wip: implemented backend

rpxy-lib/Cargo.toml

@@ -15,15 +15,15 @@ publish = false
 default = ["http3-s2n", "sticky-cookie", "cache"]
 http3-quinn = ["socket2"]                         #"quinn", "h3", "h3-quinn", ]
 http3-s2n = []                                    #"h3", "s2n-quic", "s2n-quic-rustls", "s2n-quic-h3"]
-sticky-cookie = []                                #"base64", "sha2", "chrono"]
+sticky-cookie = ["base64", "sha2", "chrono"]
 cache = []                                        #"http-cache-semantics", "lru"]
 native-roots = []                                 #"hyper-rustls/native-tokio"]
 
 [dependencies]
-# rand = "0.8.5"
+rand = "0.8.5"
-# rustc-hash = "1.1.0"
+rustc-hash = "1.1.0"
 # bytes = "1.5.0"
-# derive_builder = "0.12.0"
+derive_builder = "0.12.0"
 futures = { version = "0.3.29", features = ["alloc", "async-await"] }
 tokio = { version = "1.34.0", default-features = false, features = [
   "net",
@@ -34,13 +34,13 @@ tokio = { version = "1.34.0", default-features = false, features = [
   "fs",
 ] }
 async-trait = "0.1.74"
-# hot_reload = "0.1.4" # reloading certs
 
 # Error handling
 anyhow = "1.0.75"
 thiserror = "1.0.50"
 
 # http and tls
+hot_reload = "0.1.4" # reloading certs
 http = "1.0.0"
 # http-body-util = "0.1.0"
 hyper = { version = "1.0.1", default-features = false }
@@ -75,14 +75,14 @@ socket2 = { version = "0.5.5", features = ["all"], optional = true }
 # http-cache-semantics = { path = "../submodules/rusty-http-cache-semantics/", optional = true }
 # lru = { version = "0.12.0", optional = true }
 
-# # cookie handling for sticky cookie
+# cookie handling for sticky cookie
-# chrono = { version = "0.4.31", default-features = false, features = [
+chrono = { version = "0.4.31", default-features = false, features = [
-#   "unstable-locales",
+  "unstable-locales",
-#   "alloc",
+  "alloc",
-#   "clock",
+  "clock",
-# ], optional = true }
+], optional = true }
-# base64 = { version = "0.21.5", optional = true }
+base64 = { version = "0.21.5", optional = true }
-# sha2 = { version = "0.10.8", default-features = false, optional = true }
+sha2 = { version = "0.10.8", default-features = false, optional = true }
 
 
 # [dev-dependencies]

rpxy-lib/src/backend/backend_main.rs

@@ -0,0 +1,136 @@
+use crate::{
+  certs::CryptoSource,
+  error::*,
+  log::*,
+  name_exp::{ByteName, ServerName},
+  AppConfig, AppConfigList,
+};
+use derive_builder::Builder;
+use rustc_hash::FxHashMap as HashMap;
+use std::borrow::Cow;
+
+use super::upstream::PathManager;
+
+/// Struct serving information to route incoming connections, like server name to be handled and tls certs/keys settings.
+#[derive(Builder)]
+pub struct BackendApp<T>
+where
+  T: CryptoSource,
+{
+  #[builder(setter(into))]
+  /// backend application name, e.g., app1
+  pub app_name: String,
+  #[builder(setter(custom))]
+  /// server name, e.g., example.com, in [[ServerName]] object
+  pub server_name: ServerName,
+  /// struct of reverse proxy serving incoming request
+  pub path_manager: PathManager,
+  /// tls settings: https redirection with 30x
+  #[builder(default)]
+  pub https_redirection: Option<bool>,
+  /// TLS settings: source meta for server cert, key, client ca cert
+  #[builder(default)]
+  pub crypto_source: Option<T>,
+}
+impl<'a, T> BackendAppBuilder<T>
+where
+  T: CryptoSource,
+{
+  pub fn server_name(&mut self, server_name: impl Into<Cow<'a, str>>) -> &mut Self {
+    self.server_name = Some(server_name.to_server_name());
+    self
+  }
+}
+
+/// HashMap and some meta information for multiple Backend structs.
+pub struct BackendAppManager<T>
+where
+  T: CryptoSource,
+{
+  /// HashMap of Backend structs, key is server name
+  pub apps: HashMap<ServerName, BackendApp<T>>,
+  /// for plaintext http
+  pub default_server_name: Option<ServerName>,
+}
+
+impl<T> Default for BackendAppManager<T>
+where
+  T: CryptoSource,
+{
+  fn default() -> Self {
+    Self {
+      apps: HashMap::<ServerName, BackendApp<T>>::default(),
+      default_server_name: None,
+    }
+  }
+}
+
+impl<T> TryFrom<&AppConfig<T>> for BackendApp<T>
+where
+  T: CryptoSource + Clone,
+{
+  type Error = RpxyError;
+
+  fn try_from(app_config: &AppConfig<T>) -> Result<Self, Self::Error> {
+    let mut backend_builder = BackendAppBuilder::default();
+    let path_manager = PathManager::try_from(app_config)?;
+    backend_builder
+      .app_name(app_config.app_name.clone())
+      .server_name(app_config.server_name.clone())
+      .path_manager(path_manager);
+    // TLS settings and build backend instance
+    let backend = if app_config.tls.is_none() {
+      backend_builder.build()?
+    } else {
+      let tls = app_config.tls.as_ref().unwrap();
+      backend_builder
+        .https_redirection(Some(tls.https_redirection))
+        .crypto_source(Some(tls.inner.clone()))
+        .build()?
+    };
+    Ok(backend)
+  }
+}
+
+impl<T> TryFrom<&AppConfigList<T>> for BackendAppManager<T>
+where
+  T: CryptoSource + Clone,
+{
+  type Error = RpxyError;
+
+  fn try_from(config_list: &AppConfigList<T>) -> Result<Self, Self::Error> {
+    let mut manager = Self::default();
+    for app_config in config_list.inner.iter() {
+      let backend: BackendApp<T> = BackendApp::try_from(app_config)?;
+      manager
+        .apps
+        .insert(app_config.server_name.clone().to_server_name(), backend);
+
+      info!(
+        "Registering application {} ({})",
+        &app_config.server_name, &app_config.app_name
+      );
+    }
+
+    // default backend application for plaintext http requests
+    if let Some(default_app_name) = &config_list.default_app {
+      let default_server_name = manager
+        .apps
+        .iter()
+        .filter(|(_k, v)| &v.app_name == default_app_name)
+        .map(|(_, v)| v.server_name.clone())
+        .collect::<Vec<_>>();
+
+      if !default_server_name.is_empty() {
+        info!(
+          "Serving plaintext http for requests to unconfigured server_name by app {} (server_name: {}).",
+          &default_app_name,
+          (&default_server_name[0]).try_into().unwrap_or_else(|_| "".to_string())
+        );
+
+        manager.default_server_name = Some(default_server_name[0].clone());
+      }
+    }
+    Ok(manager)
+  }
+}

