404/403 can be handled with plugins

bin/handlers/README.md

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+replace the standard 404 / 403 responses with plugins
+
+
+# usage
+
+load plugins either globally with `--on404 ~/dev/copyparty/bin/handlers/sorry.py` or for a specific volume with `:c,on404=~/handlers/sorry.py`
+
+
+# api
+
+each plugin must define a `main()` which takes 3 arguments;
+
+* `cli` is an instance of [copyparty/httpcli.py](https://github.com/9001/copyparty/blob/hovudstraum/copyparty/httpcli.py) (the monstrosity itself)
+* `vn` is the VFS which overlaps with the requested URL, and
+* `rem` is the URL remainder below the VFS mountpoint
+    * so `vn.vpath + rem` == `cli.vpath` == original request
+
+
+# examples
+
+## on404
+
+* [sorry.py](answer.py) replies with a custom message instead of the usual 404
+* [nooo.py](nooo.py) replies with an endless noooooooooooooo
+* [never404.py](never404.py) 100% guarantee that 404 will never be a thing again as it automatically creates dummy files whenever necessary
+* [caching-proxy.py](caching-proxy.py) transforms copyparty into a squid/varnish knockoff
+
+## on403
+
+* [ip-ok.py](ip-ok.py) disables security checks if client-ip is 1.2.3.4
+
+
+# notes
+
+* on403 only works for trivial stuff (basic http access) since I haven't been able to think of any good usecases for it (was just easy to add while doing on404)

bin/handlers/caching-proxy.py

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+# assume each requested file exists on another webserver and
+# download + mirror them as they're requested
+# (basically pretend we're warnish)
+
+import os
+import requests
+
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from copyparty.httpcli import HttpCli
+
+
+def main(cli: "HttpCli", vn, rem):
+    url = "https://mirrors.edge.kernel.org/alpine/" + rem
+    abspath = os.path.join(vn.realpath, rem)
+
+    # sneaky trick to preserve a requests-session between downloads
+    # so it doesn't have to spend ages reopening https connections;
+    # luckily we can stash it inside the copyparty client session,
+    # name just has to be definitely unused so "hacapo_req_s" it is
+    req_s = getattr(cli.conn, "hacapo_req_s", None) or requests.Session()
+    setattr(cli.conn, "hacapo_req_s", req_s)
+
+    try:
+        os.makedirs(os.path.dirname(abspath), exist_ok=True)
+        with req_s.get(url, stream=True, timeout=69) as r:
+            r.raise_for_status()
+            with open(abspath, "wb", 64 * 1024) as f:
+                for buf in r.iter_content(chunk_size=64 * 1024):
+                    f.write(buf)
+    except:
+        os.unlink(abspath)
+        return "false"
+
+    return "retry"

bin/handlers/ip-ok.py

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+# disable permission checks and allow access if client-ip is 1.2.3.4
+
+
+def main(cli, vn, rem):
+    if cli.ip == "1.2.3.4":
+        return "allow"

bin/handlers/never404.py

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+# create a dummy file and let copyparty return it
+
+
+def main(cli, vn, rem):
+    print("hello", cli.ip)
+
+    abspath = vn.canonical(rem)
+    with open(abspath, "wb") as f:
+        f.write(b"404? not on MY watch!")
+
+    return "retry"

bin/handlers/nooo.py

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+# reply with an endless "noooooooooooooooooooooooo"
+
+
+def say_no():
+    yield b"n"
+    while True:
+        yield b"o" * 4096
+
+
+def main(cli, vn, rem):
+    cli.send_headers(None, 404, "text/plain")
+
+    for chunk in say_no():
+        cli.s.sendall(chunk)
+
+    return "false"

bin/handlers/sorry.py

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+# sends a custom response instead of the usual 404
+
+
+def main(cli, vn, rem):
+    msg = f"sorry {cli.ip} but {cli.vpath} doesn't exist"
+
+    return str(cli.reply(msg.encode("utf-8"), 404, "text/plain"))