From cedf1d0b0023b07e0ed97bce6e1c6e11a50257f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kyle=20Bl=C3=B6m?= <kylejbloom@gmail.com>
Date: Mon, 30 Jan 2017 09:13:43 -0800
Subject: [PATCH] Added new tests, new request logic, and handler file

Added new tests for alternate uses for alternate range request types.

Changed error handlnig for new request logic that simplifies the integration logic

Moved the error handler and the content range handler to their own handler file to prevent circular imports.
---
 sanic/exceptions.py  |  78 ++------------------------
 sanic/handlers.py    | 127 +++++++++++++++++++++++++++++++++++++++++++
 sanic/response.py    |  32 -----------
 sanic/sanic.py       |   4 +-
 sanic/static.py      |  32 +++++------
 tests/test_static.py |  39 ++++++++++++-
 6 files changed, 188 insertions(+), 124 deletions(-)
 create mode 100644 sanic/handlers.py

diff --git a/sanic/exceptions.py b/sanic/exceptions.py
index a98c9e14..370882be 100644
--- a/sanic/exceptions.py
+++ b/sanic/exceptions.py
@@ -1,8 +1,3 @@
-from .response import text, html
-from .log import log
-from traceback import format_exc, extract_tb
-import sys
-
 TRACEBACK_STYLE = '''
     <style>
         body {
@@ -138,6 +133,10 @@ class PayloadTooLarge(SanicException):
     status_code = 413
 
 
+class HeaderNotFound(SanicException):
+    status_code = 400
+
+
 class ContentRangeError(SanicException):
     status_code = 416
 
