Settings code: one file per daemon (closes #227)

internal/config now keeps waf's settings in waf.go and rproxy's in
rproxy.go. config.go keeps what both read: the package doc,
SWW_COMMAND, the environment reader, listen addresses, sizes and
netblock lists. The app URL reader and the default trusted proxies,
which only rproxy uses, move to rproxy.go. config_test.go becomes
waf_test.go, beside rproxy_test.go. Code is moved, not changed.

Model: opus-5-5

SPEC.md

@@ -830,9 +830,12 @@ The changes hold in front of every app, and no setting undoes them:
 
         A user's or an organisation's page has a path of one segment, such as
         `/alice`. So on any app, `q` skips these rules on every path of one
-        segment, such as `/search`. Such a path keeps 932250 when it ends in a
-        server-side script's extension, such as `/index.php`, so `ls -la` is
-        refused there. The extensions are these, in upper or lower case:
+        segment, such as `/search`. But it skips 932250 only on a path made of
+        the characters a name may hold: letters, digits, `-`, `_` and dots, the
+        first a letter or digit. So `ls -la` is refused on
+        `/login.jsp;jsessionid=abc`. `q` also keeps 932250 on a path that ends
+        in a server-side script's extension, such as `/index.php`. The
+        extensions are these, in upper or lower case:
         - `.php`;
         - `.phtml`;
         - `.php5`;

internal/config/rproxy.go

@@ -48,7 +48,17 @@ type RProxy struct {
 	settings []slog.Attr
 }
 
+// defaultUpstreamURL is the default of SWRP_UPSTREAM_URL.
+const defaultUpstreamURL = "http://127.0.0.1:8081"
+
+// privateRanges are the private address ranges, the default trusted
+// proxies.
+const privateRanges = "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
+
 var (
+	errNotUpstreamURL = errors.New(
+		"is not a URL with only a scheme, a host and an optional port, " +
+			"such as http://127.0.0.1:8081")
 	errNeedsWAFBackend = errors.New(
 		"is required: it is waf's URL, such as http://waf:8080")
 	errNotDisposition  = errors.New("is not allow or deny")
@@ -124,6 +134,14 @@ func (c *RProxy) LogValue() slog.Value {
 	return slog.GroupValue(c.settings...)
 }
 
+// appURL reads a setting that is the app's URL.
+func (e *environment) appURL(name, defaultValue string) *url.URL {
+	upstream, err := parseUpstreamURL(e.value(name, defaultValue))
+	e.check(name, err)
+
+	return upstream
+}
+
 // wafBackend reads the setting that is waf's URL, which must be set.
 func (e *environment) wafBackend(name string) *url.URL {
 	value := e.value(name, "")
@@ -190,3 +208,32 @@ func parseMilliseconds(value string) (time.Duration, bool) {
 
 	return time.Duration(n) * time.Millisecond, true
 }
+
+// parseUpstreamURL reads the app's URL: http or https, a host and an
+// optional port from 1 to 65535, and nothing else, since the request's
+// own path and query go to the app unchanged.
+func parseUpstreamURL(value string) (*url.URL, error) {
+	upstream, err := url.Parse(value)
+	if err != nil {
+		return nil, fmt.Errorf("%q %w", value, errNotUpstreamURL)
+	}
+
+	onlySchemeAndHost := (upstream.Scheme == "http" || upstream.Scheme == "https") &&
+		upstream.Hostname() != "" && upstream.User == nil &&
+		upstream.Opaque == "" &&
+		(upstream.Path == "" || upstream.Path == "/") &&
+		upstream.RawQuery == "" &&
+		upstream.Fragment == ""
+	if !onlySchemeAndHost {
+		return nil, fmt.Errorf("%q %w", value, errNotUpstreamURL)
+	}
+
+	if upstream.Port() != "" {
+		port, err := strconv.ParseUint(upstream.Port(), 10, 16)
+		if err != nil || port == 0 {
+			return nil, fmt.Errorf("%q %w", value, errNotUpstreamURL)
+		}
+	}
+
+	return upstream, nil
+}

internal/coreruleset/coreruleset_test.go

@@ -1078,12 +1078,14 @@ func TestGiteaSearchOnAUsersOrAnOrganisationsPageLetsLsThrough(t *testing.T) {
 	}
 
 	// 932250 still applies on a path that ends in a server-side script's
-	// extension, to another field, and on a path of two segments.
+	// extension or holds a character no name holds, to another field, and on
+	// a path of two segments.
 	for _, target := range []string{
 		"/index.php?q=ls%20-la",
 		"/INDEX.PHP?q=ls%20-la",
 		"/index%2Ephp?q=ls%20-la",
 		"/search.cgi?q=ls%20-la",
+		"/login.jsp;jsessionid=abc?q=ls%20-la",
 		"/alice?tab=ls%20-la",
 		"/alice/tools?q=ls%20-la",
 	} {

internal/coreruleset/gitea.conf

@@ -146,9 +146,12 @@ SecRule REQUEST_FILENAME "@rx ^/[^/]+$" \
     ctl:ruleRemoveTargetById=932120;ARGS:q,\
     ctl:ruleRemoveTargetById=932260;ARGS:q"
 
-# On those pages q skips 932250 too, which refused ls -la. A path keeps it when
-# it ends in a server-side script's extension, such as /index.php or /search.cgi.
-SecRule REQUEST_FILENAME "@rx ^/[^/]+$" \
+# On those pages q skips 932250 too, which refused ls -la, but only on a path
+# made of the characters a user's or an organisation's name may hold. Those are
+# letters, digits, -, _ and dots, the first a letter or digit, so
+# /login.jsp;jsessionid=abc keeps 932250. A path that ends in a server-side
+# script's extension keeps it too, such as /index.php or /search.cgi.
+SecRule REQUEST_FILENAME "@rx ^/[0-9A-Za-z][-.\w]*$" \
     "id:900606,phase:1,pass,nolog,chain"
     SecRule REQUEST_FILENAME "!@rx \.(?:php|phtml|php5|cgi|pl|py|asp|aspx|jsp)$" \
         "t:lowercase,ctl:ruleRemoveTargetById=932250;ARGS:q"