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//! PFCP message header.
use crate::error::PfcpError;
use crate::message::MsgType;
use crate::types::{Seid, SequenceNumber};
/// Represents a PFCP message header.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Header {
pub version: u8,
pub has_fo: bool, // Follow-on
pub has_mp: bool, // Message Priority
pub has_seid: bool,
pub message_type: MsgType,
pub length: u16,
pub seid: Seid,
pub sequence_number: SequenceNumber,
pub message_priority: u8,
}
impl Header {
/// Creates a new Header.
pub fn new(
message_type: MsgType,
has_seid: bool,
seid: impl Into<Seid>,
sequence_number: impl Into<SequenceNumber>,
) -> Self {
Header {
version: 1,
has_fo: false,
has_mp: false,
has_seid,
message_type,
length: 0, // Will be set later
seid: seid.into(),
sequence_number: sequence_number.into(),
message_priority: 0,
}
}
/// Returns the length of the header in bytes.
pub fn len(&self) -> u16 {
let mut length = 8;
if self.has_seid {
length += 8;
}
length
}
/// Reports whether a Header is empty.
pub fn is_empty(&self) -> bool {
self.length == 0
}
/// Serializes the Header into a byte vector.
pub fn marshal(&self) -> Vec<u8> {
let mut data = vec![0; self.len() as usize];
self.marshal_to(&mut data);
data
}
/// Serializes the Header into an existing buffer.
///
/// This method appends the marshaled header to the provided buffer,
/// allowing for buffer reuse and avoiding allocations.
///
/// # Examples
///
/// ```
/// use rs_pfcp::message::header::Header;
/// use rs_pfcp::message::MsgType;
///
/// let header = Header::new(MsgType::HeartbeatRequest, false, 0, 123);
///
/// // Reuse buffer
/// let mut buf = Vec::new();
/// header.marshal_into(&mut buf);
/// assert_eq!(buf.len(), header.len() as usize);
/// ```
pub fn marshal_into(&self, buf: &mut Vec<u8>) {
let start = buf.len();
buf.resize(start + self.len() as usize, 0);
self.marshal_to(&mut buf[start..]);
}
/// Serializes the Header into a byte slice.
pub fn marshal_to(&self, b: &mut [u8]) {
let flags = (self.version << 5)
| ((self.has_fo as u8) << 2)
| ((self.has_mp as u8) << 1)
| (self.has_seid as u8);
b[0] = flags;
b[1] = self.message_type as u8;
b[2..4].copy_from_slice(&self.length.to_be_bytes());
let mut offset = 4;
if self.has_seid {
b[offset..offset + 8].copy_from_slice(&self.seid.0.to_be_bytes());
offset += 8;
}
let seq_bytes = self.sequence_number.0.to_be_bytes();
b[offset..offset + 3].copy_from_slice(&seq_bytes[1..]);
b[offset + 3] = self.message_priority;
}
/// Deserializes a byte slice into a Header.
pub fn unmarshal(b: &[u8]) -> Result<Self, PfcpError> {
if b.len() < 8 {
return Err(PfcpError::MessageParseError {
message_type: None,
reason: format!(
"Header too short (expected at least 8 bytes, got {})",
b.len()
),
});
}
let flags = b[0];
let version = flags >> 5;
let has_fo = (flags & 0x04) >> 2 == 1;
let has_mp = (flags & 0x02) >> 1 == 1;
let has_seid = (flags & 0x01) == 1;
let message_type = MsgType::from(b[1]);
let length = u16::from_be_bytes([b[2], b[3]]);
let mut offset = 4;
let seid = if has_seid {
if b.len() < offset + 8 {
return Err(PfcpError::MessageParseError {
message_type: Some(message_type),
reason: format!(
"Header with SEID flag set but too short (expected at least {} bytes, got {})",
offset + 8,
b.len()
),
});
}
offset += 8;
u64::from_be_bytes([
b[offset - 8],
b[offset - 7],
b[offset - 6],
b[offset - 5],
b[offset - 4],
b[offset - 3],
b[offset - 2],
b[offset - 1],
])
} else {
0
};
if b.len() < offset + 4 {
return Err(PfcpError::MessageParseError {
message_type: Some(message_type),
reason: format!(
"Header sequence number part too short (expected at least {} bytes, got {})",
offset + 4,
b.len()
),
});
}
let sequence_number = SequenceNumber::new(u32::from_be_bytes([
0,
b[offset],
b[offset + 1],
b[offset + 2],
]));
let message_priority = b[offset + 3];
Ok(Header {
version,
has_fo,
has_mp,
has_seid,
message_type,
length,
seid: Seid(seid),
sequence_number,
message_priority,
})
}
}