Add custom filter for DWS and Tanishq Dubey trademarks

- Create custom_filter.go with DWS/Tanishq Dubey term detection
- Block variations including:
  - DWS, Dubey Web Services, DWS Engineering LLC
  - Tanishq Dubey, tdubey
  - Leet speak variations (dub3y, t4nishq, dw5, etc.)
  - Combined terms (dubeydns, dws-ddns, etc.)
- Update frontend to show 'reserved' message for blocked terms
- Filters are case-insensitive and handle separators

Protects brand identity and personal name from being used
in user subdomains

internal/handlers/custom_filter.go

@@ -0,0 +1,147 @@
+package handlers
+
+import (
+	"strings"
+	"unicode"
+)
+
+// CustomFilter contains terms related to DWS and Tanishq Dubey that should be blocked
+type CustomFilter struct {
+	blockedTerms []string
+}
+
+// NewCustomFilter creates a new custom filter with DWS and personal name variations
+func NewCustomFilter() *CustomFilter {
+	return &CustomFilter{
+		blockedTerms: []string{
+			// DWS variations
+			"dws",
+			"dubey",
+			"dubeyweb",
+			"dubeywebservices",
+			"dubeyweb services",
+			"dubey-engineering",
+			"dubeyengineering",
+			"dwsengineering",
+			"dws-engineering",
+			"dws-engineering-llc",
+			"dwsengineeringllc",
+			"dwsllc",
+			"dws-llc",
+			"webservices",
+			"web-services",
+			"dubeycorp",
+			"dubey-corp",
+			"dubeyinc",
+			"dubey-inc",
+
+			// Tanishq Dubey variations
+			"tanishq",
+			"tanishqdubey",
+			"tanishq-dubey",
+			"tdubey",
+			"t-dubey",
+			"tanishq-d",
+			"tdub",
+			"tanish",
+			"dubey-t",
+			"dubeytanishq",
+			"dubey-tanishq",
+
+			// Leet speak variations
+			"dub3y",
+			"dub3yweb",
+			"t4nishq",
+			"t4n1shq",
+			"tan1shq",
+			"dub3y3ng1n33r1ng",
+			"dw5",
+			"dw$",
+			"dub3yc0rp",
+
+			// Common combinations
+			"dubeydns",
+			"dubey-ddns",
+			"dwsdns",
+			"dws-ddns",
+			"tanishqdns",
+			"tanishq-ddns",
+			"tdubeydns",
+			"tdubey-ddns",
+		},
+	}
+}
+
+// IsBlocked checks if the given text contains any blocked terms
+func (cf *CustomFilter) IsBlocked(text string) bool {
+	normalized := cf.normalize(text)
+
+	for _, term := range cf.blockedTerms {
+		if strings.Contains(normalized, term) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// normalize prepares text for comparison by:
+// - Converting to lowercase
+// - Removing common separators
+// - Converting leet speak to normal text
+func (cf *CustomFilter) normalize(text string) string {
+	// Convert to lowercase
+	text = strings.ToLower(text)
+
+	// Remove separators
+	replacer := strings.NewReplacer(
+		"-", "",
+		"_", "",
+		".", "",
+		" ", "",
+	)
+	text = replacer.Replace(text)
+
+	// Convert leet speak
+	text = cf.leetToNormal(text)
+
+	return text
+}
+
+// leetToNormal converts common leet speak characters to normal letters
+func (cf *CustomFilter) leetToNormal(text string) string {
+	replacements := map[rune]rune{
+		'0': 'o',
+		'1': 'i',
+		'3': 'e',
+		'4': 'a',
+		'5': 's',
+		'6': 'g',
+		'7': 't',
+		'8': 'b',
+		'9': 'g',
+		'@': 'a',
+		'$': 's',
+		'!': 'i',
+		'|': 'i',
+		'+': 't',
+	}
+
+	result := make([]rune, len(text))
+	for i, char := range text {
+		if replacement, ok := replacements[char]; ok {
+			result[i] = replacement
+		} else {
+			result[i] = unicode.ToLower(char)
+		}
+	}
+
+	return string(result)
+}
+
+// GetBlockedTerms returns a copy of the blocked terms list (for testing/debugging)
+func (cf *CustomFilter) GetBlockedTerms() []string {
+	terms := make([]string, len(cf.blockedTerms))
+	copy(terms, cf.blockedTerms)
+	return terms
+}

internal/handlers/handlers.go

@@ -16,7 +16,10 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-var profanityDetector = goaway.NewProfanityDetector()
+var (
+	profanityDetector = goaway.NewProfanityDetector()
+	customFilter      = NewCustomFilter()
+)
 
 type WebHandler struct {
 	db     *database.DB
@@ -57,6 +60,11 @@ func (h *WebHandler) ClaimSpace(c *gin.Context) {
 		return
 	}
 
+	if customFilter.IsBlocked(subdomain) {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Subdomain is reserved"})
+		return
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 
@@ -103,6 +111,15 @@ func (h *WebHandler) CheckSubdomain(c *gin.Context) {
 		return
 	}
 
+	if customFilter.IsBlocked(subdomain) {
+		c.JSON(http.StatusOK, gin.H{
+			"available": false,
+			"subdomain": subdomain,
+			"reason":    "reserved",
+		})
+		return
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 

web/static/js/app.js

@@ -37,6 +37,10 @@ document.addEventListener('DOMContentLoaded', function() {
                 availabilityStatus.textContent = '✗ Contains inappropriate content';
                 availabilityStatus.className = 'status taken';
                 claimBtn.disabled = true;
+            } else if (data.reason === 'reserved') {
+                availabilityStatus.textContent = '✗ This subdomain is reserved';
+                availabilityStatus.className = 'status taken';
+                claimBtn.disabled = true;
             } else {
                 availabilityStatus.textContent = '✗ Already taken';
                 availabilityStatus.className = 'status taken';