File syn_wg.h¶

WireGuard VPN client — Noise IK, pure C99, cooperative. More...

#include "../common/syn_defs.h"
#include "../port/syn_port_socket.h"
#include "../pt/syn_pt.h"
#include "../sched/syn_task.h"
#include "syn_sntp.h"
#include <stdbool.h>

Classes¶

Type	Name
struct	SYN_WG WireGuard client context — caller-owned.
struct	SYN_WgConfig WireGuard peer configuration — set once at init.
struct	SYN_WgSession Active session derived from a completed handshake.
struct	SYN_WgStats WireGuard tunnel statistics structure.

Public Types¶

Type	Name
enum	SYN_WgState WireGuard client connection state.

Public Functions¶

Type	Name
void	syn_wg_disconnect (SYN_WG * wg) Disconnect the WireGuard tunnel and close socket.
SYN_Status	syn_wg_get_stats (const SYN_WG * wg, SYN_WgStats * stats) Retrieve WireGuard tunnel metrics and statistics.
void	syn_wg_init (SYN_WG * wg, const SYN_WgConfig * config, SYN_SNTP * sntp, uint8_t * rx_buf, size_t rx_buf_size, uint8_t * tx_buf, size_t tx_buf_size) Initialize the WireGuard client.
SYN_Status	syn_wg_send (SYN_WG * wg, const uint8_t * ip_packet, size_t len) Send an IP packet through the WireGuard tunnel.
SYN_PT_Status	syn_wg_task (SYN_PT * pt, SYN_Task * task) Cooperative protothread task — drives the WireGuard client.

Public Static Functions¶

Type	Name
bool	syn_wg_is_established (const SYN_WG * wg) Check if the tunnel is established and ready for data.

Macros¶

Type	Name
define	SYN_WG_INITIATION_SIZE `148`
define	SYN_WG_KEEPALIVE_TIMEOUT `10`
define	SYN_WG_MSG_COOKIE `3`
define	SYN_WG_MSG_INITIATION `1`
define	SYN_WG_MSG_RESPONSE `2`
define	SYN_WG_MSG_TRANSPORT `4`
define	SYN_WG_MTU `1420`
define	SYN_WG_REJECT_AFTER_TIME `180`
define	SYN_WG_REKEY_AFTER_TIME `120`
define	SYN_WG_REKEY_TIMEOUT `5`
define	SYN_WG_RESPONSE_SIZE `92`
define	SYN_WG_TRANSPORT_OVERHEAD `32`

Detailed Description¶

Implements a WireGuard client as a cooperative protothread task. Handles the Noise_IKpsk2 handshake, ChaCha20-Poly1305 transport encryption, keepalive timers, and rekeying.

The client connects to a single WireGuard peer (server) over UDP. Decrypted IP packets are delivered to user code via a callback. User code sends packets into the tunnel via syn_wg_send().

No TUN device, no host routing — all traffic is handled in userspace. The host OS only sees a single UDP socket.

Requires: BLAKE2S, CHACHA20POLY1305, X25519, SNTP.

** **

static SYN_WG wg;
static uint8_t rx[1500], tx[1500];

SYN_WgConfig cfg = {
    .endpoint = { .ip = {1,2,3,4}, .port = 51820 },
    .keepalive_interval_s = 25,
};
memcpy(cfg.private_key, my_key, 32);
memcpy(cfg.peer_public_key, server_key, 32);

syn_wg_init(&wg, &cfg, &sntp, rx, sizeof(rx), tx, sizeof(tx));
wg.on_recv = my_handler;

syn_task_create(&tasks[1], "wg", syn_wg_task, 1, &wg);

Public Types Documentation¶

enum SYN_WgState¶

WireGuard client connection state.

enum SYN_WgState {
    SYN_WG_DISCONNECTED,
    SYN_WG_HANDSHAKE_INIT,
    SYN_WG_ESTABLISHED
};

Public Functions Documentation¶

function syn_wg_disconnect¶

Disconnect the WireGuard tunnel and close socket.

void syn_wg_disconnect (
    SYN_WG * wg
)

Parameters:

wg Client context.

function syn_wg_get_stats¶

Retrieve WireGuard tunnel metrics and statistics.

