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plan9fox/sys/src/9/ip/rudp.c
cinap_lenrek b638c7753d devip: use the routing table for local source ip address selection 
when making outgoing connections, the source ip was selected
by just iterating from the first to the last interface and
trying each local address until a route was found. the result
was kind of hard to predict as it depends on the interface
order.

this change replaces the algorithm with the route lookup algorithm
that we already have which takes more specific desination and
source prefixes into account. so the order of interfaces does
not matter anymore.
2019-11-10 19:50:46 +01:00

1047 lines
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/*
* Reliable User Datagram Protocol, currently only for IPv4.
* This protocol is compatible with UDP's packet format.
* It could be done over UDP if need be.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "ip.h"
#define DEBUG 0
#define DPRINT if(DEBUG)print
#define SEQDIFF(a,b) ( (a)>=(b)?\
(a)-(b):\
0xffffffffUL-((b)-(a)) )
#define INSEQ(a,start,end) ( (start)<=(end)?\
((a)>(start)&&(a)<=(end)):\
((a)>(start)||(a)<=(end)) )
#define UNACKED(r) SEQDIFF(r->sndseq, r->ackrcvd)
#define NEXTSEQ(a) ( (a)+1 == 0 ? 1 : (a)+1 )
enum
{
UDP_PHDRSIZE = 12, /* pseudo header */
// UDP_HDRSIZE = 20, /* pseudo header + udp header */
UDP_RHDRSIZE = 36, /* pseudo header + udp header + rudp header */
UDP_IPHDR = 8, /* ip header */
IP_UDPPROTO = 254,
UDP_USEAD7 = 52, /* size of new ipv6 headers struct */
Rudprxms = 200,
Rudptickms = 50,
Rudpmaxxmit = 10,
Maxunacked = 100,
};
#define Hangupgen 0xffffffff /* used only in hangup messages */
typedef struct Udphdr Udphdr;
struct Udphdr
{
/* ip header */
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
/* pseudo header starts here */
uchar Unused;
uchar udpproto; /* Protocol */
uchar udpplen[2]; /* Header plus data length */
uchar udpsrc[4]; /* Ip source */
uchar udpdst[4]; /* Ip destination */
/* udp header */
uchar udpsport[2]; /* Source port */
uchar udpdport[2]; /* Destination port */
uchar udplen[2]; /* data length */
uchar udpcksum[2]; /* Checksum */
};
typedef struct Rudphdr Rudphdr;
struct Rudphdr
{
/* ip header */
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
/* pseudo header starts here */
uchar Unused;
uchar udpproto; /* Protocol */
uchar udpplen[2]; /* Header plus data length */
uchar udpsrc[4]; /* Ip source */
uchar udpdst[4]; /* Ip destination */
/* udp header */
uchar udpsport[2]; /* Source port */
uchar udpdport[2]; /* Destination port */
uchar udplen[2]; /* data length (includes rudp header) */
uchar udpcksum[2]; /* Checksum */
/* rudp header */
uchar relseq[4]; /* id of this packet (or 0) */
uchar relsgen[4]; /* generation/time stamp */
uchar relack[4]; /* packet being acked (or 0) */
uchar relagen[4]; /* generation/time stamp */