@@ -149,70 +148,5 @@ class ContentRangeError(SanicException):
         }
 
 
-class Handler:
-    handlers = None
-
-    def __init__(self):
-        self.handlers = {}
-        self.debug = False
-
-    def _render_traceback_html(self, exception, request):
-        exc_type, exc_value, tb = sys.exc_info()
-        frames = extract_tb(tb)
-
-        frame_html = []
-        for frame in frames:
-            frame_html.append(TRACEBACK_LINE_HTML.format(frame))
-
-        return TRACEBACK_WRAPPER_HTML.format(
-            style=TRACEBACK_STYLE,
-            exc_name=exc_type.__name__,
-            exc_value=exc_value,
-            frame_html=''.join(frame_html),
-            uri=request.url)
-
-    def add(self, exception, handler):
-        self.handlers[exception] = handler
-
-    def response(self, request, exception):
-        """
-        Fetches and executes an exception handler and returns a response object
-
-        :param request: Request
-        :param exception: Exception to handle
-        :return: Response object
-        """
-        handler = self.handlers.get(type(exception), self.default)
-        try:
-            response = handler(request=request, exception=exception)
-        except:
-            log.error(format_exc())
-            if self.debug:
-                response_message = (
-                    'Exception raised in exception handler "{}" '
-                    'for uri: "{}"\n{}').format(
-                        handler.__name__, request.url, format_exc())
-                log.error(response_message)
-                return text(response_message, 500)
-            else:
-                return text('An error occurred while handling an error', 500)
-        return response
-
-    def default(self, request, exception):
-        log.error(format_exc())
-        if issubclass(type(exception), SanicException):
-            return text(
-                'Error: {}'.format(exception),
-                status=getattr(exception, 'status_code', 500),
-                headers=getattr(exception, 'headers', dict())
-            )
-        elif self.debug:
-            html_output = self._render_traceback_html(exception, request)
-
-            response_message = (
-                'Exception occurred while handling uri: "{}"\n{}'.format(
-                    request.url, format_exc()))
-            log.error(response_message)
-            return html(html_output, status=500)
-        else:
-            return html(INTERNAL_SERVER_ERROR_HTML, status=500)
+class InvalidRangeType(ContentRangeError):
+    pass
diff --git a/sanic/handlers.py b/sanic/handlers.py
new file mode 100644
index 00000000..c78a1488
--- /dev/null
+++ b/sanic/handlers.py
@@ -0,0 +1,127 @@
+from .response import text, html
+from .log import log
+from traceback import format_exc, extract_tb
+import sys
+from .exceptions import SanicException, HeaderNotFound, InvalidRangeType
+from .exceptions import INTERNAL_SERVER_ERROR_HTML, TRACEBACK_LINE_HTML
+from .exceptions import TRACEBACK_STYLE, TRACEBACK_WRAPPER_HTML
+from .exceptions import ContentRangeError
+
+
+class ErrorHandler:
+    handlers = None
+
+    def __init__(self):
+        self.handlers = {}
+        self.debug = False
+
+    def _render_traceback_html(self, exception, request):
+        exc_type, exc_value, tb = sys.exc_info()
+        frames = extract_tb(tb)
+
+        frame_html = []
+        for frame in frames:
+            frame_html.append(TRACEBACK_LINE_HTML.format(frame))
+
+        return TRACEBACK_WRAPPER_HTML.format(
+            style=TRACEBACK_STYLE,
+            exc_name=exc_type.__name__,
+            exc_value=exc_value,
+            frame_html=''.join(frame_html),
+            uri=request.url)
+
+    def add(self, exception, handler):
+        self.handlers[exception] = handler
+
+    def response(self, request, exception):
+        """
+        Fetches and executes an exception handler and returns a response object
+
+        :param request: Request
+        :param exception: Exception to handle
+        :return: Response object
+        """
+        handler = self.handlers.get(type(exception), self.default)
+        try:
+            response = handler(request=request, exception=exception)
+        except Exception:
+            log.error(format_exc())
+            if self.debug:
+                response_message = (
+                    'Exception raised in exception handler "{}" '
+                    'for uri: "{}"\n{}').format(
+                        handler.__name__, request.url, format_exc())
+                log.error(response_message)
+                return text(response_message, 500)
+            else:
+                return text('An error occurred while handling an error', 500)
+        return response
+
+    def default(self, request, exception):
+        log.error(format_exc())
+        if issubclass(type(exception), SanicException):
+            return text(
+                'Error: {}'.format(exception),
+                status=getattr(exception, 'status_code', 500),
+                headers=getattr(exception, 'headers', dict())
+            )
+        elif self.debug:
+            html_output = self._render_traceback_html(exception, request)
+
+            response_message = (
+                'Exception occurred while handling uri: "{}"\n{}'.format(
+                    request.url, format_exc()))
+            log.error(response_message)
+            return html(html_output, status=500)
+        else:
+            return html(INTERNAL_SERVER_ERROR_HTML, status=500)
+
+
+class ContentRangeHandler:
+    """
+    This class is for parsing the request header
+    """
+    __slots__ = ('start', 'end', 'size', 'total', 'headers')
+
+    def __init__(self, request, stats):
+        self.total = stats.st_size
+        _range = request.headers.get('Range')
+        if _range is None:
+            raise HeaderNotFound('Range Header Not Found')
+        unit, _, value = tuple(map(str.strip, _range.partition('=')))
+        if unit != 'bytes':
+            raise InvalidRangeType(
+                '%s is not a valid Range Type' % (unit,), self)
+        start_b, _, end_b = tuple(map(str.strip, value.partition('-')))
+        try:
+            self.start = int(start_b) if start_b else None
+        except ValueError:
+            raise ContentRangeError(
+                '\'%s\' is invalid for Content Range' % (start_b,), self)
+        try:
+            self.end = int(end_b) if end_b else None
+        except ValueError:
+            raise ContentRangeError(
+                '\'%s\' is invalid for Content Range' % (end_b,), self)
+        if self.end is None:
+            if self.start is None:
+                raise ContentRangeError(
+                    'Invalid for Content Range parameters', self)
+            else:
+                # this case represents `Content-Range: bytes 5-`
+                self.end = self.total
+        else:
+            if self.start is None:
+                # this case represents `Content-Range: bytes -5`
+                self.start = self.total - self.end
+                self.end = self.total
+        if self.start >= self.end:
+            raise ContentRangeError(
+                'Invalid for Content Range parameters', self)
+        self.size = self.end - self.start
+        self.headers = {
+            'Content-Range': "bytes %s-%s/%s" % (
+                self.start, self.end, self.total)}
+
+    def __bool__(self):
+        return self.size > 0
diff --git a/sanic/response.py b/sanic/response.py
index 287eec26..41d2167d 100644
--- a/sanic/response.py
+++ b/sanic/response.py
@@ -140,38 +140,6 @@ class HTTPResponse:
         return self._cookies
 
 
-class ContentRangeHandler:
-    """
-    This class is for parsing the request header
-    """
-    __slots__ = ('start', 'end', 'size', 'total', 'headers')
-
-    def __init__(self, request, stats):
-        self.size = self.start = 0
-        self.end = None
-        self.headers = dict()
-        self.total = stats.st_size
-        _range = request.headers.get('Range')
-        if _range is None:
-            return
-        unit, _, value = tuple(map(str.strip, _range.partition('=')))
-        if unit != 'bytes':
-            return
-        start_b, _, end_b = tuple(map(str.strip, value.partition('-')))
-        try:
-            self.start = int(start_b) if start_b else 0
-            self.end = int(end_b) if end_b else 0
-        except ValueError:
-            self.start = self.end = 0
-            return
-        self.size = self.end - self.start
-        self.headers['Content-Range'] = "bytes %s-%s/%s" % (
-            self.start, self.end, self.total)
-
-    def __bool__(self):
-        return self.size != 0
-
-
 def json(body, status=200, headers=None, **kwargs):
     """
     Returns response object with body in json format.
diff --git a/sanic/sanic.py b/sanic/sanic.py
index 8b9dbc78..4dd487cc 100644
--- a/sanic/sanic.py
+++ b/sanic/sanic.py
@@ -8,7 +8,7 @@ from traceback import format_exc
 import logging
 
