devsdp.c

著名操作系统Plan 9的第三版的部分核心源代码。现在很难找到了。Plan 9是bell实验室开发的Unix后继者。

		b->wp[pad-1] = pad;
		b->wp += pad;
	}

	/* Make space to fit sdp header */
	b = padblock(b, 4 + c->out.cipherivlen);
	b->rp[0] = (type << 4) | subtype;
	c->out.seq++;
	if(c->out.seq == (1<<24)) {
		c->out.seq = 0;
		c->out.seqwrap++;
	}
	b->rp[1] = c->out.seq>>16;
	b->rp[2] = c->out.seq>>8;
	b->rp[3] = c->out.seq;
	
	if(c->out.cipher)
		(*c->out.cipher)(&c->out, b->rp+4, BLEN(b)-4);

	// auth
	if(c->out.auth) {
		b->wp += c->out.authlen;
		(*c->out.auth)(&c->out, b->rp, BLEN(b));
	}
	
	convwriteblock(c, b);
}

// assume hold conv lock
static void
convoconnect(Conv *c, int op, ulong dialid, ulong acceptid)
{
	Block *b;

	c->lstats.outPackets++;
	assert(c->chan != nil);
	b = allocb(9);
	b->wp[0] = (TConnect << 4) | op;
	hnputl(b->wp+1, dialid);
	hnputl(b->wp+5, acceptid);
	b->wp += 9;

	if(!waserror()) {
		convwriteblock(c, b);
		poperror();
	}
}

static Block *
convreadblock(Conv *c, int n)
{
	Block *b;
	Chan *ch;

	qlock(&c->readlk);
	if(waserror()) {
		c->readproc = nil;
		qunlock(&c->readlk);
		nexterror();
	}
	qlock(c);
	if(c->state == CClosed) {
		qunlock(c);
		error("closed");
	}
	c->readproc = up;
	ch = c->chan;
	assert(c->ref > 0);
	qunlock(c);

	b = devtab[ch->type]->bread(ch, n, 0);
	c->readproc = nil;
	poperror();
	qunlock(&c->readlk);

	return b;
}

static int
readready(void *a)
{
	Conv *c = a;

	return c->in.controlpkt != nil || (c->state == CClosed) || (c->state == CRemoteClose);
}

static Block *
readcontrol(Conv *c, int n)
{
	Block *b;

	USED(n);

	qlock(&c->in.controllk);
	if(waserror()) {
		qunlock(&c->in.controllk);
		nexterror();
	}
	qlock(c);	// this lock is not held during the sleep below

	for(;;) {
		if(c->chan == nil || c->state == CClosed) {
			qunlock(c);
if(0)print("readcontrol: return error - state = %s\n", convstatename[c->state]);
			error("conversation closed");
		}

		if(c->in.controlpkt != nil)
			break;

		if(c->state == CRemoteClose) {
			qunlock(c);
if(0)print("readcontrol: return nil - state = %s\n", convstatename[c->state]);
			poperror();
			return nil;
		}
		qunlock(c);
		sleep(&c->in.controlready, readready, c);
		qlock(c);
	}

	convack(c);

	b = c->in.controlpkt;
	c->in.controlpkt = nil;
	qunlock(c);
	poperror();
	qunlock(&c->in.controllk);
	return b;
}


static int
writeready(void *a)
{
	Conv *c = a;

	return c->out.controlpkt == nil || (c->state == CClosed) || (c->state == CRemoteClose);
}

