diffserv.cpp

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// Copyright (C) 2026 Douglas Quigg (dstroy0) <dquigg123@gmail.com>
// SPDX-License-Identifier: AGPL-3.0-or-later
 
/**
 * @file diffserv.cpp
 * @brief DiffServ QoS marking (RFC 2474) - the two server-wide DSCP defaults.
 *
 * Owns the default DSCP applied to outbound TCP connections and the default for UDP datagrams. The
 * per-listener override (pc_listen_set_dscp) lives in listener.cpp and the per-connection setter
 * (pc_conn_set_dscp) in tcp.cpp - each next to the pcb pool it touches - but both read these defaults.
 */
 
#include "diffserv.h"
 
#if PC_ENABLE_DIFFSERV
 
namespace
{
/// The single owner of all DiffServ file-scope state.
struct DiffServCtx
{
    uint8_t tcp_dscp; ///< server-wide default DSCP for outbound TCP connections (0 = best-effort)
    uint8_t udp_dscp; ///< default DSCP for outbound UDP datagrams (0 = best-effort)
};
DiffServCtx s_diffserv = {0, 0};
} // namespace
 
void pc_set_default_dscp(uint8_t dscp)
{
    s_diffserv.tcp_dscp = (uint8_t)(dscp & 0x3F);
}
 
uint8_t pc_diffserv_default_dscp(void)
{
    return s_diffserv.tcp_dscp;
}
 
void pc_udp_set_dscp(uint8_t dscp)
{
    s_diffserv.udp_dscp = (uint8_t)(dscp & 0x3F);
}
 
uint8_t pc_diffserv_udp_dscp(void)
{
    return s_diffserv.udp_dscp;
}
 
#endif // PC_ENABLE_DIFFSERV