Repository: go-playground/validator
Pull request #912 (2022-03-15 10:17:06)

fix: Remove underscore from RFC-1123 based regex
RFC-1123 is based on RFC-952, which doesn't allow underscores. RFC-1123
must be therefore implemented with the same constraint to disallow
underscores in host names.

## Fixes Or Enhances

- Regex that implement RFC-1123 don't allow underscores anymore

**Make sure that you've checked the boxes below before you submit PR:**
- [x] Tests exist or have been written that cover this particular change.

@go-playground/validator-maintainers

coveralls: 
[![Coverage Status](https://coveralls.io/builds/47370514/badge)](https://coveralls.io/builds/47370514)

Coverage remained the same at 75.136% when pulling **329d5a500b22b8705dcbd4414ecf53a6b488da30 on sdillen:fix/rfc1123** into **58d5778b183e89cc374ca4ebbf06da1eed088a63 on go-playground:master**.


Patch:
diff --git a/regexes.go b/regexes.go
index 48e51d5..a8668f8 100644
--- a/regexes.go
+++ b/regexes.go
@@ -37,12 +37,12 @@ const (
 	latitudeRegexString              = "^[-+]?([1-8]?\\d(\\.\\d+)?|90(\\.0+)?)$"
 	longitudeRegexString             = "^[-+]?(180(\\.0+)?|((1[0-7]\\d)|([1-9]?\\d))(\\.\\d+)?)$"
 	sSNRegexString                   = `^[0-9]{3}[ -]?(0[1-9]|[1-9][0-9])[ -]?([1-9][0-9]{3}|[0-9][1-9][0-9]{2}|[0-9]{2}[1-9][0-9]|[0-9]{3}[1-9])$`
-	hostnameRegexStringRFC952        = `^[a-zA-Z]([a-zA-Z0-9\-]+[\.]?)*[a-zA-Z0-9]$`                                                                      // https://tools.ietf.org/html/rfc952
-	hostnameRegexStringRFC1123       = `^([a-zA-Z0-9]{1}[a-zA-Z0-9_-]{0,62}){1}(\.[a-zA-Z0-9_]{1}[a-zA-Z0-9_-]{0,62})*?$`                                 // accepts hostname starting with a digit https://tools.ietf.org/html/rfc1123
-	fqdnRegexStringRFC1123           = `^([a-zA-Z0-9]{1}[a-zA-Z0-9_-]{0,62})(\.[a-zA-Z0-9_]{1}[a-zA-Z0-9_-]{0,62})*?(\.[a-zA-Z]{1}[a-zA-Z0-9]{0,62})\.?$` // same as hostnameRegexStringRFC1123 but must contain a non numerical TLD (possibly ending with '.')
-	btcAddressRegexString            = `^[13][a-km-zA-HJ-NP-Z1-9]{25,34}$`                                                                                // bitcoin address
-	btcAddressUpperRegexStringBech32 = `^BC1[02-9AC-HJ-NP-Z]{7,76}$`                                                                                      // bitcoin bech32 address https://en.bitcoin.it/wiki/Bech32
-	btcAddressLowerRegexStringBech32 = `^bc1[02-9ac-hj-np-z]{7,76}$`                                                                                      // bitcoin bech32 address https://en.bitcoin.it/wiki/Bech32
+	hostnameRegexStringRFC952        = `^[a-zA-Z]([a-zA-Z0-9\-]+[\.]?)*[a-zA-Z0-9]$`                                                                   // https://tools.ietf.org/html/rfc952
+	hostnameRegexStringRFC1123       = `^([a-zA-Z0-9]{1}[a-zA-Z0-9-]{0,62}){1}(\.[a-zA-Z0-9]{1}[a-zA-Z0-9-]{0,62})*?$`                                 // accepts hostname starting with a digit https://tools.ietf.org/html/rfc1123
+	fqdnRegexStringRFC1123           = `^([a-zA-Z0-9]{1}[a-zA-Z0-9-]{0,62})(\.[a-zA-Z0-9]{1}[a-zA-Z0-9-]{0,62})*?(\.[a-zA-Z]{1}[a-zA-Z0-9]{0,62})\.?$` // same as hostnameRegexStringRFC1123 but must contain a non numerical TLD (possibly ending with '.')
+	btcAddressRegexString            = `^[13][a-km-zA-HJ-NP-Z1-9]{25,34}$`                                                                             // bitcoin address
+	btcAddressUpperRegexStringBech32 = `^BC1[02-9AC-HJ-NP-Z]{7,76}$`                                                                                   // bitcoin bech32 address https://en.bitcoin.it/wiki/Bech32
+	btcAddressLowerRegexStringBech32 = `^bc1[02-9ac-hj-np-z]{7,76}$`                                                                                   // bitcoin bech32 address https://en.bitcoin.it/wiki/Bech32
 	ethAddressRegexString            = `^0x[0-9a-fA-F]{40}$`
 	ethAddressUpperRegexString       = `^0x[0-9A-F]{40}$`
 	ethAddressLowerRegexString       = `^0x[0-9a-f]{40}$`


Test patch:
diff --git a/validator_test.go b/validator_test.go
index a5b1fa2..6aee559 100644
--- a/validator_test.go
+++ b/validator_test.go
@@ -9151,6 +9151,7 @@ func TestHostnameRFC1123Validation(t *testing.T) {
 		{"test.example24.com.", false},
 		{"test24.example24.com.", false},
 		{"example.", false},
+		{"test_example", false},
 		{"192.168.0.1", true},
 		{"email@example.com", false},
 		{"2001:cdba:0000:0000:0000:0000:3257:9652", false},
@@ -9199,6 +9200,7 @@ func TestHostnameRFC1123AliasValidation(t *testing.T) {
 		{"test.example24.com.", false},
 		{"test24.example24.com.", false},
 		{"example.", false},
+		{"test_example", false},
 		{"192.168.0.1", true},
 		{"email@example.com", false},
 		{"2001:cdba:0000:0000:0000:0000:3257:9652", false},