return a - b;
}
+// Buffer functions
+// TODO: convert to ringbuffers to avoid memmove() operations.
+
+// Store data into the buffer
+static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
+ if(buf->maxsize <= buf->used)
+ return 0;
+ if(len > buf->maxsize - buf->used)
+ len = buf->maxsize - buf->used;
+ if(len > buf->size - buf->used) {
+ size_t newsize = buf->size;
+ do {
+ newsize *= 2;
+ } while(newsize < buf->used + len);
+ if(newsize > buf->maxsize)
+ newsize = buf->maxsize;
+ char *newdata = realloc(buf->data, newsize);
+ if(!newdata)
+ return -1;
+ buf->data = newdata;
+ buf->size = newsize;
+ }
+ memcpy(buf->data + buf->used, data, len);
+ buf->used += len;
+ return len;
+}
+
+// Get data from the buffer. data can be NULL.
+static ssize_t buffer_get(struct buffer *buf, void *data, size_t len) {
+ if(len > buf->used)
+ len = buf->used;
+ if(data)
+ memcpy(data, buf->data, len);
+ if(len < buf->used)
+ memmove(buf->data, buf->data + len, buf->used - len);
+ buf->used -= len;
+ return len;
+}
+
+// Copy data from the buffer without removing it.
+static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t len) {
+ if(offset >= buf->used)
+ return 0;
+ if(offset + len > buf->used)
+ len = buf->used - offset;
+ memcpy(data, buf->data + offset, len);
+ return len;
+}
+
+static bool buffer_init(struct buffer *buf, uint32_t len, uint32_t maxlen) {
+ memset(buf, 0, sizeof *buf);
+ buf->data = malloc(len);
+ if(!len)
+ return false;
+ buf->size = len;
+ buf->maxsize = maxlen;
+ return true;
+}
+
+static void buffer_exit(struct buffer *buf) {
+ free(buf->data);
+ memset(buf, 0, sizeof *buf);
+}
+
+static uint32_t buffer_free(const struct buffer *buf) {
+ return buf->maxsize - buf->used;
+}
+
// Connections are stored in a sorted list.
// This gives O(log(N)) lookup time, O(N log(N)) insertion time and O(N) deletion time.
static int compare(const void *va, const void *vb) {
+ assert(va && vb);
+
const struct utcp_connection *a = *(struct utcp_connection **)va;
const struct utcp_connection *b = *(struct utcp_connection **)vb;
+ assert(a && b);
assert(a->src && b->src);
int c = (int)a->src - (int)b->src;
assert(cp);
int i = cp - utcp->connections;
- memmove(cp + i, cp + i + 1, (utcp->nconnections - i - 1) * sizeof *cp);
+ memmove(cp, cp + 1, (utcp->nconnections - i - 1) * sizeof *cp);
utcp->nconnections--;
- free(c->sndbuf);
+ buffer_exit(&c->sndbuf);
free(c);
}
if(!c)
return NULL;
- c->sndbufsize = DEFAULT_SNDBUFSIZE;
- c->maxsndbufsize = DEFAULT_MAXSNDBUFSIZE;
- c->sndbuf = malloc(c->sndbufsize);
- if(!c->sndbuf) {
+ if(!buffer_init(&c->sndbuf, DEFAULT_SNDBUFSIZE, DEFAULT_MAXSNDBUFSIZE)) {
free(c);
return NULL;
}
static void ack(struct utcp_connection *c, bool sendatleastone) {
int32_t left = seqdiff(c->snd.last, c->snd.nxt);
int32_t cwndleft = c->snd.cwnd - seqdiff(c->snd.nxt, c->snd.una);
- char *data = c->sndbuf + seqdiff(c->snd.nxt, c->snd.una);
assert(left >= 0);
struct {
struct hdr hdr;
- char data[c->utcp->mtu];
- } pkt;
+ char data[];
+ } *pkt;
+
+ pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
+ if(!pkt->data)
+ return;
- pkt.hdr.src = c->src;
- pkt.hdr.dst = c->dst;
- pkt.hdr.ack = c->rcv.nxt;
- pkt.hdr.wnd = c->snd.wnd;
- pkt.hdr.ctl = ACK;
- pkt.hdr.aux = 0;
+ pkt->hdr.src = c->src;
+ pkt->hdr.dst = c->dst;
+ pkt->hdr.ack = c->rcv.nxt;
+ pkt->hdr.wnd = c->snd.wnd;
+ pkt->hdr.ctl = ACK;
+ pkt->hdr.aux = 0;
