feat(http1): support configurable max_headers

Cargo.toml

@@ -36,6 +36,7 @@ httpdate = { version = "1.0", optional = true }
 itoa = { version = "1", optional = true }
 libc = { version = "0.2", optional = true }
 pin-project-lite = { version = "0.2.4", optional = true }
+smallvec = { version = "1.12", features = ["const_generics", "const_new"], optional = true }
 tracing = { version = "0.1", default-features = false, features = ["std"], optional = true }
 want = { version = "0.3", optional = true }
 
@@ -80,8 +81,8 @@ http1 = ["dep:futures-channel", "dep:futures-util", "dep:httparse", "dep:itoa"]
 http2 = ["dep:futures-channel", "dep:futures-util", "dep:h2"]
 
 # Client/Server
-client = ["dep:want", "dep:pin-project-lite"]
-server = ["dep:httpdate", "dep:pin-project-lite"]
+client = ["dep:want", "dep:pin-project-lite", "dep:smallvec"]
+server = ["dep:httpdate", "dep:pin-project-lite", "dep:smallvec"]
 
 # C-API support (currently unstable (no semver))
 ffi = ["dep:libc", "dep:http-body-util"]

src/client/conn/http1.rs

@@ -115,6 +115,7 @@ pub struct Builder {
     h1_writev: Option<bool>,
     h1_title_case_headers: bool,
     h1_preserve_header_case: bool,
+    h1_max_headers: Option<usize>,
     #[cfg(feature = "ffi")]
     h1_preserve_header_order: bool,
     h1_read_buf_exact_size: Option<usize>,
@@ -309,6 +310,7 @@ impl Builder {
             h1_parser_config: Default::default(),
             h1_title_case_headers: false,
             h1_preserve_header_case: false,
+            h1_max_headers: None,
             #[cfg(feature = "ffi")]
             h1_preserve_header_order: false,
             h1_max_buf_size: None,
@@ -439,6 +441,24 @@ impl Builder {
         self
     }
 
+    /// Set the maximum number of headers.
+    ///
+    /// When a response is received, the parser will reserve a buffer to store headers for optimal
+    /// performance.
+    ///
+    /// If client receives more headers than the buffer size, the error "message header too large"
+    /// is returned.
+    ///
+    /// Note that headers is allocated on the stack by default, which has higher performance. After
+    /// setting this value, headers will be allocated in heap memory, that is, heap memory
+    /// allocation will occur for each response, and there will be a performance drop of about 5%.
+    ///
+    /// Default is 100.
+    pub fn max_headers(&mut self, val: usize) -> &mut Self {
+        self.h1_max_headers = Some(val);
+        self
+    }
+
     /// Set whether to support preserving original header order.
     ///
     /// Currently, this will record the order in which headers are received, and store this
@@ -519,6 +539,9 @@ impl Builder {
             if opts.h1_preserve_header_case {
                 conn.set_preserve_header_case();
             }
+            if let Some(max_headers) = opts.h1_max_headers {
+                conn.set_http1_max_headers(max_headers);
+            }
             #[cfg(feature = "ffi")]
             if opts.h1_preserve_header_order {
                 conn.set_preserve_header_order();

src/proto/h1/conn.rs

@@ -54,6 +54,7 @@ where
                 keep_alive: KA::Busy,
                 method: None,
                 h1_parser_config: ParserConfig::default(),
+                h1_max_headers: None,
                 #[cfg(feature = "server")]
                 h1_header_read_timeout: None,
                 #[cfg(feature = "server")]
@@ -132,6 +133,10 @@ where
         self.state.h09_responses = true;
     }
 
+    pub(crate) fn set_http1_max_headers(&mut self, val: usize) {
+        self.state.h1_max_headers = Some(val);
+    }
+
     #[cfg(feature = "server")]
     pub(crate) fn set_http1_header_read_timeout(&mut self, val: Duration) {
         self.state.h1_header_read_timeout = Some(val);
@@ -207,6 +212,7 @@ where
                 cached_headers: &mut self.state.cached_headers,
                 req_method: &mut self.state.method,
                 h1_parser_config: self.state.h1_parser_config.clone(),
+                h1_max_headers: self.state.h1_max_headers,
                 #[cfg(feature = "server")]
                 h1_header_read_timeout: self.state.h1_header_read_timeout,
                 #[cfg(feature = "server")]
@@ -847,6 +853,7 @@ struct State {
     /// a body or not.
     method: Option<Method>,
     h1_parser_config: ParserConfig,
+    h1_max_headers: Option<usize>,
     #[cfg(feature = "server")]
     h1_header_read_timeout: Option<Duration>,
     #[cfg(feature = "server")]

src/proto/h1/io.rs

@@ -184,6 +184,7 @@ where
                     cached_headers: parse_ctx.cached_headers,
                     req_method: parse_ctx.req_method,
                     h1_parser_config: parse_ctx.h1_parser_config.clone(),
+                    h1_max_headers: parse_ctx.h1_max_headers,
                     #[cfg(feature = "server")]
                     h1_header_read_timeout: parse_ctx.h1_header_read_timeout,
                     #[cfg(feature = "server")]
@@ -725,6 +726,7 @@ mod tests {
                 cached_headers: &mut None,
                 req_method: &mut None,
                 h1_parser_config: Default::default(),
+                h1_max_headers: None,
                 h1_header_read_timeout: None,
                 h1_header_read_timeout_fut: &mut None,
                 h1_header_read_timeout_running: &mut false,

src/proto/h1/mod.rs

@@ -78,6 +78,7 @@ pub(crate) struct ParseContext<'a> {
     cached_headers: &'a mut Option<HeaderMap>,
     req_method: &'a mut Option<Method>,
     h1_parser_config: ParserConfig,
+    h1_max_headers: Option<usize>,
     #[cfg(feature = "server")]
     h1_header_read_timeout: Option<Duration>,
     #[cfg(feature = "server")]