VKHS

VKHS provides access to Vkontakte social network, popular mainly in Russia. Library can be used to login into the network as a standalone application (OAuth implicit flow as they call it). Having the access token, it is possible to call VK API methods.

Features

• Provides access to VK API via VKT monad and vkq command line tool.
• Supports HTTPS protocol.
• Supports http_proxy variables.
• Handles interaction with VK Login form.
• VKT monad is designed to handle long-running tasks and allows programs to recover from errors like network errors or token expirations.
• Web.VKHS.API.Simple module defines handy API wrappers. See example runhaskell scripts.

TODO

• Decrypt 'RepeatedForm' errors
• Support storing access-tokens in a temp file
• Still no support for captchas, one probably should hack defaultSupervisor and add them.
• File uploading still not functioning.
• Preserve cookies between sessions
• Make user-friendly multy-platform captcha display.
• Fix login automata behaviour regarding captcha failures.
• Re-test existing captcha-related functionality
• Re-implement VK monad as a Free monad special case.
• Runhaskell: handle some standard command line arguments.
• Network connection timeout is not handled by the coroutine supervisor.
• Enhance the way vkq accepts arguments, support multy-line messages.
• Fix grammatical mistakes here and there. Any corrections will be kindly accepted.
• Minor issues here and there. Use git grep FIXME to find them.
• Write simple RSS-feeder server, see specs

Installing

The author of this project uses Nix package manager for maintaining development environment. The default.nix file contains Nix expression describing the environment and a tree of dependencies.

Non-nix installations are possible, but this way requires user to install the right Cabal and GHC versions. The GHC version which is known to work is listed in default.nix file of the current repo.

$ cat ./default.nix | grep "ghc ?"
   ghc ? "ghc844"

means that the author used GHC-8.4.4 to build the package.

Installing with Nix

1. Make sure that Nix package manager is installed. NixOS distribution has it by default, other distros may install it as a regular application.
2. Check that NIX_PATH variable is set, and its nixpkg section points to recent nixpkgs repository. The 8916ac0 revision of release-19.03 branch is known to work.
3. Do the following:

   $ git clone https://github.com/grwlf/vkhs
   $ cd vkhs
   $ nix-shell
   
     ... Wait until dependencies are fetched
   
   (shell) $ cabal repl vkq
   > :lo Main
   > :main --help
   > ...
   
   (shell) $ cabal build
   

Installing from Hackage

To install VKHS as a library, one typically should use the Cabal package manager of Haskell, as follows:

$ cabal update
$ cabal install VKHS

Note, that Hackage may contain slightly outdated version of VKHS.

Installing from source

To install from source, one typically need to install HaskellPlatform of the right version and do the following:

$ git clone https://github.com/grwlf/vkhs
$ cd vkhs
$ cabal install

Building ctags file

./mktags.sh script may be used to build ctags tags file supported by many text editors. The script uses hasktags via haskdogs tools, available on Hackage.

$ haskdogs

VKQ command line application

vkq is a command line tool which demonstrates API usage. It can be used for logging in, -downloading music- and reading wall messages. Call vkq --help or vkq command --help to read online help.

Logging in to VK

In order to send API requests, the VK client typically needs an access token. vkq receives it as a result of signing in. Once received, the token may be saved to VKQ_ACCESS_TOKEN environment variable, into .vkhs-access-token file or passed to future instances directly using -a argument.

Saving access token in the environment variable

$ vkq login [email protected] pass123
d8a41221616ef5ba19537125dc0349bad9d529fa15314ad765911726fe98b15185ac41a7ca2c62f3bf4b9
$ export VKQ_ACCESS_TOKEN=d785932b871f096bd73aac6a35d7a7c469dd788d796463a871e5beb5c61bc6c96788ec2

Alternatively, result may be achieved using --eval option

$ eval `vkq login [email protected] pass123 --eval`

Saving access token to file

VKQ will cache the access token into a file. Newer versions of VKHS have --access-token-flag option enabled by default. Set it to empty value to disable the caching.

Performing API calls

vkq allows user to call arbitrary API method. The generic interface is as follows:

$ vkq api --help
Usage: vkq api [--verbose] [--req-per-sec N] [--interactive] [--appid APPID]
               [--user USER] [--pass PASS] [-a ACCESS_TOKEN]
               [--access-token-file FILE] METHOD [PARAMS] [--pretty]
  Call VK API method

Available options:
  --verbose                Be verbose
  --req-per-sec N          Max number of requests per second
  --interactive            Allow interactive queries
  --appid APPID            Application ID, defaults to VKHS
  --user USER              User name or email
  --pass PASS              User password
  -a ACCESS_TOKEN          Access token. Honores VKQ_ACCESS_TOKEN environment
                           variable
  --access-token-file FILE Filename to store actual access token, should be used
                           to pass its value between sessions
  METHOD                   Method name
  PARAMS                   Method arguments, KEY=VALUE[,KEY2=VALUE2[,,,]]
  --pretty                 Pretty print resulting JSON
  -h,--help                Show this help text

The session may look like the following:

$ vkq api 'users.get'
{"response":[{"first_name":"Сергей","uid":222222,"last_name":"Миронов"}]}

$ vkq api 'messages.send' 'user_id=333333' 'message="Hi there!!!"'
{"response":57505}

$ vkq api 'groups.search' 'q=Haskell'
{
    "response": [
        30,
        {
            "screen_name": "ml_mat_asm",
            "photo": "https://pp.userapi.com/c638217/v638217626/54113/v5Ib71-dDzo.jpg",
            "is_closed": 0,
            "photo_medium": "https://pp.userapi.com/c638217/v638217626/54112/Nu_si987vOc.jpg",
            "name": "Matlab | Assembler | MathCAD | Haskell | Prolog",
            "photo_big": "https://pp.userapi.com/c638217/v638217626/54111/HGnUbgUorVU.jpg",
            "gid": 78651325,
            "is_admin": 0,
            "is_member": 0,
            "type": "page"
        },
        ...
}

VKHS library/runhaskell mode

Starting from 1.7.2 the library supports runhaskell-mode.

#!/usr/bin/env runhaskell
{-# LANGUAGE RecordWildCards #-}

import Web.VKHS
import Web.VKHS.Imports

main :: IO ()
main = runVK_ defaultOptions $ do
  Sized cnt cs <- getCountries
  forM_ cs $ \Country{..} -> do
    liftIO $ tputStrLn co_title

When executed, the program asks for login/password and outputs list of countries known to VK. getCountries and several other methods are defined in Web.VKHS.API.Simple.

The distribuption contains ./app/runhaskell folder with a couple of examples.

Debugging

Verbosity may be increased using --verbose flag or o_verbose field of GenericOptions. Login automata saves latest.html file during operation.

References

• Implicit-flow authentication, see documentation in Russian for details
• VK API documentation

License

BSD3 license

Copyright (c) 2018, Sergey Mironov [email protected]