Add options to control the behavior of Request.remote_addr (#1539)

* Add options to control the behavior of Request.remote_addr

* Update tests for Request.remote_addr

* Update documentation for Request.remote_addr

docs/sanic/config.md

@@ -86,7 +86,7 @@ DB_USER = 'appuser'
 Out of the box there are just a few predefined values which can be overwritten when creating the application.
 
     | Variable                  | Default           | Description                                                                 |
-    | ------------------------- | --------- | --------------------------------------------------------- |
+    | ------------------------- | ----------------- | --------------------------------------------------------------------------- |
     | REQUEST_MAX_SIZE          | 100000000         | How big a request may be (bytes)                                            |
     | REQUEST_BUFFER_QUEUE_SIZE | 100               | Request streaming buffer queue size                                         |
     | REQUEST_TIMEOUT           | 60                | How long a request can take to arrive (sec)                                 |
@@ -95,6 +95,9 @@ Out of the box there are just a few predefined values which can be overwritten w
     | KEEP_ALIVE_TIMEOUT        | 5                 | How long to hold a TCP connection open (sec)                                |
     | GRACEFUL_SHUTDOWN_TIMEOUT | 15.0              | How long to wait to force close non-idle connection (sec)                   |
     | ACCESS_LOG                | True              | Disable or enable access log                                                |
+    | PROXIES_COUNT             | -1                | The number of proxy servers in front of the app (e.g. nginx; see below)     |
+    | FORWARDED_FOR_HEADER      | "X-Forwarded-For" | The name of "X-Forwarded-For" HTTP header that contains client and proxy ip |
+    | REAL_IP_HEADER            | "X-Real-IP"       | The name of "X-Real-IP" HTTP header that contains real client ip            |
 
