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feat: cross-connect collision resolution via is_server master + collision flag 

Protocol: added collision field to INIT_REQUEST_PKT (1 byte before ed25519_pubkey).
When two peers connect simultaneously, the one with is_server=0 (API-created
outbound link) is the master. Resolution by smaller node_id:
- We have master link + smaller node_id → send our INIT with collision=1
- We have master link + larger node_id → yield, process as slave
- Remote sends collision=1 → become slave unconditionally
- session_id change always forces reinit (genuine restart)

Removed unconditional etcp_conn_reinit on INIT_RESPONSE(0x03) — guarded by
reset_done flag. Server-side reinit now has collision check BEFORE reset_done
guard; session_id change penetrates reset_done protection.

Closes cross-connect reinit loop causing endless UP/DOWN flapping.
topo_upd
Evgeny 3 months ago
parent
0912499309
commit
409a99f56b
2 changed files with 84 additions and 27 deletions
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  1. 99
      src/etcp_connections.c
  2. 4
      src/etcp_connections.h

99
src/etcp_connections.c
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@ -50,7 +50,7 @@ static void tcp_server_on_link(struct stcp_link *link, void *arg) {
void etcp_connections_read_callback_socket(socket_t sock, void* arg);
static void etcp_link_remove_from_connections(struct ETCP_SOCKET* conn, struct ETCP_LINK* link);
static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset);
static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset, uint8_t collision);
//static int etcp_link_send_reset(struct ETCP_LINK* link);
static void etcp_link_init_timer_cbk(void* arg);
static void etcp_link_send_keepalive(struct ETCP_LINK* link);
@ -101,9 +101,9 @@ static void burst_resp_timeout_cb(void* arg) {
#define INIT_TIMEOUT_INITIAL 500
#define INIT_TIMEOUT_MAX 50000
static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset) {
static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset, uint8_t collision) {
DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "link=%p, is_server=%d, reset=%d", link, link ? link->is_server : -1, reset);
DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "link=%p, is_server=%d, reset=%d, collision=%d", link, link ? link->is_server : -1, reset, collision);
if (!link || !link->etcp || !link->etcp->instance) return;
struct ETCP_DGRAM* dgram = u_malloc(PACKET_DATA_SIZE);
@ -134,6 +134,7 @@ static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset) {
memset(req->src_ipv4, 0, 4);
memset(req->src_port, 0, 2);
}
req->collision = collision;
memcpy(req->ed25519_pubkey, link->etcp->instance->my_ed25519_pubkey, SC_PUBKEY_SIZE);
size_t offset = ETCP_INIT_REQ_SIZE;
@ -196,8 +197,8 @@ static void etcp_link_init_timer_cbk(void* arg) {
}
link->init_timer = uasync_set_timeout(link->etcp->instance->ua, link->init_timeout, link, etcp_link_init_timer_cbk, "link_init");
if (link->link_state == 1) etcp_link_send_init(link,1);// init (with etcp reset)
else etcp_link_send_init(link,0);// no etcp reset (reinit)
if (link->link_state == 1) etcp_link_send_init(link,1,0);// init (with etcp reset)
else etcp_link_send_init(link,0,0);// no etcp reset (reinit)
}
void etcp_link_restart_init_timer(struct ETCP_LINK* link) {
@ -212,7 +213,7 @@ void etcp_link_enter_init(struct ETCP_LINK* link) {//
if (!link) return;
link->link_state = 1; // handshake
if (link->is_server != 0) return;
etcp_link_send_init(link,1);// init with reset
etcp_link_send_init(link,1,0);// init with reset
etcp_link_restart_init_timer(link);
}
@ -222,7 +223,7 @@ void etcp_link_enter_reinit(struct ETCP_LINK* link) {
link->link_state = 2; // reconnect
etcp_on_link_down(link->etcp);
if (link->is_server != 0) return;
etcp_link_send_init(link,0);// init without reset
etcp_link_send_init(link,0,0);// init without reset
if (link->keepalive_timer) {// keepalive заменяяется reinit запросами
uasync_cancel_timeout(link->etcp->instance->ua, link->keepalive_timer);
@ -1743,20 +1744,49 @@ void etcp_connections_read_callback_socket(socket_t sock, void* arg) {
link->remote_only_local = req->only_local;
link->remote_type = req->type;
// For CHANNEL_INIT (0x04): if link already initialized - no reset, otherwise reset
// For INIT_REQUEST (0x02): always reset
// Check session_id: if same - no reinit, if different - client restarted, do reinit
// ── Collision handling ──
if (req->collision) {
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] INIT collision=1 from peer=%016llx — remote is master, becoming slave",
conn->log_name, (unsigned long long)peer_id);
conn->session_id = session_id;
etcp_conn_reinit(conn);
send_reset = 1;
} else {
// Check if WE have an outbound (master) link on this conn
struct ETCP_LINK* ml = conn->links;
while (ml) { if (ml->is_server == 0) break; ml = ml->next; }
if (ml) {
if (conn->instance->node_id < peer_id) {
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] COLLISION: we=master node_id=%016llx < peer=%016llx — sending collision INIT",
