Added first fuzzers as step in OSS-Fuzz integration.

CHANGES/5320.feature

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+Implements new feature of fuzzers with the purpose of integrating aiohttp with OSS-Fuzz.

fuzzers/fuzz_http_parser.py

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+#!/usr/bin/python3
+import asyncio
+import sys
+
+import atheris
+
+import aiohttp
+from aiohttp.base_protocol import BaseProtocol
+
+
+def TestOneInput(data):
+    loop = asyncio.get_event_loop()
+    pr = BaseProtocol(loop)
+    h_p = aiohttp.http_parser.HttpRequestParser(pr, loop, 32768)
+    try:
+        h_p.feed_data(data)
+    except aiohttp.http_exceptions.HttpProcessingError:
+        return
+    return
+
+
+def main():
+    atheris.Setup(sys.argv, TestOneInput, enable_python_coverage=True)
+    loop = asyncio.get_event_loop()
+    asyncio.set_event_loop(loop)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()

fuzzers/fuzz_payload_url.py

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+#!/usr/bin/python3
+import sys
+
+import atheris
+from yarl import URL
+
+from aiohttp import payload
+
+
+def TestOneInput(data):
+    fdp = atheris.FuzzedDataProvider(data)
+    original = fdp.ConsumeString(sys.maxsize)
+
+    try:
+        payload.StringPayload(original)
+    except UnicodeEncodeError:
+        None
+
+    try:
+        URL(original)
+    except ValueError:
+        None
+
+    return
+
+
+def main():
+    atheris.Setup(sys.argv, TestOneInput, enable_python_coverage=True)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()