Core Rule Set reads request bodies up to SWWAF_WAF_BODY_LIMIT (closes #116)

SWWAF_WAF_BODY_LIMIT (default off, at most 1G) has the Core Rule Set read
form data and multipart up to the limit, the rest streaming on, and JSON
and XML no larger than it, with text/json and the application and text
types ending in +json or +xml. The part read is held for the app. A size
or time limit met while reading ends the request. Content-Encoding is
refused again on these kinds. A body Coraza cannot parse, or a multipart
body failing its strict checks, adds 5, as does a multipart body the limit
cuts before the colon of a part's header. Coraza is built with
no_fs_access, so writes no file. Rule 900300 moves to phase 2.

Judgement call: Content-Encoding is refused on a JSON or XML body too
large to read, as SPEC.md allows.

Model: opus-5-5

internal/proxy/proxy.go

@@ -232,8 +232,8 @@ func newReputation(
 }
 
 // newCoreRuleSet returns the Core Rule Set at SWWAF_WAF_PARANOIA_LEVEL,
-// without the rules SWWAF_WAF_DISABLED_RULES switches off, or nil while
-// SWWAF_WAF_MODE is off.
+// without the rules SWWAF_WAF_DISABLED_RULES switches off, reading bodies
+// up to SWWAF_WAF_BODY_LIMIT, or nil while SWWAF_WAF_MODE is off.
 func newCoreRuleSet(cfg *config.Config) *waf.CoreRuleSet {
 	if cfg.WAFMode == config.WAFModeOff {
 		return nil
@@ -241,11 +241,12 @@ func newCoreRuleSet(cfg *config.Config) *waf.CoreRuleSet {
 
 	coreRuleSet, err := waf.New(waf.Params{
 		ParanoiaLevel: cfg.WAFParanoiaLevel, DisabledRules: cfg.WAFDisabledRules,
+		BodyLimit: cfg.WAFBodyLimit,
 	})
 	if err != nil {
 		// The Core Rule Set is built in, and the settings cannot break it:
-		// the paranoia level is from 1 to 4, and the id of no rule switches
-		// nothing off.
+		// the paranoia level is from 1 to 4, the body limit at most 1G, and
+		// the id of no rule switches nothing off.
 		panic(err)
 	}