#include <sys/time.h>
#include <sys/socket.h>
-#define UTCP_INTERNAL
-#include "utcp.h"
-
-#define PREP(l) char pkt[(l) + sizeof struct hdr]; struct hdr *hdr = &pkt;
-
-#define SYN 1
-#define ACK 2
-#define FIN 4
-#define RST 8
-
-struct hdr {
- uint16_t src; // Source port
- uint16_t dst; // Destination port
- uint32_t seq; // Sequence number
- uint32_t ack; // Acknowledgement number
- uint32_t wnd; // Window size
- uint16_t ctl; // Flags (SYN, ACK, FIN, RST)
- uint16_t aux; // other stuff
-};
-
-enum state {
- CLOSED,
- LISTEN,
- SYN_SENT,
- SYN_RECEIVED,
- ESTABLISHED,
- FIN_WAIT_1,
- FIN_WAIT_2,
- CLOSE_WAIT,
- CLOSING,
- LAST_ACK,
- TIME_WAIT
-};
-
-const char *strstate[] = {
- "CLOSED",
- "LISTEN",
- "SYN_SENT",
- "SYN_RECEIVED",
- "ESTABLISHED",
- "FIN_WAIT_1",
- "FIN_WAIT_2",
- "CLOSE_WAIT",
- "CLOSING",
- "LAST_ACK",
- "TIME_WAIT"
-};
-
-struct utcp_connection {
- void *priv;
- struct utcp *utcp;
- bool reapable;
-
- uint16_t src;
- uint16_t dst;
- enum state state;
-
- // The following two structures form the TCB
+#include "utcp_priv.h"
- struct {
- uint32_t una;
- uint32_t nxt;
- uint32_t wnd;
- uint32_t iss;
- } snd;
-
- struct {
- uint32_t nxt;
- uint32_t wnd;
- uint32_t irs;
- } rcv;
-
- utcp_recv_t recv;
-
- struct timeval conn_timeout;
- struct timeval rtrx_timeout;
-
- char *sndbuf;
- uint32_t sndbufsize;
-};
-
-struct utcp {
- void *priv;
-
- utcp_accept_t accept;
- utcp_pre_accept_t pre_accept;
- utcp_send_t send;
-
- uint16_t mtu;
- int timeout;
-
- struct utcp_connection **connections;
- int nconnections;
- int nallocated;
-};
+#ifdef UTCP_DEBUG
+#include <stdarg.h>
-static void set_state(struct utcp_connection *c, enum state state) {
- c->state = state;
- if(state == ESTABLISHED)
- timerclear(&c->conn_timeout);
- fprintf(stderr, "%p new state: %s\n", c->utcp, strstate[state]);
+static void debug(const char *format, ...) {
+ va_list ap;
+ va_start(ap, format);
+ vfprintf(stderr, format, ap);
+ va_end(ap);
}
static void print_packet(struct utcp *utcp, const char *dir, const void *pkt, size_t len) {
struct hdr hdr;
if(len < sizeof hdr) {
- fprintf(stderr, "%p %s: short packet (%zu bytes)\n", utcp, dir, len);
+ debug("%p %s: short packet (%zu bytes)\n", utcp, dir, len);
return;
}
memcpy(&hdr, pkt, sizeof hdr);
fprintf (stderr, "%p %s: src=%u dst=%u seq=%u ack=%u wnd=%u ctl=", utcp, dir, hdr.src, hdr.dst, hdr.seq, hdr.ack, hdr.wnd);
if(hdr.ctl & SYN)
- fprintf(stderr, "SYN");
+ debug("SYN");
if(hdr.ctl & RST)
- fprintf(stderr, "RST");
+ debug("RST");
if(hdr.ctl & FIN)
- fprintf(stderr, "FIN");
+ debug("FIN");
if(hdr.ctl & ACK)
- fprintf(stderr, "ACK");
+ debug("ACK");
if(len > sizeof hdr) {
- fprintf(stderr, " data=");
+ debug(" data=");
for(int i = sizeof hdr; i < len; i++) {
const char *data = pkt;
- fprintf(stderr, "%c", data[i] >= 32 ? data[i] : '.');
+ debug("%c", data[i] >= 32 ? data[i] : '.');
}
}
- fprintf(stderr, "\n");
+ debug("\n");
+}
+#else
+#define debug(...)
+#define print_packet(...)
