Improve value checkers and docs (#3208)

* Refactor: improve value checkers

* Docs: small improvements

[skip ci]

README.md

@@ -91,9 +91,9 @@ All data are under `data` directory. Each file in the directory represents a sub
 # comments
 include:another-file
 domain:google.com @attr1 @attr2
+full:analytics.google.com @ads
 keyword:google
-regexp:www\.google\.com$
+regexp:^odd[1-7]\.example\.org(\.[a-z]{2})?$
-full:www.google.com
 ```
 
 **Syntax:**
@@ -106,10 +106,10 @@ full:www.google.com
 
 - Comment begins with `#`. It may begin anywhere in the file. The content in the line after `#` is treated as comment and ignored in production.
 - Subdomain begins with `domain:`, followed by a valid domain name. The prefix `domain:` may be omitted.
-- Keyword begins with `keyword:`, followed by a string.
-- Regular expression begins with `regexp:`, followed by a valid regular expression (per Golang's standard).
 - Full domain begins with `full:`, followed by a complete and valid domain name.
-- Domain rules (including `domain`, `keyword`, `regexp` and `full`) may have none, one or more attributes. Each attribute begins with `@` and followed by the name of the attribute. Attributes will remain available in final lists and `dlc.dat`.
+- Keyword begins with `keyword:`, followed by a substring of a valid domain name.
+- Regular expression begins with `regexp:`, followed by a valid regular expression (per Golang's standard).
+- Domain rules (including `domain`, `full`, `keyword`, and `regexp`) may have none, one or more attributes. Each attribute begins with `@` and followed by the name of the attribute. Attributes will remain available in final lists and `dlc.dat`.
 - Domain rules may have none, one or more affiliations, which additionally adds the domain rule into the affiliated target list. Each affiliation begins with `&` and followed by the name of the target list (nomatter whether the target has a dedicated file in data path). This is a method for data management, and will not remain in the final lists or `dlc.dat`.
 - Inclusion begins with `include:`, followed by the name of another valid domain list. A simple `include:listb` in file `lista` means adding all domain rules of `listb` into `lista`. Inclusions with attributes stands for selective inclusion. `include:listb @attr1 @-attr2` means only adding those domain rules *with* `@attr1` **and** *without* `@attr2`. This is a special type for data management, and will not remain in the final lists or `dlc.dat`.
 

main.go

@@ -30,10 +30,10 @@ const (
 )
 
 var (
-	TypeChecker  = regexp.MustCompile(`^(domain|full|keyword|regexp|include)$`)
+	TypeChecker   = regexp.MustCompile(`^(domain|full|keyword|regexp|include)$`)
-	ValueChecker = regexp.MustCompile(`^[a-z0-9!\.-]+$`)
+	DomainChecker = regexp.MustCompile(`^[a-z0-9\.-]+$`)
-	AttrChecker  = regexp.MustCompile(`^[a-z0-9!-]+$`)
+	AttrChecker   = regexp.MustCompile(`^[a-z0-9!-]+$`)
-	SiteChecker  = regexp.MustCompile(`^[A-Z0-9!-]+$`)
+	SiteChecker   = regexp.MustCompile(`^[A-Z0-9!-]+$`)
 )
 
 var (
@@ -123,6 +123,8 @@ func parseEntry(line string) (Entry, error) {
 		entry.Type = strings.ToLower(kv[0])
 		if entry.Type == RuleTypeRegexp {
 			entry.Value = kv[1]
+		} else if entry.Type == RuleTypeInclude {
+			entry.Value = strings.ToUpper(kv[1])
 		} else {
 			entry.Value = strings.ToLower(kv[1])
 		}
@@ -133,12 +135,19 @@ func parseEntry(line string) (Entry, error) {
 	if !TypeChecker.MatchString(entry.Type) {
 		return entry, fmt.Errorf("invalid type: %s", entry.Type)
 	}
-	if entry.Type == RuleTypeRegexp {
+	switch entry.Type {
+	case RuleTypeRegexp:
 		if _, err := regexp.Compile(entry.Value); err != nil {
 			return entry, fmt.Errorf("invalid regexp: %s", entry.Value)
 		}
-	} else if !ValueChecker.MatchString(entry.Value) {
+	case RuleTypeInclude:
-		return entry, fmt.Errorf("invalid value: %s", entry.Value)
+		if !SiteChecker.MatchString(entry.Value) {
+			return entry, fmt.Errorf("invalid included list name: %s", entry.Value)
+		}
+	default: // `full`, `domain` and `keyword` are all (parts of) domains
+		if !DomainChecker.MatchString(entry.Value) {
+			return entry, fmt.Errorf("invalid domain: %s", entry.Value)
+		}
 	}
 
 	// Parse/Check attributes and affiliations
@@ -214,7 +223,7 @@ func parseList(refName string, refList []*Entry) error {
 			if len(entry.Affs) != 0 {
 				return fmt.Errorf("affiliation is not allowed for include:%s", entry.Value)
 			}
-			inc := &Inclusion{Source: strings.ToUpper(entry.Value)}
+			inc := &Inclusion{Source: entry.Value}
 			for _, attr := range entry.Attrs {
 				if strings.HasPrefix(attr, "-") {
 					inc.BanAttrs = append(inc.BanAttrs, attr[1:]) // Trim attribute prefix `-` character