📄 uip.c
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conn = 0;
for(c = 0; c < UIP_UDP_CONNS; ++c) {
if(uip_udp_conns[c].lport == 0) {
conn = &uip_udp_conns[c];
break;
}
}
if(conn == 0) {
return 0;
}
conn->lport = HTONS(lastport);
conn->rport = HTONS(rport);
conn->ripaddr[0] = ripaddr[0];
conn->ripaddr[1] = ripaddr[1];
return conn;
}
#endif /* UIP_UDP */
/*-----------------------------------------------------------------------------------*/
void uip_unlisten(u16_t port)
{
for(c = 0; c < UIP_LISTENPORTS; ++c) {
if(uip_listenports[c] == port) {
uip_listenports[c] = 0;
return;
}
}
}
/*-----------------------------------------------------------------------------------*/
void uip_listen(u16_t port)
{
for(c = 0; c < UIP_LISTENPORTS; ++c) {
if(uip_listenports[c] == 0) {
uip_listenports[c] = port;
return;
}
}
}
/*-----------------------------------------------------------------------------------*/
/* XXX: IP fragment reassembly: not well-tested. */
#if UIP_REASSEMBLY
#define UIP_REASS_BUFSIZE (UIP_BUFSIZE - UIP_LLH_LEN)
static u8_t uip_reassbuf[UIP_REASS_BUFSIZE];
static u8_t uip_reassbitmap[UIP_REASS_BUFSIZE / (8 * 8)];
static const u8_t bitmap_bits[8] = {0xff, 0x7f, 0x3f, 0x1f,0x0f, 0x07, 0x03, 0x01};
static u16_t uip_reasslen;
static u8_t uip_reassflags;
#define UIP_REASS_FLAG_LASTFRAG 0x01
static u8_t uip_reasstmr;
#define IP_HLEN 20
#define IP_MF 0x20
static u8_t uip_reass(void)
{
u16_t offset, len;
u16_t i;
/* If ip_reasstmr is zero, no packet is present in the buffer, so we
write the IP header of the fragment into the reassembly
buffer. The timer is updated with the maximum age. */
if(uip_reasstmr == 0) {
memcpy(uip_reassbuf, &BUF->vhl, IP_HLEN);
uip_reasstmr = UIP_REASS_MAXAGE;
uip_reassflags = 0;
memset(uip_reassbitmap, sizeof(uip_reassbitmap), 0);/* Clear the bitmap. */
}
/* Check if the incoming fragment matches the one currently present
in the reasembly buffer. If so, we proceed with copying the
fragment into the buffer. */
if(BUF->srcipaddr[0] == FBUF->srcipaddr[0] &&
BUF->srcipaddr[1] == FBUF->srcipaddr[1] &&
BUF->destipaddr[0] == FBUF->destipaddr[0] &&
BUF->destipaddr[1] == FBUF->destipaddr[1] &&
BUF->ipid[0] == FBUF->ipid[0] &&
BUF->ipid[1] == FBUF->ipid[1]) {
len = (BUF->len[0] << 8) + BUF->len[1] - (BUF->vhl & 0x0f) * 4;
offset = (((BUF->ipoffset[0] & 0x3f) << 8) + BUF->ipoffset[1]) * 8;
/* If the offset or the offset + fragment length overflows the
reassembly buffer, we discard the entire packet. */
if(offset > UIP_REASS_BUFSIZE || offset + len > UIP_REASS_BUFSIZE) {
uip_reasstmr = 0;
goto nullreturn;
}
/* Copy the fragment into the reassembly buffer, at the right
offset. */
memcpy(&uip_reassbuf[IP_HLEN + offset],(char *)BUF + (int)((BUF->vhl & 0x0f) * 4),len);
/* Update the bitmap. */
if(offset / (8 * 8) == (offset + len) / (8 * 8)) {
/* If the two endpoints are in the same byte, we only update
that byte. */
uip_reassbitmap[offset / (8 * 8)] |= bitmap_bits[(offset / 8 ) & 7] & ~bitmap_bits[((offset + len) / 8 ) & 7];
}
else {
/* If the two endpoints are in different bytes, we update the
bytes in the endpoints and fill the stuff inbetween with
0xff. */
uip_reassbitmap[offset / (8 * 8)] |= bitmap_bits[(offset / 8 ) & 7];
for(i = 1 + offset / (8 * 8); i < (offset + len) / (8 * 8); ++i) {
uip_reassbitmap[i] = 0xff;
}
uip_reassbitmap[(offset + len) / (8 * 8)] |= ~bitmap_bits[((offset + len) / 8 ) & 7];
}
/* If this fragment has the More Fragments flag set to zero, we
know that this is the last fragment, so we can calculate the
size of the entire packet. We also set the
IP_REASS_FLAG_LASTFRAG flag to indicate that we have received
the final fragment. */
if((BUF->ipoffset[0] & IP_MF) == 0) {
uip_reassflags |= UIP_REASS_FLAG_LASTFRAG;
uip_reasslen = offset + len;
}
/* Finally, we check if we have a full packet in the buffer. We do
this by checking if we have the last fragment and if all bits
in the bitmap are set. */
if(uip_reassflags & UIP_REASS_FLAG_LASTFRAG) {
/* Check all bytes up to and including all but the last byte in
the bitmap. */
