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Supporting smaller TCP_INFO shapes optionally relaxing get_opt_sized response validation with strict flag #790

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Supporting smaller TCP_INFO shapes optionally relaxing get_opt_sized response validation with strict flag #790

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20abed0
Supporting smaller TCP_INFO shapes by adding an allow_smaller flag to…
millermeares Jan 13, 2026
c8a678b
Simplify code
millermeares Jan 13, 2026
9c8d104
running cargo fmt
millermeares Jan 13, 2026
a2f8a44
Refactor to make boolean be strict rather than allow_smaller
millermeares Jan 14, 2026
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36 changes: 20 additions & 16 deletions pingora-core/src/protocols/l4/ext.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -146,14 +146,17 @@ fn get_opt<T>(
}
}

// strict: strict validation enforces exact size checks on returned objects kernels.
// passing 'false' for strict relaxes validation to allow the kernel to send smaller objects than the size of T.
// allowing smaller size values means the tail stays zeroed and those fields may be “absent,” not real zeros.
#[cfg(target_os = "linux")]
fn get_opt_sized<T>(sock: c_int, opt: c_int, val: c_int) -> io::Result<T> {
fn get_opt_sized<T>(sock: c_int, opt: c_int, val: c_int, strict: bool) -> io::Result<T> {
let mut payload = mem::MaybeUninit::zeroed();
let expected_size = mem::size_of::<T>() as socklen_t;
let mut size = expected_size;
get_opt(sock, opt, val, &mut payload, &mut size)?;

if size != expected_size {
if size > expected_size || (strict && size != expected_size) {
return Err(std::io::Error::other("get_opt size mismatch"));
}
// Assume getsockopt() will set the value properly
Expand Down Expand Up @@ -272,7 +275,7 @@ fn set_keepalive(_sock: RawSocket, _ka: &TcpKeepalive) -> io::Result<()> {
/// Get the kernel TCP_INFO for the given FD.
#[cfg(target_os = "linux")]
pub fn get_tcp_info(fd: RawFd) -> io::Result<TCP_INFO> {
get_opt_sized(fd, libc::IPPROTO_TCP, libc::TCP_INFO)
get_opt_sized(fd, libc::IPPROTO_TCP, libc::TCP_INFO, false)
}

#[cfg(all(unix, not(target_os = "linux")))]
Expand Down Expand Up @@ -304,7 +307,7 @@ pub fn set_recv_buf(_sock: RawSocket, _: usize) -> Result<()> {

#[cfg(target_os = "linux")]
pub fn get_recv_buf(fd: RawFd) -> io::Result<usize> {
get_opt_sized::<c_int>(fd, libc::SOL_SOCKET, libc::SO_RCVBUF).map(|v| v as usize)
get_opt_sized::<c_int>(fd, libc::SOL_SOCKET, libc::SO_RCVBUF, true).map(|v| v as usize)
}

#[cfg(all(unix, not(target_os = "linux")))]
Expand All @@ -319,7 +322,7 @@ pub fn get_recv_buf(_sock: RawSocket) -> io::Result<usize> {

#[cfg(target_os = "linux")]
pub fn get_snd_buf(fd: RawFd) -> io::Result<usize> {
get_opt_sized::<c_int>(fd, libc::SOL_SOCKET, libc::SO_SNDBUF).map(|v| v as usize)
get_opt_sized::<c_int>(fd, libc::SOL_SOCKET, libc::SO_SNDBUF, true).map(|v| v as usize)
}

#[cfg(all(unix, not(target_os = "linux")))]
Expand Down Expand Up @@ -403,7 +406,7 @@ pub fn set_dscp(_sock: RawSocket, _value: u8) -> Result<()> {

#[cfg(target_os = "linux")]
pub fn get_socket_cookie(fd: RawFd) -> io::Result<u64> {
get_opt_sized::<c_ulonglong>(fd, libc::SOL_SOCKET, libc::SO_COOKIE)
get_opt_sized::<c_ulonglong>(fd, libc::SOL_SOCKET, libc::SO_COOKIE, true)
}

#[cfg(all(unix, not(target_os = "linux")))]
Expand All @@ -424,23 +427,24 @@ pub fn get_original_dest(fd: RawFd) -> Result<Option<SocketAddr>> {
.or_err(SocketError, "failed get original dest, invalid IP socket")?;

let dest = if addr.is_ipv4() {
get_opt_sized::<libc::sockaddr_in>(fd, libc::SOL_IP, libc::SO_ORIGINAL_DST).map(|addr| {
SocketAddr::V4(SocketAddrV4::new(
u32::from_be(addr.sin_addr.s_addr).into(),
u16::from_be(addr.sin_port),
))
})
} else {
get_opt_sized::<libc::sockaddr_in6>(fd, libc::SOL_IPV6, libc::IP6T_SO_ORIGINAL_DST).map(
get_opt_sized::<libc::sockaddr_in>(fd, libc::SOL_IP, libc::SO_ORIGINAL_DST, true).map(
|addr| {
SocketAddr::V4(SocketAddrV4::new(
u32::from_be(addr.sin_addr.s_addr).into(),
u16::from_be(addr.sin_port),
))
},
)
} else {
get_opt_sized::<libc::sockaddr_in6>(fd, libc::SOL_IPV6, libc::IP6T_SO_ORIGINAL_DST, true)
.map(|addr| {
SocketAddr::V6(SocketAddrV6::new(
addr.sin6_addr.s6_addr.into(),
u16::from_be(addr.sin6_port),
addr.sin6_flowinfo,
addr.sin6_scope_id,
))
},
)
})
};
dest.or_err(SocketError, "failed to get original dest")
.map(Some)
Expand Down