Skip to content

Commit

Permalink
Merge pull request #2637 from cesanta/ack
Browse files Browse the repository at this point in the history 
Sending ACK when about to exhaust TCP WIN1
  • Loading branch information
@scaprile
scaprile authored Mar 2, 2024
2 parents 5384591 + 1c6f8b9 commit 2066304
Show file tree
Hide file tree
Showing 2 changed files with 42 additions and 32 deletions.
37 changes: 21 additions & 16 deletions mongoose.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4894,10 +4894,12 @@ void mg_mgr_init(struct mg_mgr *mgr) {
#define MIP_TCP_ARP_MS 100 // Timeout for ARP response
#define MIP_TCP_SYN_MS 15000 // Timeout for connection establishment
#define MIP_TCP_FIN_MS 1000 // Timeout for closing connection
#define MIP_TCP_WIN 16384 // TCP window size

struct connstate {
uint32_t seq, ack; // TCP seq/ack counters
uint64_t timer; // TCP keep-alive / ACK timer
size_t noack; // Not ACK-ed received TCP bytes
uint8_t mac[6]; // Peer MAC address
uint8_t ttype; // Timer type. 0: ack, 1: keep-alive
#define MIP_TTYPE_KEEPALIVE 0 // Connection is idle for long, send keepalive
Expand Down Expand Up @@ -5280,11 +5282,12 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
if (msgtype == 6 && ifp->ip == ip) { // DHCPNACK, release IP
ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;
} else if (msgtype == 2 && ifp->state == MG_TCPIP_STATE_UP && ip && gw &&
lease) { // DHCPOFFER
lease) { // DHCPOFFER
// select IP, (4.4.1) (fallback to IP source addr on foul play)
tx_dhcp_request_sel(ifp, ip, pkt->dhcp->siaddr ? pkt->dhcp->siaddr : pkt->ip->src);
ifp->state = MG_TCPIP_STATE_REQ; // REQUESTING state
} else if (msgtype == 5) { // DHCPACK
tx_dhcp_request_sel(ifp, ip,
pkt->dhcp->siaddr ? pkt->dhcp->siaddr : pkt->ip->src);
ifp->state = MG_TCPIP_STATE_REQ; // REQUESTING state
} else if (msgtype == 5) { // DHCPACK
if (ifp->state == MG_TCPIP_STATE_REQ && ip && gw && lease) { // got an IP
ifp->lease_expire = ifp->now + lease * 1000;
MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
Expand Down Expand Up @@ -5378,7 +5381,7 @@ static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
tcp->seq = seq;
tcp->ack = ack;
tcp->flags = flags;
tcp->win = mg_htons(8192);
tcp->win = mg_htons(MIP_TCP_WIN);
tcp->off = (uint8_t) (sizeof(*tcp) / 4 << 4);
uint32_t cs = 0;
uint16_t n = (uint16_t) (sizeof(*tcp) + len);
Expand Down Expand Up @@ -5533,17 +5536,18 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
MG_VERBOSE(("%lu SEQ %x -> %x", c->id, mg_htonl(pkt->tcp->seq), s->ack));
// Advance ACK counter
s->ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
#if 0
// Send ACK immediately
uint32_t rem_ip;
memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
MG_DEBUG((" imm ACK", c->id, mg_htonl(pkt->tcp->seq), s->ack));
tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK, c->loc.port,
c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
#else
// if not already running, setup a timer to send an ACK later
if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
#endif
s->noack += pkt->pay.len;
if (s->noack + 1500 >= MIP_TCP_WIN) {
// Send ACK immediately
MG_VERBOSE((" imm ACK", c->id, mg_htonl(pkt->tcp->seq), s->ack));
tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK,
c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "",
0);
s->noack = 0;
} else {
// if not already running, setup a timer to send an ACK later
if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
}

