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fix: don't cache server name lookups indefinitely

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This commit is contained in:
Matthias Ahouansou 2024-06-24 22:12:54 +01:00
parent de0deda179
commit ba8429cafe
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2 changed files with 285 additions and 158 deletions
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371
src/api/server_server.rs
View file

@ -6,7 +6,7 @@ use crate::{
services, utils, Error, PduEvent, Result, Ruma,
};
use axum::{response::IntoResponse, Json};
use axum_extra::headers::authorization::Credentials;
use axum_extra::headers::{authorization::Credentials, CacheControl, Header};
use get_profile_information::v1::ProfileField;
use http::header::AUTHORIZATION;
@ -96,13 +96,6 @@ impl FedDest {
}
}
fn into_uri_string(self) -> String {
match self {
Self::Literal(addr) => addr.to_string(),
Self::Named(host, ref port) => host + port,
}
}
fn hostname(&self) -> String {
match &self {
Self::Literal(addr) => addr.ip().to_string(),
@ -138,8 +131,6 @@ where
debug!("Preparing to send request to {destination}");
let mut write_destination_to_cache = false;
let cached_result = services()
.globals
.actual_destination_cache
@ -148,14 +139,63 @@ where
.get(destination)
.cloned();
let (actual_destination, host) = if let Some(result) = cached_result {
result
let actual_destination = if let Some(DestinationResponse {
actual_destination,
dest_type,
}) = cached_result
{
match dest_type {
DestType::IsIpOrHasPort => actual_destination,
DestType::LookupFailed {
well_known_retry,
well_known_backoff_mins,
} => {
if well_known_retry < Instant::now() {
find_actual_destination(destination, None, false, Some(well_known_backoff_mins))
.await
} else {
write_destination_to_cache = true;
actual_destination
}
}
let result = find_actual_destination(destination).await;
(result.0, result.1.into_uri_string())
DestType::WellKnown { expires } => {
if expires < Instant::now() {
find_actual_destination(destination, None, false, None).await
} else {
actual_destination
}
}
DestType::WellKnownSrv {
srv_expires,
well_known_expires,
well_known_host,
} => {
if well_known_expires < Instant::now() {
find_actual_destination(destination, None, false, None).await
} else if srv_expires < Instant::now() {
find_actual_destination(destination, Some(well_known_host), true, None).await
} else {
actual_destination
}
}
DestType::Srv {
well_known_retry,
well_known_backoff_mins,
srv_expires,
} => {
if well_known_retry < Instant::now() {
find_actual_destination(destination, None, false, Some(well_known_backoff_mins))
.await
} else if srv_expires < Instant::now() {
find_actual_destination(destination, None, true, Some(well_known_backoff_mins))
.await
} else {
actual_destination
}
}
}
} else {
find_actual_destination(destination, None, false, None).await
};
let actual_destination_str = actual_destination.clone().into_https_string();
@ -293,17 +333,6 @@ where
if status == 200 {
debug!("Parsing response bytes from {destination}");
let response = T::IncomingResponse::try_from_http_response(http_response);
if response.is_ok() && write_destination_to_cache {
services()
.globals
.actual_destination_cache
.write()
.await
.insert(
OwnedServerName::from(destination),
(actual_destination, host),
);
}
response.map_err(|e| {
warn!(
@ -348,42 +377,175 @@ fn add_port_to_hostname(destination_str: &str) -> FedDest {
FedDest::Named(host.to_owned(), port.to_owned())
}
/// Returns: actual_destination, host header
/// Implemented according to the specification at <https://matrix.org/docs/spec/server_server/r0.1.4#resolving-server-names>
#[derive(Clone)]
pub struct DestinationResponse {
pub actual_destination: FedDest,
pub dest_type: DestType,
}
#[derive(Clone)]
pub enum DestType {
WellKnownSrv {
srv_expires: Instant,
well_known_expires: Instant,
well_known_host: String,
},
WellKnown {
expires: Instant,
},
Srv {
srv_expires: Instant,
well_known_retry: Instant,
well_known_backoff_mins: u16,
},
IsIpOrHasPort,
LookupFailed {
well_known_retry: Instant,
well_known_backoff_mins: u16,
},
}
/// Implemented according to the specification at <https://spec.matrix.org/v1.11/server-server-api/#resolving-server-names>
/// Numbers in comments below refer to bullet points in linked section of specification
async fn find_actual_destination(destination: &'_ ServerName) -> (FedDest, FedDest) {
async fn find_actual_destination(
destination: &'_ ServerName,
// The host used to potentially lookup SRV records against, only used when only_request_srv is true
well_known_dest: Option<String>,
// Should be used when only the SRV lookup has expired
only_request_srv: bool,
