Fixes ftp download when authentication is required

conans/client/tools/net.py

@@ -33,14 +33,18 @@ def get(url, md5='', sha1='', sha256='', destination=".", filename="", keep_perm
 def ftp_download(ip, filename, login='', password=''):
     import ftplib
     try:
-        ftp = ftplib.FTP(ip, login, password)
-        ftp.login()
+        ftp = ftplib.FTP(ip)
+        ftp.login(login, password)
         filepath, filename = os.path.split(filename)
         if filepath:
             ftp.cwd(filepath)
         with open(filename, 'wb') as f:
             ftp.retrbinary('RETR ' + filename, f.write)
     except Exception as e:
+        try:
+            os.unlink(filename)
+        except OSError:
+            pass
         raise ConanException("Error in FTP download from %s\n%s" % (ip, str(e)))
     finally:
         try:

conans/test/client/tools/net_test.py

@@ -0,0 +1,42 @@
+# coding=utf-8
+
+import os
+import shutil
+import tempfile
+import unittest
+
+from conans.client.tools import chdir
+from conans.client.tools import net
+from conans.errors import ConanException
+
+
+class ToolsNetTest(unittest.TestCase):
+
+    def run(self, *args, **kwargs):
+        self.tmp_folder = tempfile.mkdtemp()
+        try:
+            with chdir(self.tmp_folder):
+                super(ToolsNetTest, self).run(*args, **kwargs)
+        finally:
+            shutil.rmtree(self.tmp_folder)
+
+    def test_ftp_auth(self):
+        filename = "/pub/example/readme.txt"
+        net.ftp_download("test.rebex.net", filename, "demo", "password")
+        self.assertTrue(os.path.exists(os.path.basename(filename)))
+
+    def test_ftp_anonymous(self):
+        filename = "1KB.zip"
+        net.ftp_download("speedtest.tele2.net", filename)
+        self.assertTrue(os.path.exists(os.path.basename(filename)))
+
+    def test_ftp_invalid_path(self):
+        with self.assertRaisesRegexp(ConanException,
+                                     "550 The system cannot find the file specified."):
+            net.ftp_download("test.rebex.net", "invalid-file", "demo", "password")
+        self.assertFalse(os.path.exists("invalid-file"))
+
+    def test_ftp_invalid_auth(self):
+        with self.assertRaisesRegexp(ConanException, "530 User cannot log in."):
+            net.ftp_download("test.rebex.net", "readme.txt", "demo", "invalid")
+        self.assertFalse(os.path.exists("readme.txt"))