wip: refactor whole module in lib

legacy-lib/src/backend/load_balance.rs

@@ -0,0 +1,135 @@
+#[cfg(feature = "sticky-cookie")]
+pub use super::{
+  load_balance_sticky::{LbStickyRoundRobin, LbStickyRoundRobinBuilder},
+  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(super) 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(super) struct PointerToUpstream {
+  pub ptr: usize,
+  pub context_lb: Option<LbContext>,
+}
+/// Trait for LB
+pub(super) trait LbWithPointer {
+  fn get_ptr(&self, req_info: Option<&LbContext>) -> PointerToUpstream;
+}
+
+#[derive(Debug, Clone, Builder)]
+/// Round Robin LB object as a pointer to the current serving upstream destination
+pub struct LbRoundRobin {
+  #[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 LbRoundRobinBuilder {
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+}
+impl LbWithPointer for LbRoundRobin {
+  /// Increment the count of upstream served up to the max value
+  fn get_ptr(&self, _info: Option<&LbContext>) -> 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_lb: None }
+  }
+}
+
+#[derive(Debug, Clone, Builder)]
+/// Random LB object to keep the object of random pools
+pub struct LbRandom {
+  #[builder(setter(custom), default)]
+  /// Number of upstream destinations
+  num_upstreams: usize,
+}
+impl LbRandomBuilder {
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+}
+impl LbWithPointer for LbRandom {
+  /// Returns the random index within the range
+  fn get_ptr(&self, _info: Option<&LbContext>) -> PointerToUpstream {
+    let mut rng = rand::thread_rng();
+    let ptr = rng.gen_range(0..self.num_upstreams);
+    PointerToUpstream { ptr, context_lb: 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(LbRandom),
+  /// Simple round robin without session persistance
+  RoundRobin(LbRoundRobin),
+  #[cfg(feature = "sticky-cookie")]
+  /// Round robin with session persistance using cookie
+  StickyRoundRobin(LbStickyRoundRobin),
+}
+impl Default for LoadBalance {
+  fn default() -> Self {
+    Self::FixToFirst
+  }
+}
+
+impl LoadBalance {
+  /// Get the index of the upstream serving the incoming request
+  pub(super) fn get_context(&self, _context_to_lb: &Option<LbContext>) -> PointerToUpstream {
+    match self {
+      LoadBalance::FixToFirst => PointerToUpstream {
+        ptr: 0usize,
+        context_lb: 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 LbContext {
+  #[cfg(feature = "sticky-cookie")]
+  pub sticky_cookie: StickyCookie,
+  #[cfg(not(feature = "sticky-cookie"))]
+  pub sticky_cookie: (),
+}

legacy-lib/src/backend/load_balance_sticky.rs

@@ -0,0 +1,132 @@
+use super::{
+  load_balance::{LbContext, LbWithPointer, 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 LbStickyRoundRobin {
+  #[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 LbStickyRoundRobinBuilder {
+  pub fn num_upstreams(&mut self, v: &usize) -> &mut Self {
+    self.num_upstreams = Some(*v);
+    self
+  }
+  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
+  }
+  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> LbStickyRoundRobin {
+  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 LbWithPointer for LbStickyRoundRobin {
+  fn get_ptr(&self, req_info: Option<&LbContext>) -> 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(LbContext {
+      sticky_cookie: new_cookie,
+    });
+    PointerToUpstream {
+      ptr,
+      context_lb: new_context,
+    }
+  }
+}

legacy-lib/src/backend/mod.rs

@@ -0,0 +1,77 @@
+mod load_balance;
+#[cfg(feature = "sticky-cookie")]
+mod load_balance_sticky;
+#[cfg(feature = "sticky-cookie")]
+mod sticky_cookie;
+mod upstream;
+mod upstream_opts;
+
+#[cfg(feature = "sticky-cookie")]
+pub use self::sticky_cookie::{StickyCookie, StickyCookieValue};
+pub use self::{
+  load_balance::{LbContext, LoadBalance},
+  upstream::{ReverseProxy, Upstream, UpstreamGroup, UpstreamGroupBuilder},
+  upstream_opts::UpstreamOption,
+};
+use crate::{
+  certs::CryptoSource,
+  utils::{BytesName, PathNameBytesExp, ServerNameBytesExp},
+};
+use derive_builder::Builder;
+use rustc_hash::FxHashMap as HashMap;
+use std::borrow::Cow;
+
+/// Struct serving information to route incoming connections, like server name to be handled and tls certs/keys settings.
+#[derive(Builder)]
+pub struct Backend<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 String ascii lower case
+  pub server_name: String,
+  /// struct of reverse proxy serving incoming request
+  pub reverse_proxy: ReverseProxy,
+
+  /// 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> BackendBuilder<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.into().to_ascii_lowercase());
+    self
+  }
+}
+
+/// HashMap and some meta information for multiple Backend structs.
+pub struct Backends<T>
+where
+  T: CryptoSource,
+{
+  pub apps: HashMap<ServerNameBytesExp, Backend<T>>, // hyper::uriで抜いたhostで引っ掛ける
+  pub default_server_name_bytes: Option<ServerNameBytesExp>, // for plaintext http
+}
+
+impl<T> Backends<T>
+where
+  T: CryptoSource,
+{
+  #[allow(clippy::new_without_default)]
+  pub fn new() -> Self {
+    Backends {
+      apps: HashMap::<ServerNameBytesExp, Backend<T>>::default(),
+      default_server_name_bytes: None,
+    }
+  }
+}