// The backoff time for the last well known failure, if any
well_known_backoff_mins: Option<u16>,
) -> FedDest {
debug!("Finding actual destination for {destination}");
let destination_str = destination.as_str().to_owned();
let mut hostname = destination_str.clone();
let actual_destination = match get_ip_with_port(&destination_str) {
let destination_str = destination.to_string();
let next_backoff_mins = well_known_backoff_mins
// Errors are recommended to be cached for up to an hour
.map(|mins| (mins * 2).min(60))
.unwrap_or(1);
let (actual_destination, dest_type) = if only_request_srv {
let destination_str = well_known_dest.unwrap_or(destination_str);
let (dest, expires) = get_srv_destination(destination_str).await;
let well_known_retry =
Instant::now() + Duration::from_secs((60 * next_backoff_mins).into());
(
dest,
if let Some(expires) = expires {
DestType::Srv {
well_known_backoff_mins: next_backoff_mins,
srv_expires: expires,
well_known_retry,
}
} else {
DestType::LookupFailed {
well_known_retry,
well_known_backoff_mins: next_backoff_mins,
}
},
)
} else {
match get_ip_with_port(&destination_str) {
Some(host_port) => {
debug!("1: IP literal with provided or default port");
host_port
(host_port, DestType::IsIpOrHasPort)
}
None => {
if let Some(pos) = destination_str.find(':') {
debug!("2: Hostname with included port");
let (host, port) = destination_str.split_at(pos);
FedDest::Named(host.to_owned(), port.to_owned())
(
FedDest::Named(host.to_owned(), port.to_owned()),
DestType::IsIpOrHasPort,
)
} else {
debug!("Requesting well known for {destination}");
match request_well_known(destination.as_str()).await {
Some(delegated_hostname) => {
debug!("Requesting well known for {destination_str}");
match request_well_known(destination_str.as_str()).await {
Some((delegated_hostname, timestamp)) => {
debug!("3: A .well-known file is available");
hostname = add_port_to_hostname(&delegated_hostname).into_uri_string();
match get_ip_with_port(&delegated_hostname) {
Some(host_and_port) => host_and_port, // 3.1: IP literal in .well-known file
// 3.1: IP literal in .well-known file
Some(host_and_port) => {
(host_and_port, DestType::WellKnown { expires: timestamp })
}
None => {
if let Some(pos) = delegated_hostname.find(':') {
debug!("3.2: Hostname with port in .well-known file");
let (host, port) = delegated_hostname.split_at(pos);
FedDest::Named(host.to_owned(), port.to_owned())
(
FedDest::Named(host.to_owned(), port.to_owned()),
DestType::WellKnown { expires: timestamp },
)
} else {
debug!("Delegated hostname has no port in this branch");
if let Some(hostname_override) =
query_srv_record(&delegated_hostname).await
{
debug!("3.3: SRV lookup successful");
let (dest, srv_expires) =
get_srv_destination(delegated_hostname.clone()).await;
(
dest,
if let Some(srv_expires) = srv_expires {
DestType::WellKnownSrv {
srv_expires,
well_known_expires: timestamp,
well_known_host: delegated_hostname,
}
} else {
DestType::WellKnown { expires: timestamp }
},
)
}
}
}
}
None => {
debug!("4: No .well-known or an error occured");
let (dest, expires) = get_srv_destination(destination_str).await;
let well_known_retry = Instant::now()
+ Duration::from_secs((60 * next_backoff_mins).into());
(
dest,
if let Some(expires) = expires {
DestType::Srv {
srv_expires: expires,
well_known_retry,
well_known_backoff_mins: next_backoff_mins,
}
} else {
DestType::LookupFailed {
well_known_retry,
well_known_backoff_mins: next_backoff_mins,
}
},
)
}
}
}
}
}
};
debug!("Actual destination: {actual_destination:?}");
let response = DestinationResponse {
actual_destination,
dest_type,
};
services()
.globals
.actual_destination_cache
.write()
.await
.insert(destination.to_owned(), response.clone());
response.actual_destination
}
/// Looks up the SRV records for federation usage
///
/// If no timestamp is returned, that means no SRV record was found
async fn get_srv_destination(delegated_hostname: String) -> (FedDest, Option<Instant>) {
if let Some((hostname_override, timestamp)) = query_srv_record(&delegated_hostname).await {
debug!("SRV lookup successful");
let force_port = hostname_override.port();
if let Ok(override_ip) = services()
@ -399,91 +561,27 @@ async fn find_actual_destination(destination: &'_ ServerName) -> (FedDest, FedDe
.unwrap()
.insert(
delegated_hostname.clone(),
(
override_ip.iter().collect(),
force_port.unwrap_or(8448),
),
(override_ip.iter().collect(), force_port.unwrap_or(8448)),
);
} else {
warn!("Using SRV record, but could not resolve to IP");
}
if let Some(port) = force_port {
FedDest::Named(delegated_hostname, format!(":{port}"))
} else {
add_port_to_hostname(&delegated_hostname)
}
} else {
debug!("3.4: No SRV records, just use the hostname from .well-known");
