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
|
"""
Basic HTTP Proxy
================
.. autoclass:: ProxyMiddleware
:copyright: 2007 Pallets
:license: BSD-3-Clause
"""
import socket
from ..datastructures import EnvironHeaders
from ..http import is_hop_by_hop_header
from ..urls import url_parse
from ..urls import url_quote
from ..wsgi import get_input_stream
try:
from http import client
except ImportError:
import httplib as client
class ProxyMiddleware(object):
"""Proxy requests under a path to an external server, routing other
requests to the app.
This middleware can only proxy HTTP requests, as that is the only
protocol handled by the WSGI server. Other protocols, such as
websocket requests, cannot be proxied at this layer. This should
only be used for development, in production a real proxying server
should be used.
The middleware takes a dict that maps a path prefix to a dict
describing the host to be proxied to::
app = ProxyMiddleware(app, {
"/static/": {
"target": "http://127.0.0.1:5001/",
}
})
Each host has the following options:
``target``:
The target URL to dispatch to. This is required.
``remove_prefix``:
Whether to remove the prefix from the URL before dispatching it
to the target. The default is ``False``.
``host``:
``"<auto>"`` (default):
The host header is automatically rewritten to the URL of the
target.
``None``:
The host header is unmodified from the client request.
Any other value:
The host header is overwritten with the value.
``headers``:
A dictionary of headers to be sent with the request to the
target. The default is ``{}``.
``ssl_context``:
A :class:`ssl.SSLContext` defining how to verify requests if the
target is HTTPS. The default is ``None``.
In the example above, everything under ``"/static/"`` is proxied to
the server on port 5001. The host header is rewritten to the target,
and the ``"/static/"`` prefix is removed from the URLs.
:param app: The WSGI application to wrap.
:param targets: Proxy target configurations. See description above.
:param chunk_size: Size of chunks to read from input stream and
write to target.
:param timeout: Seconds before an operation to a target fails.
.. versionadded:: 0.14
"""
def __init__(self, app, targets, chunk_size=2 << 13, timeout=10):
def _set_defaults(opts):
opts.setdefault("remove_prefix", False)
opts.setdefault("host", "<auto>")
opts.setdefault("headers", {})
opts.setdefault("ssl_context", None)
return opts
self.app = app
self.targets = dict(
("/%s/" % k.strip("/"), _set_defaults(v)) for k, v in targets.items()
)
self.chunk_size = chunk_size
self.timeout = timeout
def proxy_to(self, opts, path, prefix):
target = url_parse(opts["target"])
def application(environ, start_response):
headers = list(EnvironHeaders(environ).items())
headers[:] = [
(k, v)
for k, v in headers
if not is_hop_by_hop_header(k)
and k.lower() not in ("content-length", "host")
]
headers.append(("Connection", "close"))
if opts["host"] == "<auto>":
headers.append(("Host", target.ascii_host))
elif opts["host"] is None:
headers.append(("Host", environ["HTTP_HOST"]))
else:
headers.append(("Host", opts["host"]))
headers.extend(opts["headers"].items())
remote_path = path
if opts["remove_prefix"]:
remote_path = "%s/%s" % (
target.path.rstrip("/"),
remote_path[len(prefix) :].lstrip("/"),
)
content_length = environ.get("CONTENT_LENGTH")
chunked = False
if content_length not in ("", None):
headers.append(("Content-Length", content_length))
elif content_length is not None:
headers.append(("Transfer-Encoding", "chunked"))
chunked = True
try:
if target.scheme == "http":
con = client.HTTPConnection(
target.ascii_host, target.port or 80, timeout=self.timeout
)
elif target.scheme == "https":
con = client.HTTPSConnection(
target.ascii_host,
target.port or 443,
timeout=self.timeout,
context=opts["ssl_context"],
)
else:
raise RuntimeError(
"Target scheme must be 'http' or 'https', got '{}'.".format(
target.scheme
)
)
con.connect()
remote_url = url_quote(remote_path)
querystring = environ["QUERY_STRING"]
if querystring:
remote_url = remote_url + "?" + querystring
con.putrequest(environ["REQUEST_METHOD"], remote_url, skip_host=True)
for k, v in headers:
if k.lower() == "connection":
v = "close"
con.putheader(k, v)
con.endheaders()
stream = get_input_stream(environ)
while 1:
data = stream.read(self.chunk_size)
if not data:
break
if chunked:
con.send(b"%x\r\n%s\r\n" % (len(data), data))
else:
con.send(data)
resp = con.getresponse()
except socket.error:
from ..exceptions import BadGateway
return BadGateway()(environ, start_response)
start_response(
"%d %s" % (resp.status, resp.reason),
[
(k.title(), v)
for k, v in resp.getheaders()
if not is_hop_by_hop_header(k)
],
)
def read():
while 1:
try:
data = resp.read(self.chunk_size)
except socket.error:
break
if not data:
break
yield data
return read()
return application
def __call__(self, environ, start_response):
path = environ["PATH_INFO"]
app = self.app
for prefix, opts in self.targets.items():
if path.startswith(prefix):
app = self.proxy_to(opts, path, prefix)
break
return app(environ, start_response)
|