rpxy-lib/src/backend/load_balance/load_balance_main.rs

@@ -0,0 +1,135 @@
+#[cfg(feature = "sticky-cookie")]
+pub use super::{
+  load_balance_sticky::{LoadBalanceSticky, LoadBalanceStickyBuilder},
+  sticky_cookie::StickyCookie,
+};
+use derive_builder::Builder;
+use rand::Rng;
+use std::sync::{
+  atomic::{AtomicUsize, Ordering},
+  Arc,
+};
+
+/// Constants to specify a load balance option
+pub mod load_balance_options {
+  pub const FIX_TO_FIRST: &str = "none";
+  pub const ROUND_ROBIN: &str = "round_robin";
+  pub const RANDOM: &str = "random";
+  #[cfg(feature = "sticky-cookie")]
+  pub const STICKY_ROUND_ROBIN: &str = "sticky";
+}
+
+#[derive(Debug, Clone)]
+/// Pointer to upstream serving the incoming request.
+/// If 'sticky cookie'-based LB is enabled and cookie must be updated/created, the new cookie is also given.
+pub struct PointerToUpstream {
+  pub ptr: usize,
+  pub context: Option<LoadBalanceContext>,
+}
+/// Trait for LB
+pub(super) trait LoadBalanceWithPointer {
+  fn get_ptr(&self, req_info: Option<&LoadBalanceContext>) -> PointerToUpstream;
+}
+
+#[derive(Debug, Clone, Builder)]
+/// Round Robin LB object as a pointer to the current serving upstream destination
+pub struct LoadBalanceRoundRobin {
+  #[builder(default)]
+  /// Pointer to the index of the last served upstream destination
+  ptr: Arc<AtomicUsize>,
+  #[builder(setter(custom), default)]
+  /// Number of upstream destinations
+  num_upstreams: usize,
+}
+impl LoadBalanceRoundRobinBuilder {
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+}
+impl LoadBalanceWithPointer for LoadBalanceRoundRobin {
+  /// Increment the count of upstream served up to the max value
+  fn get_ptr(&self, _info: Option<&LoadBalanceContext>) -> PointerToUpstream {
+    // Get a current count of upstream served
+    let current_ptr = self.ptr.load(Ordering::Relaxed);
+
+    let ptr = if current_ptr < self.num_upstreams - 1 {
+      self.ptr.fetch_add(1, Ordering::Relaxed)
+    } else {
+      // Clear the counter
+      self.ptr.fetch_and(0, Ordering::Relaxed)
+    };
+    PointerToUpstream { ptr, context: None }
+  }
+}
+
+#[derive(Debug, Clone, Builder)]
+/// Random LB object to keep the object of random pools
+pub struct LoadBalanceRandom {
+  #[builder(setter(custom), default)]
+  /// Number of upstream destinations
+  num_upstreams: usize,
+}
+impl LoadBalanceRandomBuilder {
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+}
+impl LoadBalanceWithPointer for LoadBalanceRandom {
+  /// Returns the random index within the range
+  fn get_ptr(&self, _info: Option<&LoadBalanceContext>) -> PointerToUpstream {
+    let mut rng = rand::thread_rng();
+    let ptr = rng.gen_range(0..self.num_upstreams);
+    PointerToUpstream { ptr, context: None }
+  }
+}
+
+#[derive(Debug, Clone)]
+/// Load Balancing Option
+pub enum LoadBalance {
+  /// Fix to the first upstream. Use if only one upstream destination is specified
+  FixToFirst,
+  /// Randomly chose one upstream server
+  Random(LoadBalanceRandom),
+  /// Simple round robin without session persistance
+  RoundRobin(LoadBalanceRoundRobin),
+  #[cfg(feature = "sticky-cookie")]
+  /// Round robin with session persistance using cookie
+  StickyRoundRobin(LoadBalanceSticky),
+}
+impl Default for LoadBalance {
+  fn default() -> Self {
+    Self::FixToFirst
+  }
+}
+
+impl LoadBalance {
+  /// Get the index of the upstream serving the incoming request
+  pub fn get_context(&self, _context_to_lb: &Option<LoadBalanceContext>) -> PointerToUpstream {
+    match self {
+      LoadBalance::FixToFirst => PointerToUpstream {
+        ptr: 0usize,
+        context: None,
+      },
+      LoadBalance::RoundRobin(ptr) => ptr.get_ptr(None),
+      LoadBalance::Random(ptr) => ptr.get_ptr(None),
+      #[cfg(feature = "sticky-cookie")]
+      LoadBalance::StickyRoundRobin(ptr) => {
+        // Generate new context if sticky round robin is enabled.
+        ptr.get_ptr(_context_to_lb.as_ref())
+      }
+    }
+  }
+}
+
+#[derive(Debug, Clone)]
+/// Struct to handle the sticky cookie string,
+/// - passed from Rp module (http handler) to LB module, manipulated from req, only StickyCookieValue exists.
+/// - passed from LB module to Rp module (http handler), will be inserted into res, StickyCookieValue and Info exist.
+pub struct LoadBalanceContext {
+  #[cfg(feature = "sticky-cookie")]
+  pub sticky_cookie: StickyCookie,
+  #[cfg(not(feature = "sticky-cookie"))]
+  pub sticky_cookie: (),
+}

rpxy-lib/src/backend/load_balance/load_balance_sticky.rs

@@ -0,0 +1,137 @@
+use super::{
+  load_balance_main::{LoadBalanceContext, LoadBalanceWithPointer, PointerToUpstream},
+  sticky_cookie::StickyCookieConfig,
+  Upstream,
+};
+use crate::{constants::STICKY_COOKIE_NAME, log::*};
+use derive_builder::Builder;
+use rustc_hash::FxHashMap as HashMap;
+use std::{
+  borrow::Cow,
+  sync::{
+    atomic::{AtomicUsize, Ordering},
+    Arc,
+  },
+};
+
+#[derive(Debug, Clone, Builder)]
+/// Round Robin LB object in the sticky cookie manner
+pub struct LoadBalanceSticky {
+  #[builder(default)]
+  /// Pointer to the index of the last served upstream destination
+  ptr: Arc<AtomicUsize>,
+  #[builder(setter(custom), default)]
+  /// Number of upstream destinations
+  num_upstreams: usize,
+  #[builder(setter(custom))]
+  /// Information to build the cookie to stick clients to specific backends
+  pub sticky_config: StickyCookieConfig,
+  #[builder(setter(custom))]
+  /// Hashmaps:
+  /// - Hashmap that maps server indices to server id (string)
+  /// - Hashmap that maps server ids (string) to server indices, for fast reverse lookup
+  upstream_maps: UpstreamMap,
+}
+#[derive(Debug, Clone)]
+pub struct UpstreamMap {
+  /// Hashmap that maps server indices to server id (string)
+  upstream_index_map: Vec<String>,
+  /// Hashmap that maps server ids (string) to server indices, for fast reverse lookup
+  upstream_id_map: HashMap<String, usize>,
+}
+impl LoadBalanceStickyBuilder {
+  /// Set the number of upstream destinations
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+  /// Set the information to build the cookie to stick clients to specific backends
+  pub fn sticky_config(&mut self, server_name: &str, path_opt: &Option<String>) -> &mut Self {
+    self.sticky_config = Some(StickyCookieConfig {
+      name: STICKY_COOKIE_NAME.to_string(), // TODO: config等で変更できるように
+      domain: server_name.to_ascii_lowercase(),
+      path: if let Some(v) = path_opt {
+        v.to_ascii_lowercase()
+      } else {
+        "/".to_string()
+      },
+      duration: 300, // TODO: config等で変更できるように
+    });
+    self
+  }
+  /// Set the hashmaps: upstream_index_map and upstream_id_map
+  pub fn upstream_maps(&mut self, upstream_vec: &[Upstream]) -> &mut Self {
+    let upstream_index_map: Vec<String> = upstream_vec
+      .iter()
+      .enumerate()
+      .map(|(i, v)| v.calculate_id_with_index(i))
+      .collect();
+    let mut upstream_id_map = HashMap::default();
+    for (i, v) in upstream_index_map.iter().enumerate() {
+      upstream_id_map.insert(v.to_string(), i);
+    }
+    self.upstream_maps = Some(UpstreamMap {
+      upstream_index_map,
+      upstream_id_map,
+    });
+    self
+  }
+}
+impl<'a> LoadBalanceSticky {
+  /// Increment the count of upstream served up to the max value
+  fn simple_increment_ptr(&self) -> usize {
+    // Get a current count of upstream served
+    let current_ptr = self.ptr.load(Ordering::Relaxed);
+
+    if current_ptr < self.num_upstreams - 1 {
+      self.ptr.fetch_add(1, Ordering::Relaxed)
+    } else {
+      // Clear the counter
+      self.ptr.fetch_and(0, Ordering::Relaxed)
+    }
+  }
+  /// This is always called only internally. So 'unwrap()' is executed.
+  fn get_server_id_from_index(&self, index: usize) -> String {
+    self.upstream_maps.upstream_index_map.get(index).unwrap().to_owned()
+  }
+  /// This function takes value passed from outside. So 'result' is used.
+  fn get_server_index_from_id(&self, id: impl Into<Cow<'a, str>>) -> Option<usize> {
+    let id_str = id.into().to_string();
+    self.upstream_maps.upstream_id_map.get(&id_str).map(|v| v.to_owned())
+  }
+}
+impl LoadBalanceWithPointer for LoadBalanceSticky {
+  /// Get the pointer to the upstream server to serve the incoming request.
+  fn get_ptr(&self, req_info: Option<&LoadBalanceContext>) -> PointerToUpstream {
+    // If given context is None or invalid (not contained), get_ptr() is invoked to increment the pointer.
+    // Otherwise, get the server index indicated by the server_id inside the cookie
+    let ptr = match req_info {
+      None => {
+        debug!("No sticky cookie");
+        self.simple_increment_ptr()
+      }
+      Some(context) => {
+        let server_id = &context.sticky_cookie.value.value;
+        if let Some(server_index) = self.get_server_index_from_id(server_id) {
+          debug!("Valid sticky cookie: id={}, index={}", server_id, server_index);
+          server_index
+        } else {
+          debug!("Invalid sticky cookie: id={}", server_id);
+          self.simple_increment_ptr()
+        }
+      }
+    };
+
+    // Get the server id from the ptr.
+    // TODO: This should be simplified and optimized if ptr is not changed (id value exists in cookie).
+    let upstream_id = self.get_server_id_from_index(ptr);
+    let new_cookie = self.sticky_config.build_sticky_cookie(upstream_id).unwrap();
+    let new_context = Some(LoadBalanceContext {
+      sticky_cookie: new_cookie,
+    });
+    PointerToUpstream {
+      ptr,
+      context: new_context,
+    }
+  }
+}

rpxy-lib/src/backend/load_balance/mod.rs

@@ -0,0 +1,41 @@
+mod load_balance_main;
+#[cfg(feature = "sticky-cookie")]
+mod load_balance_sticky;
+#[cfg(feature = "sticky-cookie")]
+mod sticky_cookie;
+
+use super::upstream::Upstream;
+use thiserror::Error;
+
+pub use load_balance_main::{
+  load_balance_options, LoadBalance, LoadBalanceContext, LoadBalanceRandomBuilder, LoadBalanceRoundRobinBuilder,
+};
+#[cfg(feature = "sticky-cookie")]
+pub use load_balance_sticky::LoadBalanceStickyBuilder;
+
+/// Result type for load balancing
+type LoadBalanceResult<T> = std::result::Result<T, LoadBalanceError>;
+/// Describes things that can go wrong in the Load Balance
+#[derive(Debug, Error)]
+pub enum LoadBalanceError {
+  // backend load balance errors
+  #[cfg(feature = "sticky-cookie")]
+  #[error("Failed to cookie conversion to/from string")]
+  FailedToConversionStickyCookie,
+
+  #[cfg(feature = "sticky-cookie")]
+  #[error("Invalid cookie structure")]
+  InvalidStickyCookieStructure,
+
+  #[cfg(feature = "sticky-cookie")]
+  #[error("No sticky cookie value")]
+  NoStickyCookieValue,
+
+  #[cfg(feature = "sticky-cookie")]
+  #[error("Failed to cookie conversion into string: no meta information")]
+  NoStickyCookieNoMetaInfo,
+
+  #[cfg(feature = "sticky-cookie")]
+  #[error("Failed to build sticky cookie from config")]
+  FailedToBuildStickyCookie,
+}

rpxy-lib/src/backend/load_balance/sticky_cookie.rs

@@ -0,0 +1,205 @@
+use super::{LoadBalanceError, LoadBalanceResult};
+use chrono::{TimeZone, Utc};
+use derive_builder::Builder;
+use std::borrow::Cow;
+
+#[derive(Debug, Clone, Builder)]
+/// Cookie value only, used for COOKIE in req
+pub struct StickyCookieValue {
+  #[builder(setter(custom))]
+  /// Field name indicating sticky cookie
+  pub name: String,
+  #[builder(setter(custom))]
+  /// Upstream server_id
+  pub value: String,
+}
+impl<'a> StickyCookieValueBuilder {
+  pub fn name(&mut self, v: impl Into<Cow<'a, str>>) -> &mut Self {
+    self.name = Some(v.into().to_ascii_lowercase());
+    self
+  }
+  pub fn value(&mut self, v: impl Into<Cow<'a, str>>) -> &mut Self {
+    self.value = Some(v.into().to_string());
+    self
+  }
+}
+impl StickyCookieValue {
+  pub fn try_from(value: &str, expected_name: &str) -> LoadBalanceResult<Self> {
+    if !value.starts_with(expected_name) {
+      return Err(LoadBalanceError::FailedToConversionStickyCookie);
+    };
+    let kv = value.split('=').map(|v| v.trim()).collect::<Vec<&str>>();
+    if kv.len() != 2 {
+      return Err(LoadBalanceError::InvalidStickyCookieStructure);
+    };
+    if kv[1].is_empty() {
+      return Err(LoadBalanceError::NoStickyCookieValue);
+    }
+    Ok(StickyCookieValue {
+      name: expected_name.to_string(),
+      value: kv[1].to_string(),
+    })
+  }
+}
+
+#[derive(Debug, Clone, Builder)]
+/// Struct describing sticky cookie meta information used for SET-COOKIE in res
+pub struct StickyCookieInfo {
+  #[builder(setter(custom))]
+  /// Unix time
+  pub expires: i64,
+
+  #[builder(setter(custom))]
+  /// Domain
+  pub domain: String,
+
+  #[builder(setter(custom))]
+  /// Path
+  pub path: String,
+}
+impl<'a> StickyCookieInfoBuilder {
+  pub fn domain(&mut self, v: impl Into<Cow<'a, str>>) -> &mut Self {
+    self.domain = Some(v.into().to_ascii_lowercase());
+    self
+  }
+  pub fn path(&mut self, v: impl Into<Cow<'a, str>>) -> &mut Self {
+    self.path = Some(v.into().to_ascii_lowercase());
+    self
+  }
+  pub fn expires(&mut self, duration_secs: i64) -> &mut Self {
+    let current = Utc::now().timestamp();
+    self.expires = Some(current + duration_secs);
+    self
+  }
+}
+
+#[derive(Debug, Clone, Builder)]
+/// Struct describing sticky cookie
+pub struct StickyCookie {
+  #[builder(setter(custom))]
+  /// Upstream server_id
+  pub value: StickyCookieValue,
+  #[builder(setter(custom), default)]
+  /// Upstream server_id
+  pub info: Option<StickyCookieInfo>,
+}
+
+impl<'a> StickyCookieBuilder {
+  /// Set the value of sticky cookie
+  pub fn value(&mut self, n: impl Into<Cow<'a, str>>, v: impl Into<Cow<'a, str>>) -> &mut Self {
+    self.value = Some(StickyCookieValueBuilder::default().name(n).value(v).build().unwrap());
+    self
+  }
+  /// Set the meta information of sticky cookie
+  pub fn info(
+    &mut self,
+    domain: impl Into<Cow<'a, str>>,
+    path: impl Into<Cow<'a, str>>,
+    duration_secs: i64,
+  ) -> &mut Self {
+    let info = StickyCookieInfoBuilder::default()
+      .domain(domain)
+      .path(path)
+      .expires(duration_secs)
+      .build()
+      .unwrap();
+    self.info = Some(Some(info));
+    self
+  }
+}
+
+impl TryInto<String> for StickyCookie {
+  type Error = LoadBalanceError;
+
+  fn try_into(self) -> LoadBalanceResult<String> {
+    if self.info.is_none() {
+      return Err(LoadBalanceError::NoStickyCookieNoMetaInfo);
+    }
+    let info = self.info.unwrap();
+    let chrono::LocalResult::Single(expires_timestamp) = Utc.timestamp_opt(info.expires, 0) else {
+      return Err(LoadBalanceError::FailedToConversionStickyCookie);
+    };
+    let exp_str = expires_timestamp.format("%a, %d-%b-%Y %T GMT").to_string();
+    let max_age = info.expires - Utc::now().timestamp();
+
+    Ok(format!(
+      "{}={}; expires={}; Max-Age={}; path={}; domain={}",
+      self.value.name, self.value.value, exp_str, max_age, info.path, info.domain
+    ))
+  }
+}
+
+#[derive(Debug, Clone)]
+/// Configuration to serve incoming requests in the manner of "sticky cookie".
+/// Including a dictionary to map Ids included in cookie and upstream destinations,
+/// and expiration of cookie.
+/// "domain" and "path" in the cookie will be the same as the reverse proxy options.
+pub struct StickyCookieConfig {
+  pub name: String,
+  pub domain: String,
+  pub path: String,
+  pub duration: i64,
+}
+impl<'a> StickyCookieConfig {
+  pub fn build_sticky_cookie(&self, v: impl Into<Cow<'a, str>>) -> LoadBalanceResult<StickyCookie> {
+    StickyCookieBuilder::default()
+      .value(self.name.clone(), v)
+      .info(&self.domain, &self.path, self.duration)
+      .build()
+      .map_err(|_| LoadBalanceError::FailedToBuildStickyCookie)
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use crate::constants::STICKY_COOKIE_NAME;
+
+  #[test]
+  fn config_works() {
+    let config = StickyCookieConfig {
+      name: STICKY_COOKIE_NAME.to_string(),
+      domain: "example.com".to_string(),
+      path: "/path".to_string(),
+      duration: 100,
+    };
+    let expires_unix = Utc::now().timestamp() + 100;
+    let sc_string: LoadBalanceResult<String> = config.build_sticky_cookie("test_value").unwrap().try_into();
+    let expires_date_string = Utc
+      .timestamp_opt(expires_unix, 0)
+      .unwrap()
+      .format("%a, %d-%b-%Y %T GMT")
+      .to_string();
+    assert_eq!(
+      sc_string.unwrap(),
+      format!(
+        "{}=test_value; expires={}; Max-Age={}; path=/path; domain=example.com",
+        STICKY_COOKIE_NAME, expires_date_string, 100
+      )
+    );
+  }
+  #[test]
+  fn to_string_works() {
+    let sc = StickyCookie {
+      value: StickyCookieValue {
+        name: STICKY_COOKIE_NAME.to_string(),
+        value: "test_value".to_string(),
+      },
+      info: Some(StickyCookieInfo {
+        expires: 1686221173i64,
+        domain: "example.com".to_string(),
+        path: "/path".to_string(),
+      }),
+    };
+    let sc_string: LoadBalanceResult<String> = sc.try_into();
+    let max_age = 1686221173i64 - Utc::now().timestamp();
+    assert!(sc_string.is_ok());
+    assert_eq!(
+      sc_string.unwrap(),
+      format!(
+        "{}=test_value; expires=Thu, 08-Jun-2023 10:46:13 GMT; Max-Age={}; path=/path; domain=example.com",
+        STICKY_COOKIE_NAME, max_age
+      )
+    );
+  }
+}