// c is locked
static void
writewait(Conv *c)
{
	for(;;) {
		if(c->state == CInit || c->state == CClosed || c->state == CRemoteClose)
			error("conversation closed");

		if(c->state == COpen && c->out.controlpkt == nil)
			break;

		qunlock(c);
		if(waserror()) {
			qlock(c);
			nexterror();
		}
		sleep(&c->out.controlready, writeready, c);
		poperror();
		qlock(c);
	}
}

static void
writecontrol(Conv *c, void *p, int n, int wait)
{
	Block *b;

	qlock(&c->out.controllk);
	qlock(c);
	if(waserror()) {
		qunlock(c);
		qunlock(&c->out.controllk);
		nexterror();
	}
	writewait(c);
	b = allocb(4+n);
	c->out.controlseq++;
	hnputl(b->wp, c->out.controlseq);
	memmove(b->wp+4, p, n);
	b->wp += 4+n;
	c->out.controlpkt = b;
	convretryinit(c);
	convoput(c, TControl, ControlMesg, copyblock(b, blocklen(b)));
	if(wait)
		writewait(c);
	poperror();
	qunlock(c);
	qunlock(&c->out.controllk);
}

static Block *
readdata(Conv *c, int n)
{
	Block *b;
	int nn;

	for(;;) {

		// some slack for tunneling overhead
		nn = n + 100;

		// make sure size is big enough for control messages
		if(nn < 1000)
			nn = 1000;
		b = convreadblock(c, nn);
		if(b == nil)
			return nil;
		qlock(c);
		if(waserror()) {
			qunlock(c);
			return nil;
		}
		b = conviput(c, b, 0);
		poperror();
		qunlock(c);
		if(b != nil) {
			if(BLEN(b) > n)
				b->wp = b->rp + n;
			return b;
		}
	}
}

static long
writedata(Conv *c, Block *b)
{
	int n;
	ulong seq;
	int subtype;

	qlock(c);
	if(waserror()) {
		qunlock(c);
		nexterror();
	}

	if(c->state != COpen) {
		freeb(b);
		error("conversation not open");
	}

	n = BLEN(b);
	c->lstats.outDataPackets++;
	c->lstats.outDataBytes += n;

	if(c->out.comp != nil) {
		// must generate same value as convoput
		seq = (c->out.seq + 1) & (SeqMax-1);

		subtype = (*c->out.comp)(c, 0, seq, &b);
		c->lstats.outCompDataBytes += BLEN(b);
		convoput(c, TCompData, subtype, b);
	} else
		convoput(c, TData, 0, b);

	poperror();
	qunlock(c);
	return n;
}

static void
convreader(void *a)
{
	Conv *c = a;
	Block *b;

	qlock(c);
	assert(c->reader == 1);
	while(c->dataopen == 0 && c->state != CClosed) {
		qunlock(c);
		b = nil;
		if(!waserror()) {
			b = convreadblock(c, 2000);
			poperror();
		}
		qlock(c);
		if(b == nil) {
			if(strcmp(up->error, Eintr) != 0) {
				convsetstate(c, CClosed);
				break;
			}
		} else if(!waserror()) {
			conviput(c, b, 1);
			poperror();
		}
	}
	c->reader = 0;
	convderef(c);
	qunlock(c);
	pexit("hangup", 1);
}


/* ciphers, authenticators, and compressors  */

static void
setalg(Conv *c, char *name, Algorithm *alg, Algorithm **p)
{
	for(; alg->name; alg++)
		if(strcmp(name, alg->name) == 0)
			break;
	if(alg->name == nil)
		error("unknown algorithm");

	*p = alg;
	alg->init(c);
}

static void
setsecret(OneWay *ow, char *secret)
{
	char *p;
	int i, c;
	
	i = 0;
	memset(ow->secret, 0, sizeof(ow->secret));
	for(p=secret; *p; p++) {
		if(i >= sizeof(ow->secret)*2)
			break;
		c = *p;
		if(c >= '0' && c <= '9')
			c -= '0';
		else if(c >= 'a' && c <= 'f')
			c -= 'a'-10;
		else if(c >= 'A' && c <= 'F')
			c -= 'A'-10;
		else
			error("bad character in secret");
		if((i&1) == 0)
			c <<= 4;
		ow->secret[i>>1] |= c;
		i++;
	}
}

static void
setkey(uchar *key, int n, OneWay *ow, char *prefix)
{
	uchar ibuf[SHA1dlen], obuf[MD5dlen], salt[10];
	int i, round = 0;

