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Fix: Prevent panic in DNS Socket when server list exceeds max count

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- Truncate the servers list to DNS_MAX_SERVER_COUNT to prevent panics.
- Ensure only the first `DNS_MAX_SERVER_COUNT` servers are used when constructing the `Socket`.
- This prevents overflow issues when the provided server list is larger than the allowed maximum.
This commit is contained in:
Jamie Bird 2024-09-12 11:28:27 +01:00
parent 8025752013
commit 4739cc7fc6
1 changed files with 12 additions and 8 deletions
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20
src/socket/dns.rs
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@ -1,3 +1,4 @@
use core::cmp::min;
#[cfg(feature = "async")] #[cfg(feature = "async")]
use core::task::Waker; use core::task::Waker;
@ -149,15 +150,15 @@ pub struct Socket<'a> {
impl<'a> Socket<'a> { impl<'a> Socket<'a> {
/// Create a DNS socket. /// Create a DNS socket.
/// ///
/// # Panics /// Truncates the server list if `servers.len() > MAX_SERVER_COUNT`
///
/// Panics if `servers.len() > MAX_SERVER_COUNT`
pub fn new<Q>(servers: &[IpAddress], queries: Q) -> Socket<'a> pub fn new<Q>(servers: &[IpAddress], queries: Q) -> Socket<'a>
where where
Q: Into<ManagedSlice<'a, Option<DnsQuery>>>, Q: Into<ManagedSlice<'a, Option<DnsQuery>>>,
{ {
let truncated_servers = &servers[..min(servers.len(), DNS_MAX_SERVER_COUNT)];
Socket { Socket {
servers: Vec::from_slice(servers).unwrap(), servers: Vec::from_slice(truncated_servers).unwrap(),
queries: queries.into(), queries: queries.into(),
hop_limit: None, hop_limit: None,
} }
@ -165,11 +166,14 @@ impl<'a> Socket<'a> {
/// Update the list of DNS servers, will replace all existing servers /// Update the list of DNS servers, will replace all existing servers
/// ///
/// # Panics /// Truncates the server list if `servers.len() > MAX_SERVER_COUNT`
///
/// Panics if `servers.len() > MAX_SERVER_COUNT`
pub fn update_servers(&mut self, servers: &[IpAddress]) { pub fn update_servers(&mut self, servers: &[IpAddress]) {
self.servers = Vec::from_slice(servers).unwrap(); if servers.len() > DNS_MAX_SERVER_COUNT {
net_trace!("Max DNS Servers exceeded. Increase MAX_SERVER_COUNT");
self.servers = Vec::from_slice(&servers[..DNS_MAX_SERVER_COUNT]).unwrap();
} else {
self.servers = Vec::from_slice(servers).unwrap();
}
} }
/// Return the time-to-live (IPv4) or hop limit (IPv6) value used in outgoing packets. /// Return the time-to-live (IPv4) or hop limit (IPv6) value used in outgoing packets.