do {
uint32_t seglen = left > c->utcp->mtu ? c->utcp->mtu : left;
- pkt.hdr.seq = c->snd.nxt;
+ pkt->hdr.seq = c->snd.nxt;
- memcpy(pkt.data, data, seglen);
+ buffer_copy(&c->sndbuf, pkt->data, seqdiff(c->snd.nxt, c->snd.una), seglen);
c->snd.nxt += seglen;
- data += seglen;
left -= seglen;
if(c->state != ESTABLISHED && !left && seglen) {
case FIN_WAIT_1:
case CLOSING:
seglen--;
- pkt.hdr.ctl |= FIN;
+ pkt->hdr.ctl |= FIN;
break;
default:
break;
}
}
- print_packet(c->utcp, "send", &pkt, sizeof pkt.hdr + seglen);
- c->utcp->send(c->utcp, &pkt, sizeof pkt.hdr + seglen);
+ print_packet(c->utcp, "send", pkt, sizeof pkt->hdr + seglen);
+ c->utcp->send(c->utcp, pkt, sizeof pkt->hdr + seglen);
} while(left);
+
+ free(pkt);
}
ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
return -1;
}
- uint32_t bufused = seqdiff(c->snd.nxt, c->snd.una);
-
- /* Check our send buffer.
- * - If it's big enough, just put the data in there.
- * - If not, decide whether to enlarge if possible.
- * - Cap len so it doesn't overflow our buffer.
- */
-
- if(len > c->sndbufsize - bufused && c->sndbufsize < c->maxsndbufsize) {
- uint32_t newbufsize;
- if(c->sndbufsize > c->maxsndbufsize / 2)
- newbufsize = c->maxsndbufsize;
- else
- newbufsize = c->sndbufsize * 2;
- if(bufused + len > newbufsize) {
- if(bufused + len > c->maxsndbufsize)
- newbufsize = c->maxsndbufsize;
- else
- newbufsize = bufused + len;
- }
- char *newbuf = realloc(c->sndbuf, newbufsize);
- if(newbuf) {
- c->sndbuf = newbuf;
- c->sndbufsize = newbufsize;
- }
- }
-
- if(len > c->sndbufsize - bufused)
- len = c->sndbufsize - bufused;
-
- if(!len) {
- errno == EWOULDBLOCK;
+ len = buffer_put(&c->sndbuf, data, len);
+ if(len <= 0) {
+ errno = EWOULDBLOCK;
return 0;
}
- memcpy(c->sndbuf + bufused, data, len);
c->snd.last += len;
-
ack(c, false);
return len;
}
hdr->dst = tmp;
}
+static void retransmit(struct utcp_connection *c) {
+ if(c->state == CLOSED || c->snd.nxt == c->snd.una)
+ return;
+
+ struct utcp *utcp = c->utcp;
+
+ struct {
+ struct hdr hdr;
+ char data[];
+ } *pkt;
+
+ pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
+ if(!pkt)
+ return;
+
+ pkt->hdr.src = c->src;
+ pkt->hdr.dst = c->dst;
+
+ switch(c->state) {
+ case LISTEN:
+ // TODO: this should not happen
+ break;
+
+ case SYN_SENT:
+ pkt->hdr.seq = c->snd.iss;
+ pkt->hdr.ack = 0;
+ pkt->hdr.wnd = c->rcv.wnd;
+ pkt->hdr.ctl = SYN;
+ print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
+ utcp->send(utcp, pkt, sizeof pkt->hdr);
+ break;
+
+ case SYN_RECEIVED:
+ pkt->hdr.seq = c->snd.nxt;
+ pkt->hdr.ack = c->rcv.nxt;
+ pkt->hdr.ctl = SYN | ACK;
+ print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
+ utcp->send(utcp, pkt, sizeof pkt->hdr);
+ break;
+
+ case ESTABLISHED:
+ case FIN_WAIT_1:
+ pkt->hdr.seq = c->snd.una;
+ pkt->hdr.ack = c->rcv.nxt;
+ pkt->hdr.ctl = ACK;
+ uint32_t len = seqdiff(c->snd.nxt, c->snd.una);
+ if(c->state == FIN_WAIT_1)
+ len--;
+ if(len > utcp->mtu)
+ len = utcp->mtu;
+ else {
+ if(c->state == FIN_WAIT_1)
+ pkt->hdr.ctl |= FIN;
+ }
+ buffer_copy(&c->sndbuf, pkt->data, 0, len);
+ print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr + len);
+ utcp->send(utcp, pkt, sizeof pkt->hdr + len);
+ break;
+
+ default:
+ // TODO: implement
+ abort();
+ }
+
+ free(pkt);
+}
+
+
ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
if(!utcp) {
errno = EFAULT;
// It is for an existing connection.
