First attempt at CGI support.

examples/cgi_debug.cgi

@@ -0,0 +1,9 @@
+#!/usr/bin/env python
+"""
+This is a demo CGI script that prints a bunch of debug information about
+the request as an HTML document. Place it in the cgi-bin/ directory of your
+server.
+"""
+import cgi
+
+cgi.test()

examples/echo_server.py

@@ -7,7 +7,7 @@ import jetforce
 
 
 def echo(environ, send_status):
-    url = environ["URL"]
+    url = environ["GEMINI_URL"]
     send_status(jetforce.Status.SUCCESS, "text/gemini")
     yield f"Received path: {url}".encode()
 

jetforce.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3.7
 import argparse
 import asyncio
+import codecs
 import dataclasses
 import datetime
 import mimetypes
@@ -83,15 +84,16 @@ class Request:
     def __init__(self, environ: dict):
         self.environ = environ
 
-        url = urllib.parse.urlparse(environ["URL"])
-        self.scheme = url.scheme
-        self.hostname = url.hostname
-        self.port = url.port
-        self.path = url.path
-        self.params = url.params
-        self.query = url.query
-        self.fragment = url.fragment
-        self.url = url.geturl()
+        self.url = environ["GEMINI_URL"]
+
+        url_parts = urllib.parse.urlparse(self.url)
+        self.scheme = url_parts.scheme
+        self.hostname = url_parts.hostname
+        self.port = url_parts.port
+        self.path = url_parts.path
+        self.params = url_parts.params
+        self.query = url_parts.query
+        self.fragment = url_parts.fragment
 
 
 @dataclasses.dataclass
@@ -198,11 +200,18 @@ class StaticDirectoryApplication(JetforceApplication):
     directory listing will be auto-generated.
     """
 
-    def __init__(self, directory: str = "/var/gemini", index_file: str = "index.gmi"):
+    def __init__(
+        self,
+        root_directory: str = "/var/gemini",
+        index_file: str = "index.gmi",
+        cgi_directory: str = "cgi-bin/",
+    ):
         super().__init__()
         self.routes.append((RoutePattern(), self.serve_static_file))
 
-        self.root = pathlib.Path(directory).resolve(strict=True)
+        self.root = pathlib.Path(root_directory).resolve(strict=True)
+        self.cgi_directory = cgi_directory.strip("/") + "/"
+
         self.index_file = index_file
         self.mimetypes = mimetypes.MimeTypes()
         self.mimetypes.add_type("text/gemini", ".gmi")
@@ -220,6 +229,9 @@ class StaticDirectoryApplication(JetforceApplication):
         filesystem_path = self.root / filename
 
         if filesystem_path.is_file():
+            if str(filename).startswith(self.cgi_directory):
+                if os.access(filesystem_path, os.X_OK):
+                    return self.run_cgi_script(filesystem_path, request.environ)
             mimetype = self.guess_mimetype(filesystem_path.name)
             generator = self.load_file(filesystem_path)
             return Response(Status.SUCCESS, mimetype, generator)
@@ -233,6 +245,36 @@ class StaticDirectoryApplication(JetforceApplication):
         else:
             return Response(Status.NOT_FOUND, "Not Found")
 
+    def run_cgi_script(self, filesystem_path: pathlib.Path, environ: dict):
+        script_name = str(filesystem_path)
+        cgi_env = environ.copy()
+        cgi_env["GATEWAY_INTERFACE"] = "GCI/1.1"
+        cgi_env["SCRIPT_NAME"] = script_name
+
+        out = subprocess.Popen(
+            [script_name],
+            stdout=subprocess.PIPE,
+            env=cgi_env,
+            bufsize=1,
+            universal_newlines=True,
+            errors="surrogateescape",
+        )
+
+        # Try to get the mimetype from the CGI response's content-type.
+        # Discard all other response headers for now.
+        mimetype = "text/plain"
+        for line in out.stdout:
+            header = line.lower().strip()
+            if header.startswith("content-type:"):
+                mimetype = header.split(":", maxsplit=1)[1]
+            elif not header:
+                # A empty line signals the end of the headers
+                break
+
+        # Re-encode the rest of the body as bytes
+        body = codecs.iterencode(out.stdout, encoding="utf-8", errors="surrogateescape")
+        return Response(Status.SUCCESS, mimetype, body)
+
     def load_file(self, filesystem_path: pathlib.Path):
         with filesystem_path.open("rb") as fp:
             data = fp.read(1024)
@@ -325,13 +367,23 @@ class GeminiRequestHandler:
     def build_environ(self) -> typing.Dict[str, typing.Any]:
         """
         Construct a dictionary that will be passed to the application handler.
+
+        Variable names conform to the CGI spec defined in RFC 3875.
         """
+        url_parts = urllib.parse.urlparse(self.url)
         return {
-            "SERVER_HOST": self.server.host,
-            "SERVER_PORT": self.server.port,
-            "REMOTE_ADDR": self.remote_addr,
+            "GEMINI_URL": self.url,
             "HOSTNAME": self.server.hostname,
-            "URL": self.url,
+            "PATH_INFO": url_parts.path,
+            "QUERY_STRING": url_parts.query,
+            "SERVER_NAME": self.server.hostname,
+            "SERVER_PORT": str(self.server.port),
+            "SERVER_PROTOCOL": "GEMINI",
+            "SERVER_SOFTWARE": f"jetforce/{__version__}",
+            "REMOTE_ADDR": self.remote_addr,
+            "REMOTE_HOST": self.remote_addr,
+            "REMOTE_USER": "",
+            "REQUEST_METHOD": "GET",
         }
 
     async def parse_header(self) -> None:
@@ -522,14 +574,19 @@ def run_server() -> None:
     """
     parser = command_line_parser()
     parser.add_argument(
-        "--dir", help="Path on the filesystem to serve", default="/var/gemini"
+        "--root-dir", help="Root path on the filesystem to serve", default="/var/gemini"
+    )
+    parser.add_argument(
+        "--cgi-dir",
+        help="CGI script folder, relative to the root path",
+        default="cgi-bin/",
     )
     parser.add_argument(
         "--index-file", help="The gemini directory index file", default="index.gmi"
     )
     args = parser.parse_args()
 
-    app = StaticDirectoryApplication(args.dir, args.index_file)
+    app = StaticDirectoryApplication(args.root_dir, args.index_file, args.cgi_dir)
     server = GeminiServer(
         host=args.host,
         port=args.port,