	while(n > 0){
		for(i=0; i<round+1; i++)
			salt[i] = 'A'+round;
		sha1((uchar*)prefix, strlen(prefix), ibuf, sha1(salt, round+1, nil, nil));
		md5(ibuf, SHA1dlen, obuf, md5(ow->secret, sizeof(ow->secret), nil, nil));
		i = (n<MD5dlen) ? n : MD5dlen;
		memmove(key, obuf, i);
		key += i;
		n -= i;
		if(++round > sizeof salt)
			panic("setkey: you ask too much");
	}
}

static void
cipherfree(Conv *c)
{
	if(c->in.cipherstate) {
		free(c->in.cipherstate);
		c->in.cipherstate = nil;
	}
	if(c->out.cipherstate) {
		free(c->out.cipherstate);
		c->out.cipherstate = nil;
	}
	c->in.cipher = nil;
	c->in.cipherblklen = 0;
	c->out.cipherblklen = 0;
	c->in.cipherivlen = 0;
	c->out.cipherivlen = 0;
}

static void
authfree(Conv *c)
{
	if(c->in.authstate) {
		free(c->in.authstate);
		c->in.authstate = nil;
	}
	if(c->out.authstate) {
		free(c->out.authstate);
		c->out.authstate = nil;
	}
	c->in.auth = nil;
	c->in.authlen = 0;
	c->out.authlen = 0;
}

static void
compfree(Conv *c)
{
	if(c->in.compstate) {
		free(c->in.compstate);
		c->in.compstate = nil;
	}
	if(c->out.compstate) {
		free(c->out.compstate);
		c->out.compstate = nil;
	}
	c->in.comp = nil;
}

static void
nullcipherinit(Conv *c)
{
	cipherfree(c);
}

static int
desencrypt(OneWay *ow, uchar *p, int n)
{
	uchar *pp, *ip, *eip, *ep;
	DESstate *ds = ow->cipherstate;

	if(n < 8 || (n & 0x7 != 0))
		return 0;
	ep = p + n;
	memmove(p, ds->ivec, 8);
	for(p += 8; p < ep; p += 8){
		pp = p;
		ip = ds->ivec;
		for(eip = ip+8; ip < eip; )
			*pp++ ^= *ip++;
		block_cipher(ds->expanded, p, 0);
		memmove(ds->ivec, p, 8);
	}
	return 1;
}

static int
desdecrypt(OneWay *ow, uchar *p, int n)
{
	uchar tmp[8];
	uchar *tp, *ip, *eip, *ep;
	DESstate *ds = ow->cipherstate;

	if(n < 8 || (n & 0x7 != 0))
		return 0;
	ep = p + n;
	memmove(ds->ivec, p, 8);
	p += 8;
	while(p < ep){
		memmove(tmp, p, 8);
		block_cipher(ds->expanded, p, 1);
		tp = tmp;
		ip = ds->ivec;
		for(eip = ip+8; ip < eip; ){
			*p++ ^= *ip;
			*ip++ = *tp++;
		}
	}
	return 1;
}

static void
descipherinit(Conv *c)
{
	uchar key[8];
	uchar ivec[8];
	int i;
	int n = c->cipher->keylen;

	cipherfree(c);
	
	if(n > sizeof(key))
		n = sizeof(key);

	/* in */
	memset(key, 0, sizeof(key));
	setkey(key, n, &c->in, "cipher");
	memset(ivec, 0, sizeof(ivec));
	c->in.cipherblklen = 8;
	c->in.cipherivlen = 8;
	c->in.cipher = desdecrypt;
	c->in.cipherstate = smalloc(sizeof(DESstate));
	setupDESstate(c->in.cipherstate, key, ivec);
	