add_port_to_hostname(&delegated_hostname)
}
}
}
}
}
None => {
debug!("4: No .well-known or an error occured");
match query_srv_record(&destination_str).await {
Some(hostname_override) => {
debug!("4: SRV record found");
let force_port = hostname_override.port();
if let Ok(override_ip) = services()
.globals
.dns_resolver()
.lookup_ip(hostname_override.hostname())
.await
{
services()
.globals
.tls_name_override
.write()
.unwrap()
.insert(
hostname.clone(),
(
override_ip.iter().collect(),
force_port.unwrap_or(8448),
),
);
FedDest::Named(delegated_hostname, format!(":{port}")),
Some(timestamp),
)
} else {
warn!("Using SRV record, but could not resolve to IP");
(add_port_to_hostname(&delegated_hostname), Some(timestamp))
}
if let Some(port) = force_port {
FedDest::Named(hostname.clone(), format!(":{port}"))
} else {
add_port_to_hostname(&hostname)
debug!("No SRV records found");
(add_port_to_hostname(&delegated_hostname), None)
}
}
None => {
debug!("5: No SRV record found");
add_port_to_hostname(&destination_str)
}
}
}
}
}
}
};
debug!("Actual destination: {actual_destination:?}");
// Can't use get_ip_with_port here because we don't want to add a port
// to an IP address if it wasn't specified
let hostname = if let Ok(addr) = hostname.parse::<SocketAddr>() {
FedDest::Literal(addr)
} else if let Ok(addr) = hostname.parse::<IpAddr>() {
FedDest::Named(addr.to_string(), ":8448".to_owned())
} else if let Some(pos) = hostname.find(':') {
let (host, port) = hostname.split_at(pos);
FedDest::Named(host.to_owned(), port.to_owned())
} else {
FedDest::Named(hostname, ":8448".to_owned())
};
(actual_destination, hostname)
}
async fn query_given_srv_record(record: &str) -> Option<FedDest> {
async fn query_given_srv_record(record: &str) -> Option<(FedDest, Instant)> {
services()
.globals
.dns_resolver()
@ -491,16 +589,19 @@ async fn query_given_srv_record(record: &str) -> Option<FedDest> {
.await
.map(|srv| {
srv.iter().next().map(|result| {
(
FedDest::Named(
result.target().to_string().trim_end_matches('.').to_owned(),
format!(":{}", result.port()),
),
srv.as_lookup().valid_until(),
)
})
})
.unwrap_or(None)
}
async fn query_srv_record(hostname: &'_ str) -> Option<FedDest> {
async fn query_srv_record(hostname: &'_ str) -> Option<(FedDest, Instant)> {
let hostname = hostname.trim_end_matches('.');
if let Some(host_port) = query_given_srv_record(&format!("_matrix-fed._tcp.{hostname}.")).await
@ -511,7 +612,7 @@ async fn query_srv_record(hostname: &'_ str) -> Option<FedDest> {
}
}
async fn request_well_known(destination: &str) -> Option<String> {
async fn request_well_known(destination: &str) -> Option<(String, Instant)> {
let response = services()
.globals
.default_client()
@ -519,14 +620,40 @@ async fn request_well_known(destination: &str) -> Option<String> {
.send()
.await;
debug!("Got well known response");
if let Err(e) = &response {
let response = match response {
Err(e) => {
debug!("Well known error: {e:?}");
return None;
}
let text = response.ok()?.text().await;
Ok(r) => r,
};
let mut headers = response.headers().values();
let cache_for = CacheControl::decode(&mut headers)
.ok()
.and_then(|cc| {
// Servers should respect the cache control headers present on the response, or use a sensible default when headers are not present.
if cc.no_store() || cc.no_cache() {
Some(Duration::ZERO)
} else {
cc.max_age()
// Servers should additionally impose a maximum cache time for responses: 48 hours is recommended.
.map(|age| age.min(Duration::from_secs(60 * 60 * 48)))
}
})
// The recommended sensible default is 24 hours.
.unwrap_or_else(|| Duration::from_secs(60 * 60 * 24));
let text = response.text().await;
debug!("Got well known response text");
let host = || {
let body: serde_json::Value = serde_json::from_str(&text.ok()?).ok()?;
Some(body.get("m.server")?.as_str()?.to_owned())
body.get("m.server")?.as_str().map(ToOwned::to_owned)
};
host().map(|host| (host, Instant::now() + cache_for))
}
/// # `GET /_matrix/federation/v1/version`

4
src/service/globals/mod.rs
View file

@ -5,7 +5,7 @@ use ruma::{
OwnedRoomId, OwnedServerName, OwnedUserId, RoomAliasId,
};
use crate::api::server_server::FedDest;
use crate::api::server_server::DestinationResponse;
use crate::{services, Config, Error, Result};
use futures_util::FutureExt;
@ -37,7 +37,7 @@ use tracing::{error, info};
use base64::{engine::general_purpose, Engine as _};
type WellKnownMap = HashMap<OwnedServerName, (FedDest, String)>;
type WellKnownMap = HashMap<OwnedServerName, DestinationResponse>;
type TlsNameMap = HashMap<String, (Vec<IpAddr>, u16)>;
type RateLimitState = (Instant, u32); // Time if last failed try, number of failed tries
type SyncHandle = (