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Python: Model outgoing http client requests
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Lines changed: 314 additions & 2 deletions

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‎python/ql/src/semmle/python/web/ClientHttpRequest.qll‎

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import semmle.python.web.client.StdLib
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import semmle.python.web.client.Requests

‎python/ql/src/semmle/python/web/Http.qll‎

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@@ -89,17 +89,59 @@ abstract class CookieSet extends CookieOperation {}
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/** Generic taint sink in a http response */
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abstract class HttpResponseTaintSink extends TaintSink {
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override predicate sinks(TaintKind kind) {
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override predicate sinks(TaintKind kind) {
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kind instanceof ExternalStringKind
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}
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}
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abstract class HttpRedirectTaintSink extends TaintSink {
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override predicate sinks(TaintKind kind) {
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override predicate sinks(TaintKind kind) {
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kind instanceof ExternalStringKind
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}
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}
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module Client {
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// TODO: user-input in other than URL:
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// - `data`, `json` for `requests.post`
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// - `body` for `HTTPConnection.request`
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// - headers?
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// TODO: Add more library support
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// - urllib3 https://github.com/urllib3/urllib3
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// - httpx https://github.com/encode/httpx
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/**
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* An outgoing http request
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*
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* For example:
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* conn = HTTPConnection('example.com')
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conn.request('GET', '/path')
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*/
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abstract class HttpRequest extends CallNode {
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/** Get any ControlFlowNode that is used to construct the final URL.
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*
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* In the HTTPConnection example, there is a result for both `'example.com'` and for `'/path'`.
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*/
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abstract ControlFlowNode getAUrlPart();
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abstract string getMethodUpper();
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}
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/** Taint sink for the URL-part of an outgoing http request */
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class HttpRequestUrlTaintSink extends TaintSink {
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HttpRequestUrlTaintSink() {
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this = any(HttpRequest r).getAUrlPart()
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}
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override predicate sinks(TaintKind kind) {
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kind instanceof ExternalStringKind
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}
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}
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}

‎python/ql/src/semmle/python/web/client/Requests.qll‎

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/**
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* Modeling outgoing HTTP requests using the `requests` package
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* https://pypi.org/project/requests/
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*/
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import python
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private import semmle.python.web.Http
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class RequestsHttpRequest extends Client::HttpRequest {
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CallableValue func;
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string method;
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RequestsHttpRequest() {
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method = httpVerbLower() and
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func = Module::named("requests").attr(method).(CallableValue) and
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this = func.getACall()
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}
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override ControlFlowNode getAUrlPart() { result = func.getNamedArgumentForCall(this, "url") }
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override string getMethodUpper() { result = method.toUpperCase() }
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}

‎python/ql/src/semmle/python/web/client/StdLib.qll‎

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import python
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private import semmle.python.web.Http
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ClassValue httpConnectionClass() {
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// Python 2
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result = Value::named("httplib.HTTPConnection")
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or
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result = Value::named("httplib.HTTPSConnection")
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or
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// Python 3
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result = Value::named("http.client.HTTPConnection")
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or
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result = Value::named("http.client.HTTPSConnection")
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or
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// six
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result = Value::named("six.moves.http_client.HTTPConnection")
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or
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result = Value::named("six.moves.http_client.HTTPSConnection")
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}
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class HttpConnectionHttpRequest extends Client::HttpRequest {
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CallNode constructor_call;
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CallableValue func;
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HttpConnectionHttpRequest() {
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exists(ClassValue cls, AttrNode call_origin, Value constructor_call_value |
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cls = httpConnectionClass() and
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func = cls.lookup("request") and
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this = func.getACall() and
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this.getFunction().pointsTo(_, _, call_origin) and
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call_origin.getObject().pointsTo(_, constructor_call_value, constructor_call) and
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cls = constructor_call_value.getClass() and
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constructor_call = cls.getACall()
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)
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}
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override ControlFlowNode getAUrlPart() {
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result = func.getNamedArgumentForCall(this, "url")
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or
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result = constructor_call.getArg(0)
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or
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result = constructor_call.getArgByName("host")
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}
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override string getMethodUpper() {
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exists(string method |
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result = method.toUpperCase() and
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func.getNamedArgumentForCall(this, "method").pointsTo(Value::forString(method))
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)
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}
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}

‎python/ql/test/2/library-tests/web/client/stdlib/ClientHttpRequests.expected‎

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| test.py:6:5:6:32 | ControlFlowNode for Attribute() | test.py:5:27:5:39 | ControlFlowNode for Str | GET |
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| test.py:6:5:6:32 | ControlFlowNode for Attribute() | test.py:6:25:6:31 | ControlFlowNode for Str | GET |
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| test.py:15:5:15:33 | ControlFlowNode for Attribute() | test.py:10:28:10:40 | ControlFlowNode for Str | POST |
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| test.py:15:5:15:33 | ControlFlowNode for Attribute() | test.py:15:26:15:32 | ControlFlowNode for Str | POST |
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| test.py:20:5:20:33 | ControlFlowNode for Attribute() | test.py:19:27:19:39 | ControlFlowNode for Str | <NO METHOD> |
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| test.py:20:5:20:33 | ControlFlowNode for Attribute() | test.py:20:26:20:32 | ControlFlowNode for Str | <NO METHOD> |
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| test.py:30:5:30:32 | ControlFlowNode for Attribute() | test.py:28:27:28:30 | ControlFlowNode for fake | GET |
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| test.py:30:5:30:32 | ControlFlowNode for Attribute() | test.py:30:25:30:31 | ControlFlowNode for Str | GET |
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| test.py:37:5:37:29 | ControlFlowNode for req_meth() | test.py:35:27:35:39 | ControlFlowNode for Str | HEAD |
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| test.py:37:5:37:29 | ControlFlowNode for req_meth() | test.py:37:22:37:28 | ControlFlowNode for Str | HEAD |