+#endif
+
+static void set_state(struct utcp_connection *c, enum state state) {
+ c->state = state;
+ if(state == ESTABLISHED)
+ timerclear(&c->conn_timeout);
+ debug("%p new state: %s\n", c->utcp, strstate[state]);
}
static inline void list_connections(struct utcp *utcp) {
- fprintf(stderr, "%p has %d connections:\n", utcp, utcp->nconnections);
+ debug("%p has %d connections:\n", utcp, utcp->nconnections);
for(int i = 0; i < utcp->nconnections; i++)
- fprintf(stderr, " %u -> %u state %s\n", utcp->connections[i]->src, utcp->connections[i]->dst, strstate[utcp->connections[i]->state]);
+ debug(" %u -> %u state %s\n", utcp->connections[i]->src, utcp->connections[i]->dst, strstate[utcp->connections[i]->state]);
+}
+
+static int32_t seqdiff(uint32_t a, uint32_t b) {
+ return a - b;
}
// Connections are stored in a sorted list.
memmove(cp + i, cp + i + 1, (utcp->nconnections - i - 1) * sizeof *cp);
utcp->nconnections--;
+ free(c->sndbuf);
free(c);
}
else
utcp->nallocated *= 2;
struct utcp_connection **new_array = realloc(utcp->connections, utcp->nallocated * sizeof *utcp->connections);
- if(!new_array) {
- errno = ENOMEM;
+ if(!new_array)
return NULL;
- }
utcp->connections = new_array;
}
struct utcp_connection *c = calloc(1, sizeof *c);
- if(!c) {
- errno = ENOMEM;
+ if(!c)
+ return NULL;
+
+ c->sndbufsize = DEFAULT_SNDBUFSIZE;
+ c->maxsndbufsize = DEFAULT_MAXSNDBUFSIZE;
+ c->sndbuf = malloc(c->sndbufsize);
+ if(!c->sndbuf) {
+ free(c);
return NULL;
}
c->snd.una = c->snd.iss;
c->snd.nxt = c->snd.iss + 1;
c->rcv.wnd = utcp->mtu;
+ c->snd.last = c->snd.nxt;
+ c->snd.cwnd = utcp->mtu;
c->utcp = utcp;
- c->sndbufsize = 65536;
- c->sndbuf = malloc(c->sndbufsize);
- if(!c->sndbuf)
- c->sndbufsize = 0;
// Add it to the sorted list of connections
hdr.dst = c->dst;
hdr.seq = c->snd.iss;
hdr.ack = 0;
- hdr.ctl = SYN;
hdr.wnd = c->rcv.wnd;
+ hdr.ctl = SYN;
+ hdr.aux = 0;
set_state(c, SYN_SENT);
void utcp_accept(struct utcp_connection *c, utcp_recv_t recv, void *priv) {
if(c->reapable || c->state != SYN_RECEIVED) {
- fprintf(stderr, "Error: accept() called on invalid connection %p in state %s\n", c, strstate[c->state]);
+ debug("Error: accept() called on invalid connection %p in state %s\n", c, strstate[c->state]);
return;
}
- fprintf(stderr, "%p accepted, %p %p\n", c, recv, priv);
+ debug("%p accepted, %p %p\n", c, recv, priv);
c->recv = recv;
c->priv = priv;
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 = c->snd.cwnd - seqdiff(c->snd.nxt, c->snd.una);
+ char *data = c->sndbuf + seqdiff(c->snd.nxt, c->snd.una);
+
+ fprintf(stderr, "ack, left=%d, cwndleft=%d, sendatleastone=%d\n", left, cwndleft, sendatleastone);
+ if(left < 0)
+ abort();
+
+ if(cwndleft <= 0)
+ cwndleft = 0;
+
+ if(cwndleft < left)
+ left = cwndleft;
+
+ if(!left && !sendatleastone)
+ return;
+
+ struct {
+ struct hdr hdr;
+ char data[c->utcp->mtu];
+ } pkt;
+
+ 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;
+
+ memcpy(pkt.data, data, seglen);
+
+ c->snd.nxt += seglen;
+ data += 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;
+ }
+ }
+
+ print_packet(c->utcp, "send", &pkt, sizeof pkt.hdr + seglen);
+ c->utcp->send(c->utcp, &pkt, sizeof pkt.hdr + seglen);
+ } while(left);
+}
+
ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
if(c->reapable) {
- fprintf(stderr, "Error: send() called on closed connection %p\n", c);
+ debug("Error: send() called on closed connection %p\n", c);
errno = EBADF;
return -1;
}
case LISTEN:
case SYN_SENT:
case SYN_RECEIVED:
- fprintf(stderr, "Error: send() called on unconnected connection %p\n", c);
+ debug("Error: send() called on unconnected connection %p\n", c);
errno = ENOTCONN;
return -1;
case ESTABLISHED:
case CLOSING:
case LAST_ACK:
case TIME_WAIT:
- fprintf(stderr, "Error: send() called on closing connection %p\n", c);
+ debug("Error: send() called on closing connection %p\n", c);
errno = EPIPE;
return -1;
}
return -1;
}
- uint32_t bufused = c->snd.nxt - c->snd.una;
+ uint32_t bufused = seqdiff(c->snd.nxt, c->snd.una);
- if(len > c->sndbufsize - bufused)
- len = c->sndbufsize - bufused;
-
- memcpy(c->sndbuf + (c->snd.nxt - c->snd.una), data, len);
-
- // Send segments
-
- struct {
- struct hdr hdr;
- char data[c->utcp->mtu];
- } pkt;
+ /* 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.
