}
// Buffer functions
-// TODO: convert to ringbuffers to avoid memmove() operations.
+static bool buffer_wraps(struct buffer *buf) {
+ return buf->size - buf->offset < buf->used;
+}
+
+static bool buffer_resize(struct buffer *buf, uint32_t newsize) {
+ char *newdata = realloc(buf->data, newsize);
+
+ if(!newdata) {
+ return false;
+ }
+
+ buf->data = newdata;
+
+ if(buffer_wraps(buf)) {
+ // Shift the right part of the buffer until it hits the end of the new buffer.
+ // Old situation:
+ // [345......012]
+ // New situation:
+ // [345.........|........012]
+ uint32_t tailsize = buf->size - buf->offset;
+ uint32_t newoffset = newsize - tailsize;
+ memmove(buf + newoffset, buf + buf->offset, tailsize);
+ buf->offset = newoffset;
+ }
+
+ buf->size = newsize;
+ return true;
+}
// Store data into the buffer
static ssize_t buffer_put_at(struct buffer *buf, size_t offset, const void *data, size_t len) {
debug("buffer_put_at %lu %lu %lu\n", (unsigned long)buf->used, (unsigned long)offset, (unsigned long)len);
+ // Ensure we don't store more than maxsize bytes in total
size_t required = offset + len;
if(required > buf->maxsize) {
required = buf->maxsize;
}
+ // Check if we need to resize the buffer
if(required > buf->size) {
size_t newsize = buf->size;
if(!newsize) {
- newsize = required;
- } else {
- do {
- newsize *= 2;
- } while(newsize < required);
+ newsize = 4096;
}
+ do {
+ newsize *= 2;
+ } while(newsize < required);
+
if(newsize > buf->maxsize) {
newsize = buf->maxsize;
}
- char *newdata = realloc(buf->data, newsize);
-
- if(!newdata) {
+ if(!buffer_resize(buf, newsize)) {
return -1;
}
+ }
- buf->data = newdata;
- buf->size = newsize;
+ uint32_t realoffset = buf->offset + offset;
+
+ if(buf->size - buf->offset < offset) {
+ // The offset wrapped
+ realoffset -= buf->size;
}
- memcpy(buf->data + offset, data, len);
+ if(buf->size - realoffset < len) {
+ // The new chunk of data must be wrapped
+ memcpy(buf->data + realoffset, data, buf->size - realoffset);
+ memcpy(buf->data, (char *)data + buf->size - realoffset, len - (buf->size - realoffset));
+ } else {
+ memcpy(buf->data + realoffset, data, len);
+ }
if(required > buf->used) {
buf->used = required;
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) {
- len = buf->used;
+// Copy data from the buffer without removing it.
+static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t len) {
+ // Ensure we don't copy more than is actually stored in the buffer
+ if(offset >= buf->used) {
+ return 0;
}
- if(data) {
- memcpy(data, buf->data, len);
+ if(buf->used - offset < len) {
+ len = buf->used - offset;
}
- if(len < buf->used) {
- memmove(buf->data, buf->data + len, buf->used - len);
+ 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
+ memcpy(data, buf->data + realoffset, buf->size - realoffset);
+ memcpy((char *)data + buf->size - realoffset, buf->data, len - (buf->size - realoffset));
+ } else {
+ memcpy(data, buf->data + realoffset, 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;
- }
+// Get data from the buffer.
+static ssize_t buffer_get(struct buffer *buf, void *data, size_t len) {
+ len = buffer_copy(buf, data, 0, len);
- if(offset + len > buf->used) {
- len = buf->used - offset;
+ if(buf->size - buf->offset < len) {
+ buf->offset -= buf->size;
}
- memcpy(data, buf->data + offset, len);
+ buf->offset += len;
+ buf->used -= len;
return len;
}
-static bool buffer_init(struct buffer *buf, uint32_t len, uint32_t maxlen) {
- memset(buf, 0, sizeof(*buf));
+// Discard data from the buffer.
+static ssize_t buffer_discard(struct buffer *buf, size_t len) {
+ if(buf->used < len) {
+ len = buf->used;
+ }
- if(len) {
- buf->data = malloc(len);
+ if(buf->size - buf->offset < len) {
+ buf->offset -= buf->size;
+ }
- if(!buf->data) {
- return false;
- }
+ buf->offset += len;
+ buf->used -= len;
+
+ return len;
+}
+
+static bool buffer_set_size(struct buffer *buf, uint32_t minsize, uint32_t maxsize) {
+ if(maxsize < minsize) {
+ maxsize = minsize;
}
- buf->size = len;
- buf->maxsize = maxlen;
- return true;
+ buf->maxsize = maxsize;
+
+ return buf->size >= minsize || buffer_resize(buf, minsize);
}
static void buffer_exit(struct buffer *buf) {
return NULL;
}
- if(!buffer_init(&c->sndbuf, DEFAULT_SNDBUFSIZE, DEFAULT_MAXSNDBUFSIZE)) {
+ if(!buffer_set_size(&c->sndbuf, DEFAULT_SNDBUFSIZE, DEFAULT_MAXSNDBUFSIZE)) {
free(c);
return NULL;
}
- if(!buffer_init(&c->rcvbuf, DEFAULT_RCVBUFSIZE, DEFAULT_MAXRCVBUFSIZE)) {
+ if(!buffer_set_size(&c->rcvbuf, DEFAULT_RCVBUFSIZE, DEFAULT_MAXRCVBUFSIZE)) {
buffer_exit(&c->sndbuf);
free(c);
return NULL;
if(!utcp->srtt) {
utcp->srtt = rtt;
utcp->rttvar = rtt / 2;
- utcp->rto = rtt + max(2 * rtt, CLOCK_GRANULARITY);
} else {
utcp->rttvar = (utcp->rttvar * 3 + absdiff(utcp->srtt, rtt)) / 4;
utcp->srtt = (utcp->srtt * 7 + rtt) / 8;
- utcp->rto = utcp->srtt + max(utcp->rttvar, CLOCK_GRANULARITY);
}
+ utcp->rto = utcp->srtt + max(4 * utcp->rttvar, CLOCK_GRANULARITY);
+
if(utcp->rto > MAX_RTO) {
utcp->rto = MAX_RTO;
}
struct {
struct hdr hdr;
uint8_t data[];
- } *pkt;
-
- pkt = malloc(sizeof(pkt->hdr) + c->utcp->mtu);
-
- if(!pkt) {
- return;
- }
+ } *pkt = c->utcp->pkt;
pkt->hdr.src = c->src;
pkt->hdr.dst = c->dst;
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) {
if(is_reliable(c) || (c->state != SYN_SENT && c->state != SYN_RECEIVED)) {
len = buffer_put(&c->sndbuf, data, len);
+ } else {
+ return 0;
}
if(len <= 0) {
struct {
struct hdr hdr;
uint8_t data[];
- } *pkt;
-
- pkt = malloc(sizeof(pkt->hdr) + c->utcp->mtu);
-
- if(!pkt) {
- return;
- }
+ } *pkt = c->utcp->pkt;
pkt->hdr.src = c->src;
pkt->hdr.dst = c->dst;
c->rtt_start.tv_sec = 0; // invalidate RTT timer
cleanup:
- free(pkt);
+ return;
}
/* Update receive buffer and SACK entries after consuming data.
ptr += 2;
}
+ bool has_data = len || (hdr.ctl & (SYN | FIN));
+
// Try to match the packet to an existing connection
struct utcp_connection *c = find_connection(utcp, hdr.dst, hdr.src);
c->flags = UTCP_TCP;
}
+synack:
// Return SYN+ACK, go to SYN_RECEIVED state
c->snd.wnd = hdr.wnd;
c->rcv.irs = hdr.seq;
// 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.
break;
}
- // 1b. Drop packets with a sequence number not in our receive window.