	/* out */
	memset(key, 0, sizeof(key));
	setkey(key, n, &c->out, "cipher");
	for(i=0; i<8; i++)
		ivec[i] = nrand(256);
	c->out.cipherblklen = 8;
	c->out.cipherivlen = 8;
	c->out.cipher = desencrypt;
	c->out.cipherstate = smalloc(sizeof(DESstate));
	setupDESstate(c->out.cipherstate, key, ivec);
}

static int
rc4encrypt(OneWay *ow, uchar *p, int n)
{
	CipherRc4 *cr = ow->cipherstate;

	if(n < 4)
		return 0;

	hnputl(p, cr->cseq);
	p += 4;
	n -= 4;
	rc4(&cr->current, p, n);
	cr->cseq += n;
	return 1;
}

static int
rc4decrypt(OneWay *ow, uchar *p, int n)
{
	CipherRc4 *cr = ow->cipherstate;
	RC4state tmpstate;
	ulong seq;
	long d, dd;

	if(n < 4)
		return 0;

	seq = nhgetl(p);
	p += 4;
	n -= 4;
	d = seq-cr->cseq;
	if(d == 0) {
		rc4(&cr->current, p, n);
		cr->cseq += n;
		if(cr->ovalid) {
			dd = cr->cseq - cr->lgseq;
			if(dd > RC4back)
				cr->ovalid = 0;
		}
	} else if(d > 0) {
//print("missing packet: %uld %ld\n", seq, d);
		// this link is hosed 
		if(d > RC4forward)
			return 0;
		cr->lgseq = seq;
		if(!cr->ovalid) {
			cr->ovalid = 1;
			cr->oseq = cr->cseq;
			memmove(&cr->old, &cr->current, sizeof(RC4state));
		}
		rc4skip(&cr->current, d);
		rc4(&cr->current, p, n);
		cr->cseq = seq+n;
	} else {
//print("reordered packet: %uld %ld\n", seq, d);
		dd = seq - cr->oseq;
		if(!cr->ovalid || -d > RC4back || dd < 0)
			return 0;
		memmove(&tmpstate, &cr->old, sizeof(RC4state));
		rc4skip(&tmpstate, dd);
		rc4(&tmpstate, p, n);
		return 1;
	}

	// move old state up
	if(cr->ovalid) {
		dd = cr->cseq - RC4back - cr->oseq;
		if(dd > 0) {
			rc4skip(&cr->old, dd);
			cr->oseq += dd;
		}
	}

	return 1;
}

static void
rc4cipherinit(Conv *c)
{
	uchar key[32];
	CipherRc4 *cr;
	int n;

	cipherfree(c);

	n = c->cipher->keylen;
	if(n > sizeof(key))
		n = sizeof(key);

	/* in */
	memset(key, 0, sizeof(key));
	setkey(key, n, &c->in, "cipher");
	c->in.cipherblklen = 1;
	c->in.cipherivlen = 4;
	c->in.cipher = rc4decrypt;
	cr = smalloc(sizeof(CipherRc4));
	memset(cr, 0, sizeof(*cr));
	setupRC4state(&cr->current, key, n);
	c->in.cipherstate = cr;

	/* out */
	memset(key, 0, sizeof(key));
	setkey(key, n, &c->out, "cipher");
	c->out.cipherblklen = 1;
	c->out.cipherivlen = 4;
	c->out.cipher = rc4encrypt;
	cr = smalloc(sizeof(CipherRc4));
	memset(cr, 0, sizeof(*cr));
	setupRC4state(&cr->current, key, n);
	c->out.cipherstate = cr;
}

static void
nullauthinit(Conv *c)
{
	authfree(c);
}

static void
shaauthinit(Conv *c)
{
	authfree(c);
}

static void
seanq_hmac_md5(uchar hash[MD5dlen], ulong wrap, uchar *t, long tlen, uchar *key, long klen)
{
	uchar ipad[65], opad[65], wbuf[4];
	int i;
	DigestState *digest;
	uchar innerhash[MD5dlen];

