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Diffstat (limited to 'crates/chat-server/src/service.rs')
| -rw-r--r-- | crates/chat-server/src/service.rs | 438 |
1 files changed, 438 insertions, 0 deletions
diff --git a/crates/chat-server/src/service.rs b/crates/chat-server/src/service.rs new file mode 100644 index 0000000..3f9b6ee --- /dev/null +++ b/crates/chat-server/src/service.rs @@ -0,0 +1,438 @@ +// Copyright (C) 2026 Doan Luu Duc Tai <doan@luuduct.ai> +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU Affero General Public License as +// published by the Free Software Foundation, either version 3 of the +// License, or (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Affero General Public License for more details. +// +// You should have received a copy of the GNU Affero General Public License +// along with this program. If not, see <https://www.gnu.org/licenses/>. + +use crate::store::Store; +use anyhow::{Context, Result, ensure}; +use base64::{Engine, prelude::BASE64_STANDARD}; +use serde_json::{Value, json}; +use std::collections::HashMap; +use std::time::{Duration, Instant}; + +struct Challenge { + certificate: String, + text: String, + expiry: Instant, + setup: bool, +} + +struct Session { + identity: String, + expiry: Instant, +} + +pub(crate) struct Service { + pub(crate) store: Store, + pub(crate) origin: String, + setup_token: String, + challenges: HashMap<String, Challenge>, + sessions: HashMap<String, Session>, + window: Instant, + attempts: u16, +} + +pub(crate) fn token() -> Result<String> { + let mut bytes = [0; 32]; + openssl::rand::rand_bytes(&mut bytes)?; + Ok(hex::encode(bytes)) +} + +pub(crate) fn field<'a>(request: &'a Value, key: &str) -> Result<&'a str> { + request + .get(key) + .and_then(Value::as_str) + .context("Missing string field") +} + +fn ciphertext(request: &Value) -> Result<&str> { + let encoded = field(request, "ciphertext")?; + ensure!( + encoded.len() <= 65_536 && BASE64_STANDARD.decode(encoded)?.len() >= 64, + "Invalid ciphertext length" + ); + Ok(encoded) +} + +fn identifier(value: &str) -> Result<()> { + ensure!( + value.len() == 64 && value.bytes().all(|byte| byte.is_ascii_hexdigit()), + "Invalid identifier" + ); + Ok(()) +} + +impl Service { + pub(crate) fn new(store: Store, origin: String, setup_token: String) -> Self { + Self { + store, + origin, + setup_token, + challenges: HashMap::new(), + sessions: HashMap::new(), + window: Instant::now(), + attempts: 0, + } + } + + fn owner_id(&self) -> Result<String> { + stack_chat_crypto::public_identity(&self.store.owner()?.context("Owner not initialized")?) + } + + fn challenge(&mut self, request: &Value) -> Result<Value> { + if self.window.elapsed() >= Duration::from_secs(60) { + self.window = Instant::now(); + self.attempts = 0; + } + ensure!(self.attempts < 60, "Authentication rate exceeded"); + self.attempts = self + .attempts + .checked_add(1) + .context("Rate counter overflow")?; + self.challenges + .retain(|_, challenge| challenge.expiry > Instant::now()); + ensure!(self.challenges.len() < 128, "Too many pending challenges"); + let certificate = field(request, "public")?; + let fingerprint = stack_chat_crypto::public_identity(certificate)?; + let setup = self.store.owner()?.is_none(); + if setup { + let supplied = field(request, "setup_token")?; + ensure!( + self.setup_token.len() == 64 + && supplied.len() == 64 + && openssl::memcmp::eq(supplied.as_bytes(), self.setup_token.as_bytes()), + "Invalid setup credential" + ); + } + let nonce = token()?; + let expires = std::time::SystemTime::now() + .duration_since(std::time::UNIX_EPOCH)? + .as_secs() + .checked_add(60) + .context("Clock overflow")?; + let owner = if setup { + fingerprint.clone() + } else { + self.owner_id()? + }; + let text = format!( + "stack-chat-auth/v1\n{}\n{fingerprint}\n{nonce}\n{expires}\n{owner}", + self.origin + ); + self.challenges.insert( + nonce.clone(), + Challenge { + certificate: certificate.into(), + text: text.clone(), + expiry: Instant::now() + .checked_add(Duration::from_secs(60)) + .context("Clock overflow")?, + setup, + }, + ); + Ok(json!({"id":nonce,"challenge":text})) + } + + fn authenticate(&mut self, request: &Value) -> Result<Value> { + let challenge = self + .challenges + .remove(field(request, "id")?) + .context("Missing or consumed challenge")?; + ensure!