};
/*
* one state structure per destination
*/
typedef struct Reliable Reliable;
struct Reliable
{
Ref;
Reliable *next;
uchar addr[IPaddrlen]; /* always V6 when put here */
ushort port;
Block *unacked; /* unacked msg list */
Block *unackedtail; /* and its tail */
int timeout; /* time since first unacked msg sent */
int xmits; /* number of times first unacked msg sent */
ulong sndseq; /* next packet to be sent */
ulong sndgen; /* and its generation */
ulong rcvseq; /* last packet received */
ulong rcvgen; /* and its generation */
ulong acksent; /* last ack sent */
ulong ackrcvd; /* last msg for which ack was rcvd */
/* flow control */
QLock lock;
Rendez vous;
int blocked;
};
/* MIB II counters */
typedef struct Rudpstats Rudpstats;
struct Rudpstats
{
ulong rudpInDatagrams;
ulong rudpNoPorts;
ulong rudpInErrors;
ulong rudpOutDatagrams;
};
typedef struct Rudppriv Rudppriv;
struct Rudppriv
{
Ipht ht;
/* MIB counters */
Rudpstats ustats;
/* non-MIB stats */
ulong csumerr; /* checksum errors */
ulong lenerr; /* short packet */
ulong rxmits; /* # of retransmissions */
ulong orders; /* # of out of order pkts */
/* keeping track of the ack kproc */
int ackprocstarted;
QLock apl;
};
static ulong generation = 0;
static Rendez rend;
/*
* protocol specific part of Conv
*/
typedef struct Rudpcb Rudpcb;
struct Rudpcb
{
QLock;
uchar headers;
uchar randdrop;
Reliable *r;
};
/*
* local functions
*/
void relsendack(Conv*, Reliable*, int);
int reliput(Conv*, Block*, uchar*, ushort);
Reliable *relstate(Rudpcb*, uchar*, ushort, char*);
void relput(Reliable*);
void relforget(Conv *, uchar*, int, int);
void relackproc(void *);
void relackq(Reliable *, Block*);
void relhangup(Conv *, Reliable*);
void relrexmit(Conv *, Reliable*);
void relput(Reliable*);
void rudpkick(void *x);
static void
rudpstartackproc(Proto *rudp)
{
Rudppriv *rpriv;
char kpname[KNAMELEN];
rpriv = rudp->priv;
if(rpriv->ackprocstarted == 0){
qlock(&rpriv->apl);
if(rpriv->ackprocstarted == 0){
sprint(kpname, "#I%drudpack", rudp->f->dev);
kproc(kpname, relackproc, rudp);
rpriv->ackprocstarted = 1;
}
qunlock(&rpriv->apl);
}
}
static char*
rudpconnect(Conv *c, char **argv, int argc)
{
char *e;
Rudppriv *upriv;
upriv = c->p->priv;
rudpstartackproc(c->p);
e = Fsstdconnect(c, argv, argc);
Fsconnected(c, e);
iphtadd(&upriv->ht, c);
return e;
}
static int
rudpstate(Conv *c, char *state, int n)
{
Rudpcb *ucb;
Reliable *r;
int m;
m = snprint(state, n, "%s", c->inuse?"Open":"Closed");
ucb = (Rudpcb*)c->ptcl;
qlock(ucb);
for(r = ucb->r; r; r = r->next)
m += snprint(state+m, n-m, " %I/%ld", r->addr, UNACKED(r));
m += snprint(state+m, n-m, "\n");
qunlock(ucb);
return m;
}
static char*
rudpannounce(Conv *c, char** argv, int argc)
{
char *e;
Rudppriv *upriv;
upriv = c->p->priv;
rudpstartackproc(c->p);
e = Fsstdannounce(c, argv, argc);
if(e != nil)