‎python/ql/test/2/library-tests/web/client/stdlib/ClientHttpRequests.ql‎

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import python
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import semmle.python.web.Http
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import semmle.python.web.ClientHttpRequest
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from Client::HttpRequest req, string method
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where
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if exists(req.getMethodUpper())
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then method = req.getMethodUpper()
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else method = "<NO METHOD>"
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select req, req.getAUrlPart(), method

‎python/ql/test/2/library-tests/web/client/stdlib/test.py‎

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from httplib import HTTPConnection, HTTPSConnection
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def basic():
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conn = HTTPConnection('example.com')
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conn.request('GET', '/path')
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def indirect_caller():
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conn = HTTPSConnection('example.com')
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indirect_callee(conn)
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def indirect_callee(conn):
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conn.request('POST', '/path')
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def method_not_known(method):
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conn = HTTPConnection('example.com')
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conn.request(method, '/path')
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def sneaky_setting_host():
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# We don't handle that the host is overwritten directly.
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# A contrived example; you're not supposed to do this, but you certainly can.
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fake = 'fakehost.com'
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real = 'realhost.com'
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conn = HTTPConnection(fake)
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conn.host = real
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conn.request('GET', '/path')
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def tricky_not_attribute_node():
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# A contrived example; you're not supposed to do this, but you certainly can.
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conn = HTTPConnection('example.com')
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req_meth = conn.request
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req_meth('HEAD', '/path')

‎python/ql/test/3/library-tests/web/client/stdlib/ClientHttpRequests.expected‎

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| test.py:6:5:6:32 | ControlFlowNode for Attribute() | test.py:5:27:5:39 | ControlFlowNode for Str | GET |
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| test.py:6:5:6:32 | ControlFlowNode for Attribute() | test.py:6:25:6:31 | ControlFlowNode for Str | GET |
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| test.py:15:5:15:33 | ControlFlowNode for Attribute() | test.py:10:28:10:40 | ControlFlowNode for Str | POST |
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| test.py:15:5:15:33 | ControlFlowNode for Attribute() | test.py:15:26:15:32 | ControlFlowNode for Str | POST |
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| test.py:20:5:20:33 | ControlFlowNode for Attribute() | test.py:19:27:19:39 | ControlFlowNode for Str | <NO METHOD> |
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| test.py:20:5:20:33 | ControlFlowNode for Attribute() | test.py:20:26:20:32 | ControlFlowNode for Str | <NO METHOD> |
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| test.py:30:5:30:32 | ControlFlowNode for Attribute() | test.py:28:27:28:30 | ControlFlowNode for fake | GET |
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| test.py:30:5:30:32 | ControlFlowNode for Attribute() | test.py:30:25:30:31 | ControlFlowNode for Str | GET |
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| test.py:37:5:37:29 | ControlFlowNode for req_meth() | test.py:35:27:35:39 | ControlFlowNode for Str | HEAD |
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| test.py:37:5:37:29 | ControlFlowNode for req_meth() | test.py:37:22:37:28 | ControlFlowNode for Str | HEAD |

‎python/ql/test/3/library-tests/web/client/stdlib/ClientHttpRequests.ql‎

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import python
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import semmle.python.web.Http
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import semmle.python.web.ClientHttpRequest
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from Client::HttpRequest req, string method
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where
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if exists(req.getMethodUpper())
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then method = req.getMethodUpper()
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else method = "<NO METHOD>"
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select req, req.getAUrlPart(), method

‎python/ql/test/3/library-tests/web/client/stdlib/test.py‎

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from http.client import HTTPConnection, HTTPSConnection
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def basic():
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conn = HTTPConnection('example.com')
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conn.request('GET', '/path')
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def indirect_caller():
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conn = HTTPSConnection('example.com')
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indirect_callee(conn)
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def indirect_callee(conn):
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conn.request('POST', '/path')
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def method_not_known(method):
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conn = HTTPConnection('example.com')
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conn.request(method, '/path')
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def sneaky_setting_host():
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# We don't handle that the host is overwritten directly.
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# A contrived example; you're not supposed to do this, but you certainly can.
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fake = 'fakehost.com'
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real = 'realhost.com'
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conn = HTTPConnection(fake)
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conn.host = real
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conn.request('GET', '/path')
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def tricky_not_attribute_node():
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# A contrived example; you're not supposed to do this, but you certainly can.
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conn = HTTPConnection('example.com')
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req_meth = conn.request
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req_meth('HEAD', '/path')

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