 from .config import Config
-from .exceptions import Handler
+from .handlers import ErrorHandler
 from .log import log
 from .response import HTTPResponse
 from .router import Router
@@ -36,7 +36,7 @@ class Sanic:
             name = getmodulename(frame_records[1])
         self.name = name
         self.router = router or Router()
-        self.error_handler = error_handler or Handler()
+        self.error_handler = error_handler or ErrorHandler()
         self.config = Config()
         self.request_middleware = deque()
         self.response_middleware = deque()
diff --git a/sanic/static.py b/sanic/static.py
index e0255334..14a20464 100644
--- a/sanic/static.py
+++ b/sanic/static.py
@@ -1,12 +1,15 @@
-from aiofiles.os import stat
+from mimetypes import guess_type
 from os import path
 from re import sub
 from time import strftime, gmtime
-from mimetypes import guess_type
 from urllib.parse import unquote
 
+from aiofiles.os import stat
+
 from .exceptions import FileNotFound, InvalidUsage, ContentRangeError
-from .response import file, HTTPResponse, ContentRangeHandler
+from .exceptions import HeaderNotFound
+from .response import file, HTTPResponse
+from .handlers import ContentRangeHandler
 
 
 def register(app, uri, file_or_directory, pattern,
@@ -56,30 +59,27 @@ def register(app, uri, file_or_directory, pattern,
             stats = None
             if use_modified_since:
                 stats = await stat(file_path)
-                modified_since = strftime('%a, %d %b %Y %H:%M:%S GMT',
-                                          gmtime(stats.st_mtime))
+                modified_since = strftime(
+                    '%a, %d %b %Y %H:%M:%S GMT', gmtime(stats.st_mtime))
                 if request.headers.get('If-Modified-Since') == modified_since:
                     return HTTPResponse(status=304)
                 headers['Last-Modified'] = modified_since
             _range = None
             if use_content_range:
+                _range = None
                 if not stats:
                     stats = await stat(file_path)
                 headers['Accept-Ranges'] = 'bytes'
                 headers['Content-Length'] = str(stats.st_size)
                 if request.method != 'HEAD':
-                    _range = ContentRangeHandler(request, stats)
-                    # If the start byte is greater than the size
-                    # of the entire file or if the end is
-                    if _range.start >= _range.total or _range.end == 0:
-                        raise ContentRangeError('Content-Range malformed',
-                                                _range)
-                    if _range.start == 0 and _range.size == 0:
-                        _range = None
+                    try:
+                        _range = ContentRangeHandler(request, stats)
+                    except HeaderNotFound:
+                        pass
                     else:
-                        headers['Content-Length'] = str(_range.size)
-                        for k, v in _range.headers.items():
-                            headers[k] = v
+                        del headers['Content-Length']
+                        for key, value in _range.headers.items():
+                            headers[key] = value
             if request.method == 'HEAD':
                 return HTTPResponse(
                     headers=headers,
diff --git a/tests/test_static.py b/tests/test_static.py
index 601b0deb..6b7647d0 100644
--- a/tests/test_static.py
+++ b/tests/test_static.py
@@ -86,8 +86,43 @@ def test_static_content_range_correct(static_file_path, static_file_content):
     assert response.status == 200
     assert 'Content-Length' in response.headers
     assert 'Content-Range' in response.headers
-    assert int(response.headers['Content-Length']) == 19-12
-    assert response.body == bytes(static_file_content)[12:19]
+    static_content = bytes(static_file_content)[12:19]
+    assert int(response.headers['Content-Length']) == len(static_content)
+    assert response.body == static_content
+
+
+def test_static_content_range_front(static_file_path, static_file_content):
+    app = Sanic('test_static')
+    app.static('/testing.file', static_file_path, use_content_range=True)
+
+    headers = {
+        'Range': 'bytes=12-'
+    }
+    request, response = sanic_endpoint_test(
+        app, uri='/testing.file', headers=headers)
+    assert response.status == 200
+    assert 'Content-Length' in response.headers
+    assert 'Content-Range' in response.headers
+    static_content = bytes(static_file_content)[12:]
+    assert int(response.headers['Content-Length']) == len(static_content)
+    assert response.body == static_content
+
+
+def test_static_content_range_back(static_file_path, static_file_content):
+    app = Sanic('test_static')
+    app.static('/testing.file', static_file_path, use_content_range=True)
+
+    headers = {
+        'Range': 'bytes=-12'
+    }
+    request, response = sanic_endpoint_test(
+        app, uri='/testing.file', headers=headers)
+    assert response.status == 200
+    assert 'Content-Length' in response.headers
+    assert 'Content-Range' in response.headers
+    static_content = bytes(static_file_content)[-12:]
+    assert int(response.headers['Content-Length']) == len(static_content)
+    assert response.body == static_content
 
 
 def test_static_content_range_empty(static_file_path, static_file_content):