conn->log_name, (unsigned long long)conn->instance->node_id, (unsigned long long)peer_id);
memory_pool_free(e_sock->instance->pkt_pool, pkt);
etcp_link_send_init(ml, 0, 1);
return;
}
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] COLLISION: peer smaller, yielding master, processing as slave",
conn->log_name);
}
// Normal reinit check (skip if reset_done=1 unless session_id changed)
if (!conn->reset_done) {
if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || !conn->got_initial_pkt) {
send_reset = 1; // Client explicitly requested reset, or new session, or server waiting for first packet
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT existing link: code=0x%02x sess=%08x→%08x got_init=%d initialized=%d links_up=%d reset_done=%d",
conn->log_name, code, conn->session_id, session_id, conn->got_initial_pkt, conn->initialized, conn->links_up, conn->reset_done);
send_reset = 1;
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT existing link: code=0x%02x sess=%08x→%08x got_init=%d initialized=%d links_up=%d",
conn->log_name, code, conn->session_id, session_id, conn->got_initial_pkt, conn->initialized, conn->links_up);
conn->session_id = session_id;
etcp_conn_reinit(conn);
}
} else if (conn->session_id != session_id) {
send_reset = 1;
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT existing link (session changed): sess=%08x→%08x",
conn->log_name, conn->session_id, session_id);
conn->session_id = session_id;
if (!conn->reset_done) etcp_conn_reinit(conn);
else DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT skipped — reset_done=1", conn->log_name);
etcp_conn_reinit(conn);
} else {
send_reset = 0; // Same session, no reinit needed
send_reset = 0;
DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "same session_id, skip reinit");
}
}
// Cancel existing timers
if (link->init_timer) {
@ -1773,14 +1803,41 @@ void etcp_connections_read_callback_socket(socket_t sock, void* arg) {
link->remote_only_local = req->only_local;
link->remote_type = req->type;
// For new links: reset if client requested or session changed
// ── Collision handling ──
if (req->collision) {
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] INIT collision=1 from peer=%016llx — remote is master, becoming slave",
conn->log_name, (unsigned long long)peer_id);
conn->session_id = session_id;
etcp_conn_reinit(conn);
send_reset = 1;
} else {
// Check if WE have an outbound (master) link
struct ETCP_LINK* ml = conn->links;
while (ml) { if (ml->is_server == 0) break; ml = ml->next; }
if (ml && conn->instance->node_id < peer_id) {
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] COLLISION: we=master node_id=%016llx < peer=%016llx — sending collision INIT",
conn->log_name, (unsigned long long)conn->instance->node_id, (unsigned long long)peer_id);
memory_pool_free(e_sock->instance->pkt_pool, pkt);
etcp_link_send_init(ml, 0, 1);
return;
}
// Normal reinit check (skip if reset_done=1 unless session_id changed)
if (!conn->reset_done) {
if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || !conn->got_initial_pkt) {
send_reset = 1;
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT new link: code=0x%02x sess=%08x→%08x got_init=%d initialized=%d links_up=%d reset_done=%d",
conn->log_name, code, conn->session_id, session_id, conn->got_initial_pkt, conn->initialized, conn->links_up, conn->reset_done);
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT new link: code=0x%02x sess=%08x→%08x got_init=%d initialized=%d links_up=%d",
conn->log_name, code, conn->session_id, session_id, conn->got_initial_pkt, conn->initialized, conn->links_up);
conn->session_id = session_id;
etcp_conn_reinit(conn);
}
} else if (conn->session_id != session_id) {
send_reset = 1;
DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT new link (session changed): sess=%08x→%08x",
conn->log_name, conn->session_id, session_id);
conn->session_id = session_id;
if (!conn->reset_done) etcp_conn_reinit(conn);
else DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT skipped — reset_done=1", conn->log_name);
etcp_conn_reinit(conn);
}
}
link->keepalive_interval=(req->keepalive[0]<<8) | req->keepalive[1];
link->recovery_interval=((req->recovery[0]<<8) | req->recovery[1])*100;// timebase в link, timebase/100 в кодограмме

4
src/etcp_connections.h
Unescape View File

@ -76,8 +76,8 @@ struct ETCP_INIT_REQUEST_PKT {
// V2 fields (NAT_DIRECT detection):
uint8_t src_ipv4[4]; // 23: client interface_addr IPv4 (big-endian, 0 if N/A)
uint8_t src_port[2]; // 27: client interface_addr port (big-endian)
// V3 fields:
uint8_t ed25519_pubkey[SC_PUBKEY_SIZE]; // 29: client Ed25519 pubkey (32 bytes)
uint8_t collision; // 29: 1 = cross-connect, remote claims master
uint8_t ed25519_pubkey[SC_PUBKEY_SIZE]; // 30: client Ed25519 pubkey (32 bytes)
} __attribute__((packed));
#define ETCP_INIT_REQ_SIZE sizeof(struct ETCP_INIT_REQUEST_PKT)

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