+ */
- 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;
-
- uint32_t left = len;
-
- while(left) {
- uint32_t seglen = left > c->utcp->mtu ? c->utcp->mtu : left;
- pkt.hdr.seq = c->snd.nxt;
-
- memcpy(pkt.data, data, seglen);
+ 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;
+ }
+ }
- c->snd.nxt += seglen;
- data += seglen;
- left -= seglen;
+ if(len > c->sndbufsize - bufused)
+ len = c->sndbufsize - bufused;
- print_packet(c->utcp, "send", &pkt, sizeof pkt.hdr + seglen);
- c->utcp->send(c->utcp, &pkt, sizeof pkt.hdr + seglen);
+ if(!len) {
+ errno == EWOULDBLOCK;
+ return 0;
}
- fprintf(stderr, "len=%zu\n", len);
+ memcpy(c->sndbuf + bufused, data, len);
+ c->snd.last += len;
+
+ ack(c, false);
return len;
}
hdr->dst = tmp;
}
-static int32_t seqdiff(uint32_t a, uint32_t b) {
- return a - b;
-}
-
int utcp_recv(struct utcp *utcp, const void *data, size_t len) {
if(!utcp) {
errno = EFAULT;
return 0;
}
- fprintf(stderr, "%p state %s\n", c->utcp, strstate[c->state]);
+ debug("%p state %s\n", c->utcp, strstate[c->state]);
// In case this is for a CLOSED connection, ignore the packet.
// TODO: make it so incoming packets can never match a CLOSED connection.
#endif
if(!acceptable) {
- fprintf(stderr, "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;
// ackno should not roll back, and it should also not be bigger than snd.nxt.
if(hdr.ctl & ACK && (seqdiff(hdr.ack, c->snd.nxt) > 0 || seqdiff(hdr.ack, c->snd.una) < 0)) {
- fprintf(stderr, "Packet ack seqno out of range, %u %u %u\n", hdr.ack, c->snd.una, c->snd.nxt);
+ debug("Packet ack seqno out of range, %u %u %u\n", hdr.ack, c->snd.una, c->snd.nxt);
// Ignore unacceptable RST packets.
if(hdr.ctl & RST)
return 0;
c->snd.una = hdr.ack;
if(advanced) {
- fprintf(stderr, "%p advanced %u\n", utcp, advanced);
+ debug("%p advanced %u\n", utcp, advanced);
// Make room in the send buffer.
// TODO: try to avoid memmoving too much. Circular buffer?
uint32_t left = seqdiff(c->snd.nxt, hdr.ack);
if(left)
memmove(c->sndbuf, c->sndbuf + advanced, left);
+ c->dupack = 0;
+ c->snd.cwnd += utcp->mtu;
+ if(c->snd.cwnd > c->maxsndbufsize)
+ c->snd.cwnd = c->maxsndbufsize;
+ debug("%p increasing cwnd to %u\n", utcp, c->snd.cwnd);
+
+ // Check if we have sent a FIN that is now ACKed.