for(i = 0; i < uip_reasslen / (8 * 8) - 1; ++i) {
if(uip_reassbitmap[i] != 0xff) {
goto nullreturn;
}
}
/* Check the last byte in the bitmap. It should contain just the
right amount of bits. */
if(uip_reassbitmap[uip_reasslen / (8 * 8)] != (u8_t)~bitmap_bits[uip_reasslen / 8 & 7]) {
goto nullreturn;
}
/* If we have come this far, we have a full packet in the
buffer, so we allocate a pbuf and copy the packet into it. We
also reset the timer. */
uip_reasstmr = 0;
memcpy(BUF, FBUF, uip_reasslen);
/* Pretend to be a "normal" (i.e., not fragmented) IP packet
from now on. */
BUF->ipoffset[0] = BUF->ipoffset[1] = 0;
BUF->len[0] = uip_reasslen >> 8;
BUF->len[1] = uip_reasslen & 0xff;
BUF->ipchksum = 0;
BUF->ipchksum = ~(uip_ipchksum());
return uip_reasslen;
}
}
nullreturn:
return 0;
}
#endif /* UIP_REASSEMBL */
/*-----------------------------------------------------------------------------------*/
static void uip_add_rcv_nxt(u16_t n)
{
uip_add32(uip_conn->rcv_nxt, n);
uip_conn->rcv_nxt[0] = uip_acc32[0];
uip_conn->rcv_nxt[1] = uip_acc32[1];
uip_conn->rcv_nxt[2] = uip_acc32[2];
uip_conn->rcv_nxt[3] = uip_acc32[3];
}
/*-----------------------------------------------------------------------------------*/
void uip_process(u8_t flag)
{
register struct uip_conn *uip_connr = uip_conn;
uip_appdata = &uip_buf[40 + UIP_LLH_LEN];
if(flag == UIP_TIMER) { /* Check if we were invoked because of the perodic timer fireing. */
#if UIP_REASSEMBLY
if(uip_reasstmr != 0) {
--uip_reasstmr;
}
#endif /* UIP_REASSEMBLY */
/* Increase the initial sequence number. */
if(++iss[3] == 0) {
if(++iss[2] == 0) {
if(++iss[1] == 0) {
++iss[0];
}
}
}
uip_len = 0;
if(uip_connr->tcpstateflags == TIME_WAIT || uip_connr->tcpstateflags == FIN_WAIT_2) {
++(uip_connr->timer);
if(uip_connr->timer == UIP_TIME_WAIT_TIMEOUT) {
uip_connr->tcpstateflags = CLOSED;
}
}
else if(uip_connr->tcpstateflags != CLOSED) {
/* If the connection has outstanding data, we increase the
connection's timer and see if it has reached the RTO value
in which case we retransmit. */
if(uip_outstanding(uip_connr)) {
if(uip_connr->timer-- == 0) {
if(uip_connr->nrtx == UIP_MAXRTX ||
((uip_connr->tcpstateflags == SYN_SENT ||
uip_connr->tcpstateflags == SYN_RCVD) &&
uip_connr->nrtx == UIP_MAXSYNRTX)) {
uip_connr->tcpstateflags = CLOSED;
/* We call UIP_APPCALL() with uip_flags set to
UIP_TIMEDOUT to inform the application that the
connection has timed out. */
uip_flags = UIP_TIMEDOUT;
UIP_APPCALL();
/* We also send a reset packet to the remote host. */
BUF->flags = TCP_RST | TCP_ACK;
goto tcp_send_nodata;
}
/* Exponential backoff. */
uip_connr->timer = UIP_RTO << (uip_connr->nrtx > 4?4: uip_connr->nrtx);
++(uip_connr->nrtx);
/* Ok, so we need to retransmit. We do this differently
depending on which state we are in. In ESTABLISHED, we
call upon the application so that it may prepare the
data for the retransmit. In SYN_RCVD, we resend the
SYNACK that we sent earlier and in LAST_ACK we have to
retransmit our FINACK. */
UIP_STAT(++uip_stat.tcp.rexmit);
switch(uip_connr->tcpstateflags & TS_MASK) {
case SYN_RCVD:
/* In the SYN_RCVD state, we should retransmit our
SYNACK. */
goto tcp_send_synack;
#if UIP_ACTIVE_OPEN
case SYN_SENT:
/* In the SYN_SENT state, we retransmit out SYN. */
BUF->flags = 0;
goto tcp_send_syn;
#endif /* UIP_ACTIVE_OPEN */
case ESTABLISHED:
/* In the ESTABLISHED state, we call upon the application
to do the actual retransmit after which we jump into
the code for sending out the packet (the apprexmit
label). */
uip_len = 0;
uip_slen = 0;
uip_flags = UIP_REXMIT;
UIP_APPCALL();
goto apprexmit;
case FIN_WAIT_1:
case CLOSING :
case LAST_ACK :
/* In all these states we should retransmit a FINACK. */
goto tcp_send_finack;
}//end of switch.
}
}
else if((uip_connr->tcpstateflags & TS_MASK) == ESTABLISHED) {
/* If there was no need for a retransmission, we poll the
application for new data. */
uip_len = 0;
uip_slen = 0;
uip_flags = UIP_POLL;
UIP_APPCALL();
goto appsend;
}
}
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