File size: 8,066 Bytes
9c6594c
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
from __future__ import annotations

import html
import inspect
import sys
import traceback
import typing

from starlette._utils import is_async_callable
from starlette.concurrency import run_in_threadpool
from starlette.requests import Request
from starlette.responses import HTMLResponse, PlainTextResponse, Response
from starlette.types import ASGIApp, Message, Receive, Scope, Send

STYLES = """
p {
    color: #211c1c;
}
.traceback-container {
    border: 1px solid #038BB8;
}
.traceback-title {
    background-color: #038BB8;
    color: lemonchiffon;
    padding: 12px;
    font-size: 20px;
    margin-top: 0px;
}
.frame-line {
    padding-left: 10px;
    font-family: monospace;
}
.frame-filename {
    font-family: monospace;
}
.center-line {
    background-color: #038BB8;
    color: #f9f6e1;
    padding: 5px 0px 5px 5px;
}
.lineno {
    margin-right: 5px;
}
.frame-title {
    font-weight: unset;
    padding: 10px 10px 10px 10px;
    background-color: #E4F4FD;
    margin-right: 10px;
    color: #191f21;
    font-size: 17px;
    border: 1px solid #c7dce8;
}
.collapse-btn {
    float: right;
    padding: 0px 5px 1px 5px;
    border: solid 1px #96aebb;
    cursor: pointer;
}
.collapsed {
  display: none;
}
.source-code {
  font-family: courier;
  font-size: small;
  padding-bottom: 10px;
}
"""

JS = """
<script type="text/javascript">
    function collapse(element){
        const frameId = element.getAttribute("data-frame-id");
        const frame = document.getElementById(frameId);

        if (frame.classList.contains("collapsed")){
            element.innerHTML = "&#8210;";
            frame.classList.remove("collapsed");
        } else {
            element.innerHTML = "+";
            frame.classList.add("collapsed");
        }
    }
</script>
"""

TEMPLATE = """
<html>
    <head>
        <style type='text/css'>
            {styles}
        </style>
        <title>Starlette Debugger</title>
    </head>
    <body>
        <h1>500 Server Error</h1>
        <h2>{error}</h2>
        <div class="traceback-container">
            <p class="traceback-title">Traceback</p>
            <div>{exc_html}</div>
        </div>
        {js}
    </body>
</html>
"""

FRAME_TEMPLATE = """
<div>
    <p class="frame-title">File <span class="frame-filename">{frame_filename}</span>,
    line <i>{frame_lineno}</i>,
    in <b>{frame_name}</b>
    <span class="collapse-btn" data-frame-id="{frame_filename}-{frame_lineno}" onclick="collapse(this)">{collapse_button}</span>
    </p>
    <div id="{frame_filename}-{frame_lineno}" class="source-code {collapsed}">{code_context}</div>
</div>
"""  # noqa: E501

LINE = """
<p><span class="frame-line">
<span class="lineno">{lineno}.</span> {line}</span></p>
"""

CENTER_LINE = """
<p class="center-line"><span class="frame-line center-line">
<span class="lineno">{lineno}.</span> {line}</span></p>
"""


class ServerErrorMiddleware:
    """
    Handles returning 500 responses when a server error occurs.

    If 'debug' is set, then traceback responses will be returned,
    otherwise the designated 'handler' will be called.

    This middleware class should generally be used to wrap *everything*
    else up, so that unhandled exceptions anywhere in the stack
    always result in an appropriate 500 response.
    """

    def __init__(
        self,
        app: ASGIApp,
        handler: typing.Callable[[Request, Exception], typing.Any] | None = None,
        debug: bool = False,
    ) -> None:
        self.app = app
        self.handler = handler
        self.debug = debug

    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
        if scope["type"] != "http":
            await self.app(scope, receive, send)
            return

        response_started = False

        async def _send(message: Message) -> None:
            nonlocal response_started, send

            if message["type"] == "http.response.start":
                response_started = True
            await send(message)

        try:
            await self.app(scope, receive, _send)
        except Exception as exc:
            request = Request(scope)
            if self.debug:
                # In debug mode, return traceback responses.
                response = self.debug_response(request, exc)
            elif self.handler is None:
                # Use our default 500 error handler.
                response = self.error_response(request, exc)
            else:
                # Use an installed 500 error handler.
                if is_async_callable(self.handler):
                    response = await self.handler(request, exc)
                else:
                    response = await run_in_threadpool(self.handler, request, exc)

            if not response_started:
                await response(scope, receive, send)

            # We always continue to raise the exception.
            # This allows servers to log the error, or allows test clients
            # to optionally raise the error within the test case.
            raise exc

    def format_line(self, index: int, line: str, frame_lineno: int, frame_index: int) -> str:
        values = {
            # HTML escape - line could contain < or >
            "line": html.escape(line).replace(" ", "&nbsp"),
            "lineno": (frame_lineno - frame_index) + index,
        }

        if index != frame_index:
            return LINE.format(**values)
        return CENTER_LINE.format(**values)

    def generate_frame_html(self, frame: inspect.FrameInfo, is_collapsed: bool) -> str:
        code_context = "".join(
            self.format_line(
                index,
                line,
                frame.lineno,
                frame.index,  # type: ignore[arg-type]
            )
            for index, line in enumerate(frame.code_context or [])
        )

        values = {
            # HTML escape - filename could contain < or >, especially if it's a virtual
            # file e.g. <stdin> in the REPL
            "frame_filename": html.escape(frame.filename),
            "frame_lineno": frame.lineno,
            # HTML escape - if you try very hard it's possible to name a function with <
            # or >
            "frame_name": html.escape(frame.function),
            "code_context": code_context,
            "collapsed": "collapsed" if is_collapsed else "",
            "collapse_button": "+" if is_collapsed else "&#8210;",
        }
        return FRAME_TEMPLATE.format(**values)

    def generate_html(self, exc: Exception, limit: int = 7) -> str:
        traceback_obj = traceback.TracebackException.from_exception(exc, capture_locals=True)

        exc_html = ""
        is_collapsed = False
        exc_traceback = exc.__traceback__
        if exc_traceback is not None:
            frames = inspect.getinnerframes(exc_traceback, limit)
            for frame in reversed(frames):
                exc_html += self.generate_frame_html(frame, is_collapsed)
                is_collapsed = True

        if sys.version_info >= (3, 13):  # pragma: no cover
            exc_type_str = traceback_obj.exc_type_str
        else:  # pragma: no cover
            exc_type_str = traceback_obj.exc_type.__name__

        # escape error class and text
        error = f"{html.escape(exc_type_str)}: {html.escape(str(traceback_obj))}"

        return TEMPLATE.format(styles=STYLES, js=JS, error=error, exc_html=exc_html)

    def generate_plain_text(self, exc: Exception) -> str:
        return "".join(traceback.format_exception(type(exc), exc, exc.__traceback__))

    def debug_response(self, request: Request, exc: Exception) -> Response:
        accept = request.headers.get("accept", "")

        if "text/html" in accept:
            content = self.generate_html(exc)
            return HTMLResponse(content, status_code=500)
        content = self.generate_plain_text(exc)
        return PlainTextResponse(content, status_code=500)

    def error_response(self, request: Request, exc: Exception) -> Response:
        return PlainTextResponse("Internal Server Error", status_code=500)