rpxy-lib/src/backend/mod.rs

@@ -0,0 +1,14 @@
+mod backend_main;
+mod load_balance;
+mod upstream;
+mod upstream_opts;
+
+pub use backend_main::{BackendAppBuilderError, BackendAppManager};
+pub use upstream::Upstream;
+// #[cfg(feature = "sticky-cookie")]
+// pub use sticky_cookie::{StickyCookie, StickyCookieValue};
+// pub use self::{
+//   load_balance::{LbContext, LoadBalance},
+//   upstream::{ReverseProxy, Upstream, UpstreamGroup, UpstreamGroupBuilder},
+//   upstream_opts::UpstreamOption,
+// };

rpxy-lib/src/backend/upstream.rs

@@ -0,0 +1,266 @@
+#[cfg(feature = "sticky-cookie")]
+use super::load_balance::LoadBalanceStickyBuilder;
+use super::load_balance::{
+  load_balance_options as lb_opts, LoadBalance, LoadBalanceContext, LoadBalanceRandomBuilder,
+  LoadBalanceRoundRobinBuilder,
+};
+// use super::{BytesName, LbContext, PathNameBytesExp, UpstreamOption};
+use super::upstream_opts::UpstreamOption;
+use crate::{
+  certs::CryptoSource,
+  error::RpxyError,
+  globals::{AppConfig, UpstreamUri},
+  log::*,
+  name_exp::{ByteName, PathName},
+};
+#[cfg(feature = "sticky-cookie")]
+use base64::{engine::general_purpose, Engine as _};
+use derive_builder::Builder;
+use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
+#[cfg(feature = "sticky-cookie")]
+use sha2::{Digest, Sha256};
+use std::borrow::Cow;
+
+#[derive(Debug, Clone)]
+/// Handler for given path to route incoming request to path's corresponding upstream server(s).
+pub struct PathManager {
+  /// HashMap of upstream candidate server info, key is path name
+  /// TODO: HashMapでいいのかは疑問。max_by_keyでlongest prefix matchしてるのも無駄っぽいが。。。
+  inner: HashMap<PathName, UpstreamCandidates>,
+}
+
+impl<T> TryFrom<&AppConfig<T>> for PathManager
+where
+  T: CryptoSource,
+{
+  type Error = RpxyError;
+  fn try_from(app_config: &AppConfig<T>) -> Result<Self, Self::Error> {
+    let mut inner: HashMap<PathName, UpstreamCandidates> = HashMap::default();
+
+    app_config.reverse_proxy.iter().for_each(|rpc| {
+      let upstream_vec: Vec<Upstream> = rpc.upstream.iter().map(Upstream::from).collect();
+      let elem = UpstreamCandidatesBuilder::default()
+        .upstream(&upstream_vec)
+        .path(&rpc.path)
+        .replace_path(&rpc.replace_path)
+        .load_balance(&rpc.load_balance, &upstream_vec, &app_config.server_name, &rpc.path)
+        .options(&rpc.upstream_options)
+        .build()
+        .unwrap();
+      inner.insert(elem.path.clone(), elem);
+    });
+
+    if app_config.reverse_proxy.iter().filter(|rpc| rpc.path.is_none()).count() >= 2 {
+      error!("Multiple default reverse proxy setting");
+      return Err(RpxyError::InvalidReverseProxyConfig);
+    }
+
+    if !(inner.iter().all(|(_, elem)| {
+      !(elem.options.contains(&UpstreamOption::ForceHttp11Upstream)
+        && elem.options.contains(&UpstreamOption::ForceHttp2Upstream))
+    })) {
+      error!("Either one of force_http11 or force_http2 can be enabled");
+      return Err(RpxyError::InvalidUpstreamOptionSetting);
+    }
+
+    Ok(PathManager { inner })
+  }
+}
+
+impl PathManager {
+  /// Get an appropriate upstream destinations for given path string.
+  /// trie使ってlongest prefix match させてもいいけどルート記述は少ないと思われるので、
+  /// コスト的にこの程度で十分では。
+  pub fn get<'a>(&self, path_str: impl Into<Cow<'a, str>>) -> Option<&UpstreamCandidates> {
+    let path_name = &path_str.to_path_name();
+
+    let matched_upstream = self
+      .inner
+      .iter()
+      .filter(|(route_bytes, _)| {
+        match path_name.starts_with(route_bytes) {
+          true => {
+            route_bytes.len() == 1 // route = '/', i.e., default
+              || match path_name.get(route_bytes.len()) {
+                None => true, // exact case
+                Some(p) => p == &b'/', // sub-path case
+              }
+          }
+          _ => false,
+        }
+      })
+      .max_by_key(|(route_bytes, _)| route_bytes.len());
+    if let Some((path, u)) = matched_upstream {
+      debug!(
+        "Found upstream: {:?}",
+        path.try_into().unwrap_or_else(|_| "<none>".to_string())
+      );
+      Some(u)
+    } else {
+      None
+    }
+  }
+}
+
+#[derive(Debug, Clone)]
+/// Upstream struct just containing uri without path
+pub struct Upstream {
+  /// Base uri without specific path
+  pub uri: hyper::Uri,
+}
+impl From<&UpstreamUri> for Upstream {
+  fn from(value: &UpstreamUri) -> Self {
+    Self {
+      uri: value.inner.clone(),
+    }
+  }
+}
+impl Upstream {
+  #[cfg(feature = "sticky-cookie")]
+  /// Hashing uri with index to avoid collision
+  pub fn calculate_id_with_index(&self, index: usize) -> String {
+    let mut hasher = Sha256::new();
+    let uri_string = format!("{}&index={}", self.uri.clone(), index);