+ // 1b. Discard data that is not in our receive window.
if(is_reliable(c)) {
bool acceptable;
// 3. Advance snd.una
advanced = seqdiff(hdr.ack, c->snd.una);
- prevrcvnxt = c->rcv.nxt;
if(advanced) {
// RTT measurement
assert(data_acked >= 0);
+#ifndef NDEBUG
int32_t bufused = seqdiff(c->snd.last, c->snd.una);
assert(data_acked <= bufused);
+#endif
if(data_acked) {
- buffer_get(&c->sndbuf, NULL, data_acked);
+ buffer_discard(&c->sndbuf, data_acked);
}
// Also advance snd.nxt if possible
case CLOSING:
if(c->snd.una == c->snd.last) {
gettimeofday(&c->conn_timeout, NULL);
- c->conn_timeout.tv_sec += 60;
+ c->conn_timeout.tv_sec += utcp->timeout;
set_state(c, TIME_WAIT);
}
break;
case SYN_RECEIVED:
+ // This is a retransmit of a SYN, send back the SYNACK.
+ goto synack;
+
case ESTABLISHED:
case FIN_WAIT_1:
case FIN_WAIT_2:
case FIN_WAIT_2:
gettimeofday(&c->conn_timeout, NULL);
- c->conn_timeout.tv_sec += 60;
+ c->conn_timeout.tv_sec += utcp->timeout;
set_state(c, TIME_WAIT);
break;
}
// Now we send something back if:
- // - we advanced rcv.nxt (ie, we got some data that needs to be ACKed)
+ // - we received data, so we have to send back an ACK
// -> sendatleastone = true
// - 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) {
- ack(c, len || prevrcvnxt != c->rcv.nxt);
+ ack(c, has_data);
}
return 0;
utcp->pre_accept = pre_accept;
utcp->send = send;
utcp->priv = priv;
- utcp->mtu = DEFAULT_MTU;
+ utcp_set_mtu(utcp, DEFAULT_MTU);
utcp->timeout = DEFAULT_USER_TIMEOUT; // sec
utcp->rto = START_RTO; // usec
}
void utcp_set_mtu(struct utcp *utcp, uint16_t mtu) {
- // TODO: handle overhead of the header
- if(utcp) {
- utcp->mtu = mtu;
+ if(!utcp) {
+ return;
}
+
+ if(mtu <= sizeof(struct hdr)) {
+ return;
+ }
+
+ if(mtu > utcp->mtu) {
+ char *new = realloc(utcp->pkt, mtu + sizeof(struct hdr));
+
+ if(!new) {
+ return;
+ }
+
+ utcp->pkt = new;
+ }
+
+ utcp->mtu = mtu;
}
void utcp_reset_timers(struct utcp *utcp) {
continue;
}
- c->rtrx_timeout = now;
- c->conn_timeout = then;
+ if(timerisset(&c->rtrx_timeout)) {
+ c->rtrx_timeout = now;
+ }
+
+ if(timerisset(&c->conn_timeout)) {
+ c->conn_timeout = then;
+ }
+
c->rtt_start.tv_sec = 0;
}
}
void utcp_offline(struct utcp *utcp, bool offline) {
+ struct timeval now;
+ gettimeofday(&now, NULL);
+
for(int i = 0; i < utcp->nconnections; i++) {
struct utcp_connection *c = utcp->connections[i];
- if(!c->reapable) {
- utcp_expect_data(c, offline);
-
- // If we are online again, reset the retransmission timers, but keep the connection timeout as it is,
- // to prevent peers toggling online/offline state frequently from keeping connections alive
- // if there is no progress in sending actual data.
- if(!offline) {
- gettimeofday(&utcp->connections[i]->rtrx_timeout, NULL);
- utcp->connections[i]->rtt_start.tv_sec = 0;
+ if(c->reapable) {
+ continue;
+ }
+
+ utcp_expect_data(c, offline);
+
+ if(!offline) {
+ if(timerisset(&c->rtrx_timeout)) {
+ c->rtrx_timeout = now;
}
+
+ utcp->connections[i]->rtt_start.tv_sec = 0;
}
}
projects / utcp / blobdiff