httpb

An HTTP Basic client that provides finer granularity over the handling of HTTP requests and responses.

Data Types

• Url :: string() | binary().
• Body :: binary().
• Data :: binary().
• Headers :: #{atom() => binary()}.
• Reason :: term().
• Method :: delete | get | head | options | post | put | trace.
• Result :: #{status => integer(), headers => headers(), body => body()}.
• Socket :: gen_tcp:socket() | ssl:sslsocket().
• Options :: #{socket_opts => proplists:proplist(), timeout => timeout()}.
• Connection :: #{scheme => http | https, host => string(), port => non_neg_integer(), socket => socket()}.

Exports

httpb:close(Connection) -> ok | {error, Reason}

Close the Connection.

httpb:content_length(Headers) -> Length.

Return the content length.

httpb:controlling_process(Connection, Pid) -> ok | {error, Reason}

See gen_tcp:controlling_process/2 or ssl:controlling_process/2.

httpb:getopts(Connection, Options) -> {ok, Options} | {error, Reason}

See inet:getopts/2 or ssl:getopts/2.

httpb:is_chunked(Headers) -> true | false

Return true if Transfer-Encoding is present and equal to chunked.

httpb:is_keep_alive(Headers) -> true | false

Return false if Connection header is present and equal to close; otherwise true.

httpb:one_request(Method, Url, Headers, Body) -> {ok, Result} | {error, Reason}

httpb:one_request(Method, Url, Headers, Body, Options) -> {ok, Result} | {error, Reason}

A helper function for when the caller needs only make a single request and close the connection.

httpb:recv(Connection, Length) -> {ok, Data} | {error, Reason}

httpb:recv(Connection, Length, Timeout) -> {ok, Data} | {error, Reason}

Receives a packet from a Connection in passive mode ({active, false}). A closed Connection is indicated by return value {error, closed}.

Argument Length is meaningful only when the Connection is in mode raw and denotes the number of bytes to read. If Length = 0, all available bytes are returned. If Length > 0, exactly Length bytes are returned, or an error; possibly discarding less than Length bytes of data when the Connection gets closed from the other side.

Optional argument Timeout specifies a time-out in milliseconds; default value is 30000.

httpb:recv_chunk(Connection) -> {ok, Data} | {error, Reason}

httpb:recv_chunk(Connection, Timeout) -> {ok, Data} | {error, Reason}

Read the next chunk from the Connection. A zero length Data chunk typically indicated end of the response body.

Optional argument Timeout specifies a time-out in milliseconds; default value is 30000.

httpb:request(Method, Url, Headers, Body) -> {ok, Connection} | {error, Reason}

httpb:request(Method, Url, Headers, Body, Options) -> {ok, Connection} | {error, Reason}

Start an initial HTTP/1.1 request, returning the Connection on success.

The Options map can contain socket_opts and/or timeout. socket_opts is a property list of socket options passed through to gen_tcp:connect/4 or ssl:connect/4. The connection timeout defaults to 30000 milliseconds.

httpb:request(Connection, Method, Url, Headers, Body) -> {ok, Connection} | {error, Reason}

Given an already open connection, send a request.

Headers is a map keyed by header names as atoms, eg. accept or content_type, underscores will be converted to hyphens (-). The values must be binary strings. A host header will be generated from the Connection host and port, not the Url.

By design there is no help with the content_length header; its under the caller’s control. Its possible to specify a non-zero content_length and provide an initially empty body. The caller should follow a successful request with httpb:send(Connection, Body).

The Body argument is ignored for head and trace methods. To support OPTIONS * HTTP/1.1, specify a Url without a path http://localhost, which only applies to the options method.

httpb:response(Connection) -> {ok, Result} | {error, Reason}

httpb:response(Connection, Timeout) -> {ok, Result} | {error, Reason}

Read the HTTP response line and headers. If the response is chunked, then no body is returned, see httpb:recv_chunk/1,2; otherwise read as much of the body as possible.

Optional argument Timeout specifies a time-out in milliseconds; default value is 30000.

httpb:send(Connection, Data) -> ok | {error, Reason}

Send Data to the Connection.

httpb:send_chunk(Connection, Data) -> ok | {error, Reason}

Send Data as an HTTP formatted chunk to the Connection.

httpb:setopts(Connection, Options) -> ok | {error, Reason}

See inet:setopts/2 or ssl:setopts/2.

Examples

• Simple request-response-close:

1> {ok, Conn} = httpb:request(get, "https://example.com/", #{}, <<>>).
{ok,#{host => <<"example.com">>,port => 443,scheme => https,
      socket =>
          {sslsocket,{gen_tcp,#Port<0.5>,tls_connection,undefined},
                     [<0.113.0>,<0.112.0>]}}}
2> {ok, Result} = httpb:response(Conn).
{ok,#{body =>
          <<"<!doctype html>\n<html>\n<head>\n    <title>Example Domain</title>\n\n ... </html>\n">>,
      headers =>
          #{age => <<"408052">>,cache_control => <<"max-age=604800">>,
            content_length => <<"1256">>,
            content_type => <<"text/html; charset=UTF-8">>,
            date => <<"Thu, 06 Jan 2022 17:48:22 GMT">>,
            etag => <<"\"3147526947+gzip+ident\"">>,
            expires => <<"Thu, 13 Jan 2022 17:48:22 GMT">>,
            last_modified => <<"Thu, 17 Oct 2019 07:18:26 GMT">>,
            server => <<"ECS (chb/0286)">>,
            vary => <<"Accept-Encoding">>,x_cache => <<"HIT">>},
      status => 200}}
3> httpb:close(Conn).
ok

