}
}
-static bool is_reliable(struct utcp_connection *c) {
- return c->flags & UTCP_RELIABLE;
-}
-
static int32_t seqdiff(uint32_t a, uint32_t b) {
return a - b;
}
return len;
}
-// Copy data from the buffer without removing it.
-static ssize_t buffer_call(struct utcp_connection *c, struct buffer *buf, size_t offset, size_t len) {
- if(!c->recv) {
- return len;
- }
-
- // Ensure we don't copy more than is actually stored in the buffer
- if(offset >= buf->used) {
- return 0;
- }
-
- if(buf->used - offset < len) {
- len = buf->used - offset;
- }
-
- uint32_t realoffset = buf->offset + offset;
-
- if(buf->size - buf->offset <= offset) {
- // The offset wrapped
- realoffset -= buf->size;
- }
-
- if(buf->size - realoffset < len) {
- // The data is wrapped
- ssize_t rx1 = c->recv(c, buf->data + realoffset, buf->size - realoffset);
-
- if(rx1 < buf->size - realoffset) {
- return rx1;
- }
-
- // The channel might have been closed by the previous callback
- if(!c->recv) {
- return len;
- }
-
- ssize_t rx2 = c->recv(c, buf->data, len - (buf->size - realoffset));
-
- if(rx2 < 0) {
- return rx2;
- } else {
- return rx1 + rx2;
- }
- } else {
- return c->recv(c, buf->data + realoffset, len);
- }
-}
-
// Discard data from the buffer.
static ssize_t buffer_discard(struct buffer *buf, size_t len) {
if(buf->used < len) {
return NULL;
}
- assert((flags & ~0x1f) == 0);
+ assert(flags == 0); // UDP only
c->flags = flags;
c->recv = recv;
return c;
}
-struct utcp_connection *utcp_connect(struct utcp *utcp, uint16_t dst, utcp_recv_t recv, void *priv) {
- return utcp_connect_ex(utcp, dst, recv, priv, UTCP_TCP);
-}
-
void utcp_accept(struct utcp_connection *c, utcp_recv_t recv, void *priv) {
if(c->reapable || c->state != SYN_RECEIVED) {
debug(c, "accept() called on invalid connection in state %s\n", c, strstate[c->state]);
debug(c, "accepted %p %p\n", c, recv, priv);
c->recv = recv;
c->priv = priv;
- c->do_poll = true;
set_state(c, ESTABLISHED);
}
static void ack(struct utcp_connection *c, bool sendatleastone) {
int32_t left = seqdiff(c->snd.last, c->snd.nxt);
- int32_t cwndleft = is_reliable(c) ? min(c->snd.cwnd, c->snd.wnd) - seqdiff(c->snd.nxt, c->snd.una) : MAX_UNRELIABLE_SIZE;
+ int32_t cwndleft = MAX_UNRELIABLE_SIZE;
assert(left >= 0);
pkt->hdr.src = c->src;
pkt->hdr.dst = c->dst;
pkt->hdr.ack = c->rcv.nxt;
- pkt->hdr.wnd = is_reliable(c) ? c->rcvbuf.maxsize : 0;
+ pkt->hdr.wnd = 0;
pkt->hdr.ctl = ACK;
pkt->hdr.aux = 0;
c->snd.nxt += seglen;
left -= seglen;
- if(!is_reliable(c)) {
- if(left) {
- pkt->hdr.ctl |= MF;
- } else {
- pkt->hdr.ctl &= ~MF;
- }
- }
-
if(seglen && fin_wanted(c, c->snd.nxt)) {
seglen--;
pkt->hdr.ctl |= FIN;
print_packet(c, "send", pkt, sizeof(pkt->hdr) + seglen);
c->utcp->send(c->utcp, pkt, sizeof(pkt->hdr) + seglen);
- if(left && !is_reliable(c)) {
+ if(left) {
pkt->hdr.wnd += seglen;
}
} while(left);
return -1;
}
- // Check if we need to be able to buffer all data
-
- if(c->flags & UTCP_NO_PARTIAL) {
- if(len > buffer_free(&c->sndbuf)) {
- if(len > c->sndbuf.maxsize) {
- errno = EMSGSIZE;
- return -1;
- } else {
- errno = EWOULDBLOCK;
- return 0;
- }
- }
- }
-
// Add data to send buffer.