	for(i=0; i<64; i++){
		ipad[i] = 0x36;
		opad[i] = 0x5c;
	}
	ipad[64] = opad[64] = 0;
	for(i=0; i<klen; i++){
		ipad[i] ^= key[i];
		opad[i] ^= key[i];
	}
	hnputl(wbuf, wrap);
	digest = md5(ipad, 64, nil, nil);
	digest = md5(wbuf, sizeof(wbuf), nil, digest);
	md5(t, tlen, innerhash, digest);
	digest = md5(opad, 64, nil, nil);
	md5(innerhash, MD5dlen, hash, digest);
}

static int
md5auth(OneWay *ow, uchar *t, int tlen)
{
	uchar hash[MD5dlen];
	int r;

	if(tlen < ow->authlen)
		return 0;
	tlen -= ow->authlen;

	memset(hash, 0, MD5dlen);
	seanq_hmac_md5(hash, ow->seqwrap, t, tlen, (uchar*)ow->authstate, 16);
	r = memcmp(t+tlen, hash, ow->authlen) == 0;
	memmove(t+tlen, hash, ow->authlen);
	return r;
}

static void
md5authinit(Conv *c)
{
	int keylen;

	authfree(c);

	keylen = c->auth->keylen;
	if(keylen > 16)
		keylen = 16;

	/* in */
	c->in.authstate = smalloc(16);
	memset(c->in.authstate, 0, 16);
	setkey(c->in.authstate, keylen, &c->in, "auth");
	c->in.authlen = 12;
	c->in.auth = md5auth;
	
	/* out */
	c->out.authstate = smalloc(16);
	memset(c->out.authstate, 0, 16);
	setkey(c->out.authstate, keylen, &c->out, "auth");
	c->out.authlen = 12;
	c->out.auth = md5auth;
}

static void
nullcompinit(Conv *c)
{
	compfree(c);
}

static int
thwackcomp(Conv *c, int, ulong seq, Block **bp)
{
	Block *b, *bb;
	int nn;

	// add ack info
	b = padblock(*bp, 4);
	b->rp[0] = (c->in.window>>1) & 0xff;
	b->rp[1] = c->in.seq>>16;
	b->rp[2] = c->in.seq>>8;
	b->rp[3] = c->in.seq;

	bb = allocb(BLEN(b));
	nn = thwack(c->out.compstate, bb->wp, b->rp, BLEN(b), seq, c->lstats.outCompStats);
	if(nn < 0) {
		freeb(bb);
		*bp = b;
		return ThwackU;
	} else {
		bb->wp += nn;
		freeb(b);
		*bp = bb;
		return ThwackC;
	}
}

static int
thwackuncomp(Conv *c, int subtype, ulong seq, Block **bp)
{
	Block *b, *bb;
	ulong mask;
	ulong mseq;
	int n;

	switch(subtype) {
	default:
		return 0;
	case ThwackU:
		b = *bp;
		mask = b->rp[0];
		mseq = (b->rp[1]<<16) | (b->rp[2]<<8) | b->rp[3];
		b->rp += 4;
		thwackack(c->out.compstate, mseq, mask);
		return 1;
	case ThwackC:
		bb = *bp;
		b = allocb(ThwMaxBlock);
		n = unthwack(c->in.compstate, b->wp, ThwMaxBlock, bb->rp, BLEN(bb), seq);
		freeb(bb);
		if(n < 0) {
print("unthwack failed: %r!\n");
			freeb(b);
			return 0;
		}
		b->wp += n;
		mask = b->rp[0];
		mseq = (b->rp[1]<<16) | (b->rp[2]<<8) | b->rp[3];
		thwackack(c->out.compstate, mseq, mask);
		b->rp += 4;
		*bp = b;
		return 1;
	}
}

static void
thwackcompinit(Conv *c)
{
	compfree(c);

	c->in.compstate = malloc(sizeof(Unthwack));
	if(c->in.compstate == nil)
		error(Enomem);
	unthwackinit(c->in.compstate);
	c->out.compstate = malloc(sizeof(Thwack));
	if(c->out.compstate == nil)
		error(Enomem);
	thwackinit(c->out.compstate);
	c->in.comp = thwackuncomp;
	c->out.comp = thwackcomp;
}