From 82262a6100b184e4768ca1747ae402cb9b418196 Mon Sep 17 00:00:00 2001
From: ThibG <thib@sitedethib.com>
Date: Sun, 12 Jan 2020 14:17:03 +0100
Subject: [PATCH] Fix invalid votes from the API being accepted (#12601)

* Fix invalid votes from the API being accepted

Fixes #12556

- Ensure `choice` is an integer instead of silently converting to 0
- Ensure `choice` corresponds to an actual choice of the poll

* Please CodeClimate
---
 app/services/vote_service.rb     | 2 +-
 app/validators/vote_validator.rb | 8 ++++++++
 config/locales/en.yml            | 1 +
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/app/services/vote_service.rb b/app/services/vote_service.rb
index cb7dce6e8a..19e4533321 100644
--- a/app/services/vote_service.rb
+++ b/app/services/vote_service.rb
@@ -20,7 +20,7 @@ class VoteService < BaseService
 
         ApplicationRecord.transaction do
           @choices.each do |choice|
-            @votes << @poll.votes.create!(account: @account, choice: choice)
+            @votes << @poll.votes.create!(account: @account, choice: Integer(choice))
           end
         end
       else
diff --git a/app/validators/vote_validator.rb b/app/validators/vote_validator.rb
index 2e1818bdb9..b1692562d4 100644
--- a/app/validators/vote_validator.rb
+++ b/app/validators/vote_validator.rb
@@ -4,10 +4,18 @@ class VoteValidator < ActiveModel::Validator
   def validate(vote)
     vote.errors.add(:base, I18n.t('polls.errors.expired')) if vote.poll.expired?
 
+    vote.errors.add(:base, I18n.t('polls.errors.invalid_choice')) if invalid_choice?(vote)
+
     if vote.poll.multiple? && vote.poll.votes.where(account: vote.account, choice: vote.choice).exists?
       vote.errors.add(:base, I18n.t('polls.errors.already_voted'))
     elsif !vote.poll.multiple? && vote.poll.votes.where(account: vote.account).exists?
       vote.errors.add(:base, I18n.t('polls.errors.already_voted'))
     end
   end
+
+  private
+
+  def invalid_choice?(vote)
+    vote.choice.negative? || vote.choice >= vote.poll.options.size
+  end
 end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 62f2226e3a..d768cef332 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -922,6 +922,7 @@ en:
       duration_too_long: is too far into the future
       duration_too_short: is too soon
       expired: The poll has already ended
+      invalid_choice: The chosen vote option does not exist
       over_character_limit: cannot be longer than %{max} characters each
       too_few_options: must have more than one item
       too_many_options: can't contain more than %{max} items