 ### The different Timeout variables:
 
@@ -143,3 +146,17 @@ Firefox client hard keepalive limit = 115 seconds
 Opera 11 client hard keepalive limit = 120 seconds
 Chrome 13+ client keepalive limit > 300+ seconds
 ```
+
+### About proxy servers and client ip
+
+When you use a reverse proxy server (e.g. nginx), the value of `request.ip` will contain ip of a proxy, typically `127.0.0.1`. To determine the real client ip, `X-Forwarded-For` and `X-Real-IP` HTTP headers are used. But client can fake these headers if they have not been overridden by a proxy. Sanic has a set of options to determine the level of confidence in these headers.
+
+* If you have a single proxy, set `PROXIES_COUNT` to `1`. Then Sanic will use `X-Real-IP` if available or the last ip from `X-Forwarded-For`.
+
+* If you have multiple proxies, set `PROXIES_COUNT` equal to their number to allow Sanic to select the correct ip from `X-Forwarded-For`.
+
+* If you don't use a proxy, set `PROXIES_COUNT` to `0` to ignore these headers and prevent ip falsification.
+
+* If you don't use `X-Real-IP` (e.g. your proxy sends only `X-Forwarded-For`), set `REAL_IP_HEADER` to an empty string.
+
+The real ip will be available in `request.remote_addr`. If HTTP headers are unavailable or untrusted, `request.remote_addr` will be an empty string; in this case use `request.ip` instead.

docs/sanic/deploying.md

@@ -64,6 +64,26 @@ of the memory leak.
 
 See the [Gunicorn Docs](http://docs.gunicorn.org/en/latest/settings.html#max-requests) for more information.
 
+## Running behind a reverse proxy
+
+Sanic can be used with a reverse proxy (e.g. nginx). There's a simple example of nginx configuration:
+
+```
+server {
+  listen 80;
+  server_name example.org;
+
+  location / {
+    proxy_pass http://127.0.0.1:8000;
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+  }
+}
+```
+
+If you want to get real client ip, you should configure `X-Real-IP` and `X-Forwarded-For` HTTP headers and set `app.config.PROXIES_COUNT` to `1`; see the configuration page for more information.
+
 ## Disable debug logging
 
 To improve the performance add `debug=False` and `access_log=False` in the `run` arguments.

sanic/config.py

@@ -25,6 +25,9 @@ DEFAULT_CONFIG = {
     "WEBSOCKET_WRITE_LIMIT": 2 ** 16,
     "GRACEFUL_SHUTDOWN_TIMEOUT": 15.0,  # 15 sec
     "ACCESS_LOG": True,
+    "PROXIES_COUNT": -1,
+    "FORWARDED_FOR_HEADER": "X-Forwarded-For",
+    "REAL_IP_HEADER": "X-Real-IP",
 }
 
 

sanic/request.py

@@ -355,19 +355,38 @@ class Request(dict):
 
     @property
     def remote_addr(self):
-        """Attempt to return the original client ip based on X-Forwarded-For.
+        """Attempt to return the original client ip based on X-Forwarded-For
+        or X-Real-IP. If HTTP headers are unavailable or untrusted, returns
+        an empty string.
 
         :return: original client ip.
         """
         if not hasattr(self, "_remote_addr"):
-            forwarded_for = self.headers.get("X-Forwarded-For", "").split(",")
+            if self.app.config.PROXIES_COUNT == 0:
+                self._remote_addr = ""
+            elif self.app.config.REAL_IP_HEADER and self.headers.get(
+                self.app.config.REAL_IP_HEADER
+            ):
+                self._remote_addr = self.headers[
+                    self.app.config.REAL_IP_HEADER
+                ]
+            elif self.app.config.FORWARDED_FOR_HEADER:
+                forwarded_for = self.headers.get(
+                    self.app.config.FORWARDED_FOR_HEADER, ""
+                ).split(",")
                 remote_addrs = [
                     addr
                     for addr in [addr.strip() for addr in forwarded_for]
                     if addr
                 ]
-            if len(remote_addrs) > 0:
+                if self.app.config.PROXIES_COUNT == -1:
                     self._remote_addr = remote_addrs[0]
+                elif len(remote_addrs) >= self.app.config.PROXIES_COUNT:
+                    self._remote_addr = remote_addrs[
+                        -self.app.config.PROXIES_COUNT
+                    ]
+                else:
+                    self._remote_addr = ""
             else:
                 self._remote_addr = ""
         return self._remote_addr

tests/test_requests.py

@@ -29,7 +29,7 @@ def test_sync(app):
     assert response.text == "Hello"
 
 
-def test_remote_address(app):
+def test_ip(app):
     @app.route("/")
     def handler(request):
         return text("{}".format(request.ip))
@@ -203,11 +203,23 @@ def test_content_type(app):
     assert response.text == "application/json"
 
 
-def test_remote_addr(app):
+def test_remote_addr_with_two_proxies(app):
+    app.config.PROXIES_COUNT = 2
+
     @app.route("/")
     async def handler(request):
         return text(request.remote_addr)
 
+    headers = {"X-Real-IP": "127.0.0.2", "X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.0.2"
+    assert response.text == "127.0.0.2"
+
+    headers = {"X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == ""
+    assert response.text == ""
+
     headers = {"X-Forwarded-For": "127.0.0.1, 127.0.1.2"}
     request, response = app.test_client.get("/", headers=headers)
     assert request.remote_addr == "127.0.0.1"
@@ -222,6 +234,86 @@ def test_remote_addr(app):
     assert request.remote_addr == "127.0.0.1"
     assert response.text == "127.0.0.1"
 
+    headers = {
+        "X-Forwarded-For": ", 127.0.2.2, ,  ,127.0.0.1, ,   ,,127.0.1.2"
+    }
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.0.1"
+    assert response.text == "127.0.0.1"
+
+
+def test_remote_addr_with_infinite_number_of_proxies(app):
+    app.config.PROXIES_COUNT = -1
+
+    @app.route("/")
+    async def handler(request):
+        return text(request.remote_addr)
+
+    headers = {"X-Real-IP": "127.0.0.2", "X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.0.2"
+    assert response.text == "127.0.0.2"
+
+    headers = {"X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.1.1"
+    assert response.text == "127.0.1.1"
+
+    headers = {
+        "X-Forwarded-For": "127.0.0.5, 127.0.0.4, 127.0.0.3, 127.0.0.2, 127.0.0.1"
+    }
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.0.5"
+    assert response.text == "127.0.0.5"
+
+
+def test_remote_addr_without_proxy(app):
+    app.config.PROXIES_COUNT = 0
+
+    @app.route("/")
+    async def handler(request):
+        return text(request.remote_addr)
+
+    headers = {"X-Real-IP": "127.0.0.2", "X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == ""
+    assert response.text == ""
+
+    headers = {"X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == ""
+    assert response.text == ""
+
+    headers = {"X-Forwarded-For": "127.0.0.1, 127.0.1.2"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == ""
+    assert response.text == ""
+
+
+def test_remote_addr_custom_headers(app):
+    app.config.PROXIES_COUNT = 1
+    app.config.REAL_IP_HEADER = "Client-IP"
+    app.config.FORWARDED_FOR_HEADER = "Forwarded"
+
+    @app.route("/")
+    async def handler(request):
+        return text(request.remote_addr)
+
+    headers = {"X-Real-IP": "127.0.0.2", "Forwarded": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.1.1"
+    assert response.text == "127.0.1.1"
+
+    headers = {"X-Forwarded-For": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == ""
+    assert response.text == ""
+
+    headers = {"Client-IP": "127.0.0.2", "Forwarded": "127.0.1.1"}
+    request, response = app.test_client.get("/", headers=headers)
+    assert request.remote_addr == "127.0.0.2"
+    assert response.text == "127.0.0.2"
+
 
 def test_match_info(app):
     @app.route("/api/v1/user/<user_id>/")