Add minimum link quantity constraint

app/models/link.js

@@ -20,6 +20,14 @@ LinkSchema.pre('save', function (next) {
 LinkSchema.methods = {
 };
 
+/**
+* Mark as obsolete the links with an age equal to or below a given date
+**/
+LinkSchema.statics.currentValidLinks = function (fpr, done) {
+  var Link = this.model('Link');
+  Link.find({ target: fpr, obsolete: false }, done);
+}
+
 /**
 * Mark as obsolete the links with an age equal to or below a given date
 **/

app/service/KeychainService.js

@@ -406,6 +406,12 @@ function KeyService (conn, conf, PublicKeyService) {
           });
           async.forEachSeries(newcomers, function (newcomer, newcomerTested) {
             async.waterfall([
+              function (next) {
+                if (block.number > 0)
+                  checkHaveEnoughLinks(newcomer, newLinks, next);
+                else
+                  next();
+              },
               function (next) {
                 // Check the newcomer IS RECOGNIZED BY the WoT + other newcomers
                 // (check we have a path WoT => newcomer)
@@ -454,6 +460,20 @@ function KeyService (conn, conf, PublicKeyService) {
     }
   }
 
+  function checkHaveEnoughLinks(target, newLinks, done) {
+    async.waterfall([
+      function (next){
+        Link.currentValidLinks(target, next);
+      },
+      function (links, next){
+        var count = links.length;
+        if (newLinks[target] && newLinks[target].length)
+          count += newLinks[target].length;
+        next(count < LINK_QUANTITY_MIN && 'Key ' + target.substring(24) + ' does not have enough links (' + count + '/' + LINK_QUANTITY_MIN + ')');
+      },
+    ], done);
+  }
+
   function checkProofOfWork (block, done) {
     var powRegexp = new RegExp('^0{' + MINIMUM_ZERO_START + '}');
     if (!block.hash.match(powRegexp))