(challenge.expiry > Instant::now(), "Expired challenge"); + stack_chat_crypto::verify_proof( + &challenge.certificate, + &challenge.text, + field(request, "signature")?, + )?; + let identity = stack_chat_crypto::public_identity(&challenge.certificate)?; + if challenge.setup { + self.store.install_owner(&challenge.certificate)?; + self.setup_token.clear(); + } + let owner = identity == self.owner_id()?; + if !owner { + self.store.register(&identity, &challenge.certificate)?; + } + self.sessions + .retain(|_, session| session.expiry > Instant::now()); + ensure!(self.sessions.len() < 256, "Too many sessions"); + let credential = token()?; + self.sessions.insert( + credential.clone(), + Session { + identity: identity.clone(), + expiry: Instant::now() + .checked_add(Duration::from_mins(30)) + .context("Clock overflow")?, + }, + ); + Ok(json!({"token":credential,"owner":owner,"id":identity,"expires_seconds":1800})) + } + + fn principal(&mut self, request: &Value) -> Result<String> { + self.sessions + .retain(|_, session| session.expiry > Instant::now()); + Ok(self + .sessions + .get(field(request, "token")?) + .context("Missing or expired session")? + .identity + .clone()) + } + + fn authorized(&self, request: &Value, identity: &str) -> Result<String> { + let conversation = field(request, "conversation")?; + identifier(conversation)?; + ensure!( + identity == conversation || identity == self.owner_id()?, + "Forbidden conversation" + ); + self.store.conversation(conversation)?; + Ok(conversation.into()) + } + + pub(crate) fn call(&mut self, request: &Value) -> Result<Value> { + match field(request, "op")? { + "config" => Ok( + json!({"owner":self.store.owner()?,"origin":self.origin,"protocol":"stack-chat/v1"}), + ), + "challenge" => self.challenge(request), + "authenticate" => self.authenticate(request), + _ => self.authenticated(request), + } + } + + fn authenticated(&mut self, request: &Value) -> Result<Value> { + let identity = self.principal(request)?; + let operation = field(request, "op")?; + if operation == "lock" { + self.sessions.remove(field(request, "token")?); + return Ok(json!({"locked":true})); + } + if operation == "inbox" { + ensure!(identity == self.owner_id()?, "Owner only"); + return self.store.inbox(); + } + let conversation = self.authorized(request, &identity)?; + match operation { + "history" => self.store.messages( + &conversation, + request + .get("count") + .and_then(Value::as_u64) + .context("Missing count")?, + request.get("before").and_then(Value::as_u64).unwrap_or(0), + ), + "profile" => { + ensure!(identity == conversation, "Visitor only"); + self.store.profile(&conversation, ciphertext(request)?)?; + Ok(json!({"stored":true})) + } + "send" => { + let id = field(request, "id")?; + identifier(id)?; + self.store + .send(&conversation, id, &identity, ciphertext(request)?) + } + _ => anyhow::bail!("Unknown operation"), + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + use tempfile::TempDir; + + struct Identity { + file: String, + public: String, + fingerprint: String, + } + + fn crypto(request: &Value) -> Result<Value> { + let response = + stack_chat_crypto::dispatch(&request.to_string()).map_err(anyhow::Error::msg)?; + Ok(serde_json::from_str(&response)?) + } + + fn identity(name: &str, owner: &str) -> Result<Identity> { + let created = crypto( + &json!({"op":"create","origin":"http://127.0.0.1:9080","name":name,"password":"test-only-strong-password","owner":owner}), + )?; + let file = field(&created, "file")?; + let opened = crypto( + &json!({"op":"open","origin":"http://127.0.0.1:9080","file":file,"password":"test-only-strong-password"}), + )?; + Ok(Identity { + file: file.into(), + public: field(&opened, "public")?.into(), + fingerprint: field(&opened, "fingerprint")?.into(), + }) + } + + fn authenticate(service: &mut Service, identity: &Identity, setup: &str) -> Result<Value> { + let challenge = service + .call(&json!({"op":"challenge","public":identity.public,"setup_token":setup}))?; + let proof = crypto( + &json!({"op":"proof","file":identity.file,"password":"test-only-strong-password","origin":service.origin,"challenge":field(&challenge,"challenge")?}), + )?; + let request = json!({"op":"authenticate","id":field(&challenge,"id")?,"signature":field(&proof,"signature")?}); + let result = service.call(&request)?; + ensure!(service.call(&request).is_err(), "Challenge was replayed"); + Ok(result) + } + + fn reject_expired_and_failed_proofs(service: &mut Service, identity: &Identity) -> Result<()> { + let challenge = service.call(&json!({"op":"challenge","public":identity.public}))?; + let challenge_id = field(&challenge, "id")?; + service + .challenges + .get_mut(challenge_id) + .context("Challenge")? + .expiry = Instant::now(); + let expired = json!