add SCGI compliance docs

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

README.md

@@ -39,6 +39,8 @@ WARNING: the (currently non-extant) development branch is filled with lava,
 
 [CGI compliance](docs/CGI.md)
 
+[SCGI compliance](docs/SCGI.md)
+
 [Gopher specific information](docs/GOPHER.md)
 
 [Extra notes](docs/MISC.md)

core/cgi.go

@@ -78,8 +78,6 @@ func generateCGIEnv(client *Client, request *Request) []string {
 func generateSCGIEnv(client *Client, request *Request) []*envVar {
 	env := append(scgiEnv, newEnvVar("REMOTE_ADDR", client.IP()))
 	env = append(env, newEnvVar("QUERY_STRING", request.Params()))
-	env = append(env, newEnvVar("SCRIPT_NAME", request.Path().Relative()))
-	env = append(env, newEnvVar("SCRIPT_FILENAME", request.Path().Absolute()))
 	env = append(env, newEnvVar("REQUEST_URI", request.Path().Selector()))
 	return env
 }

docs/SCGI.md

@@ -0,0 +1,24 @@
+# SCGI Compliance
+
+The list of environment variables sent are as follows:
+
+```
+# Set
+SCGI
+SERVER_SOFTWARE
+SERVER_PROTOCOL
+SERVER_NAME
+SERVER_PORT
+REMOTE_ADDR
+QUERY_STRING
+DOCUMENT_ROOT
+REQUEST_URI
+
+# NOT set
+    Env Var     |                  Reasoning
+----------------------------------------------
+CONTENT_LENGTH  | We always make the equivalent of HTTP GET requests, so
+                | content length will always be 0. This is a very HTTP-centric
+                | variable which we do not support.
+[...]           | (See skipped CGI variables under CGI compliance doc).
+```

docs/USAGE.md

@@ -90,6 +90,29 @@ e.g. scripts within cgi-bin to the root directory:
 Entries are parsed, compiled, and so matched-against in order. They are matched against
 relative paths so please bear this in mind if you have user directories enabled.
 
+# SCGI Request Mapping Regex
+
+Request mapping is parsed as a new-line separated list of remap statements of form:
+
+`/regex/matched/against -> /var/run/gopher_scgi.sock`
+
+Internally, the request remapping statements are parsed as (shown as Python code):
+
+`/match_statement -> /template_statement.sock`
+
+```Python
+# Where the match statement is compiled using
+regex = "(?m)" + "/match_statement".removeprefix("/") + "$"
+
+# And the template is stored as
+template = "/template_statement.sock"
+
+```
+
+e.g. everything under scgi to the SCGI socket:
+
+`/scgi/(?P<uri>[^/]+) -> /var/run/gopher_scgi.sock`
+
 # User server spaces
 
 When user server spaces are enabled, they are accessed via the following gopher URL: