host header invalid for http+unix:// url values

[fp]

TLDR; when sending a http+unix:// request, the host: header should be url encoded.

Assuming a request like the following is made is made to a unix domain socket:

    Uri = <<"http+unix://%2ftmp%2ferllambda.sock/erllambda/erllambda_test">>,
    Headers = [{<<"accept">>, <<"application/json">>}],
    case hackney:request( get, Uri, Headers, <<>>, [] ) of
        {ok, Status, RespHeaders, Ref} ->
            {ok, Body} = hackney:body( Ref ),
            DecodeBody = decode_body( Body ),
            {ok, Status, RespHeaders, DecodeBody};
        Otherwise -> Otherwise
    end.

This results in a 400 response from cowboy (correctly) because the host header is sent as the unix domain socket file name, but not url encoded. The full trace:

[hackney trace 80 <0.494.0> 2017:01:28 17:32:04 4144] request 
   Content: [{module,hackney},
             {line,308},
             {method,get},
             {url,{hackney_url,hackney_local_tcp,http_unix,
                               <<"/tmp/erllambda.sock">>,
                               <<"/erllambda/erllambda_test">>,
                               <<"/erllambda/erllambda_test">>,<<>>,<<>>,
                               "/tmp/erllambda.sock",0,<<>>,<<>>}},
             {headers,[{<<"accept">>,<<"application/json">>}]},
             {body,<<>>},
             {options,[]}]

[hackney trace 60 <0.494.0> 2017:01:28 17:32:04 4144] request without proxy 
   Content: [{module,hackney},{line,689}]

[hackney trace 60 <0.494.0> 2017:01:28 17:32:04 4144] connect 
   Content: [{module,hackney_connect},
             {line,33},
             {transport,hackney_local_tcp},
             {host,"/tmp/erllambda.sock"},
             {port,0},
             {dynamic,true}]

[hackney trace 80 <0.494.0> 2017:01:28 17:32:04 4145] no socket in the pool 
   Content: [{module,hackney_connect},{line,200},{pool,default}]

[hackney trace 80 <0.494.0> 2017:01:28 17:32:04 4147] new connection 
   Content: [{module,hackney_connect},{line,248}]

[hackney trace 40 <0.494.0> 2017:01:28 17:32:04 4147] perform request 
   Content: [{module,hackney_request},
             {line,97},
             {header_data,<<"GET /erllambda/erllambda_test HTTP/1.1\r\naccept: application/json\r\nUser-Agent: hackney/1.6.5\r\nHost: /tmp/erllambda.sock\r\n\r\n">>},
             {perform_all,true},
             {expect,false}]

[hackney trace 80 <0.494.0> 2017:01:28 17:32:04 4147] got response 
   Content: [{module,hackney},
             {line,372},
             {response,
                 {ok,400,
                     [{<<"content-length">>,<<"0">>}],
                     {client,
                         {1485,624724,144075},
                         {metrics_ng,metrics_dummy},
                         hackney_local_tcp,"/tmp/erllambda.sock",0,
                         <<"/tmp/erllambda.sock:0">>,[],#Port<0.16734>,
                         {default,#Ref<0.0.3.8154>,
                             {"/tmp/erllambda.sock",0,hackney_local_tcp},
                             <0.496.0>,hackney_local_tcp},
                         #Ref<0.0.3.8154>,true,hackney_pool,5000,false,5,
                         false,5,nil,nil,
                         {hparser,response,4096,10,0,on_body,<<>>,
                             {1,1},
                             undefined,[],0,undefined,undefined,undefined,
                             undefined,waiting},
                         connected,waiting,nil,normal,false,false,false,
                         undefined,false,#Fun<hackney_request.send.2>,waiting,
                         nil,4096,<<>>,[],
                         {1,1},
                         0,nil,nil,<<"GET">>,<<"/erllambda/erllambda_test">>,
                         nil}}},
             {client,
                 {client,
                     {1485,624724,144075},
                     {metrics_ng,metrics_dummy},
                     hackney_local_tcp,"/tmp/erllambda.sock",0,
                     <<"/tmp/erllambda.sock:0">>,[],#Port<0.16734>,
                     {default,#Ref<0.0.3.8154>,
                         {"/tmp/erllambda.sock",0,hackney_local_tcp},
                         <0.496.0>,hackney_local_tcp},
                     #Ref<0.0.3.8154>,true,hackney_pool,5000,false,5,false,5,
                     nil,nil,nil,connected,start,nil,normal,false,false,false,
                     undefined,false,nil,waiting,nil,4096,<<>>,[],undefined,
                     nil,nil,nil,nil,undefined,nil}}]

[hackney trace 80 <0.496.0> 2017:01:28 17:32:04 4147] checkin: socket is not ok~n 
   Content: [{module,hackney_pool},
             {line,286},
             {socket,#Port<0.16734>},
             {peername,{error,einval}}]

[fp]

PR to fix this coming later today.

[fp]

This fixed makes the hackney side of things correct, and also requires a corresponding changes to cow_http_hd:reg_name/2 to accept the percent encoded value according to the specs: ninenines/cowlib#53