+ uint32_t prevrcvnxt = c->rcv.nxt;
+
// 1. Drop invalid packets.
// 1a. Drop packets that should not happen in our current state.
#endif
if(!acceptable) {
- debug("Packet not acceptable, %u <= %u + %zu < %u\n", c->rcv.nxt, hdr.seq, len, c->rcv.nxt + c->rcv.wnd);
+ debug("Packet not acceptable, %u <= %u + %zu < %u\n", c->rcv.nxt, hdr.seq, len, c->rcv.nxt + c->rcv.wnd);
// Ignore unacceptable RST packets.
if(hdr.ctl & RST)
return 0;
// Otherwise, send an ACK back in the hope things improve.
- goto ack;
+ ack(c, true);
+ return 0;
}
c->snd.wnd = hdr.wnd; // TODO: move below
// 3. Advance snd.una
uint32_t advanced = seqdiff(hdr.ack, c->snd.una);
- uint32_t prevrcvnxt = c->rcv.nxt;
+ prevrcvnxt = c->rcv.nxt;
if(advanced) {
int32_t data_acked = advanced;
int32_t bufused = seqdiff(c->snd.last, c->snd.una);
assert(data_acked <= bufused);
- // Make room in the send buffer.
- // TODO: try to avoid memmoving too much. Circular buffer?
- uint32_t left = bufused - data_acked;
- if(data_acked && left)
- memmove(c->sndbuf, c->sndbuf + data_acked, left);
+ if(data_acked)
+ buffer_get(&c->sndbuf, NULL, data_acked);
c->snd.una = hdr.ack;
c->dupack = 0;
c->snd.cwnd += utcp->mtu;
- if(c->snd.cwnd > c->maxsndbufsize)
- c->snd.cwnd = c->maxsndbufsize;
+ if(c->snd.cwnd > c->sndbuf.maxsize)
+ c->snd.cwnd = c->sndbuf.maxsize;
// Check if we have sent a FIN that is now ACKed.
switch(c->state) {
} else {
if(!len) {
c->dupack++;
- if(c->dupack >= 3) {
+ if(c->dupack == 3) {
debug("Triplicate ACK\n");
//TODO: Resend one packet and go to fast recovery mode. See RFC 6582.
- //abort();
+ //We do a very simple variant here; reset the nxt pointer to the last acknowledged packet from the peer.
+ //This will cause us to start retransmitting, but at the same speed as the incoming ACKs arrive,
+ //thus preventing a drop in speed.
+ c->snd.nxt = c->snd.una;
}
}
}
rxd = c->recv(c, data, len);
if(rxd != len) {
// TODO: once we have a receive buffer, handle the application not accepting all data.
