Fix yhirose#1768

Author: yhirose

httplib.h

@@ -2418,6 +2418,7 @@ inline bool is_valid_path(const std::string &path) {
     auto beg = i;
     while (i < path.size() && path[i] != '/') {
       if (path[i] == '\0') { return false; }
+      else if (path[i] == '\\') { return false; }
       i++;
     }
 

test/test.cc

@@ -2509,6 +2509,12 @@ TEST_F(ServerTest, GetMethodOutOfBaseDirMount2) {
   EXPECT_EQ(StatusCode::NotFound_404, res->status);
 }
 
+TEST_F(ServerTest, GetMethodOutOfBaseDirMountWithBackslash) {
+  auto res = cli_.Get("/mount/%2e%2e%5c/www2/dir/test.html");
+  ASSERT_TRUE(res);
+  EXPECT_EQ(StatusCode::NotFound_404, res->status);
+}
+
 TEST_F(ServerTest, PostMethod303) {
   auto res = cli_.Post("/1", "body", "text/plain");
   ASSERT_TRUE(res);