+    hasher.update(uri_string.as_bytes());
+    let digest = hasher.finalize();
+    general_purpose::URL_SAFE_NO_PAD.encode(digest)
+  }
+}
+#[derive(Debug, Clone, Builder)]
+/// Struct serving multiple upstream servers for, e.g., load balancing.
+pub struct UpstreamCandidates {
+  #[builder(setter(custom))]
+  /// Upstream server(s)
+  pub inner: Vec<Upstream>,
+
+  #[builder(setter(custom), default)]
+  /// Path like "/path" in [[PathName]] associated with the upstream server(s)
+  pub path: PathName,
+
+  #[builder(setter(custom), default)]
+  /// Path in [[PathName]] that will be used to replace the "path" part of incoming url
+  pub replace_path: Option<PathName>,
+
+  #[builder(setter(custom), default)]
+  /// Load balancing option
+  pub load_balance: LoadBalance,
+
+  #[builder(setter(custom), default)]
+  /// Activated upstream options defined in [[UpstreamOption]]
+  pub options: HashSet<UpstreamOption>,
+}
+
+impl UpstreamCandidatesBuilder {
+  /// Set the upstream server(s)
+  pub fn upstream(&mut self, upstream_vec: &[Upstream]) -> &mut Self {
+    self.inner = Some(upstream_vec.to_vec());
+    self
+  }
+  /// Set the path like "/path" in [[PathName]] associated with the upstream server(s), default is "/"
+  pub fn path(&mut self, v: &Option<String>) -> &mut Self {
+    let path = match v {
+      Some(p) => p.to_path_name(),
+      None => "/".to_path_name(),
+    };
+    self.path = Some(path);
+    self
+  }
+  /// Set the path in [[PathName]] that will be used to replace the "path" part of incoming url
+  pub fn replace_path(&mut self, v: &Option<String>) -> &mut Self {
+    self.replace_path = Some(v.to_owned().as_ref().map_or_else(|| None, |v| Some(v.to_path_name())));
+    self
+  }
+  /// Set the load balancing option
+  pub fn load_balance(
+    &mut self,
+    v: &Option<String>,
+    // upstream_num: &usize,
+    upstream_vec: &Vec<Upstream>,
+    _server_name: &str,
+    _path_opt: &Option<String>,
+  ) -> &mut Self {
+    let upstream_num = &upstream_vec.len();
+    let lb = if let Some(x) = v {
+      match x.as_str() {
+        lb_opts::FIX_TO_FIRST => LoadBalance::FixToFirst,
+        lb_opts::RANDOM => LoadBalance::Random(
+          LoadBalanceRandomBuilder::default()
+            .num_upstreams(upstream_num)
+            .build()
+            .unwrap(),
+        ),
+        lb_opts::ROUND_ROBIN => LoadBalance::RoundRobin(
+          LoadBalanceRoundRobinBuilder::default()
+            .num_upstreams(upstream_num)
+            .build()
+            .unwrap(),
+        ),
+        #[cfg(feature = "sticky-cookie")]
+        lb_opts::STICKY_ROUND_ROBIN => LoadBalance::StickyRoundRobin(
+          LoadBalanceStickyBuilder::default()
+            .num_upstreams(upstream_num)
+            .sticky_config(_server_name, _path_opt)
+            .upstream_maps(upstream_vec) // TODO:
+            .build()
+            .unwrap(),
+        ),
+        _ => {
+          error!("Specified load balancing option is invalid.");
+          LoadBalance::default()
+        }
+      }
+    } else {
+      LoadBalance::default()
+    };
+    self.load_balance = Some(lb);
+    self
+  }
+  /// Set the activated upstream options defined in [[UpstreamOption]]
+  pub fn options(&mut self, v: &Option<Vec<String>>) -> &mut Self {
+    let opts = if let Some(opts) = v {
+      opts
+        .iter()
+        .filter_map(|str| UpstreamOption::try_from(str.as_str()).ok())
+        .collect::<HashSet<UpstreamOption>>()
+    } else {
+      Default::default()
+    };
+    self.options = Some(opts);
+    self
+  }
+}
+
+impl UpstreamCandidates {
+  /// Get an enabled option of load balancing [[LoadBalance]]
+  pub fn get(&self, context_to_lb: &Option<LoadBalanceContext>) -> (Option<&Upstream>, Option<LoadBalanceContext>) {
+    let pointer_to_upstream = self.load_balance.get_context(context_to_lb);
+    debug!("Upstream of index {} is chosen.", pointer_to_upstream.ptr);
+    debug!("Context to LB (Cookie in Request): {:?}", context_to_lb);
+    debug!(
+      "Context from LB (Set-Cookie in Response): {:?}",
+      pointer_to_upstream.context
+    );
+    (self.inner.get(pointer_to_upstream.ptr), pointer_to_upstream.context)
+  }
+}
+
+#[cfg(test)]
+mod test {
+  #[allow(unused)]
+  use super::*;
+
+  #[cfg(feature = "sticky-cookie")]
+  #[test]
+  fn calc_id_works() {
+    let uri = "https://www.rust-lang.org".parse::<hyper::Uri>().unwrap();
+    let upstream = Upstream { uri };
+    assert_eq!(
+      "eGsjoPbactQ1eUJjafYjPT3ekYZQkaqJnHdA_FMSkgM",
+      upstream.calculate_id_with_index(0)
+    );
+    assert_eq!(
+      "tNVXFJ9eNCT2mFgKbYq35XgH5q93QZtfU8piUiiDxVA",
+      upstream.calculate_id_with_index(1)
+    );
+  }
+}