legacy-lib/src/backend/sticky_cookie.rs

@@ -0,0 +1,208 @@
+use std::borrow::Cow;
+
+use crate::error::*;
+use chrono::{TimeZone, Utc};
+use derive_builder::Builder;
+
+#[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) -> Result<Self> {
+    if !value.starts_with(expected_name) {
+      return Err(RpxyError::LoadBalance(
+        "Failed to cookie conversion from string".to_string(),
+      ));
+    };
+    let kv = value.split('=').map(|v| v.trim()).collect::<Vec<&str>>();
+    if kv.len() != 2 {
+      return Err(RpxyError::LoadBalance("Invalid cookie structure".to_string()));
+    };
+    if kv[1].is_empty() {
+      return Err(RpxyError::LoadBalance("No sticky cookie value".to_string()));
+    }
+    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 {
+  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
+  }
+  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 = RpxyError;
+
+  fn try_into(self) -> Result<String> {
+    if self.info.is_none() {
+      return Err(RpxyError::LoadBalance(
+        "Failed to cookie conversion into string: no meta information".to_string(),
+      ));
+    }
+    let info = self.info.unwrap();
+    let chrono::LocalResult::Single(expires_timestamp) = Utc.timestamp_opt(info.expires, 0) else {
+      return Err(RpxyError::LoadBalance("Failed to cookie conversion into string".to_string()));
+    };
+    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>>) -> Result<StickyCookie> {
+    StickyCookieBuilder::default()
+      .value(self.name.clone(), v)
+      .info(&self.domain, &self.path, self.duration)
+      .build()
+      .map_err(|_| RpxyError::LoadBalance("Failed to build sticky cookie from config".to_string()))
+  }
+}
+
+#[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: Result<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: Result<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
+      )
+    );
+  }
+}

legacy-lib/src/backend/upstream.rs

@@ -0,0 +1,201 @@
+#[cfg(feature = "sticky-cookie")]
+use super::load_balance::LbStickyRoundRobinBuilder;
+use super::load_balance::{load_balance_options as lb_opts, LbRandomBuilder, LbRoundRobinBuilder, LoadBalance};
+use super::{BytesName, LbContext, PathNameBytesExp, UpstreamOption};
+use crate::log::*;
+#[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)]
+pub struct ReverseProxy {
+  pub upstream: HashMap<PathNameBytesExp, UpstreamGroup>, // 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。。。
+}
+
+impl ReverseProxy {
+  /// Get an appropriate upstream destination for given path string.
+  pub fn get<'a>(&self, path_str: impl Into<Cow<'a, str>>) -> Option<&UpstreamGroup> {
+    // 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
+    let path_bytes = &path_str.to_path_name_vec();
+
+    let matched_upstream = self
+      .upstream
+      .iter()
+      .filter(|(route_bytes, _)| {
+        match path_bytes.starts_with(route_bytes) {
+          true => {
+            route_bytes.len() == 1 // route = '/', i.e., default
+            || match path_bytes.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: {:?}",
+        String::from_utf8(_path.0.clone()).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 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 UpstreamGroup {
+  #[builder(setter(custom))]
+  /// Upstream server(s)
+  pub upstream: Vec<Upstream>,
+  #[builder(setter(custom), default)]
+  /// Path like "/path" in [[PathNameBytesExp]] associated with the upstream server(s)
+  pub path: PathNameBytesExp,
+  #[builder(setter(custom), default)]
+  /// Path in [[PathNameBytesExp]] that will be used to replace the "path" part of incoming url
+  pub replace_path: Option<PathNameBytesExp>,
+
+  #[builder(setter(custom), default)]
+  /// Load balancing option
+  pub lb: LoadBalance,
+  #[builder(setter(custom), default)]
+  /// Activated upstream options defined in [[UpstreamOption]]
+  pub opts: HashSet<UpstreamOption>,
+}
+
+impl UpstreamGroupBuilder {
+  pub fn upstream(&mut self, upstream_vec: &[Upstream]) -> &mut Self {
+    self.upstream = Some(upstream_vec.to_vec());
+    self
+  }
+  pub fn path(&mut self, v: &Option<String>) -> &mut Self {
+    let path = match v {
+      Some(p) => p.to_path_name_vec(),
+      None => "/".to_path_name_vec(),
+    };
+    self.path = Some(path);
+    self
+  }
+  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_vec())),
+    );
+    self
+  }
+  pub fn lb(
+    &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(LbRandomBuilder::default().num_upstreams(upstream_num).build().unwrap()),
+        lb_opts::ROUND_ROBIN => LoadBalance::RoundRobin(
+          LbRoundRobinBuilder::default()
+            .num_upstreams(upstream_num)
+            .build()
+            .unwrap(),
+        ),
+        #[cfg(feature = "sticky-cookie")]
+        lb_opts::STICKY_ROUND_ROBIN => LoadBalance::StickyRoundRobin(
+          LbStickyRoundRobinBuilder::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.lb = Some(lb);
+    self
+  }
+  pub fn opts(&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.opts = Some(opts);
+    self
+  }
+}
+
+impl UpstreamGroup {
+  /// Get an enabled option of load balancing [[LoadBalance]]
+  pub fn get(&self, context_to_lb: &Option<LbContext>) -> (Option<&Upstream>, Option<LbContext>) {
+    let pointer_to_upstream = self.lb.get_context(context_to_lb);
+    debug!("Upstream of index {} is chosen.", pointer_to_upstream.ptr);
+    debug!("Context to LB (Cookie in Req): {:?}", context_to_lb);
+    debug!(
+      "Context from LB (Set-Cookie in Res): {:?}",
+      pointer_to_upstream.context_lb
+    );
+    (
+      self.upstream.get(pointer_to_upstream.ptr),
+      pointer_to_upstream.context_lb,
+    )
+  }
+}
+
+#[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)
+    );
+  }
+}

legacy-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) -> Result<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::Other(anyhow!("Unsupported header option"))),
+    }
+  }
+}