debug("%p new state: %s\n", c->utcp, strstate[state]);
}
+static bool fin_wanted(struct utcp_connection *c, uint32_t seq) {
+ if(seq != c->snd.last)
+ return false;
+ switch(c->state) {
+ case FIN_WAIT_1:
+ case CLOSING:
+ case LAST_ACK:
+ return true;
+ default:
+ return false;
+ }
+}
+
static inline void list_connections(struct utcp *utcp) {
debug("%p has %d connections:\n", utcp, utcp->nconnections);
for(int i = 0; i < utcp->nconnections; i++)
// 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) {
+static ssize_t buffer_put_at(struct buffer *buf, size_t offset, 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) {
+
+ debug("buffer_put_at %zu %zu %zu\n", buf->used, offset, len);
+
+ size_t required = offset + len;
+ if(required > buf->maxsize) {
+ if(offset >= buf->maxsize)
+ return 0;
+ abort();
+ len = buf->maxsize - offset;
+ required = buf->maxsize;
+ }
+
+ if(required > buf->size) {
size_t newsize = buf->size;
- do {
- newsize *= 2;
- } while(newsize < buf->used + len);
+ if(!newsize) {
+ newsize = required;
+ } else {
+ do {
+ newsize *= 2;
+ } while(newsize < buf->used + len);
+ }
if(newsize > buf->maxsize)
newsize = buf->maxsize;
char *newdata = realloc(buf->data, newsize);
buf->data = newdata;
buf->size = newsize;
}
- memcpy(buf->data + buf->used, data, len);
- buf->used += len;
+
+ memcpy(buf->data + offset, data, len);
+ if(required > buf->used)
+ buf->used = required;
return len;
}
+static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
+ return buffer_put_at(buf, buf->used, data, 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)
c->src = src;
c->dst = dst;
+#ifdef UTCP_DEBUG
+#warning debugging
+ c->snd.iss = 0;
+#else
c->snd.iss = rand();
+#endif
c->snd.una = c->snd.iss;
c->snd.nxt = c->snd.iss + 1;
c->rcv.wnd = utcp->mtu;
} *pkt;
pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
- if(!pkt->data)
+ if(!pkt)
return;
pkt->hdr.src = c->src;
c->snd.nxt += seglen;
left -= seglen;
- if(c->state != ESTABLISHED && !left && seglen) {
- switch(c->state) {
- case FIN_WAIT_1:
- case CLOSING:
- seglen--;
- pkt->hdr.ctl |= FIN;
- break;
- default:
- break;
- }
+ if(seglen && fin_wanted(c, c->snd.nxt)) {
+ seglen--;
+ pkt->hdr.ctl |= FIN;
}
print_packet(c->utcp, "send", pkt, sizeof pkt->hdr + seglen);
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 SYN_SENT:
+ // Send our SYN again
+ 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:
+ // Send SYNACK again
+ 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:
+ 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 = seqdiff(c->snd.last, c->snd.una);
+ if(len > utcp->mtu)
+ len = utcp->mtu;
+ if(fin_wanted(c, c->snd.una + len)) {
+ len--;
+ pkt->hdr.ctl |= FIN;
+ }
+ c->snd.nxt = c->snd.una + len;
+ 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;
+
+ case CLOSED:
+ case LISTEN:
+ case TIME_WAIT:
+ case FIN_WAIT_2:
+ // We shouldn't need to retransmit anything in this state.
+#ifdef UTCP_DEBUG
+ abort();
+#endif
+ timerclear(&c->rtrx_timeout);
+ break;
+ }
+
+ free(pkt);
+}
+
+
ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
if(!utcp) {
errno = EFAULT;
case TIME_WAIT:
break;
default:
+#ifdef UTCP_DEBUG
abort();
+#endif
+ break;
}
// 1b. Drop packets with a sequence number not in our receive window.
#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
set_state(c, CLOSED);
return 0;
default:
+#ifdef UTCP_DEBUG
abort();
+#endif
+ break;
}
}
} 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;
}
}
}
// Ehm, no. We should never receive a second SYN.
goto reset;
default:
+#ifdef UTCP_DEBUG
abort();
+#endif
+ return 0;
}
// SYN counts as one sequence number
case SYN_SENT:
case SYN_RECEIVED:
// This should never happen.
+#ifdef UTCP_DEBUG
abort();
+#endif
+ return 0;
case ESTABLISHED:
case FIN_WAIT_1:
case FIN_WAIT_2:
// Ehm no, We should never receive more data after a FIN.
goto reset;
default:
+#ifdef UTCP_DEBUG
abort();
+#endif
+ return 0;
}
ssize_t rxd;
case SYN_SENT:
case SYN_RECEIVED:
// This should never happen.
