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Better acks
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@cpq
cpq committed Mar 3, 2024
1 parent 91bc79c commit 1bf5ce5
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Showing 2 changed files with 56 additions and 26 deletions.
40 changes: 28 additions & 12 deletions mongoose.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4894,12 +4894,13 @@ 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
#define MIP_TCP_WIN 6000 // 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
uint32_t acked; // Last ACK-ed number
size_t unacked; // Not acked 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 @@ -5371,6 +5372,14 @@ static void rx_udp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
uint8_t flags, uint16_t sport, uint16_t dport,
uint32_t seq, uint32_t ack, const void *buf, size_t len) {
#if 0
uint8_t opts[] = {2, 4, 5, 0xb4, 4, 2, 0, 0}; // MSS = 1460, SACK permitted
if (flags & TH_SYN) {
// Handshake? Set MSS
buf = opts;
len = sizeof(opts);
}
#endif
struct ip *ip =
tx_ip(ifp, dst_mac, 6, ifp->ip, dst_ip, sizeof(struct tcp) + len);
struct tcp *tcp = (struct tcp *) (ip + 1);
Expand All @@ -5383,6 +5392,8 @@ static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
tcp->flags = flags;
tcp->win = mg_htons(MIP_TCP_WIN);
tcp->off = (uint8_t) (sizeof(*tcp) / 4 << 4);
// if (flags & TH_SYN) tcp->off = 0x70; // Handshake? header size 28 bytes

uint32_t cs = 0;
uint16_t n = (uint16_t) (sizeof(*tcp) + len);
uint8_t pseudo[] = {0, ip->proto, (uint8_t) (n >> 8), (uint8_t) (n & 255)};
Expand All @@ -5393,7 +5404,7 @@ static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
tcp->csum = csumfin(cs);
MG_VERBOSE(("TCP %M:%hu -> %M:%hu fl %x len %u", mg_print_ip4, &ip->src,
mg_ntohs(tcp->sport), mg_print_ip4, &ip->dst,
mg_ntohs(tcp->dport), tcp->flags, (int) len));
mg_ntohs(tcp->dport), tcp->flags, len));
// mg_hexdump(ifp->tx.ptr, PDIFF(ifp->tx.ptr, tcp + 1) + len);
return ether_output(ifp, PDIFF(ifp->tx.ptr, tcp + 1) + len);
}
Expand Down Expand Up @@ -5512,6 +5523,7 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
} else if (pkt->pay.len == 0) {
// TODO(cpq): handle this peer's ACK
} else if (seq != s->ack) {
#if 0
uint32_t ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
if (s->ack == ack) {
MG_VERBOSE(("ignoring duplicate pkt"));
Expand All @@ -5521,6 +5533,7 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "",
0);
}
#endif
} else if (io->size - io->len < pkt->pay.len &&
!mg_iobuf_resize(io, io->len + pkt->pay.len)) {
mg_error(c, "oom");
Expand All @@ -5536,14 +5549,17 @@ 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);
s->noack += pkt->pay.len;
if (s->noack + 1500 >= MIP_TCP_WIN) {
s->unacked += pkt->pay.len;
// size_t diff = s->acked <= s->ack ? s->ack - s->acked : s->ack;
if (s->unacked > MIP_TCP_WIN / 2 && s->acked != s->ack) {
// Send ACK immediately
MG_VERBOSE((" imm ACK", c->id, mg_htonl(pkt->tcp->seq), s->ack));
MG_VERBOSE(("%lu imm ACK %lu", c->id, s->acked));
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), "",
c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), NULL,
0);
s->noack = 0;
s->unacked = 0;
s->acked = s->ack;
if (s->ttype != MIP_TTYPE_KEEPALIVE) settmout(c, MIP_TTYPE_KEEPALIVE);
} else {
// if not already running, setup a timer to send an ACK later
if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
Expand Down Expand Up @@ -5787,11 +5803,11 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
uint32_t rem_ip;
memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
if (now > s->timer) {
if (s->ttype == MIP_TTYPE_ACK) {
if (s->ttype == MIP_TTYPE_ACK && s->acked != s->ack) {
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;
mg_htonl(s->seq), mg_htonl(s->ack), NULL, 0);
s->acked = s->ack;
} else if (s->ttype == MIP_TTYPE_ARP) {
mg_error(c, "ARP timeout");
} else if (s->ttype == MIP_TTYPE_SYN) {
Expand All @@ -5805,7 +5821,7 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
} else {
MG_VERBOSE(("%lu keepalive", c->id));
tx_tcp(ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
mg_htonl(s->seq - 1), mg_htonl(s->ack), "", 0);
mg_htonl(s->seq - 1), mg_htonl(s->ack), NULL, 0);
}
}