rpxy-lib/src/backend/upstream_opts.rs

@@ -0,0 +1,22 @@
+use crate::error::*;
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq)]
+pub enum UpstreamOption {
+  OverrideHost,
+  UpgradeInsecureRequests,
+  ForceHttp11Upstream,
+  ForceHttp2Upstream,
+  // TODO: Adds more options for heder override
+}
+impl TryFrom<&str> for UpstreamOption {
+  type Error = RpxyError;
+  fn try_from(val: &str) -> RpxyResult<Self> {
+    match val {
+      "override_host" => Ok(Self::OverrideHost),
+      "upgrade_insecure_requests" => Ok(Self::UpgradeInsecureRequests),
+      "force_http11_upstream" => Ok(Self::ForceHttp11Upstream),
+      "force_http2_upstream" => Ok(Self::ForceHttp2Upstream),
+      _ => Err(RpxyError::UnsupportedUpstreamOption),
+    }
+  }
+}

rpxy-lib/src/error.rs

@@ -8,4 +8,15 @@ pub type RpxyResult<T> = std::result::Result<T, RpxyError>;
 pub enum RpxyError {
   #[error("IO error: {0}")]
   Io(#[from] std::io::Error),
+
+  // backend errors
+  #[error("Invalid reverse proxy setting")]
+  InvalidReverseProxyConfig,
+  #[error("Invalid upstream option setting")]
+  InvalidUpstreamOptionSetting,
+  #[error("Failed to build backend app")]
+  FailedToBuildBackendApp(#[from] crate::backend::BackendAppBuilderError),
+
+  #[error("Unsupported upstream option")]
+  UnsupportedUpstreamOption,
 }

rpxy-lib/src/lib.rs

@@ -1,3 +1,4 @@
+mod backend;
 mod certs;
 mod constants;
 mod count;
@@ -5,6 +6,7 @@ mod error;
 mod globals;
 mod hyper_executor;
 mod log;
+mod name_exp;
 mod proxy;
 
 use crate::{error::*, globals::Globals, log::*, proxy::Proxy};
@@ -70,8 +72,8 @@ where
     term_notify: term_notify.clone(),
   });
 
-  // TODO: 1. build backends, and make it contained in Arc
+  // 1. build backends, and make it contained in Arc
-  // app_config_list: app_config_list.clone(),
+  let app_manager = Arc::new(backend::BackendAppManager::try_from(app_config_list)?);
 
   // TODO: 2. build message handler with Arc-ed http_client and backends, and make it contained in Arc as well
   // // build message handler including a request forwarder