• If the connection is not going to be reused for more requests, the above can be done using the helper function one_request/4,5:

1> httpb:one_request(get, "https://example.com/", #{}, <<>>).
{ok,#{body =>
          <<"<!doctype html>\n<html>\n<head>\n    <title>Example Domain</title>\n\n    <meta charset=\"utf-8\" />\n    <meta "...>>,
      headers =>
          #{age => <<"554779">>,cache_control => <<"max-age=604800">>,
            content_length => <<"1256">>,
            content_type => <<"text/html; charset=UTF-8">>,
            date => <<"Sat, 21 May 2022 13:01:06 GMT">>,
            etag => <<"\"3147526947+ident\"">>,
            expires => <<"Sat, 28 May 2022 13:01:06 GMT">>,
            last_modified => <<"Thu, 17 Oct 2019 07:18:26 GMT">>,
            server => <<"ECS (chb/0286)">>,
            vary => <<"Accept-Encoding">>,x_cache => <<"HIT">>},
      status => 200}}
2>

• It is possible to send multiple requests over the same connection:

1> {ok, Conn} = httpb:request(get, "http://snert.com/about.html", #{}, <<>>).
{ok,#{host => <<"snert.com">>,method => get,port => 80,
      scheme => http,socket => #Port<0.7>}}
2> {ok, About} = httpb:response(Conn).
{ok,#{body =>
          <<"<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\">\n<html>\n<head>\n<meta http-equiv=\"Content-Type\" "...>>,
      headers =>
          #{accept_ranges => <<"bytes">>,connection => <<"keep-alive">>,
            content_length => <<"5090">>,
            content_type => <<"text/html">>,
            date => <<"Sat, 21 May 2022 14:49:49 GMT">>,
            etag => <<"\"56fbba85-13e2\"">>,
            last_modified => <<"Wed, 30 Mar 2016 11:37:41 GMT">>,
            server => <<"nginx/1.13.0">>},
      status => 200}}
3> {ok, Conn} = httpb:request(Conn, get, "http://snert.com/snert.html", #{}, <<>>).
{ok,#{host => <<"snert.com">>,method => get,port => 80,
      scheme => http,socket => #Port<0.7>}}
4> {ok, Snert} = httpb:response(Conn).
{ok,#{body =>
          <<"<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\">\n<html>\n<head>\n<meta http-equiv=\"Content-Type\" "...>>,
      headers =>
          #{accept_ranges => <<"bytes">>,connection => <<"keep-alive">>,
            content_length => <<"4436">>,
            content_type => <<"text/html">>,
            date => <<"Sat, 21 May 2022 14:49:49 GMT">>,
            etag => <<"\"5324973c-1154\"">>,
            last_modified => <<"Sat, 15 Mar 2014 18:09:00 GMT">>,
            server => <<"nginx/1.13.0">>},
      status => 200}}
5> httpb:close(Conn).
ok

• Those multiple requests can be pipelined, though the responses must be read in the same order:

1> {ok, Conn} = httpb:request(get, "http://snert.com/about.html", #{}, <<>>).
{ok,#{host => <<"snert.com">>,method => get,port => 80,
      scheme => http,socket => #Port<0.7>}}
2> {ok, Conn} = httpb:request(Conn, get, "http://snert.com/snert.html", #{}, <<>>).
{ok,#{host => <<"snert.com">>,method => get,port => 80,
      scheme => http,socket => #Port<0.7>}}
3> {ok, About} = httpb:response(Conn).
{ok,#{body =>
          <<"<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\">\n<html>\n<head>\n<meta http-equiv=\"Content-Type\" "...>>,
      headers =>
          #{accept_ranges => <<"bytes">>,connection => <<"keep-alive">>,
            content_length => <<"5090">>,
            content_type => <<"text/html">>,
            date => <<"Wed, 01 Jun 2022 20:41:21 GMT">>,
            etag => <<"\"56fbba85-13e2\"">>,
            last_modified => <<"Wed, 30 Mar 2016 11:37:41 GMT">>,
            server => <<"nginx/1.13.0">>},
      status => 200}}
4> {ok, Snert} = httpb:response(Conn).
{ok,#{body =>
          <<"<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\">\n<html>\n<head>\n<meta http-equiv=\"Content-Type\" "...>>,
      headers =>
          #{accept_ranges => <<"bytes">>,connection => <<"keep-alive">>,
            content_length => <<"4436">>,
            content_type => <<"text/html">>,
            date => <<"Wed, 01 Jun 2022 20:41:22 GMT">>,
            etag => <<"\"5324973c-1154\"">>,
            last_modified => <<"Sat, 15 Mar 2014 18:09:00 GMT">>,
            server => <<"nginx/1.13.0">>},
      status => 200}}
5> httpb:close(Conn).
ok

Copyright

Copyright 2021, 2022 by Anthony Howe. All rights reserved.

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.