- fprintf(stderr, "c->recv(%p, %p, %zu) returned %zd\n", c, data, len, rxd);
abort();
}
if(rxd < 0)
int utcp_close(struct utcp_connection *c) {
if(utcp_shutdown(c, SHUT_RDWR))
return -1;
+ c->recv = NULL;
+ c->poll = NULL;
c->reapable = true;
return 0;
}
return -1;
}
+ c->recv = NULL;
+ c->poll = NULL;
c->reapable = true;
switch(c->state) {
return 0;
}
-static void retransmit(struct utcp_connection *c) {
- if(c->state == CLOSED || c->snd.nxt == c->snd.una)
- return;
-
- struct utcp *utcp = c->utcp;
-
- struct {
- struct hdr hdr;
- char data[c->utcp->mtu];
- } pkt;
-
- pkt.hdr.src = c->src;
- pkt.hdr.dst = c->dst;
-
- switch(c->state) {
- case LISTEN:
- // TODO: this should not happen
- break;
-
- case SYN_SENT:
- pkt.hdr.seq = c->snd.iss;
- pkt.hdr.ack = 0;
- pkt.hdr.wnd = c->rcv.wnd;
- pkt.hdr.ctl = SYN;
- print_packet(c->utcp, "rtrx", &pkt, sizeof pkt.hdr);
- utcp->send(utcp, &pkt, sizeof pkt.hdr);
- break;
-
- case SYN_RECEIVED:
- pkt.hdr.seq = c->snd.nxt;
- pkt.hdr.ack = c->rcv.nxt;
- pkt.hdr.ctl = SYN | ACK;
- print_packet(c->utcp, "rtrx", &pkt, sizeof pkt.hdr);
- utcp->send(utcp, &pkt, sizeof pkt.hdr);
- break;
-
- case ESTABLISHED:
- case FIN_WAIT_1:
- pkt.hdr.seq = c->snd.una;
- pkt.hdr.ack = c->rcv.nxt;
- pkt.hdr.ctl = ACK;
- uint32_t len = seqdiff(c->snd.nxt, c->snd.una);
- if(c->state == FIN_WAIT_1)
- len--;
- if(len > utcp->mtu)
- len = utcp->mtu;
- else {
- if(c->state == FIN_WAIT_1)
- pkt.hdr.ctl |= FIN;
- }
- memcpy(pkt.data, c->sndbuf, len);
- print_packet(c->utcp, "rtrx", &pkt, sizeof pkt.hdr + len);
- utcp->send(utcp, &pkt, sizeof pkt.hdr + len);
- break;
-
- default:
- // TODO: implement
- abort();
- }
-}
-
/* Handle timeouts.
* One call to this function will loop through all connections,
* checking if something needs to be resent or not.
* The return value is the time to the next timeout in milliseconds,
* or maybe a negative value if the timeout is infinite.
*/
-int utcp_timeout(struct utcp *utcp) {
+struct timeval utcp_timeout(struct utcp *utcp) {
struct timeval now;
gettimeofday(&now, NULL);
struct timeval next = {now.tv_sec + 3600, now.tv_usec};
retransmit(c);
}
- if(c->poll && c->sndbufsize < c->maxsndbufsize / 2)
- c->poll(c, c->maxsndbufsize - c->sndbufsize);
+ if(c->poll && buffer_free(&c->sndbuf) && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
+ c->poll(c, buffer_free(&c->sndbuf));
if(timerisset(&c->conn_timeout) && timercmp(&c->conn_timeout, &next, <))
next = c->conn_timeout;
struct timeval diff;
timersub(&next, &now, &diff);
- if(diff.tv_sec < 0)
- return 0;
- return diff.tv_sec * 1000 + diff.tv_usec / 1000;
+ return diff;
}
struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_send_t send, void *priv) {
for(int i = 0; i < utcp->nconnections; i++) {
if(!utcp->connections[i]->reapable)
debug("Warning, freeing unclosed connection %p\n", utcp->connections[i]);
- free(utcp->connections[i]->sndbuf);
+ buffer_exit(&utcp->connections[i]->sndbuf);
free(utcp->connections[i]);
}
free(utcp->connections);
}
size_t utcp_get_sndbuf(struct utcp_connection *c) {
- return c->maxsndbufsize;
+ return c->sndbuf.maxsize;
}
size_t utcp_get_sndbuf_free(struct utcp_connection *c) {
- return c->maxsndbufsize - c->sndbufsize;
+ return buffer_free(&c->sndbuf);
}
void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
- c->maxsndbufsize = size;
- if(c->maxsndbufsize != size)
- c->maxsndbufsize = -1;
+ c->sndbuf.maxsize = size;
+ if(c->sndbuf.maxsize != size)
+ c->sndbuf.maxsize = -1;
}
bool utcp_get_nodelay(struct utcp_connection *c) {
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