+ switch(c->state) {
+ case FIN_WAIT_1:
+ if(c->snd.una == c->snd.last)
+ set_state(c, FIN_WAIT_2);
+ break;
+ case CLOSING:
+ if(c->snd.una == c->snd.last) {
+ gettimeofday(&c->conn_timeout, NULL);
+ c->conn_timeout.tv_sec += 60;
+ set_state(c, TIME_WAIT);
+ }
+ break;
+ default:
+ break;
+ }
+ } else {
+ if(!len) {
+ c->dupack++;
+ if(c->dupack >= 3) {
+ debug("Triplicate ACK\n");
+ abort();
+ }
+ }
}
// 4. Update timers
set_state(c, CLOSING);
break;
case FIN_WAIT_2:
+ gettimeofday(&c->conn_timeout, NULL);
+ c->conn_timeout.tv_sec += 60;
set_state(c, TIME_WAIT);
break;
case CLOSE_WAIT:
// FIN counts as one sequence number
c->rcv.nxt++;
+ len++;
// Inform the application that the peer closed the connection.
if(c->recv) {
return 0;
ack:
- hdr.src = c->src;
- hdr.dst = c->dst;
- hdr.seq = c->snd.nxt;
- hdr.ack = c->rcv.nxt;
- hdr.ctl = ACK;
- print_packet(c->utcp, "send", &hdr, sizeof hdr);
- utcp->send(utcp, &hdr, sizeof hdr);
+ ack(c, true);
return 0;
reset:
}
int utcp_shutdown(struct utcp_connection *c, int dir) {
- fprintf(stderr, "%p shutdown %d\n", c->utcp, dir);
+ debug("%p shutdown %d\n", c->utcp, dir);
if(!c) {
errno = EFAULT;
return -1;
}
if(c->reapable) {
- fprintf(stderr, "Error: shutdown() called on closed connection %p\n", c);
+ debug("Error: shutdown() called on closed connection %p\n", c);
errno = EBADF;
return -1;
}
return 0;
}
- // Send FIN
-
- struct hdr hdr;
-
- hdr.src = c->src;
- hdr.dst = c->dst;
- hdr.seq = c->snd.nxt;
- hdr.ack = c->rcv.nxt;
- hdr.wnd = c->snd.wnd;
- hdr.ctl = FIN | ACK;
-
- c->snd.nxt += 1;
+ c->snd.last++;
- print_packet(c->utcp, "send", &hdr, sizeof hdr);
- c->utcp->send(c->utcp, &hdr, sizeof hdr);
+ ack(c, false);
return 0;
}
}
if(c->reapable) {
- fprintf(stderr, "Error: abort() called on closed connection %p\n", c);
+ debug("Error: abort() called on closed connection %p\n", c);
errno = EBADF;
return -1;
}
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);
if(c->state == CLOSED) {
if(c->reapable) {
- fprintf(stderr, "Reaping %p\n", c);
+ debug("Reaping %p\n", c);
free_connection(c);
i--;
}
void utcp_exit(struct utcp *utcp) {
if(!utcp)
return;
- for(int i = 0; i < utcp->nconnections; i++)
- free_connection(utcp->connections[i]);
+ 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);
+ free(utcp->connections[i]);
+ }
+ free(utcp->connections);
free(utcp);
}
-int utcp_set_connection_timeout(struct utcp *u, int timeout) {
- int prev = u->timeout;
+uint16_t utcp_get_mtu(struct utcp *utcp) {
+ return utcp->mtu;
+}
+
+void utcp_set_mtu(struct utcp *utcp, uint16_t mtu) {
+ // TODO: handle overhead of the header
+ utcp->mtu = mtu;
+}
+
+int utcp_get_user_timeout(struct utcp *u) {
+ return u->timeout;
+}
+
+void utcp_set_user_timeout(struct utcp *u, int timeout) {
u->timeout = timeout;
- return prev;
+}
+
+size_t utcp_get_sndbuf(struct utcp_connection *c) {
+ return c->maxsndbufsize;
+}
+
+void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
+ c->maxsndbufsize = size;
+ if(c->maxsndbufsize != size)
+ c->maxsndbufsize = -1;
+}
+
+bool utcp_get_nodelay(struct utcp_connection *c) {
+ return c->nodelay;
+}
+
+void utcp_set_nodelay(struct utcp_connection *c, bool nodelay) {
+ c->nodelay = nodelay;
+}
+
+bool utcp_get_keepalive(struct utcp_connection *c) {
+ return c->keepalive;
+}
+
+void utcp_set_keepalive(struct utcp_connection *c, bool keepalive) {
+ c->keepalive = keepalive;
+}
+
+size_t utcp_get_outq(struct utcp_connection *c) {
+ return seqdiff(c->snd.nxt, c->snd.una);
}
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