- if(is_reliable(c)) {
- len = buffer_put(&c->sndbuf, data, len);
- } else if(c->state != SYN_SENT && c->state != SYN_RECEIVED) {
+ if(c->state != SYN_SENT && c->state != SYN_RECEIVED) {
if(len > MAX_UNRELIABLE_SIZE || buffer_put(&c->sndbuf, data, len) != (ssize_t)len) {
errno = EMSGSIZE;
return -1;
}
if(len <= 0) {
- if(is_reliable(c)) {
- errno = EWOULDBLOCK;
- return 0;
- } else {
- return len;
- }
+ return len;
}
c->snd.last += len;
ack(c, false);
- if(!is_reliable(c)) {
- c->snd.una = c->snd.nxt = c->snd.last;
- buffer_discard(&c->sndbuf, c->sndbuf.used);
- }
-
- if(is_reliable(c) && !timespec_isset(&c->rtrx_timeout)) {
- start_retransmit_timer(c);
- }
-
- if(is_reliable(c) && !timespec_isset(&c->conn_timeout)) {
- clock_gettime(UTCP_CLOCK, &c->conn_timeout);
- c->conn_timeout.tv_sec += c->utcp->timeout;
- }
+ c->snd.una = c->snd.nxt = c->snd.last;
+ buffer_discard(&c->sndbuf, c->sndbuf.used);
return len;
}
hdr->dst = tmp;
}
-static void fast_retransmit(struct utcp_connection *c) {
- if(c->state == CLOSED || c->snd.last == c->snd.una) {
- debug(c, "fast_retransmit() called but nothing to retransmit!\n");
- return;
- }
-
- struct utcp *utcp = c->utcp;
-
- struct {
- struct hdr hdr;
- uint8_t data[];
- } *pkt = c->utcp->pkt;
-
- pkt->hdr.src = c->src;
- pkt->hdr.dst = c->dst;
- pkt->hdr.wnd = c->rcvbuf.maxsize;
- pkt->hdr.aux = 0;
-
- switch(c->state) {
- case ESTABLISHED:
- case FIN_WAIT_1:
- case CLOSE_WAIT:
- case CLOSING:
- case LAST_ACK:
- // Send unacked data again.
- pkt->hdr.seq = c->snd.una;
- pkt->hdr.ack = c->rcv.nxt;
- pkt->hdr.ctl = ACK;
- uint32_t len = min(seqdiff(c->snd.last, c->snd.una), utcp->mss);
-
- if(fin_wanted(c, c->snd.una + len)) {
- len--;
- pkt->hdr.ctl |= FIN;
- }
-
- buffer_copy(&c->sndbuf, pkt->data, 0, len);
- print_packet(c, "rtrx", pkt, sizeof(pkt->hdr) + len);
- utcp->send(utcp, pkt, sizeof(pkt->hdr) + len);
- break;
-
- default:
- break;
- }
-}
-
static void retransmit(struct utcp_connection *c) {
if(c->state == CLOSED || c->snd.last == c->snd.una) {
debug(c, "retransmit() called but nothing to retransmit!\n");
struct utcp *utcp = c->utcp;
- if(utcp->retransmit) {
- utcp->retransmit(c);
- }
-
struct {
struct hdr hdr;
uint8_t data[];
break;
case ESTABLISHED:
+ break;
+
case FIN_WAIT_1:
case CLOSE_WAIT:
case CLOSING:
if(fin_wanted(c, c->snd.una + len)) {
len--;
pkt->hdr.ctl |= FIN;
+ } else {
+ break;
}
- // RFC 5681 slow start after timeout
- uint32_t flightsize = seqdiff(c->snd.nxt, c->snd.una);
- c->snd.ssthresh = max(flightsize / 2, utcp->mss * 2); // eq. 4
- c->snd.cwnd = utcp->mss;
- debug_cwnd(c);
+ assert(len == 0);
- buffer_copy(&c->sndbuf, pkt->data, 0, len);
print_packet(c, "rtrx", pkt, sizeof(pkt->hdr) + len);
utcp->send(utcp, pkt, sizeof(pkt->hdr) + len);
-
- c->snd.nxt = c->snd.una + len;
break;
case CLOSED:
return;
}
-/* Update receive buffer and SACK entries after consuming data.
- *
- * Situation:
- *
- * |.....0000..1111111111.....22222......3333|
- * |---------------^
- *
- * 0..3 represent the SACK entries. The ^ indicates up to which point we want
- * to remove data from the receive buffer. The idea is to substract "len"
- * from the offset of all the SACK entries, and then remove/cut down entries
- * that are shifted to before the start of the receive buffer.
- *
- * There are three cases:
- * - the SACK entry is after ^, in that case just change the offset.
