yt/core/http: handle end wildcard "/{$}" in http path pattern

Pattern "/path/{$}" matches only "/path/" and "/path".
Required for proper directory handling without careless matching everything.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@tracto.ai>

---

Pull Request resolved: https://github.com/ytsaurus/ytsaurus/pull/1109
commit_hash:096a09ff25498226420f9a5ed40b7b1b91328b7f

2 files changed, 33 insertions, 1 deletions

diff --git a/yt/yt/core/http/server.cpp b/yt/yt/core/http/server.cpp
index 43ca58c795..feaad321da 100644
--- a/yt/yt/core/http/server.cpp
+++ b/yt/yt/core/http/server.cpp
@@ -537,13 +537,30 @@ IServerPtr CreateServer(
 
 ////////////////////////////////////////////////////////////////////////////////
 
+/*!
+ *  Path matching semantic is copied from go standard library.
+ *  See https://golang.org/pkg/net/http/#ServeMux
+ *
+ *  Supported features:
+ *  - matching path exactly: "/path/name"
+ *  - matching path prefix: "/path/" matches all with prefix "/path/"
+ *  - trailing-slash redirection: matching "/path/" implies "/path"
+ *  - end of path wildcard: "/path/{$}" matches only "/path/" and "/path"
+ */
 void TRequestPathMatcher::Add(const TString& pattern, const IHttpHandlerPtr& handler)
 {
     if (pattern.empty()) {
         THROW_ERROR_EXCEPTION("Empty pattern is invalid");
     }
 
-    if (pattern.back() == '/') {
+    if (pattern.EndsWith("/{$}")) {
+        auto withoutWildcard = pattern.substr(0, pattern.size() - 3);
+
+        Exact_[withoutWildcard] = handler;
+        if (withoutWildcard.size() > 1) {
+            Exact_[withoutWildcard.substr(0, withoutWildcard.size() - 1)] = handler;
+        }
+    } else if (pattern.back() == '/') {
         Subtrees_[pattern] = handler;
 
         auto withoutSlash = pattern.substr(0, pattern.size() - 1);
diff --git a/yt/yt/core/http/unittests/http_ut.cpp b/yt/yt/core/http/unittests/http_ut.cpp
index 7030a2350f..4849ed0333 100644
--- a/yt/yt/core/http/unittests/http_ut.cpp
+++ b/yt/yt/core/http/unittests/http_ut.cpp
@@ -1377,6 +1377,21 @@ TEST(THttpHandlerMatchingTest, Simple)
     EXPECT_EQ(h3.Get(), handlers3->Match(TStringBuf("/a")).Get());
     EXPECT_EQ(h2.Get(), handlers3->Match(TStringBuf("/a/")).Get());
     EXPECT_EQ(h2.Get(), handlers3->Match(TStringBuf("/a/b")).Get());
+
+    {
+        auto handlers = New<TRequestPathMatcher>();
+        handlers->Add("/{$}", h1);
+        handlers->Add("/a/{$}", h2);
+        handlers->Add("/a/b", h3);
+
+        EXPECT_EQ(h1.Get(), handlers->Match(TStringBuf("/")).Get());
+        EXPECT_EQ(h2.Get(), handlers->Match(TStringBuf("/a")).Get());
+        EXPECT_EQ(h2.Get(), handlers->Match(TStringBuf("/a/")).Get());
+        EXPECT_EQ(h3.Get(), handlers->Match(TStringBuf("/a/b")).Get());
+        EXPECT_FALSE(handlers->Match(TStringBuf("/a/b/")).Get());
+        EXPECT_FALSE(handlers->Match(TStringBuf("/a/c")).Get());
+        EXPECT_FALSE(handlers->Match(TStringBuf("/d")).Get());
+    }
 }
 
 ////////////////////////////////////////////////////////////////////////////////