fix(git-gate): use smart http for smolmachines pushes

bot_bottle/git_http_backend.py

@@ -0,0 +1,149 @@
+"""Tiny smart-HTTP wrapper for git-gate repos.
+
+Used by the smolmachines backend where `git://` push traffic over the
+host-published Docker port can hang before receive-pack reaches hooks.
+The wrapper serves the same `/git/*.git` bare repos through
+`git http-backend`, so pre-receive and upstream forwarding remain the
+git-gate enforcement point.
+"""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from pathlib import Path
+from urllib.parse import urlsplit
+
+
+DEFAULT_PORT = 9420
+
+
+class GitHttpHandler(BaseHTTPRequestHandler):
+    server_version = "bot-bottle-git-http/1"
+
+    def do_GET(self) -> None:
+        self._run_backend()
+
+    def do_POST(self) -> None:
+        self._run_backend()
+
+    def _run_backend(self) -> None:
+        parsed = urlsplit(self.path)
+        if self._is_upload_pack(parsed.path, parsed.query):
+            repo_dir = self._repo_dir(parsed.path)
+            if repo_dir is None:
+                self.send_error(404)
+                return
+            hook_path = os.environ.get(
+                "GIT_GATE_ACCESS_HOOK", "/etc/git-gate/access-hook",
+            )
+            hook = subprocess.run(
+                [hook_path, "upload-pack",
+                 str(repo_dir), self.client_address[0], self.client_address[0]],
+                capture_output=True,
+                check=False,
+            )
+            if hook.returncode != 0:
+                self.send_response(403)
+                self.send_header("Content-Type", "text/plain; charset=utf-8")
+                self.end_headers()
+                self.wfile.write(hook.stderr or hook.stdout)
+                return
+        env = os.environ.copy()
+        env.update({
+            "GIT_PROJECT_ROOT": os.environ.get("GIT_PROJECT_ROOT", "/git"),
+            "GIT_HTTP_EXPORT_ALL": "1",
+            "REQUEST_METHOD": self.command,
+            "PATH_INFO": parsed.path,
+            "QUERY_STRING": parsed.query,
+            "CONTENT_TYPE": self.headers.get("content-type", ""),
+            "CONTENT_LENGTH": self.headers.get("content-length", "0"),
+            "REMOTE_ADDR": self.client_address[0],
+            "REMOTE_PORT": str(self.client_address[1]),
+            "REMOTE_USER": "",
+            "SERVER_NAME": self.server.server_name,
+            "SERVER_PORT": str(self.server.server_port),
+            "SERVER_PROTOCOL": self.request_version,
+        })
+        for header, variable in (
+            ("accept", "HTTP_ACCEPT"),
+            ("content-encoding", "HTTP_CONTENT_ENCODING"),
+            ("git-protocol", "HTTP_GIT_PROTOCOL"),
+            ("user-agent", "HTTP_USER_AGENT"),
+        ):
+            value = self.headers.get(header)
+            if value:
+                env[variable] = value
+        length = int(self.headers.get("content-length", "0") or "0")
+        body = self.rfile.read(length) if length else b""
+        proc = subprocess.run(
+            ["git", "http-backend"],
+            input=body,
+            env=env,
+            capture_output=True,
+            check=False,
+        )
+        self._write_cgi_response(proc.stdout)
+
+    def _repo_dir(self, path: str) -> Path | None:
+        root = Path(os.environ.get("GIT_PROJECT_ROOT", "/git")).resolve()
+        relative = path.lstrip("/").split(".git", 1)[0] + ".git"
+        candidate = (root / relative).resolve()
+        if root not in (candidate, *candidate.parents):
+            return None
+        if not candidate.is_dir():
+            return None
+        return candidate
+
+    @staticmethod
+    def _is_upload_pack(path: str, query: str) -> bool:
+        if path.endswith("/git-upload-pack"):
+            return True
+        if path.endswith("/info/refs"):
+            return any(
+                pair == "service=git-upload-pack"
+                for pair in query.split("&")
+            )
+        return False
+
+    def _write_cgi_response(self, raw: bytes) -> None:
+        head, sep, body = raw.partition(b"\r\n\r\n")
+        line_sep = b"\r\n"
+        if not sep:
+            head, sep, body = raw.partition(b"\n\n")
+            line_sep = b"\n"
+        status = 200
+        headers: list[tuple[str, str]] = []
+        for line in head.split(line_sep):
+            if not line:
+                continue
+            key, _, value = line.decode("latin1").partition(":")
+            value = value.strip()
+            if key.lower() == "status":
+                status = int(value.split()[0])
+            else:
+                headers.append((key, value))
+        self.send_response(status)
+        for key, value in headers:
+            self.send_header(key, value)
+        self.end_headers()
+        self.wfile.write(body)
+
+    def log_message(self, fmt: str, *args: object) -> None:
+        sys.stdout.write(fmt % args + "\n")
+        sys.stdout.flush()
+
+
+def main() -> int:
+    port = int(os.environ.get("GIT_HTTP_PORT", str(DEFAULT_PORT)))
+    server = ThreadingHTTPServer(("0.0.0.0", port), GitHttpHandler)
+    sys.stdout.write(f"git-http listening on 0.0.0.0:{port}\n")
+    sys.stdout.flush()
+    server.serve_forever()
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())