Function build_proxy_v2_header

common/src/proxy_protocol.rs:35–108

Builds a PROXY protocol v2 header for TCP connections # Arguments `client_addr` - The original client's socket address `server_addr` - The server's socket address (destination) # Returns A byte vector containing the complete PROXY v2 header

(client_addr: &SocketAddr, server_addr: &SocketAddr)

/// # Returns
/// A byte vector containing the complete PROXY v2 header
pub fn build_proxy_v2_header(client_addr: &SocketAddr, server_addr: &SocketAddr) -> Vec<u8> {
    let mut header = Vec::with_capacity(52); // Max size for IPv6

    // 1. Signature (12 bytes)
    header.extend_from_slice(&PROXY_V2_SIGNATURE);

    // Determine address family and protocol
    let (af_proto, addr_len, addr_data) = match (client_addr.ip(), server_addr.ip()) {
        (IpAddr::V4(src_ip), IpAddr::V4(dst_ip)) => {
            // IPv4 + TCP
            let af_proto = AF_INET | STREAM;
            let mut data = Vec::with_capacity(12);
            data.extend_from_slice(&src_ip.octets()); // 4 bytes src addr
            data.extend_from_slice(&dst_ip.octets()); // 4 bytes dst addr
            data.extend_from_slice(&client_addr.port().to_be_bytes()); // 2 bytes src port
            data.extend_from_slice(&server_addr.port().to_be_bytes()); // 2 bytes dst port
            (af_proto, 12u16, data)
        }
        (IpAddr::V6(src_ip), IpAddr::V6(dst_ip)) => {
            // IPv6 + TCP
            let af_proto = AF_INET6 | STREAM;
            let mut data = Vec::with_capacity(36);
            data.extend_from_slice(&src_ip.octets()); // 16 bytes src addr
            data.extend_from_slice(&dst_ip.octets()); // 16 bytes dst addr
            data.extend_from_slice(&client_addr.port().to_be_bytes()); // 2 bytes src port
            data.extend_from_slice(&server_addr.port().to_be_bytes()); // 2 bytes dst port
            (af_proto, 36u16, data)
        }
        (IpAddr::V4(src_ip), IpAddr::V6(_)) => {
            // Mixed: convert IPv4 to IPv6-mapped address
            let src_v6 = src_ip.to_ipv6_mapped();
            let dst_v6 = match server_addr.ip() {
                IpAddr::V6(ip) => ip,
                _ => unreachable!(),
            };
            let af_proto = AF_INET6 | STREAM;
            let mut data = Vec::with_capacity(36);
            data.extend_from_slice(&src_v6.octets());
            data.extend_from_slice(&dst_v6.octets());
            data.extend_from_slice(&client_addr.port().to_be_bytes());
            data.extend_from_slice(&server_addr.port().to_be_bytes());
            (af_proto, 36u16, data)
        }
        (IpAddr::V6(_), IpAddr::V4(dst_ip)) => {
            // Mixed: convert IPv4 to IPv6-mapped address
            let src_v6 = match client_addr.ip() {
                IpAddr::V6(ip) => ip,
                _ => unreachable!(),
            };
            let dst_v6 = dst_ip.to_ipv6_mapped();
            let af_proto = AF_INET6 | STREAM;
            let mut data = Vec::with_capacity(36);
            data.extend_from_slice(&src_v6.octets());
            data.extend_from_slice(&dst_v6.octets());
            data.extend_from_slice(&client_addr.port().to_be_bytes());
            data.extend_from_slice(&server_addr.port().to_be_bytes());
            (af_proto, 36u16, data)
        }