Expand Down
42 changes: 28 additions & 14 deletions src/net_builtin.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,12 +12,13 @@
#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
#define MIP_TCP_WIN 6000 // 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
uint32_t acked; // Last ACK-ed number
size_t unacked; // Not acked 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 @@ -489,6 +490,14 @@ static void rx_udp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
uint8_t flags, uint16_t sport, uint16_t dport,
uint32_t seq, uint32_t ack, const void *buf, size_t len) {
#if 0
uint8_t opts[] = {2, 4, 5, 0xb4, 4, 2, 0, 0}; // MSS = 1460, SACK permitted
if (flags & TH_SYN) {
// Handshake? Set MSS
buf = opts;
len = sizeof(opts);
}
#endif
struct ip *ip =
tx_ip(ifp, dst_mac, 6, ifp->ip, dst_ip, sizeof(struct tcp) + len);
struct tcp *tcp = (struct tcp *) (ip + 1);
Expand All @@ -501,6 +510,8 @@ static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
tcp->flags = flags;
tcp->win = mg_htons(MIP_TCP_WIN);
tcp->off = (uint8_t) (sizeof(*tcp) / 4 << 4);
// if (flags & TH_SYN) tcp->off = 0x70; // Handshake? header size 28 bytes

uint32_t cs = 0;
uint16_t n = (uint16_t) (sizeof(*tcp) + len);
uint8_t pseudo[] = {0, ip->proto, (uint8_t) (n >> 8), (uint8_t) (n & 255)};
Expand All @@ -511,7 +522,7 @@ static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
tcp->csum = csumfin(cs);
MG_VERBOSE(("TCP %M:%hu -> %M:%hu fl %x len %u", mg_print_ip4, &ip->src,
mg_ntohs(tcp->sport), mg_print_ip4, &ip->dst,
mg_ntohs(tcp->dport), tcp->flags, (int) len));
mg_ntohs(tcp->dport), tcp->flags, len));
// mg_hexdump(ifp->tx.ptr, PDIFF(ifp->tx.ptr, tcp + 1) + len);
return ether_output(ifp, PDIFF(ifp->tx.ptr, tcp + 1) + len);
}
Expand Down Expand Up @@ -630,6 +641,7 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
} else if (pkt->pay.len == 0) {
// TODO(cpq): handle this peer's ACK
} else if (seq != s->ack) {
#if 0
uint32_t ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
if (s->ack == ack) {
MG_VERBOSE(("ignoring duplicate pkt"));
Expand All @@ -639,6 +651,7 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "",
0);
}
#endif
} else if (io->size - io->len < pkt->pay.len &&
!mg_iobuf_resize(io, io->len + pkt->pay.len)) {
mg_error(c, "oom");
Expand All @@ -654,16 +667,17 @@ 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);
s->noack += pkt->pay.len;
if (s->noack + 1500 >= MIP_TCP_WIN) {
s->unacked += pkt->pay.len;
// size_t diff = s->acked <= s->ack ? s->ack - s->acked : s->ack;
if (s->unacked > MIP_TCP_WIN / 2 && s->acked != s->ack) {
// Send ACK immediately
MG_VERBOSE((" imm ACK", c->id, mg_htonl(pkt->tcp->seq), s->ack));
MG_VERBOSE(("%lu imm ACK %lu", c->id, s->acked));
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), "",
c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), NULL,
0);
s->noack = 0;
// restart the ACK timer if already running
if (s->ttype == MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
s->unacked = 0;
s->acked = s->ack;
if (s->ttype != MIP_TTYPE_KEEPALIVE) settmout(c, MIP_TTYPE_KEEPALIVE);
} else {
// if not already running, setup a timer to send an ACK later
if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
Expand Down Expand Up @@ -907,11 +921,11 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
uint32_t rem_ip;
memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
if (now > s->timer) {
if (s->ttype == MIP_TTYPE_ACK) {
if (s->ttype == MIP_TTYPE_ACK && s->acked != s->ack) {
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;
mg_htonl(s->seq), mg_htonl(s->ack), NULL, 0);
s->acked = s->ack;
} else if (s->ttype == MIP_TTYPE_ARP) {
mg_error(c, "ARP timeout");
} else if (s->ttype == MIP_TTYPE_SYN) {
Expand All @@ -925,7 +939,7 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
} else {
MG_VERBOSE(("%lu keepalive", c->id));
tx_tcp(ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
mg_htonl(s->seq - 1), mg_htonl(s->ack), "", 0);
mg_htonl(s->seq - 1), mg_htonl(s->ack), NULL, 0);
}
}

Expand Down

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