+#ifdef UTCP_DEBUG
abort();
+#endif
+ break;
case ESTABLISHED:
set_state(c, CLOSE_WAIT);
break;
// Ehm, no. We should never receive a second FIN.
goto reset;
default:
+#ifdef UTCP_DEBUG
abort();
+#endif
+ break;
}
// FIN counts as one sequence number
}
int utcp_shutdown(struct utcp_connection *c, int dir) {
- debug("%p shutdown %d\n", c ? c->utcp : NULL, dir);
+ debug("%p shutdown %d at %u\n", c ? c->utcp : NULL, dir, c ? c->snd.last : 0);
if(!c) {
errno = EFAULT;
return -1;
return -1;
}
- // TODO: handle dir
+ if(!(dir == UTCP_SHUT_RD || dir == UTCP_SHUT_WR || dir == UTCP_SHUT_RDWR)) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ // TCP does not have a provision for stopping incoming packets.
+ // The best we can do is to just ignore them.
+ if(dir == UTCP_SHUT_RD || dir == UTCP_SHUT_RDWR)
+ c->recv = NULL;
+
+ // The rest of the code deals with shutting down writes.
+ if(dir == UTCP_SHUT_RD)
+ return 0;
switch(c->state) {
case CLOSED:
- return 0;
case LISTEN:
+ errno = ENOTCONN;
+ return -1;
+
case SYN_SENT:
set_state(c, CLOSED);
return 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[];
- } *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);
-}
-
/* 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};
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;
+}
+
+bool utcp_is_active(struct utcp *utcp) {
+ if(!utcp)
+ return false;
+
+ for(int i = 0; i < utcp->nconnections; i++)
+ if(utcp->connections[i]->state != CLOSED && utcp->connections[i]->state != TIME_WAIT)
+ return true;
+
+ return false;
}
struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_send_t send, void *priv) {
}
uint16_t utcp_get_mtu(struct utcp *utcp) {
- return utcp->mtu;
+ return utcp ? utcp->mtu : 0;
}
void utcp_set_mtu(struct utcp *utcp, uint16_t mtu) {
// TODO: handle overhead of the header
- utcp->mtu = mtu;
+ if(utcp)
+ utcp->mtu = mtu;
}
int utcp_get_user_timeout(struct utcp *u) {
- return u->timeout;
+ return u ? u->timeout : 0;
}
void utcp_set_user_timeout(struct utcp *u, int timeout) {
- u->timeout = timeout;
+ if(u)
+ u->timeout = timeout;
}
size_t utcp_get_sndbuf(struct utcp_connection *c) {
- return c->sndbuf.maxsize;
+ return c ? c->sndbuf.maxsize : 0;
}
size_t utcp_get_sndbuf_free(struct utcp_connection *c) {
- return buffer_free(&c->sndbuf);
+ if(c && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
+ return buffer_free(&c->sndbuf);
+ else
+ return 0;
}
void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
+ if(!c)
+ return;
c->sndbuf.maxsize = size;
if(c->sndbuf.maxsize != size)
c->sndbuf.maxsize = -1;
}
bool utcp_get_nodelay(struct utcp_connection *c) {
- return c->nodelay;
+ return c ? c->nodelay : false;
}
void utcp_set_nodelay(struct utcp_connection *c, bool nodelay) {
- c->nodelay = nodelay;
+ if(c)
+ c->nodelay = nodelay;
}
bool utcp_get_keepalive(struct utcp_connection *c) {
- return c->keepalive;
+ return c ? c->keepalive : false;
}
void utcp_set_keepalive(struct utcp_connection *c, bool keepalive) {
- c->keepalive = keepalive;
+ if(c)
+ c->keepalive = keepalive;
}
size_t utcp_get_outq(struct utcp_connection *c) {
- return seqdiff(c->snd.nxt, c->snd.una);
+ return c ? seqdiff(c->snd.nxt, c->snd.una) : 0;
}
void utcp_set_recv_cb(struct utcp_connection *c, utcp_recv_t recv) {
- c->recv = recv;
+ if(c)
+ c->recv = recv;
}
void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
- c->poll = poll;
+ if(c)
+ c->poll = poll;
+}
+
+void utcp_set_accept_cb(struct utcp *utcp, utcp_accept_t accept, utcp_pre_accept_t pre_accept) {
+ if(utcp) {
+ utcp->accept = accept;
+ utcp->pre_accept = pre_accept;
+ }
}