- * - the SACK entry starts before and ends after ^, so we have to
- * change both its offset and size.
- * - the SACK entry is completely before ^, in that case delete it.
- */
-static void sack_consume(struct utcp_connection *c, size_t len) {
- debug(c, "sack_consume %lu\n", (unsigned long)len);
-
- if(len > c->rcvbuf.used) {
- debug(c, "all SACK entries consumed\n");
- c->sacks[0].len = 0;
- return;
- }
-
- buffer_discard(&c->rcvbuf, len);
-
- for(int i = 0; i < NSACKS && c->sacks[i].len;) {
- if(len < c->sacks[i].offset) {
- c->sacks[i].offset -= len;
- i++;
- } else if(len < c->sacks[i].offset + c->sacks[i].len) {
- c->sacks[i].len -= len - c->sacks[i].offset;
- c->sacks[i].offset = 0;
- i++;
- } else {
- if(i < NSACKS - 1) {
- memmove(&c->sacks[i], &c->sacks[i + 1], (NSACKS - 1 - i) * sizeof(c->sacks)[i]);
- c->sacks[NSACKS - 1].len = 0;
- } else {
- c->sacks[i].len = 0;
- break;
- }
- }
- }
-
- for(int i = 0; i < NSACKS && c->sacks[i].len; i++) {
- debug(c, "SACK[%d] offset %u len %u\n", i, c->sacks[i].offset, c->sacks[i].len);
- }
-}
-
-static void handle_out_of_order(struct utcp_connection *c, uint32_t offset, const void *data, size_t len) {
- debug(c, "out of order packet, offset %u\n", offset);
- // Packet loss or reordering occured. Store the data in the buffer.
- ssize_t rxd = buffer_put_at(&c->rcvbuf, offset, data, len);
-
- if(rxd <= 0) {
- debug(c, "packet outside receive buffer, dropping\n");
- return;
- }
-
- if((size_t)rxd < len) {
- debug(c, "packet partially outside receive buffer\n");
- len = rxd;
- }
-
- // Make note of where we put it.
- for(int i = 0; i < NSACKS; i++) {
- if(!c->sacks[i].len) { // nothing to merge, add new entry
- debug(c, "new SACK entry %d\n", i);
- c->sacks[i].offset = offset;
- c->sacks[i].len = rxd;
- break;
- } else if(offset < c->sacks[i].offset) {
- if(offset + rxd < c->sacks[i].offset) { // insert before
- if(!c->sacks[NSACKS - 1].len) { // only if room left
- debug(c, "insert SACK entry at %d\n", i);
- memmove(&c->sacks[i + 1], &c->sacks[i], (NSACKS - i - 1) * sizeof(c->sacks)[i]);
- c->sacks[i].offset = offset;
- c->sacks[i].len = rxd;
- } else {
- debug(c, "SACK entries full, dropping packet\n");
- }
-
- break;
- } else { // merge
- debug(c, "merge with start of SACK entry at %d\n", i);
- c->sacks[i].offset = offset;
- break;
- }
- } else if(offset <= c->sacks[i].offset + c->sacks[i].len) {
- if(offset + rxd > c->sacks[i].offset + c->sacks[i].len) { // merge
- debug(c, "merge with end of SACK entry at %d\n", i);
- c->sacks[i].len = offset + rxd - c->sacks[i].offset;
- // TODO: handle potential merge with next entry
- }
-
- break;
- }
- }
-
- for(int i = 0; i < NSACKS && c->sacks[i].len; i++) {
- debug(c, "SACK[%d] offset %u len %u\n", i, c->sacks[i].offset, c->sacks[i].len);
- }
-}
-
-static void handle_in_order(struct utcp_connection *c, const void *data, size_t len) {
- if(c->recv) {
- ssize_t rxd = c->recv(c, data, len);
-
- if(rxd != (ssize_t)len) {
- // TODO: handle the application not accepting all data.
- abort();
- }
- }
-
- // Check if we can process out-of-order data now.
- if(c->sacks[0].len && len >= c->sacks[0].offset) {
- debug(c, "incoming packet len %lu connected with SACK at %u\n", (unsigned long)len, c->sacks[0].offset);
-
- if(len < c->sacks[0].offset + c->sacks[0].len) {
- size_t offset = len;
- len = c->sacks[0].offset + c->sacks[0].len;
- size_t remainder = len - offset;
-
- ssize_t rxd = buffer_call(c, &c->rcvbuf, offset, remainder);
-
- if(rxd != (ssize_t)remainder) {
- // TODO: handle the application not accepting all data.