({"op":"authenticate","id":challenge_id,"signature":""}); + ensure!( + service.call(&expired).is_err(), + "Expired challenge accepted" + ); + ensure!( + !service.challenges.contains_key(challenge_id), + "Expired challenge retained" + ); + let invalid = service.call(&json!({"op":"challenge","public":identity.public}))?; + let invalid_id = field(&invalid, "id")?; + ensure!( + service + .call(&json!({"op":"authenticate","id":invalid_id,"signature":""})) + .is_err(), + "Invalid proof accepted" + ); + ensure!( + !service.challenges.contains_key(invalid_id), + "Failed challenge reusable" + ); + service.attempts = 60; + ensure!( + service + .call(&json!({"op":"challenge","public":identity.public})) + .is_err(), + "Challenge rate bound" + ); + ensure!( + service.store.install_owner(&identity.public).is_err(), + "Owner overwritten" + ); + Ok(()) + } + + #[test] + fn authorization_replays_history_and_snapshot_recovery() -> Result<()> { + let directory = TempDir::new()?; + let path = directory.path().join("chat.sqlite"); + let setup = token()?; + let mut service = Service::new( + Store::open(&path)?, + "http://127.0.0.1:9080".into(), + setup.clone(), + ); + let owner = identity("Owner", "")?; + ensure!( + service + .call(&json!({"op":"challenge","public":owner.public,"setup_token":"wrong"})) + .is_err(), + "Setup unauthenticated" + ); + let owner_session = authenticate(&mut service, &owner, &setup)?; + ensure!( + owner_session.get("owner") == Some(&json!(true)), + "Owner role" + ); + let visitor = identity("Visitor", &owner.public)?; + let visitor_session = authenticate(&mut service, &visitor, "")?; + let visitor_token = field(&visitor_session, "token")?; + let owner_token = field(&owner_session, "token")?; + let ciphertext = BASE64_STANDARD.encode([42; 128]); + let message_id = token()?; + let send = json!({"op":"send","conversation":visitor.fingerprint,"token":visitor_token,"id":message_id,"ciphertext":ciphertext}); + service.call(&send)?; + service.call(&send)?; + let conflicting = json!({"op":"send","conversation":visitor.fingerprint,"token":visitor_token,"id":message_id,"ciphertext":BASE64_STANDARD.encode([43;128])}); + ensure!( + service.call(&conflicting).is_err(), + "Conflicting ID accepted" + ); + let empty = service.call(&json!({"op":"history","conversation":visitor.fingerprint,"token":visitor_token,"count":0}))?; + ensure!( + empty + .get("messages") + .and_then(Value::as_array) + .is_some_and(Vec::is_empty), + "N=0" + ); + ensure!( + empty + .get("conversation") + .and_then(|value| value.get("total")) + == Some(&json!(1)), + "Retry duplicated message" + ); + ensure!( + service + .call(&json!({"op":"inbox","token":visitor_token})) + .is_err(), + "Visitor read inbox" + ); + ensure!(service.call(&json!({"op":"history","conversation":owner.fingerprint,"token":visitor_token,"count":1})).is_err(), "Wrong conversation accepted"); + service.call(&json!({"op":"send","conversation":visitor.fingerprint,"token":owner_token,"id":token()?,"ciphertext":ciphertext}))?; + let latest = service.call(&json!({"op":"history","conversation":visitor.fingerprint,"token":visitor_token,"count":1}))?; + let sequence = latest + .get("messages") + .and_then(Value::as_array) + .and_then(|messages| messages.first()) + .and_then(|message| message.get("seq")) + .context("Sequence")?; + let older = service.call(&json!({"op":"history","conversation":visitor.fingerprint,"token":visitor_token,"count":1,"before":sequence}))?; + ensure!( + older + .get("messages") + .and_then(Value::as_array) + .is_some_and(|messages| messages.len() == 1), + "Pagination" + ); + ensure!(service.call(&json!({"op":"history","conversation":visitor.fingerprint,"token":visitor_token,"count":51})).is_err(), "History quota"); + reject_expired_and_failed_proofs(&mut service, &visitor)?; + let snapshot = directory.path().join("snapshot.sqlite"); + service.store.snapshot(&snapshot)?; + let restored = Store::open(&snapshot)?; + ensure!( + restored.owner()? == Some(owner.public), + "Owner missing after restore" + ); + ensure!( + restored.conversation(&visitor.fingerprint)?.get("total") == Some(&json!(2)), + "Restored count" + ); + service.call(&json!({"op":"lock","token":visitor_token}))?; + ensure!(service.call(&json!({"op":"history","conversation":visitor.fingerprint,"token":visitor_token,"count":0})).is_err(), "Locked session accepted"); + let session = service.sessions.get_mut(owner_token).context("Session")?; + session.expiry = Instant::now(); + ensure!( + service + .call(&json!({"op":"inbox","token":owner_token})) + .is_err(), + "Expired session accepted" + ); + Ok(()) + } +} |