1

I copied the code straight from the inets User's Guide:

$ erl
Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] 

Eshell V8.2  (abort with ^G)

1> inets:start().
ok

2> {ok, Pid} = inets:start(httpd, [{port, 0}, {server_name,"httpd_test"}, {server_root,"/tmp"}, {document_root,"/tmp/htdocs"}, {bind_address, "localhost"}]).

=ERROR REPORT==== 25-Feb-2018::03:08:14 ===
Failed initiating web server: 
undefined
{invalid_option,{non_existing,{document_root,"/tmp/htdocs"}}}

** exception error: no match of right hand side value 
                    {error,
                        {{shutdown,
                             {failed_to_start_child,
                                 {httpd_manager,{127,0,0,1},60152,default},
                                 {error,
                                     {invalid_option,
                                         {non_existing,{document_root,"/tmp/htdocs"}}}}}},
                         {child,undefined,
                             {httpd_instance_sup,{127,0,0,1},60152,default},
                             {httpd_instance_sup,start_link,
                                 [[{port,60152},
                                   {bind_address,{127,0,0,1}},
                                   {server_name,"httpd_test"},
                                   {server_root,"/tmp"},
                                   {document_root,"/tmp/htdocs"}],
                                  15000,
                                  {<0.73.0>,#Port<0.904>},
                                  []]},
                             permanent,infinity,supervisor,
                             [httpd_instance_sup]}}}
3>

document_root is an invalid option? Okay, I'll check the list of valid options and correct the mistake in the example....hmmmm, there doesn't seem to be one.

Okay, I needed to do this:

$ cd /tmp
$ mkdir htdocs

Now, I'm trying to bind to an ipv6 version of localhost, but I'm having no luck. The httpd docs say:

{bind_address, ip_address() | hostname() | any}

and ip_address() is defined as:

ip_address() = {N1,N2,N3,N4} % IPv4 | {K1,K2,K3,K4,K5,K6,K7,K8} % IPv6

but N and K are not defined. If N is an integer, what is a K? I tried:

{bind_address, {0,0,0,0,0,0,0,1}}

but I got an error:

$ erl
Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V8.2  (abort with ^G)

1> inets:start().
ok

2> inets:start(httpd, [{port, 0}, {server_name, "httpd_test"}, {server_root, "."}, {document_root, "./htdocs"}, {bind_address,{0,0,0,0,0,0,0,1}}]).
{error,{listen,{exit,badarg}}}

Yet, with an ipv4 address everything works as expected:

3> inets:start(httpd, [{port, 0}, {server_name, "httpd_test"}, {server_root, "."}, {document_root, "./htdocs"}, {bind_address,{127,0,0,1}}]).
{ok,<0.74.0>}

4> httpd:info(pid(0,74,0)).        
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {server_name,"httpd_test"},
 {bind_address,{127,0,0,1}},
 {server_root,"."},
 {port,63069},
 {document_root,"./htdocs"}]

5> httpc:request("http://localhost:63069/file1.txt").
{ok,{{"HTTP/1.1",200,"OK"},
     [{"date","Mon, 26 Feb 2018 03:02:33 GMT"},
      {"etag","nCZT0114"},
      {"server","inets/6.3.4"},
      {"content-length","14"},
      {"content-type","text/plain"},
      {"last-modified","Mon, 26 Feb 2018 02:51:52 GMT"}],
     "Hello, world!\n"}}

/ets/hosts:

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1   localhost
255.255.255.255 broadcasthost
::1             localhost

Next, I tried {bind_address, any}:

$ erl
Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V8.2  (abort with ^G)

1> inets:start().
ok

2> {ok, Server} = inets:start(httpd, [{port, 0}, {server_name, "httpd_test"}, {server_root, "."}, {document_root, "./htdocs"}, {bind_address, any}]).
{ok,<0.72.0>}

3> httpd:info(Server).
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {server_name,"httpd_test"},
 {bind_address,any},
 {server_root,"."},
 {port,63679},
 {document_root,"./htdocs"}]

But, I can't perform a get request with an ipv6 address:

4> httpc:request("http://[::1]:63679/file1.txt").          
{error,{failed_connect,[{to_address,{"::1",63679}},
                        {inet,[inet],nxdomain}]}}

5> httpc:request("http://127.0.0.1:63679/file1.txt").
{ok,{{"HTTP/1.1",200,"OK"},
     [{"date","Mon, 26 Feb 2018 03:13:35 GMT"},
      {"etag","nCZT0114"},
      {"server","inets/6.3.4"},
      {"content-length","14"},
      {"content-type","text/plain"},
      {"last-modified","Mon, 26 Feb 2018 02:51:52 GMT"}],
     "Hello, world!\n"}}

Okay, I solved the error I got when I tried to bind the server to an ipv6 address: I needed to specify the option {ipfamily, inet6}:

inets:start(httpd, [{port, 0}, 
                    {server_name, "httpd_test"}, 
                    {server_root, "."}, 
                    {document_root, "./htdocs"}, 
                    {ipfamily, inet6}, 
                    {bind_address,{0,0,0,0,0,0,0,1}}]).