- abort();
- }
- }
- }
-
- if(c->rcvbuf.used) {
- sack_consume(c, len);
- }
-
- c->rcv.nxt += len;
-}
-
static void handle_unreliable(struct utcp_connection *c, const struct hdr *hdr, const void *data, size_t len) {
// Fast path for unfragmented packets
if(!hdr->wnd && !(hdr->ctl & MF)) {
c->rcv.nxt = hdr->seq + len;
return;
}
-
- // Ensure reassembled packet are not larger than 64 kiB
- if(hdr->wnd >= MAX_UNRELIABLE_SIZE || hdr->wnd + len > MAX_UNRELIABLE_SIZE) {
- return;
- }
-
- // Don't accept out of order fragments
- if(hdr->wnd && hdr->seq != c->rcv.nxt) {
- return;
- }
-
- // Reset the receive buffer for the first fragment
- if(!hdr->wnd) {
- buffer_clear(&c->rcvbuf);
- }
-
- ssize_t rxd = buffer_put_at(&c->rcvbuf, hdr->wnd, data, len);
-
- if(rxd != (ssize_t)len) {
- return;
- }
-
- // Send the packet if it's the final fragment
- if(!(hdr->ctl & MF)) {
- buffer_call(c, &c->rcvbuf, 0, hdr->wnd + len);
- }
-
- c->rcv.nxt = hdr->seq + len;
}
static void handle_incoming_data(struct utcp_connection *c, const struct hdr *hdr, const void *data, size_t len) {
- if(!is_reliable(c)) {
- handle_unreliable(c, hdr, data, len);
- return;
- }
-
- uint32_t offset = seqdiff(hdr->seq, c->rcv.nxt);
-
- if(offset) {
- handle_out_of_order(c, offset, data, len);
- } else {
- handle_in_order(c, data, len);
- }
+ handle_unreliable(c, hdr, data, len);
}
-
ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
const uint8_t *ptr = data;
c->flags = init[3] & 0x7;
} else {
- c->flags = UTCP_TCP;
+ c->flags = UTCP_UDP;
}
synack:
break;
}
- // 1b. Discard data that is not in our receive window.
-
- if(is_reliable(c)) {
- bool acceptable;
-
- if(c->state == SYN_SENT) {
- acceptable = true;
- } else if(len == 0) {
- acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0;
- } else {
- int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
-
- // cut already accepted front overlapping
- if(rcv_offset < 0) {
- acceptable = len > (size_t) - rcv_offset;
-
- if(acceptable) {
- ptr -= rcv_offset;
- len += rcv_offset;
- hdr.seq -= rcv_offset;
- }
- } else {
- acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
- }
- }
-
- if(!acceptable) {
- debug(c, "packet not acceptable, %u <= %u + %lu < %u\n", c->rcv.nxt, hdr.seq, (unsigned long)len, c->rcv.nxt + c->rcvbuf.maxsize);
-
- // Ignore unacceptable RST packets.
- if(hdr.ctl & RST) {
- return 0;
- }
-
- // Otherwise, continue processing.
- len = 0;
- }
- } else {
#if UTCP_DEBUG
- int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
+ int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
- if(rcv_offset) {
- debug(c, "packet out of order, offset %u bytes", rcv_offset);
- }
+ if(rcv_offset) {
+ debug(c, "packet out of order, offset %u bytes", rcv_offset);
+ }
#endif
- }
c->snd.wnd = hdr.wnd; // TODO: move below
// ackno should not roll back, and it should also not be bigger than what we ever could have sent
// (= snd.una + c->sndbuf.used).