return e;
Fsconnected(c, nil);
iphtadd(&upriv->ht, c);
return nil;
}
static void
rudpcreate(Conv *c)
{
c->rq = qopen(64*1024, Qmsg, 0, 0);
c->wq = qopen(64*1024, Qkick, rudpkick, c);
}
static void
rudpclose(Conv *c)
{
Rudpcb *ucb;
Reliable *r, *nr;
Rudppriv *upriv;
upriv = c->p->priv;
iphtrem(&upriv->ht, c);
/* force out any delayed acks */
ucb = (Rudpcb*)c->ptcl;
qlock(ucb);
for(r = ucb->r; r != nil; r = r->next){
if(r->acksent != r->rcvseq)
relsendack(c, r, 0);
}
qunlock(ucb);
qclose(c->rq);
qclose(c->wq);
qclose(c->eq);
ipmove(c->laddr, IPnoaddr);
ipmove(c->raddr, IPnoaddr);
c->lport = 0;
c->rport = 0;
ucb->headers = 0;
ucb->randdrop = 0;
qlock(ucb);
for(r = ucb->r; r; r = nr){
if(r->acksent != r->rcvseq)
relsendack(c, r, 0);
nr = r->next;
relhangup(c, r);
relput(r);
}
ucb->r = 0;
qunlock(ucb);
}
/*
* randomly don't send packets
*/
static void
doipoput(Conv *c, Fs *f, Block *bp, int x, int ttl, int tos)
{
Rudpcb *ucb;
ucb = (Rudpcb*)c->ptcl;
if(ucb->randdrop && nrand(100) < ucb->randdrop)
freeblist(bp);
else
ipoput4(f, bp, x, ttl, tos, nil);
}
int
flow(void *v)
{
Reliable *r = v;
return UNACKED(r) <= Maxunacked;
}
void
rudpkick(void *x)
{
Conv *c = x;
Udphdr *uh;
ushort rport;
uchar laddr[IPaddrlen], raddr[IPaddrlen];
Block *bp;
Rudpcb *ucb;
Rudphdr *rh;
Reliable *r;
int dlen, ptcllen;
Rudppriv *upriv;
Fs *f;
upriv = c->p->priv;
f = c->p->f;
netlog(c->p->f, Logrudp, "rudp: kick\n");
bp = qget(c->wq);
if(bp == nil)
return;
ucb = (Rudpcb*)c->ptcl;
switch(ucb->headers) {
case 7:
/* get user specified addresses */
bp = pullupblock(bp, UDP_USEAD7);
if(bp == nil)
return;
ipmove(raddr, bp->rp);
bp->rp += IPaddrlen;
ipmove(laddr, bp->rp);
bp->rp += IPaddrlen;
/* pick interface closest to dest */
if(ipforme(f, laddr) != Runi)
findlocalip(f, laddr, raddr);
bp->rp += IPaddrlen; /* Ignore ifc address */
rport = nhgets(bp->rp);
bp->rp += 2+2; /* Ignore local port */
break;
default:
ipmove(raddr, c->raddr);
ipmove(laddr, c->laddr);
rport = c->rport;
break;
}
dlen = blocklen(bp);
/* Make space to fit rudp & ip header */
bp = padblock(bp, UDP_IPHDR+UDP_RHDRSIZE);
uh = (Udphdr *)(bp->rp);
uh->vihl = IP_VER4;
rh = (Rudphdr*)uh;
ptcllen = dlen + (UDP_RHDRSIZE-UDP_PHDRSIZE);
uh->Unused = 0;
uh->udpproto = IP_UDPPROTO;
uh->frag[0] = 0;
uh->frag[1] = 0;
hnputs(uh->udpplen, ptcllen);
switch(ucb->headers){
case 7:
v6tov4(uh->udpdst, raddr);
hnputs(uh->udpdport, rport);
v6tov4(uh->udpsrc, laddr);
break;
default:
v6tov4(uh->udpdst, c->raddr);
hnputs(uh->udpdport, c->rport);
if(ipcmp(c->laddr, IPnoaddr) == 0)
findlocalip(f, c->laddr, c->raddr);
v6tov4(uh->udpsrc, c->laddr);
break;
}
hnputs(uh->udpsport, c->lport);
hnputs(uh->udplen, ptcllen);
uh->udpcksum[0] = 0;
uh->udpcksum[1] = 0;
qlock(ucb);
r = relstate(ucb, raddr, rport, "kick");
r->sndseq = NEXTSEQ(r->sndseq);
hnputl(rh->relseq, r->sndseq);
hnputl(rh->relsgen, r->sndgen);