However, my httpc:request() still fails:

4> httpd:info(Server).
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {ipfamily,inet6},  
 {server_name,"httpd_test"},
 {bind_address,{0,0,0,0,0,0,0,1}},
 {server_root,"."},
 {port,51284},
 {document_root,"./htdocs"}]

5> httpc:request("http://[::1]:51284/file1.txt").
{error,{failed_connect,[{to_address,{"::1",52489}},
                        {inet,[inet],nxdomain}]}

I can use curl to make a get request with an ipv6 address:

~$ curl -v "http://[::1]:52489/file1.txt"
*   Trying ::1...
* TCP_NODELAY set
* Connected to ::1 (::1) port 52489 (#0)
> GET /file1.txt HTTP/1.1
> Host: [::1]:52489
> User-Agent: curl/7.58.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Date: Mon, 26 Feb 2018 05:07:07 GMT
< Server: inets/6.3.4
< Content-Type: text/plain
< Etag: nCZT0114
< Content-Length: 14
< Last-Modified: Mon, 26 Feb 2018 02:51:52 GMT
< 
Hello, world!
* Connection #0 to host ::1 left intact

That leads me to believe that httpc:request() is having trouble with the ipv6 address.

Okay, I tried to configure the client for ipv6:

1> inets:start().
ok

2> {ok, Client} = inets:start(httpc, [{profile, client1_config}] ). 
{ok,<0.72.0>}

3> Client.
<0.72.0>

7> httpc:set_options([{ipfamily, inet6}], client1_config).    
ok

Fingers crossed....

8> httpc:request("http://[::1]:52489/file1.txt", client1_config). 
{error,
    {failed_connect,
        [{to_address,{"::1",52489}},
         {inet6,[inet6],nxdomain}]}}

Then I tried (spacing added by me for legibility):

9> httpc:request(
         get, 
         "http://[::1]:52489/file1.txt", 
         [], 
         [{ipv6_host_with_brackets, true}], 
         client1_config
   ).
** exception error: no function clause matching httpc:request(get,"http://[::1]:52489/file1.txt",[],
                                                              [{ipv6_host_with_brackets,true}],
                                                              client1_config) (httpc.erl, line 149)

The error makes no sense to me. There is a five arg version of httpc:request(), and I've carefully checked the types of all the args, and my types are correct:

httpc:request(atom, string, list_of_tuples, list_of_tuples, atom)

Okay, the second argument is actually a tuple: {string, []}. Here's where I'm at now with the server:

7> httpd:info(Server).
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {ipfamily,inet6},
 {server_name,"httpd_test"},
 {bind_address,{0,0,0,0,0,0,0,1}},
 {server_root,"."},
 {port,53686},
 {document_root,"./htdocs"}]

And the client:

32> httpc:get_options(all, client1_config).
{ok,[{proxy,{undefined,[]}},
     {https_proxy,{undefined,[]}},
     {pipeline_timeout,0},
     {max_pipeline_length,2},
     {max_keep_alive_length,5},
     {keep_alive_timeout,120000},
     {max_sessions,2},
     {cookies,disabled},
     {verbose,verbose},
     {ipfamily,inet6},
     {ip,default},
     {port,default},
     {socket_opts,[]}]}

But my client still can't connect with an ipv6 address. I don't know if I'm supposed to be using the httpc:request() Option {ipv6_host_with_brackets, true} or not, so I've been trying it both ways:

34> httpc:request(get, {"http://[::1]:52489/file1.txt", []}, [], [{ipv6_host_with_brackets, true}], client1_config).    
(<0.124.0>) << {dbg,{ok,[{matched,nonode@nohost,1}]}}
(<0.124.0>) << {#Ref<0.0.3.431>,
                {ok,<<16,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0>>}}
(<0.124.0>) << {inet_async,#Port<0.981>,5,{error,econnrefused}}
(<0.124.0>) << {'EXIT',#Port<0.981>,normal}
(<0.124.0>) << {init_error,error_connecting,
                   {#Ref<0.0.3.426>,
                    {error,
                        {failed_connect,
                            [{to_address,{"::1",52489}},
                             {inet6,[inet6],econnrefused}]}}}}
{error,{failed_connect,[{to_address,{"::1",52489}},
                        {inet6,[inet6],econnrefused}]}}

35> httpc:request(get, {"http://[::1]:52489/file1.txt", []}, [], [], client1_config).                               
(<0.126.0>) << {dbg,{ok,[{matched,nonode@nohost,1}]}}
(<0.126.0>) << {#Ref<0.0.3.447>,
                {ok,<<16,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0>>}}
(<0.126.0>) << {inet_async,#Port<0.982>,6,{error,econnrefused}}
(<0.126.0>) << {'EXIT',#Port<0.982>,normal}
(<0.126.0>) << {init_error,error_connecting,
                   {#Ref<0.0.3.442>,
                    {error,
                        {failed_connect,
                            [{to_address,{"::1",52489}},
                             {inet6,[inet6],econnrefused}]}}}}
{error,{failed_connect,[{to_address,{"::1",52489}},
                        {inet6,[inet6],econnrefused}]}}

