fix: correct CHANMODES ISUPPORT classification and deduplicate MintChannelHashcash

- Move H from Type B to Type C in CHANMODES ISUPPORT string (H takes
  a parameter only when set, not when unset)
- Refactor MintChannelHashcash to delegate to hashcash.BodyHash() and
  hashcash.MintChannelStamp() instead of reimplementing them

internal/cli/api/hashcash.go

@@ -7,6 +7,8 @@ import (
 	"fmt"
 	"math/big"
 	"time"
+
+	"git.eeqj.de/sneak/neoirc/internal/hashcash"
 )
 
 const (
@@ -41,29 +43,17 @@ func MintHashcash(bits int, resource string) string {
 // a specific channel and message body. The stamp format
 // is 1:bits:YYMMDD:channel:bodyhash:counter where
 // bodyhash is the hex-encoded SHA-256 of the message
-// body bytes.
+// body bytes. Delegates to the internal/hashcash package.
 func MintChannelHashcash(
 	bits int,
 	channel string,
 	body []byte,
 ) string {
-	bodyHash := sha256.Sum256(body)
-	bodyHashHex := hex.EncodeToString(bodyHash[:])
-	date := time.Now().UTC().Format("060102")
-	prefix := fmt.Sprintf(
-		"1:%d:%s:%s:%s:",
-		bits, date, channel, bodyHashHex,
+	bodyHash := hashcash.BodyHash(body)
+
+	return hashcash.MintChannelStamp(
+		bits, channel, bodyHash,
 	)
-
-	for {
-		counter := randomCounter()
-		stamp := prefix + counter
-		hash := sha256.Sum256([]byte(stamp))
-
-		if hasLeadingZeroBits(hash[:], bits) {
-			return stamp
-		}
-	}
 }
 
 // hasLeadingZeroBits checks if hash has at least numBits

internal/handlers/api.go

@@ -300,7 +300,7 @@ func (hdlr *Handlers) deliverWelcome(
 		[]string{
 			"CHANTYPES=#",
 			"NICKLEN=32",
-			"CHANMODES=,H,," + "imnst",
+			"CHANMODES=,,H," + "imnst",
 			"NETWORK=neoirc",
 			"CASEMAPPING=ascii",
 		},