if (c->is_tls && c->is_tls_hs) {
mg_tls_handshake(c);
Expand Down Expand Up @@ -5787,6 +5791,7 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
MG_VERBOSE(("%lu ack %x %x", c->id, s->seq, s->ack));
tx_tcp(ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
s->noack = 0;
} else if (s->ttype == MIP_TTYPE_ARP) {
mg_error(c, "ARP timeout");
} else if (s->ttype == MIP_TTYPE_SYN) {
Expand Down
37 changes: 21 additions & 16 deletions src/net_builtin.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,10 +12,12 @@
#define MIP_TCP_ARP_MS 100 // Timeout for ARP response
#define MIP_TCP_SYN_MS 15000 // Timeout for connection establishment
#define MIP_TCP_FIN_MS 1000 // Timeout for closing connection
#define MIP_TCP_WIN 16384 // TCP window size

struct connstate {
uint32_t seq, ack; // TCP seq/ack counters
uint64_t timer; // TCP keep-alive / ACK timer
size_t noack; // Not ACK-ed received TCP bytes
uint8_t mac[6]; // Peer MAC address
uint8_t ttype; // Timer type. 0: ack, 1: keep-alive
#define MIP_TTYPE_KEEPALIVE 0 // Connection is idle for long, send keepalive
Expand Down Expand Up @@ -398,11 +400,12 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
if (msgtype == 6 && ifp->ip == ip) { // DHCPNACK, release IP
ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;
} else if (msgtype == 2 && ifp->state == MG_TCPIP_STATE_UP && ip && gw &&
lease) { // DHCPOFFER
lease) { // DHCPOFFER
// select IP, (4.4.1) (fallback to IP source addr on foul play)
tx_dhcp_request_sel(ifp, ip, pkt->dhcp->siaddr ? pkt->dhcp->siaddr : pkt->ip->src);
ifp->state = MG_TCPIP_STATE_REQ; // REQUESTING state
} else if (msgtype == 5) { // DHCPACK
tx_dhcp_request_sel(ifp, ip,
pkt->dhcp->siaddr ? pkt->dhcp->siaddr : pkt->ip->src);
ifp->state = MG_TCPIP_STATE_REQ; // REQUESTING state
} else if (msgtype == 5) { // DHCPACK
if (ifp->state == MG_TCPIP_STATE_REQ && ip && gw && lease) { // got an IP
ifp->lease_expire = ifp->now + lease * 1000;
MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
Expand Down Expand Up @@ -496,7 +499,7 @@ static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
tcp->seq = seq;
tcp->ack = ack;
tcp->flags = flags;
tcp->win = mg_htons(8192);
tcp->win = mg_htons(MIP_TCP_WIN);
tcp->off = (uint8_t) (sizeof(*tcp) / 4 << 4);
uint32_t cs = 0;
uint16_t n = (uint16_t) (sizeof(*tcp) + len);
Expand Down Expand Up @@ -651,17 +654,18 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
MG_VERBOSE(("%lu SEQ %x -> %x", c->id, mg_htonl(pkt->tcp->seq), s->ack));
// Advance ACK counter
s->ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
#if 0
// Send ACK immediately
uint32_t rem_ip;
memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
MG_DEBUG((" imm ACK", c->id, mg_htonl(pkt->tcp->seq), s->ack));
tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK, c->loc.port,
c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
#else
// if not already running, setup a timer to send an ACK later
if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
#endif
s->noack += pkt->pay.len;
if (s->noack + 1500 >= MIP_TCP_WIN) {
// Send ACK immediately
MG_VERBOSE((" imm ACK", c->id, mg_htonl(pkt->tcp->seq), s->ack));
tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK,
c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "",
0);
s->noack = 0;
} else {
// if not already running, setup a timer to send an ACK later
if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
}

if (c->is_tls && c->is_tls_hs) {
mg_tls_handshake(c);
Expand Down Expand Up @@ -905,6 +909,7 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
MG_VERBOSE(("%lu ack %x %x", c->id, s->seq, s->ack));
tx_tcp(ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
s->noack = 0;
} else if (s->ttype == MIP_TTYPE_ARP) {
mg_error(c, "ARP timeout");
} else if (s->ttype == MIP_TTYPE_SYN) {
Expand Down

0 comments on commit 2066304

Please sign in to comment.