36> httpc:request(get, {"http://[0:0:0:0:0:0:0:1]:52489/file1.txt", []}, [], [{ipv6_host_with_brackets, true}], client1_config).
(<0.128.0>) << {dbg,{ok,[{matched,nonode@nohost,1}]}}
(<0.128.0>) << {#Ref<0.0.3.463>,
                {ok,<<16,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0>>}}
(<0.128.0>) << {inet_async,#Port<0.983>,7,{error,econnrefused}}
(<0.128.0>) << {'EXIT',#Port<0.983>,normal}
(<0.128.0>) << {init_error,error_connecting,
                   {#Ref<0.0.3.458>,
                    {error,
                        {failed_connect,
                            [{to_address,{"0:0:0:0:0:0:0:1",52489}},
                             {inet6,[inet6],econnrefused}]}}}}
{error,{failed_connect,[{to_address,{"0:0:0:0:0:0:0:1",
                                     52489}},
                        {inet6,[inet6],econnrefused}]}}

37> httpc:request(get, {"http://[0:0:0:0:0:0:0:1]:52489/file1.txt", []}, [], [], client1_config).                       
(<0.130.0>) << {dbg,{ok,[{matched,nonode@nohost,1}]}}
(<0.130.0>) << {#Ref<0.0.3.479>,
                {ok,<<16,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0>>}}
(<0.130.0>) << {inet_async,#Port<0.984>,8,{error,econnrefused}}
(<0.130.0>) << {'EXIT',#Port<0.984>,normal}
(<0.130.0>) << {init_error,error_connecting,
                   {#Ref<0.0.3.474>,
                    {error,
                        {failed_connect,
                            [{to_address,{"0:0:0:0:0:0:0:1",52489}},
                             {inet6,[inet6],econnrefused}]}}}}
{error,{failed_connect,[{to_address,{"0:0:0:0:0:0:0:1",
                                     52489}},
                        {inet6,[inet6],econnrefused}]}}
7stud
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1 Answers1

1

Okay! I got a client to successfully make a request with an ipv6 address. For all the requests at the bottom of my question, I specified the wrong port. Once I got the client port to match the server port, then all those requests succeeded. Here's my setup:

Server config:

7> httpd:info(Server).
[{mime_types,[{"htm","text/html"},{"html","text/html"}]},
 {ipfamily,inet6},
 {server_name,"httpd_test"},
 {bind_address,{0,0,0,0,0,0,0,1}},
 {server_root,"."},
 {port,53686},
 {document_root,"./htdocs"}]

8>

Client config:

52> httpc:get_options(all, client1_config).
{ok,[{proxy,{undefined,[]}},
     {https_proxy,{undefined,[]}},
     {pipeline_timeout,0},
     {max_pipeline_length,2},
     {max_keep_alive_length,5},
     {keep_alive_timeout,120000},
     {max_sessions,2},
     {cookies,disabled},
     {verbose,false},
     {ipfamily,inet6},  
     {ip,default},
     {port,default},
     {socket_opts,[]}]}

53>

And here's the shortest syntax for a request:

53> httpc:request("http://[::1]:53686/file1.txt", client1_config).
{ok,{{"HTTP/1.1",200,"OK"},
     [{"date","Mon, 26 Feb 2018 10:21:39 GMT"},
      {"etag","nCZT0114"},
      {"server","inets/6.3.4"},
      {"content-length","14"},
      {"content-type","text/plain"},
      {"last-modified","Mon, 26 Feb 2018 02:51:52 GMT"}],
     "Hello, world!\n"}}

So the httpc:request() Option {ipv6_host_with_brackets, true} isn't required.

When I read the httpc docs, the profile part didn't really register with me. But a profile consists of the configuration options for the client, and it's also where cookies are stored, so you need to include the profile with subsequent requests.

There's a default profile, which I guess automatically gets sent with every request when you don't specify your own profile, and I think the default profile will handle cookies for you. (Nope, not by default. I found the following below the definition for httpc:set_options():

CookieMode = enabled | disabled | verify
If cookies are enabled, all valid cookies are automatically saved in the cookie database of the client manager. If option verify is used, function store_cookies/2 has to be called for the cookies to be saved. Default is disabled.

You can also add configuration options to the default profile.

But if you need to use a configuration like ipv6 for some requests and not others, then you can create a named profile and use the named profile when needed in your httpc:request()'s and the default profile for other requests (by not specifying a named profile). See httpc:set_options() for the client configuration options. Somewhat confusingly, httpc:request() has an Options argument, which allows you to specify other options (look in the docs below the definition of httpc:request/5 for a list of those options). Some of the request Options, like sync and stream, seem to be more appropriate for a profile:

A profile keeps track of proxy options, cookies, and other options that can be applied to more than one request.

http://erlang.org/doc/man/httpc.html

If you create a profile by calling inets:start(httpc, profile_name), the return value is the Pid of the client, which gets spun off in a separate process and handles requests when using that profile. You can kill the client with either of the following:

inets:stop(httpc, name_of_profile)
inets:stop(httpc, ClientPid)
7stud
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