hnputl(rh->relack, r->rcvseq); /* ACK last rcvd packet */
hnputl(rh->relagen, r->rcvgen);
if(r->rcvseq != r->acksent)
r->acksent = r->rcvseq;
hnputs(uh->udpcksum, ptclcsum(bp, UDP_IPHDR, dlen+UDP_RHDRSIZE));
relackq(r, bp);
qunlock(ucb);
upriv->ustats.rudpOutDatagrams++;
DPRINT("sent: %lud/%lud, %lud/%lud\n",
r->sndseq, r->sndgen, r->rcvseq, r->rcvgen);
doipoput(c, f, bp, 0, c->ttl, c->tos);
if(waserror()) {
relput(r);
qunlock(&r->lock);
nexterror();
}
/* flow control of sorts */
qlock(&r->lock);
if(UNACKED(r) > Maxunacked){
r->blocked = 1;
sleep(&r->vous, flow, r);
r->blocked = 0;
}
qunlock(&r->lock);
relput(r);
poperror();
}
void
rudpiput(Proto *rudp, Ipifc *ifc, Block *bp)
{
int len, olen, ottl;
Udphdr *uh;
Conv *c;
Rudpcb *ucb;
uchar raddr[IPaddrlen], laddr[IPaddrlen];
ushort rport, lport;
Rudppriv *upriv;
Fs *f;
uchar *p;
upriv = rudp->priv;
f = rudp->f;
upriv->ustats.rudpInDatagrams++;
uh = (Udphdr*)(bp->rp);
/* Put back pseudo header for checksum
* (remember old values for icmpnoconv())
*/
ottl = uh->Unused;
uh->Unused = 0;
len = nhgets(uh->udplen);
olen = nhgets(uh->udpplen);
hnputs(uh->udpplen, len);
v4tov6(raddr, uh->udpsrc);
v4tov6(laddr, uh->udpdst);
lport = nhgets(uh->udpdport);
rport = nhgets(uh->udpsport);
if(nhgets(uh->udpcksum)) {
if(ptclcsum(bp, UDP_IPHDR, len+UDP_PHDRSIZE)) {
upriv->ustats.rudpInErrors++;
upriv->csumerr++;
netlog(f, Logrudp, "rudp: checksum error %I\n", raddr);
DPRINT("rudp: checksum error %I\n", raddr);
freeblist(bp);
return;
}
}
qlock(rudp);
c = iphtlook(&upriv->ht, raddr, rport, laddr, lport);
if(c == nil){
/* no conversation found */
upriv->ustats.rudpNoPorts++;
qunlock(rudp);
netlog(f, Logudp, "udp: no conv %I!%d -> %I!%d\n", raddr, rport,
laddr, lport);
uh->Unused = ottl;
hnputs(uh->udpplen, olen);
icmpnoconv(f, bp);
freeblist(bp);
return;
}
ucb = (Rudpcb*)c->ptcl;
qlock(ucb);
qunlock(rudp);
if(reliput(c, bp, raddr, rport) < 0){
qunlock(ucb);
freeb(bp);
return;
}
/*
* Trim the packet down to data size
*/
len -= (UDP_RHDRSIZE-UDP_PHDRSIZE);
bp = trimblock(bp, UDP_IPHDR+UDP_RHDRSIZE, len);
if(bp == nil) {
netlog(f, Logrudp, "rudp: len err %I.%d -> %I.%d\n",
raddr, rport, laddr, lport);
DPRINT("rudp: len err %I.%d -> %I.%d\n",
raddr, rport, laddr, lport);
upriv->lenerr++;
return;
}
netlog(f, Logrudpmsg, "rudp: %I.%d -> %I.%d l %d\n",
raddr, rport, laddr, lport, len);
switch(ucb->headers){
case 7:
/* pass the src address */
bp = padblock(bp, UDP_USEAD7);
p = bp->rp;
ipmove(p, raddr); p += IPaddrlen;
ipmove(p, laddr); p += IPaddrlen;
ipmove(p, ifc->lifc->local); p += IPaddrlen;
hnputs(p, rport); p += 2;
hnputs(p, lport);
break;
default:
/* connection oriented rudp */
if(ipcmp(c->raddr, IPnoaddr) == 0){
/* reply with the same ip address (if not broadcast) */
if(ipforme(f, laddr) != Runi)
ipv6local(ifc, laddr, 0, raddr);
ipmove(c->laddr, laddr);
