dns.cloudflare.com left intact
* a DOH request is completed, 0 to go
* DOH Host name: ftp.thp.uni-duisburg.de
* TTL: 172276 seconds
* DOH A: 134.91.141.1
* CNAME: op2.thp.uni-duisburg.de
* CNAME: op2.thp.uni-duisburg.de
*   Trying 134.91.141.1:21...
* Connected to ftp.thp.uni-duisburg.de (134.91.141.1) port 21 (#0)
< 220 (vsFTPd 2.0.3)
> USER anonymous
< 331 Please specify the password.
> PASS ftp@example.com
< 230 Login successful.
> PWD
< 257 "/"
* Entry path is '/'
> CWD pub
* ftp_perform ends with SECONDARY: 0
< 250 Directory successfully changed.
> CWD source
< 250 Directory successfully changed.
> EPSV
* Connect data stream passively
< 229 Entering Extended Passive Mode (|||42885|)
*   Trying 134.91.141.1:42885...
* Connecting to 134.91.141.1 (134.91.141.1) port 42885
* Connected to ftp.thp.uni-duisburg.de (134.91.141.1) port 21 (#0)
> TYPE I
< 200 Switching to Binary mode.
> SIZE pstree-2.39.tar.gz
< 213 12929
> RETR pstree-2.39.tar.gz
< 150 Opening BINARY mode data connection for pstree-2.39.tar.gz (12929 bytes).
* Maxdownload = -1
* Getting file with size: 12929
{ [2896 bytes data]
* Remembering we are in dir "pub/source/"
< 226 File send OK.
* Connection #0 to host ftp.thp.uni-duisburg.de left intact

[bagder]

Execellent, thanks for verifying this!