SYN_Status syn_wg_get_stats (
    const SYN_WG * wg,
    SYN_WgStats * stats
)

Parameters:

wg Client context.
stats [out] Output statistics structure.

Returns:

SYN_OK on success.

function syn_wg_init¶

Initialize the WireGuard client.

void syn_wg_init (
    SYN_WG * wg,
    const SYN_WgConfig * config,
    SYN_SNTP * sntp,
    uint8_t * rx_buf,
    size_t rx_buf_size,
    uint8_t * tx_buf,
    size_t tx_buf_size
)

Derives the public key from the private key and prepares state. Does NOT open a socket or start a handshake — that happens when the protothread task runs.

Parameters:

wg Client context.
config Peer configuration (copied).
sntp SNTP time source (must be initialized, may not be synced yet).
rx_buf Receive buffer (at least SYN_WG_MTU + SYN_WG_TRANSPORT_OVERHEAD).
rx_buf_size Receive buffer capacity.
tx_buf Transmit buffer (same sizing).
tx_buf_size Transmit buffer capacity.

function syn_wg_send¶

Send an IP packet through the WireGuard tunnel.

SYN_Status syn_wg_send (
    SYN_WG * wg,
    const uint8_t * ip_packet,
    size_t len
)

Encrypts the packet with the current session key and sends it as a WireGuard transport message.

Parameters:

wg Client context.
ip_packet Raw IP packet to send.
len Packet length.

Returns:

SYN_OK on success, SYN_ERROR if no session or send failed.

function syn_wg_task¶

Cooperative protothread task — drives the WireGuard client.

SYN_PT_Status syn_wg_task (
    SYN_PT * pt,
    SYN_Task * task
)

Handles: NTP sync wait, handshake, incoming packet processing, keepalive, and rekeying. Pass the SYN_WG context via task->user_data.

Parameters:

pt Protothread.
task Task descriptor.

Returns:

PT status.

Public Static Functions Documentation¶

function syn_wg_is_established¶

Check if the tunnel is established and ready for data.

static inline bool syn_wg_is_established (
    const SYN_WG * wg
)

Parameters:

wg Client context.

Returns:

true if the session is active.

Macro Definition Documentation¶

define SYN_WG_INITIATION_SIZE¶

#define SYN_WG_INITIATION_SIZE `148`

Message sizes. Size of initiation message

define SYN_WG_KEEPALIVE_TIMEOUT¶

#define SYN_WG_KEEPALIVE_TIMEOUT `10`

Send keepalive if no outbound (s)

define SYN_WG_MSG_COOKIE¶

#define SYN_WG_MSG_COOKIE `3`

Cookie reply message

define SYN_WG_MSG_INITIATION¶

#define SYN_WG_MSG_INITIATION `1`

WireGuard message types. Handshake initiation message

define SYN_WG_MSG_RESPONSE¶

#define SYN_WG_MSG_RESPONSE `2`

Handshake response message

define SYN_WG_MSG_TRANSPORT¶

#define SYN_WG_MSG_TRANSPORT `4`

Encrypted transport message

define SYN_WG_MTU¶

#define SYN_WG_MTU `1420`

Default tunnel MTU (inner IP packet before encryption).

define SYN_WG_REJECT_AFTER_TIME¶

#define SYN_WG_REJECT_AFTER_TIME `180`

Drop session after this many seconds

define SYN_WG_REKEY_AFTER_TIME¶

#define SYN_WG_REKEY_AFTER_TIME `120`

WireGuard protocol timers (seconds). Initiate rekey after this many seconds

define SYN_WG_REKEY_TIMEOUT¶

#define SYN_WG_REKEY_TIMEOUT `5`

Retry handshake if no response (s)

define SYN_WG_RESPONSE_SIZE¶

#define SYN_WG_RESPONSE_SIZE `92`

Size of response message

define SYN_WG_TRANSPORT_OVERHEAD¶

#define SYN_WG_TRANSPORT_OVERHEAD `32`

WireGuard transport overhead: type(4) + receiver(4) + counter(8) + tag(16) = 32

The documentation for this class was generated from the following file src/syntropic/net/syn_wg.h