be less trusting of file lengths

Author: calvinmetcalf

lib/parseShp.js

@@ -211,11 +211,15 @@ function ParseShp (buffer, trans) {
     return new ParseShp(buffer, trans);
   }
   this.buffer = buffer;
+  this.headers = this.parseHeader();
+  if (this.headers.length < this.buffer.byteLength) {
+    this.buffer = this.buffer.slice(0, this.headers.length);
+  }
   this.shpFuncs(trans);
   this.rows = this.getRows();
 }
 ParseShp.prototype.shpFuncs = function (tran) {
-  let num = this.getShpCode();
+  let num = this.headers.shpCode;
   if (num > 20) {
     num -= 20;
   }
@@ -231,7 +235,7 @@ ParseShp.prototype.getShpCode = function () {
 ParseShp.prototype.parseHeader = function () {
   const view = this.buffer.slice(0, 100);
   return {
-    length: view.readInt32BE(6 << 2),
+    length: view.readInt32BE(6 << 2) << 1,
     version: view.readInt32LE(7 << 2),
     shpCode: view.readInt32LE(8 << 2),
     bbox: [
@@ -249,6 +253,9 @@ ParseShp.prototype.getRows = function () {
   let current;
   while (offset < len) {
     current = this.getRow(offset);
+    if (!current) {
+      break;
+    }
     offset += 8;
     offset += current.len;
     if (current.type) {

test/data/ipra_dresden_polygon.dbf

@@ -0,0 +1 @@
+GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]]

test/data/ipra_dresden_polygon.prj

@@ -301,5 +301,8 @@ describe('Shp', function () {
         return item.features.length;
       }).should.eventually.equal(3);
     });
+    it('file too long', function(){
+     return shp('http://localhost:3000/test/data/ipra_dresden_polygon');
+   });
   });
 });