ipmove(c->raddr, raddr);
c->rport = rport;
}
break;
}
if(qfull(c->rq)) {
netlog(f, Logrudp, "rudp: qfull %I.%d -> %I.%d\n",
raddr, rport, laddr, lport);
freeblist(bp);
} else {
qpass(c->rq, concatblock(bp));
}
qunlock(ucb);
}
static char *rudpunknown = "unknown rudp ctl request";
char*
rudpctl(Conv *c, char **f, int n)
{
Rudpcb *ucb;
uchar ip[IPaddrlen];
int x;
ucb = (Rudpcb*)c->ptcl;
if(n < 1)
return rudpunknown;
if(strcmp(f[0], "headers") == 0){
ucb->headers = 7; /* new headers format */
return nil;
} else if(strcmp(f[0], "hangup") == 0){
if(n < 3)
return "bad syntax";
if (parseip(ip, f[1]) == -1)
return Ebadip;
x = atoi(f[2]);
qlock(ucb);
relforget(c, ip, x, 1);
qunlock(ucb);
return nil;
} else if(strcmp(f[0], "randdrop") == 0){
x = 10; /* default is 10% */
if(n > 1)
x = atoi(f[1]);
if(x > 100 || x < 0)
return "illegal rudp drop rate";
ucb->randdrop = x;
return nil;
}
return rudpunknown;
}
void
rudpadvise(Proto *rudp, Block *bp, char *msg)
{
Udphdr *h;
uchar source[IPaddrlen], dest[IPaddrlen];
ushort psource, pdest;
Conv *s, **p;
h = (Udphdr*)(bp->rp);
v4tov6(dest, h->udpdst);
v4tov6(source, h->udpsrc);
psource = nhgets(h->udpsport);
pdest = nhgets(h->udpdport);
/* Look for a connection */
for(p = rudp->conv; (s = *p) != nil; p++) {
if(s->rport == pdest)
if(s->lport == psource)
if(ipcmp(s->raddr, dest) == 0)
if(ipcmp(s->laddr, source) == 0){
if(s->ignoreadvice)
break;
qhangup(s->rq, msg);
qhangup(s->wq, msg);
break;
}
}
freeblist(bp);
}
int
rudpstats(Proto *rudp, char *buf, int len)
{
Rudppriv *upriv;
upriv = rudp->priv;
return snprint(buf, len, "%lud %lud %lud %lud %lud %lud\n",
upriv->ustats.rudpInDatagrams,
upriv->ustats.rudpNoPorts,
upriv->ustats.rudpInErrors,
upriv->ustats.rudpOutDatagrams,
upriv->rxmits,
upriv->orders);
}
void
rudpinit(Fs *fs)
{
Proto *rudp;
rudp = smalloc(sizeof(Proto));
rudp->priv = smalloc(sizeof(Rudppriv));
rudp->name = "rudp";
rudp->connect = rudpconnect;
rudp->announce = rudpannounce;
rudp->ctl = rudpctl;
rudp->state = rudpstate;
rudp->create = rudpcreate;
rudp->close = rudpclose;
rudp->rcv = rudpiput;
rudp->advise = rudpadvise;
rudp->stats = rudpstats;
rudp->ipproto = IP_UDPPROTO;
rudp->nc = 32;
rudp->ptclsize = sizeof(Rudpcb);
Fsproto(fs, rudp);
}
/*********************************************/
/* Here starts the reliable helper functions */
/*********************************************/
/*
* Enqueue a copy of an unacked block for possible retransmissions
*/
void
relackq(Reliable *r, Block *bp)
{
Block *np;
np = copyblock(bp, blocklen(bp));
if(r->unacked)
r->unackedtail->list = np;
else {
/* restart timer */
r->timeout = 0;
r->xmits = 1;
r->unacked = np;
}
r->unackedtail = np;
np->list = nil;
}
/*
* retransmit unacked blocks
*/
void
relackproc(void *a)
{
Rudpcb *ucb;
Proto *rudp;
Reliable *r;
Conv **s, *c;
rudp = (Proto *)a;
while(waserror())
;
loop:
tsleep(&up->sleep, return0, 0, Rudptickms);
for(s = rudp->conv; *s; s++) {
c = *s;
ucb = (Rudpcb*)c->ptcl;
qlock(ucb);
for(r = ucb->r; r; r = r->next) {
if(r->unacked != nil){
r->timeout += Rudptickms;
if(r->timeout > Rudprxms*r->xmits)
relrexmit(c, r);
}
if(r->acksent != r->rcvseq)
relsendack(c, r, 0);
}
qunlock(ucb);
}
goto loop;
}
/*
* get the state record for a conversation
*/
Reliable*
relstate(Rudpcb *ucb, uchar *addr, ushort port, char *from)
{
Reliable *r, **l;
l = &ucb->r;
for(r = *l; r; r = *l){
if(memcmp(addr, r->addr, IPaddrlen) == 0 &&
port == r->port)
break;
l = &r->next;
}
/* no state for this addr/port, create some */
if(r == nil){
while(generation == 0)
generation = rand();
DPRINT("from %s new state %lud for %I!%ud\n",
from, generation, addr, port);
r = smalloc(sizeof(Reliable));
memmove(r->addr, addr, IPaddrlen);
r->port = port;
r->unacked = 0;
if(generation == Hangupgen)
generation++;
r->sndgen = generation++;
r->sndseq = 0;
r->ackrcvd = 0;
r->rcvgen = 0;
r->rcvseq = 0;
r->acksent = 0;
r->xmits = 0;
r->timeout = 0;
r->ref = 0;
incref(r); /* one reference for being in the list */
*l = r;
}
incref(r);
return r;
}
void
relput(Reliable *r)
{
if(decref(r) == 0)
free(r);
}
/*
* forget a Reliable state
*/
void
relforget(Conv *c, uchar *ip, int port, int originator)
{
Rudpcb *ucb;
Reliable *r, **l;
ucb = (Rudpcb*)c->ptcl;
l = &ucb->r;
for(r = *l; r; r = *l){
if(ipcmp(ip, r->addr) == 0 && port == r->port){
*l = r->next;
if(originator)
relsendack(c, r, 1);
relhangup(c, r);
relput(r); /* remove from the list */
break;
}
l = &r->next;
}
}
/*
* process a rcvd reliable packet. return -1 if not to be passed to user process,
* 0 therwise.
*
* called with ucb locked.
*/
int
reliput(Conv *c, Block *bp, uchar *addr, ushort port)
{
Block *nbp;
Rudpcb *ucb;
Rudppriv *upriv;
Udphdr *uh;
Reliable *r;
Rudphdr *rh;
ulong seq, ack, sgen, agen, ackreal;
int rv = -1;
/* get fields */
uh = (Udphdr*)(bp->rp);
rh = (Rudphdr*)uh;
seq = nhgetl(rh->relseq);
sgen = nhgetl(rh->relsgen);
ack = nhgetl(rh->relack);
agen = nhgetl(rh->relagen);
upriv = c->p->priv;
ucb = (Rudpcb*)c->ptcl;
r = relstate(ucb, addr, port, "input");
DPRINT("rcvd %lud/%lud, %lud/%lud, r->sndgen = %lud\n",
seq, sgen, ack, agen, r->sndgen);
/* if acking an incorrect generation, ignore */
if(ack && agen != r->sndgen)
goto out;
/* Look for a hangup */
if(sgen == Hangupgen) {
if(agen == r->sndgen)
relforget(c, addr, port, 0);
goto out;
}
/* make sure we're not talking to a new remote side */
if(r->rcvgen != sgen){
if(seq != 0 && seq != 1)
goto out;
/* new connection */
if(r->rcvgen != 0){
DPRINT("new con r->rcvgen = %lud, sgen = %lud\n", r->rcvgen, sgen);
relhangup(c, r);
}
r->rcvgen = sgen;
}
/* dequeue acked packets */
if(ack && agen == r->sndgen){
ackreal = 0;
while(r->unacked != nil && INSEQ(ack, r->ackrcvd, r->sndseq)){
nbp = r->unacked;
