refuse re-adding a dataful ghost msg

lib/ghosts.js

@@ -151,6 +151,35 @@ class Ghosts {
     })
   }
 
+  /**
+   * @param {string} tangleID
+   * @param {string} msgID
+   * @param {CB<void>} cb
+   */
+  remove(tangleID, msgID, cb) {
+    this.#loaded.onReady(() => {
+      if (!this.#maps.has(tangleID)) return cb()
+
+      const map = /** @type {Map<string, number>} */ (this.#maps.get(tangleID))
+      if (!map.has(msgID)) return cb()
+
+      const newMap = new Map(map)
+      newMap.delete(msgID)
+
+      atomic.writeFile(
+        this.#path(tangleID),
+        this.#serialize(newMap),
+        Ghosts.encodingOpts,
+        (/** @type {any} */ err) => {
+          // prettier-ignore
+          if (err) return cb(new Error('GhostDB.save() failed to write ghost file', { cause: err }))
+          this.#maps.set(tangleID, newMap)
+          cb()
+        }
+      )
+    })
+  }
+
   /**
    * @param {string} tangleID
    * @returns {Map<string, number>}

lib/index.js

@@ -355,21 +355,25 @@ function initDB(peer, config) {
     try {
       accountTangle = getAccountTangle(rec)
     } catch (err) {
-      // prettier-ignore
-      return new Error('Failed to identify the account of this msg', { cause: err })
+      return new Error('Unknown account tangle owning this msg', { cause: err })
     }
     const pubkeys = getPubkeysInAccount(accountTangle)
 
+    // Don't accept ghosts to come back, unless they are trail msgs
+    if (!!rec.msg.data && ghosts.read(tangleID).has(rec.id)) {
+      return new Error('Refusing a ghost msg to come back')
+    }
+
     let err
     if ((err = MsgV3.validate(rec.msg, tangle, pubkeys, rec.id, tangleID))) {
-      return new Error('Failed msg validation', { cause: err })
+      return new Error('Invalid msg', { cause: err })
     }
 
     // Account tangle related validations
     if (rec.msg.metadata.account === ACCOUNT_SELF) {
       const validAccountTangle = /** @type {Tangle} */ (accountTangle)
       if ((err = validateAccountMsg(rec.msg, validAccountTangle))) {
-        return new Error('Failed msg account validation', { cause: err })
+        return new Error('Invalid account msg', { cause: err })
       }
     }
 
@@ -410,11 +414,17 @@ function initDB(peer, config) {
       return cb(new Error('add() failed to verify msg', { cause: err }))
     }
 
+    // The majority of cases don't have ghosts to be removed, but this operation
+    // is silent and cheap if there are no ghosts.
+    removeGhost(tangleID, msgID, (err) => {
+      // prettier-ignore
+      if (err) return cb(new Error('add() failed to remove ghost', { cause: err }))
       logAppend(msgID, msg, (err, rec) => {
         if (err) return cb(new Error('add() failed in the log', { cause: err }))
         onRecordAdded.set(rec)
         cb(null, rec)
       })
+    })
   }
 
   /**
@@ -962,6 +972,24 @@ function initDB(peer, config) {
     })
   }
 
+  /**
+   * @param {MsgID} tangleID
+   * @param {MsgID} msgID
+   * @param {CB<void>} cb
+   */
+  function removeGhost(tangleID, msgID, cb) {
+    // prettier-ignore
+    if (typeof tangleID !== 'string') return cb(new Error('ghosts.remove() requires tangleID in the 1st arg'))
+    // prettier-ignore
+    if (typeof msgID !== 'string') return cb(new Error('ghosts.remove() requires msgID in the 2nd arg'))
+
+    ghosts.remove(tangleID, msgID, (err) => {
+      // prettier-ignore
+      if (err) cb(new Error('ghosts.remove() failed to save to disk', { cause: err }))
+      else cb()
+    })
+  }
+
   /**
    * @param {MsgID} tangleID
    * @returns {Array<string>}