Fix sanitizer skipping subdomains with underscore

Author: d3mondev

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Fixed
 - Wildcard filtering not working when wildcard tests put the domain over the 253 character limit.
+- Sanitizer accepts subdomains with underscores in them.
 
 ## [2.1.1] - 2023-04-11
 ### Fixed

internal/usecase/resolve/domainreader_test.go

@@ -29,7 +29,7 @@ func TestDomainReaderRead(t *testing.T) {
 		{name: "wildcard", haveData: "www\nftp\nmail", haveDomains: []string{"www.*.example.com"}, want: "www.www.example.com\nwww.ftp.example.com\nwww.mail.example.com\n", wantErr: io.EOF},
 		{name: "multiple wildcards", haveData: "word", haveDomains: []string{"www.*.*.example.com"}, want: "www.word.word.example.com\n", wantErr: io.EOF},
 		{name: "words multiple domains", haveData: "www\nftp\nmail", haveDomains: []string{"example.com", "example.org"}, want: "www.example.com\nwww.example.org\nftp.example.com\nftp.example.org\nmail.example.com\nmail.example.org\n", wantErr: io.EOF},
-		{name: "sanitize", haveData: "_", haveDomains: []string{"example.com"}, haveSanitizer: DefaultSanitizer, want: "\n", wantErr: io.EOF},
+		{name: "sanitize", haveData: "+", haveDomains: []string{"example.com"}, haveSanitizer: DefaultSanitizer, want: "\n", wantErr: io.EOF},
 	}
 
 	for _, test := range tests {

internal/usecase/resolve/sanitizer.go

@@ -18,7 +18,7 @@ func DefaultSanitizer(domain string) string {
 	for i := 0; i < len(domain); i++ {
 		char := domain[i]
 
-		if (char >= 'a' && char <= 'z') || (char >= '0' && char <= '9') || (char == '-') || (char == '.') {
+		if (char >= 'a' && char <= 'z') || (char >= '0' && char <= '9') || (char == '-') || (char == '_') || (char == '.') {
 			continue
 		}