r->unacked = nbp->list;
DPRINT("%lud/%lud acked, r->sndgen = %lud\n",
ack, agen, r->sndgen);
freeb(nbp);
r->ackrcvd = NEXTSEQ(r->ackrcvd);
ackreal = 1;
}
/* flow control */
if(UNACKED(r) < Maxunacked/8 && r->blocked)
wakeup(&r->vous);
/*
* retransmit next packet if the acked packet
* was transmitted more than once
*/
if(ackreal && r->unacked != nil){
r->timeout = 0;
if(r->xmits > 1){
r->xmits = 1;
relrexmit(c, r);
}
}
}
/* no message or input queue full */
if(seq == 0 || qfull(c->rq))
goto out;
/* refuse out of order delivery */
if(seq != NEXTSEQ(r->rcvseq)){
relsendack(c, r, 0); /* tell him we got it already */
upriv->orders++;
DPRINT("out of sequence %lud not %lud\n", seq, NEXTSEQ(r->rcvseq));
goto out;
}
r->rcvseq = seq;
rv = 0;
out:
relput(r);
return rv;
}
void
relsendack(Conv *c, Reliable *r, int hangup)
{
Udphdr *uh;
Block *bp;
Rudphdr *rh;
int ptcllen;
Fs *f;
bp = allocb(UDP_IPHDR + UDP_RHDRSIZE);
bp->wp += UDP_IPHDR + UDP_RHDRSIZE;
f = c->p->f;
uh = (Udphdr *)(bp->rp);
uh->vihl = IP_VER4;
rh = (Rudphdr*)uh;
ptcllen = (UDP_RHDRSIZE-UDP_PHDRSIZE);
uh->Unused = 0;
uh->udpproto = IP_UDPPROTO;
uh->frag[0] = 0;
uh->frag[1] = 0;
hnputs(uh->udpplen, ptcllen);
v6tov4(uh->udpdst, r->addr);
hnputs(uh->udpdport, r->port);
hnputs(uh->udpsport, c->lport);
if(ipcmp(c->laddr, IPnoaddr) == 0)
findlocalip(f, c->laddr, c->raddr);
v6tov4(uh->udpsrc, c->laddr);
hnputs(uh->udplen, ptcllen);
if(hangup)
hnputl(rh->relsgen, Hangupgen);
else
hnputl(rh->relsgen, r->sndgen);
hnputl(rh->relseq, 0);
hnputl(rh->relagen, r->rcvgen);
hnputl(rh->relack, r->rcvseq);
if(r->acksent < r->rcvseq)
r->acksent = r->rcvseq;
uh->udpcksum[0] = 0;
uh->udpcksum[1] = 0;
hnputs(uh->udpcksum, ptclcsum(bp, UDP_IPHDR, UDP_RHDRSIZE));
DPRINT("sendack: %lud/%lud, %lud/%lud\n", 0L, r->sndgen, r->rcvseq, r->rcvgen);
doipoput(c, f, bp, 0, c->ttl, c->tos);
}
/*
* called with ucb locked (and c locked if user initiated close)
*/
void
relhangup(Conv *c, Reliable *r)
{
int n;
Block *bp;
char hup[ERRMAX];
n = snprint(hup, sizeof(hup), "hangup %I!%d", r->addr, r->port);
qproduce(c->eq, hup, n);
/*
* dump any unacked outgoing messages
*/
for(bp = r->unacked; bp != nil; bp = r->unacked){
r->unacked = bp->list;
bp->list = nil;
freeb(bp);
}
r->rcvgen = 0;
r->rcvseq = 0;
r->acksent = 0;
if(generation == Hangupgen)
generation++;
r->sndgen = generation++;
r->sndseq = 0;
r->ackrcvd = 0;
r->xmits = 0;
r->timeout = 0;
wakeup(&r->vous);
}
/*
* called with ucb locked
*/
void
relrexmit(Conv *c, Reliable *r)
{
Rudppriv *upriv;
Block *np;
Fs *f;
upriv = c->p->priv;
f = c->p->f;
r->timeout = 0;
if(r->xmits++ > Rudpmaxxmit){
relhangup(c, r);
return;
}
upriv->rxmits++;
np = copyblock(r->unacked, blocklen(r->unacked));
DPRINT("rxmit r->ackrvcd+1 = %lud\n", r->ackrcvd+1);
doipoput(c, f, np, 0, c->ttl, c->tos);
}
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