- if(!is_reliable(c)) {
- if(hdr.ack != c->snd.last && c->state >= ESTABLISHED) {
- hdr.ack = c->snd.una;
- }
+ if(hdr.ack != c->snd.last && c->state >= ESTABLISHED) {
+ hdr.ack = c->snd.una;
}
// 2. Handle RST packets
c->recv(c, NULL, 0);
}
- if(c->poll && !c->reapable) {
- c->poll(c, 0);
- }
-
return 0;
case SYN_RECEIVED:
c->recv(c, NULL, 0);
}
- if(c->poll && !c->reapable) {
- c->poll(c, 0);
- }
-
return 0;
case CLOSING:
if(data_acked) {
buffer_discard(&c->sndbuf, data_acked);
-
- if(is_reliable(c)) {
- c->do_poll = true;
- }
}
// Also advance snd.nxt if possible
default:
break;
}
- } else {
- if(!len && is_reliable(c) && c->snd.una != c->snd.last) {
- c->dupack++;
- debug(c, "duplicate ACK %d\n", c->dupack);
-
- if(c->dupack == 3) {
- // RFC 5681 fast recovery
- debug(c, "fast recovery started\n", c->dupack);
- uint32_t flightsize = seqdiff(c->snd.nxt, c->snd.una);
- c->snd.ssthresh = max(flightsize / 2, utcp->mss * 2); // eq. 4
- c->snd.cwnd = min(c->snd.ssthresh + 3 * utcp->mss, c->sndbuf.maxsize);
-
- if(c->snd.cwnd > c->sndbuf.maxsize) {
- c->snd.cwnd = c->sndbuf.maxsize;
- }
-
- debug_cwnd(c);
-
- fast_retransmit(c);
- } else if(c->dupack > 3) {
- c->snd.cwnd += utcp->mss;
-
- if(c->snd.cwnd > c->sndbuf.maxsize) {
- c->snd.cwnd = c->sndbuf.maxsize;
- }
-
- debug_cwnd(c);
- }
-
- // We got an ACK which indicates the other side did get one of our packets.
- // Reset the retransmission timer to avoid going to slow start,
- // but don't touch the connection timeout.
- start_retransmit_timer(c);
- }
}
// 4. Update timers
if(c->snd.una == c->snd.last) {
stop_retransmit_timer(c);
timespec_clear(&c->conn_timeout);
- } else if(is_reliable(c)) {
- start_retransmit_timer(c);
- clock_gettime(UTCP_CLOCK, &c->conn_timeout);
- c->conn_timeout.tv_sec += utcp->timeout;
}
}
c->snd.last++;
set_state(c, FIN_WAIT_1);
} else {
- c->do_poll = true;
set_state(c, ESTABLISHED);
}
// 7. Process FIN stuff
- if((hdr.ctl & FIN) && (!is_reliable(c) || hdr.seq + len == c->rcv.nxt)) {
+ if(hdr.ctl & FIN) {
switch(c->state) {
case SYN_SENT:
case SYN_RECEIVED:
// - or we got an ack, so we should maybe send a bit more data
// -> sendatleastone = false
- if(is_reliable(c) || hdr.ctl & SYN || hdr.ctl & FIN) {
+ if(hdr.ctl & SYN || hdr.ctl & FIN) {
ack(c, has_data);
}
set_buffer_storage(&c->rcvbuf, NULL, min(c->rcvbuf.maxsize, DEFAULT_MAXRCVBUFSIZE));
c->recv = NULL;
- c->poll = NULL;
c->reapable = true;
}
errno = 0;
c->recv(c, NULL, 0);
}
-
- if(c->poll && !c->reapable) {
- errno = 0;
- c->poll(c, 0);
- }
}
return;
c->recv(c, NULL, 0);
}
- if(c->poll && !c->reapable) {
- c->poll(c, 0);
- }
-
continue;
}
retransmit(c);
}
- if(c->poll) {
- if((c->state == ESTABLISHED || c->state == CLOSE_WAIT) && c->do_poll) {
- c->do_poll = false;
- uint32_t len = buffer_free(&c->sndbuf);
-
- if(len) {
- c->poll(c, len);
- }
- } else if(c->state == CLOSED) {
- c->poll(c, 0);
- }
- }
-
if(timespec_isset(&c->conn_timeout) && timespec_lt(&c->conn_timeout, &next)) {
next = c->conn_timeout;
}
if(c->recv) {
c->recv(c, NULL, 0);
}
-
- if(c->poll && !c->reapable) {
- c->poll(c, 0);
- }
}
buffer_exit(&c->rcvbuf);
}
set_buffer_storage(&c->sndbuf, data, size);
-
- c->do_poll = is_reliable(c) && buffer_free(&c->sndbuf);
}
size_t utcp_get_rcvbuf(struct utcp_connection *c) {
}
}
-void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
- if(c) {
- c->poll = poll;
- c->do_poll = is_reliable(c) && buffer_free(&c->sndbuf);
- }
-}
-
void utcp_set_accept_cb(struct utcp *utcp, utcp_accept_t accept, utcp_listen_t listen) {
if(utcp) {
utcp->accept = accept;
}
}
-void utcp_set_retransmit_cb(struct utcp *utcp, utcp_retransmit_t cb) {
- utcp->retransmit = cb;
-}
-
void utcp_set_clock_granularity(long granularity) {
CLOCK_GRANULARITY = granularity;
}
projects / meshlink-tiny / blobdiff