From 81f343a46ae2274178b35740b50ab74affbcfbd9 Mon Sep 17 00:00:00 2001
From: mpostma <postma.marin@protonmail.com>
Date: Fri, 8 Jan 2021 16:23:23 +0100
Subject: [PATCH] add word limit to search queries

---
 meilisearch-core/src/lib.rs        |  1 +
 meilisearch-core/src/query_tree.rs |  3 +++
 meilisearch-http/tests/search.rs   | 29 +++++++++++++++++++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/meilisearch-core/src/lib.rs b/meilisearch-core/src/lib.rs
index bcdad62b1..947ad5fb7 100644
--- a/meilisearch-core/src/lib.rs
+++ b/meilisearch-core/src/lib.rs
@@ -39,6 +39,7 @@ pub use self::update::{EnqueuedUpdateResult, ProcessedUpdateResult, UpdateStatus
 pub use meilisearch_types::{DocIndex, DocumentId, Highlight};
 pub use meilisearch_schema::Schema;
 pub use query_words_mapper::QueryWordsMapper;
+pub use query_tree::MAX_QUERY_LEN;
 
 use compact_arena::SmallArena;
 use log::{error, trace};
diff --git a/meilisearch-core/src/query_tree.rs b/meilisearch-core/src/query_tree.rs
index c2f43818f..5d10e9bef 100644
--- a/meilisearch-core/src/query_tree.rs
+++ b/meilisearch-core/src/query_tree.rs
@@ -16,6 +16,8 @@ use crate::{store, DocumentId, DocIndex, MResult, FstSetCow};
 use crate::automaton::{build_dfa, build_prefix_dfa, build_exact_dfa};
 use crate::QueryWordsMapper;
 
+pub const MAX_QUERY_LEN: usize = 10;
+
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub enum Operation {
     And(Vec<Operation>),
@@ -181,6 +183,7 @@ fn split_query_string<'a, A: AsRef<[u8]>>(s: &str, stop_words: &'a fst::Set<A>)
         .tokens()
         .filter(|t| t.is_word())
         .map(|t| t.word.to_string())
+        .take(MAX_QUERY_LEN)
         .enumerate()
         .collect()
 }
diff --git a/meilisearch-http/tests/search.rs b/meilisearch-http/tests/search.rs
index 9da6b964e..13dc4c898 100644
--- a/meilisearch-http/tests/search.rs
+++ b/meilisearch-http/tests/search.rs
@@ -1945,3 +1945,32 @@ async fn test_filter_nb_hits_search_normal() {
     println!("result: {}", response);
     assert_eq!(response["nbHits"], 1);
 }
+
+#[actix_rt::test]
+async fn test_max_word_query() {
+    use meilisearch_core::MAX_QUERY_LEN;
+
+    let mut server = common::Server::with_uid("test");
+    let body = json!({
+        "uid": "test",
+        "primaryKey": "id",
+    });
+    server.create_index(body).await;
+    let documents = json!([
+        {"id": 1, "value": "1 2 3 4 5 6 7 8 9 10 11"},
+        {"id": 2, "value": "1 2 3 4 5 6 7 8 9 10"}]
+    );
+    server.add_or_update_multiple_documents(documents).await;
+
+    // We want to create a request where the 11 will be ignored. We have 2 documents, where a query
+    // with only one should return both, but a query with 1 and 11 should return only the first.
+    // This is how we know that outstanding query words have been ignored
+    let query = (0..MAX_QUERY_LEN)
+        .map(|_| "1")
+        .chain(std::iter::once("11"))
+        .fold(String::new(), |s, w| s + " " + w);
+    let (response, _) = server.search_post(json!({"q": query})).await;
+    assert_eq!(response["nbHits"], 2);
+    let (response, _) = server.search_post(json!({"q": "1 11"})).await;
+    assert_eq!(response["nbHits"], 1);
+}