rpxy-lib/src/name_exp.rs

@@ -0,0 +1,160 @@
+use std::borrow::Cow;
+
+/// Server name (hostname or ip address) representation in bytes-based struct
+/// for searching hashmap or key list by exact or longest-prefix matching
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Default)]
+pub struct ServerName {
+  inner: Vec<u8>, // lowercase ascii bytes
+}
+impl From<&str> for ServerName {
+  fn from(s: &str) -> Self {
+    let name = s.bytes().collect::<Vec<u8>>().to_ascii_lowercase();
+    Self { inner: name }
+  }
+}
+impl From<&[u8]> for ServerName {
+  fn from(b: &[u8]) -> Self {
+    Self {
+      inner: b.to_ascii_lowercase(),
+    }
+  }
+}
+impl TryInto<String> for &ServerName {
+  type Error = anyhow::Error;
+  fn try_into(self) -> Result<String, Self::Error> {
+    let s = std::str::from_utf8(&self.inner)?;
+    Ok(s.to_string())
+  }
+}
+impl AsRef<[u8]> for ServerName {
+  fn as_ref(&self) -> &[u8] {
+    self.inner.as_ref()
+  }
+}
+
+/// Path name, like "/path/ok", represented in bytes-based struct
+/// for searching hashmap or key list by exact or longest-prefix matching
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Default)]
+pub struct PathName {
+  inner: Vec<u8>, // lowercase ascii bytes
+}
+impl From<&str> for PathName {
+  fn from(s: &str) -> Self {
+    let name = s.bytes().collect::<Vec<u8>>().to_ascii_lowercase();
+    Self { inner: name }
+  }
+}
+impl From<&[u8]> for PathName {
+  fn from(b: &[u8]) -> Self {
+    Self {
+      inner: b.to_ascii_lowercase(),
+    }
+  }
+}
+impl TryInto<String> for &PathName {
+  type Error = anyhow::Error;
+  fn try_into(self) -> Result<String, Self::Error> {
+    let s = std::str::from_utf8(&self.inner)?;
+    Ok(s.to_string())
+  }
+}
+impl AsRef<[u8]> for PathName {
+  fn as_ref(&self) -> &[u8] {
+    self.inner.as_ref()
+  }
+}
+impl PathName {
+  pub fn len(&self) -> usize {
+    self.inner.len()
+  }
+  pub fn is_empty(&self) -> bool {
+    self.inner.len() == 0
+  }
+  pub fn get<I>(&self, index: I) -> Option<&I::Output>
+  where
+    I: std::slice::SliceIndex<[u8]>,
+  {
+    self.inner.get(index)
+  }
+  pub fn starts_with(&self, needle: &Self) -> bool {
+    self.inner.starts_with(&needle.inner)
+  }
+}
+
+/// Trait to express names in ascii-lowercased bytes
+pub trait ByteName {
+  type OutputServer: Send + Sync + 'static;
+  type OutputPath;
+  fn to_server_name(self) -> Self::OutputServer;
+  fn to_path_name(self) -> Self::OutputPath;
+}
+
+impl<'a, T: Into<Cow<'a, str>>> ByteName for T {
+  type OutputServer = ServerName;
+  type OutputPath = PathName;
+
+  fn to_server_name(self) -> Self::OutputServer {
+    ServerName::from(self.into().as_ref())
+  }
+
+  fn to_path_name(self) -> Self::OutputPath {
+    PathName::from(self.into().as_ref())
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  #[test]
+  fn bytes_name_str_works() {
+    let s = "OK_string";
+    let bn = s.to_path_name();
+    let bn_lc = s.to_server_name();
+
+    assert_eq!("ok_string".as_bytes(), bn.as_ref());
+    assert_eq!("ok_string".as_bytes(), bn_lc.as_ref());
+  }
+
+  #[test]
+  fn from_works() {
+    let s = "OK_string".to_server_name();
+    let m = ServerName::from("OK_strinG".as_bytes());
+    assert_eq!(s, m);
+    assert_eq!(s.as_ref(), "ok_string".as_bytes());
+    assert_eq!(m.as_ref(), "ok_string".as_bytes());
+  }
+
+  #[test]
+  fn get_works() {
+    let s = "OK_str".to_path_name();
+    let i = s.get(0);
+    assert_eq!(Some(&"o".as_bytes()[0]), i);
+    let i = s.get(1);
+    assert_eq!(Some(&"k".as_bytes()[0]), i);
+    let i = s.get(2);
+    assert_eq!(Some(&"_".as_bytes()[0]), i);
+    let i = s.get(3);
+    assert_eq!(Some(&"s".as_bytes()[0]), i);
+    let i = s.get(4);
+    assert_eq!(Some(&"t".as_bytes()[0]), i);
+    let i = s.get(5);
+    assert_eq!(Some(&"r".as_bytes()[0]), i);
+    let i = s.get(6);
+    assert_eq!(None, i);
+  }
+
+  #[test]
+  fn start_with_works() {
+    let s = "OK_str".to_path_name();
+    let correct = "OK".to_path_name();
+    let incorrect = "KO".to_path_name();
+    assert!(s.starts_with(&correct));
+    assert!(!s.starts_with(&incorrect));
+  }
+
+  #[test]
+  fn as_ref_works() {
+    let s = "OK_str".to_path_name();
+    assert_eq!(s.as_ref(), "ok_str".as_bytes());
+  }
+}

rpxy-lib/src/proxy/mod.rs

@@ -1,5 +1,6 @@
 mod proxy_main;
 mod socket;
+mod proxy_tls;
 
 use crate::{globals::Globals, hyper_executor::LocalExecutor};
 use hyper_util::server::{self, conn::auto::Builder as ConnectionBuilder};

rpxy-lib/src/proxy/proxy_main.rs

@@ -1,10 +1,11 @@
 use super::socket::bind_tcp_socket;
-use crate::{error::RpxyResult, globals::Globals, hyper_executor::LocalExecutor, log::*};
+use crate::{error::RpxyResult, globals::Globals, log::*};
+use hot_reload::{ReloaderReceiver, ReloaderService};
 use hyper_util::server::conn::auto::Builder as ConnectionBuilder;
 use std::{net::SocketAddr, sync::Arc};
 
 /// Proxy main object responsible to serve requests received from clients at the given socket address.
-pub(crate) struct Proxy<E = LocalExecutor> {
+pub(crate) struct Proxy<E> {
   /// global context shared among async tasks
   pub globals: Arc<Globals>,
   /// listen socket address
@@ -15,7 +16,7 @@ pub(crate) struct Proxy<E = LocalExecutor> {
   pub connection_builder: Arc<ConnectionBuilder<E>>,
 }
 
-impl Proxy {
+impl<E> Proxy<E> {
   /// Start without TLS (HTTP cleartext)
   async fn start_without_tls(&self) -> RpxyResult<()> {
     let listener_service = async {
@@ -31,14 +32,27 @@ impl Proxy {
     Ok(())
   }
 
+  /// Start with TLS (HTTPS)
+  pub(super) async fn start_with_tls(&self) -> RpxyResult<()> {
+    // let (cert_reloader_service, cert_reloader_rx) = ReloaderService::<CryptoReloader<U>, ServerCryptoBase>::new(
+    //   &self.globals.clone(),
+    //   CERTS_WATCH_DELAY_SECS,
+    //   !LOAD_CERTS_ONLY_WHEN_UPDATED,
+    // )
+    // .await
+    // .map_err(|e| anyhow::anyhow!(e))?;
+    loop {}
+    Ok(())
+  }
+
   /// Entrypoint for HTTP/1.1, 2 and 3 servers
   pub async fn start(&self) -> RpxyResult<()> {
     let proxy_service = async {
-      // if self.tls_enabled {
+      if self.tls_enabled {
-      // self.start_with_tls().await
+        self.start_with_tls().await
-      // } else {
+      } else {
-      self.start_without_tls().await
+        self.start_without_tls().await
-      // }
+      }
     };
 
     match &self.globals.term_notify {

rpxy-lib/src/proxy/proxy_tls.rs

@@ -0,0 +1,6 @@
+use super::proxy_main::Proxy;
+use crate::{log::*, error::*};
+
+impl<E> Proxy<E>{
+
+}