source: ogAgent-Git/src/opengnsys/RESTApi.py @ cc65ece

# -*- coding: utf-8 -*-
#
# Copyright (c) 201 Virtual Cable S.L.
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# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
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#      this list of conditions and the following disclaimer.
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#      may be used to endorse or promote products derived from this software
#      without specific prior written permission.
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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"""
@author: Adolfo Gómez, dkmaster at dkmon dot com
"""

# pylint: disable-msg=E1101,W0703



import os
import requests
import logging
import json
import warnings

from .log import logger

from .utils import exceptionToMessage

TIMEOUT = 5  # Connection timout, in seconds


class RESTError(Exception):
    ERRCODE = 0


class ConnectionError(RESTError):
    ERRCODE = -1


# Disable warnings log messages
try:
    import urllib3  # @UnusedImport
    requests_log = logging.getLogger ('urllib3')
    requests_log.setLevel (logging.INFO)
except Exception:
    from requests.packages import urllib3  # @Reimport
    requests_log = logging.getLogger ('requests.packages.urllib3')
    requests_log.setLevel (logging.INFO)

try:
    urllib3.disable_warnings()  # @UndefinedVariable
    warnings.simplefilter("ignore")
except Exception:
    pass  # In fact, isn't too important, but wil log warns to logging file


class REST(object):
    """
    Simple interface to remote REST apis.
    The constructor expects the "base url" as parameter, that is, the url that will be common on all REST requests
    Remember that this is a helper for "easy of use". You can provide your owns using requests lib for example.
    Examples:
       v = REST('https://example.com/rest/v1/') (Can omit trailing / if desired)
       v.sendMessage('hello?param1=1&param2=2')
         This will generate a GET message to https://example.com/rest/v1/hello?param1=1&param2=2, and return the
         deserialized JSON result or an exception
       v.sendMessage('hello?param1=1&param2=2', {'name': 'mario' })
         This will generate a POST message to https://example.com/rest/v1/hello?param1=1&param2=2, with json encoded
         body {'name': 'mario' }, and also returns
         the deserialized JSON result or raises an exception in case of error 
    """

    def __init__(self, url, ca_file=None, crt_file=None, key_file=None):
        """
        Initializes the REST helper
        url is the full url of the REST API Base, as for example "https://example.com/rest/v1".
        @param url The url of the REST API Base. The trailing '/' can be included or omitted, as desired.
        """
        self.endpoint = url

        if self.endpoint[-1] != '/':
            self.endpoint += '/'

        # Some OSs ships very old python requests lib implementations, workaround them...
        try:
            self.newerRequestLib = requests.__version__.split('.')[0] >= '1'
        except Exception:
            self.newerRequestLib = False  # I no version, guess this must be an old requests

        if not self.newerRequestLib:
            logger.debug ('TLS not available: python requests library is old')

        self.use_tls = url.startswith ('https')
        if self.use_tls:
            if not ca_file or not crt_file or not key_file:
                raise Exception ('missing TLS parameters in REST constructor')

            errs = 0
            for f in [ca_file, crt_file, key_file]:
                if not os.path.exists (f):
                    logger.error (f'{f}: No such file or directory')
                    errs += 1
            if errs:
                raise Exception ('TLS files not found')

        self.ca_file  = ca_file
        self.crt_file = crt_file
        self.key_file = key_file

        # Disable logging requests messages except for errors, ...
        logging.getLogger("requests").setLevel(logging.CRITICAL)
        # Tries to disable all warnings
        try:
            warnings.simplefilter("ignore")  # Disables all warnings
        except Exception:
            pass

    def _getUrl(self, method):
        """
        Internal method
        Composes the URL based on "method"
        @param method: Method to append to base url for composition 
        """
        url = self.endpoint + method

        return url

    def _request(self, url, data=None):
        """
        Launches the request
        @param url: The url to obtain
        @param data: if None, the request will be sent as a GET request. If != None, the request will be sent as a POST,
        with data serialized as JSON in the body.
        """
        try:
            if data is None:
                logger.debug('Requesting using GET (no data provided) {}'.format(url))
                # Old requests version does not support verify, but it do not checks ssl certificate by default
                if self.newerRequestLib:
                    if self.use_tls:
                        logger.debug ('nati: using TLS for GET')
                        r = requests.get(url, cert=(self.crt_file, self.key_file), verify=self.ca_file, timeout=TIMEOUT)
                    else:
                        r = requests.get(url, timeout=TIMEOUT)
                else:
                    r = requests.get(url)
            else:  # POST
                logger.debug('Requesting using POST {}, data: {}'.format(url, data))
                if self.newerRequestLib:
                    if self.use_tls:
                        logger.debug ('nati: using TLS for POST')
                        r = requests.post(url, data=data, headers={'content-type': 'application/json'}, cert=(self.crt_file, self.key_file), verify=self.ca_file, timeout=TIMEOUT)
                    else:
                        r = requests.post(url, data=data, headers={'content-type': 'application/json'}, timeout=TIMEOUT)
                else:
                    r = requests.post(url, data=data, headers={'content-type': 'application/json'})

            r.raise_for_status()
            ct = r.headers['Content-Type']
            if 'application/json' != ct:
                raise Exception (f'response content-type is not "application/json" but "{ct}"')
            r = json.loads(r.content)  # Using instead of r.json() to make compatible with old requests lib versions
        except requests.exceptions.RequestException as e:
            code = e.response.status_code
            logger.warning (f'request failed, HTTP code "{code}"')
            return None
        except Exception as e:
            raise ConnectionError(exceptionToMessage(e))

        return r

    def sendMessage(self, msg, data=None, processData=True):
        """
        Sends a message to remote REST server
        @param data: if None or omitted, message will be a GET, else it will send a POST
        @param processData: if True, data will be serialized to json before sending, else, data will be sent as "raw" 
        """
        #logger.debug('Invoking post message {} with data {}'.format(msg, data))

        if processData and data is not None:
            data = json.dumps(data)

        url = self._getUrl(msg)
        #logger.debug('Requesting {}'.format(url))

        try:
            res = self._request(url, data)
            return res
        except:
            logger.exception()
            return None