devip.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include "u.h"
#include "lib.h"
#include "dat.h"
#include "fns.h"
#include "error.h"

#include "devip.h"

void		hnputl(void *p, unsigned long v);
void		hnputs(void *p, unsigned short v);
unsigned long	nhgetl(void *p);
unsigned short	nhgets(void *p);
unsigned long	parseip(char *to, char *from);
void	csclose(Chan*);
long	csread(Chan*, void*, long, vlong);
long	cswrite(Chan*, void*, long, vlong);

void osipinit(void);

enum
{
	Qtopdir		= 1,	/* top level directory */
	Qcs,
	Qprotodir,		/* directory for a protocol */
	Qclonus,
	Qconvdir,		/* directory for a conversation */
	Qdata,
	Qctl,
	Qstatus,
	Qremote,
	Qlocal,
	Qlisten,

	MAXPROTO	= 4
};
#define TYPE(x) 	((int)((x).path & 0xf))
#define CONV(x) 	((int)(((x).path >> 4)&0xfff))
#define PROTO(x) 	((int)(((x).path >> 16)&0xff))
#define QID(p, c, y) 	(((p)<<16) | ((c)<<4) | (y))

typedef struct Proto	Proto;
typedef struct Conv	Conv;
struct Conv
{
	int	x;
	Ref	r;
	int	sfd;
	int	perm;
	char	owner[KNAMELEN];
	char*	state;
	ulong	laddr;
	ushort	lport;
	ulong	raddr;
	ushort	rport;
	int	restricted;
	char	cerr[KNAMELEN];
	Proto*	p;
};

struct Proto
{
	Lock	l;
	int	x;
	int	stype;
	char	name[KNAMELEN];
	int	nc;
	int	maxconv;
	Conv**	conv;
	Qid	qid;
};

static	int	np;
static	Proto	proto[MAXPROTO];
int	eipfmt(Fmt*);

static	Conv*	protoclone(Proto*, char*, int);
static	void	setladdr(Conv*);

int
ipgen(Chan *c, char *nname, Dirtab *d, int nd, int s, Dir *dp)
{
	Qid q;
	Conv *cv;
	char *p;

	USED(nname);
	q.vers = 0;
	q.type = 0;
	switch(TYPE(c->qid)) {
	case Qtopdir:
		if(s >= 1+np)
			return -1;

		if(s == 0){
			q.path = QID(s, 0, Qcs);
			devdir(c, q, "cs", 0, "network", 0666, dp);
		}else{
			s--;
			q.path = QID(s, 0, Qprotodir);
			q.type = QTDIR;
			devdir(c, q, proto[s].name, 0, "network", DMDIR|0555, dp);
		}
		return 1;
	case Qprotodir:
		if(s < proto[PROTO(c->qid)].nc) {
			cv = proto[PROTO(c->qid)].conv[s];
			sprint(up->genbuf, "%d", s);
			q.path = QID(PROTO(c->qid), s, Qconvdir);
			q.type = QTDIR;
			devdir(c, q, up->genbuf, 0, cv->owner, DMDIR|0555, dp);
			return 1;
		}
		s -= proto[PROTO(c->qid)].nc;
		switch(s) {
		default:
			return -1;
		case 0:
			p = "clone";
			q.path = QID(PROTO(c->qid), 0, Qclonus);
			break;
		}
		devdir(c, q, p, 0, "network", 0555, dp);
		return 1;
	case Qconvdir:
		cv = proto[PROTO(c->qid)].conv[CONV(c->qid)];
		switch(s) {
		default:
			return -1;
		case 0:
			q.path = QID(PROTO(c->qid), CONV(c->qid), Qdata);
			devdir(c, q, "data", 0, cv->owner, cv->perm, dp);
			return 1;
		case 1:
			q.path = QID(PROTO(c->qid), CONV(c->qid), Qctl);
			devdir(c, q, "ctl", 0, cv->owner, cv->perm, dp);
			return 1;
		case 2:
			p = "status";
			q.path = QID(PROTO(c->qid), CONV(c->qid), Qstatus);
			break;
		case 3:
			p = "remote";
			q.path = QID(PROTO(c->qid), CONV(c->qid), Qremote);
			break;
		case 4:
			p = "local";
			q.path = QID(PROTO(c->qid), CONV(c->qid), Qlocal);
			break;
		case 5:
			p = "listen";
			q.path = QID(PROTO(c->qid), CONV(c->qid), Qlisten);
			break;
		}
		devdir(c, q, p, 0, cv->owner, 0444, dp);
		return 1;
	}
	return -1;
}

static void
newproto(char *name, int type, int maxconv)
{
	int l;
	Proto *p;

	if(np >= MAXPROTO) {
		print("no %s: increase MAXPROTO", name);
		return;
	}

	p = &proto[np];
	strcpy(p->name, name);
	p->stype = type;
	p->qid.path = QID(np, 0, Qprotodir);
	p->qid.type = QTDIR;
	p->x = np++;
	p->maxconv = maxconv;
	l = sizeof(Conv*)*(p->maxconv+1);
	p->conv = mallocz(l, 1);
	if(p->conv == 0)
		panic("no memory");
}

void
ipinit(void)
{
	osipinit();

	newproto("udp", S_UDP, 10);
	newproto("tcp", S_TCP, 30);

	fmtinstall('I', eipfmt);
	fmtinstall('E', eipfmt);
	
}

Chan *
ipattach(char *spec)
{
	Chan *c;

	c = devattach('I', spec);
	c->qid.path = QID(0, 0, Qtopdir);
	c->qid.type = QTDIR;
	c->qid.vers = 0;
	return c;
}

static Walkqid*
ipwalk(Chan *c, Chan *nc, char **name, int nname)
{
	return devwalk(c, nc, name, nname, 0, 0, ipgen);
}

int
ipstat(Chan *c, uchar *dp, int n)
{
	return devstat(c, dp, n, 0, 0, ipgen);
}

Chan *
ipopen(Chan *c, int omode)
{
	Proto *p;
	ulong raddr;
	ushort rport;
	int perm, sfd;
	Conv *cv, *lcv;

	omode &= 3;
	perm = 0;
	switch(omode) {
	case OREAD:
		perm = 4;
		break;
	case OWRITE:
		perm = 2;
		break;
	case ORDWR:
		perm = 6;
		break;
	}

	switch(TYPE(c->qid)) {
	default:
		break;
	case Qtopdir:
	case Qprotodir:
	case Qconvdir:
	case Qstatus:
	case Qremote:
	case Qlocal:
		if(omode != OREAD)
			error(Eperm);
		break;
	case Qclonus:
		p = &proto[PROTO(c->qid)];
		cv = protoclone(p, up->user, -1);
		if(cv == 0)
			error(Enodev);
		c->qid.path = QID(p->x, cv->x, Qctl);
		c->qid.vers = 0;
		break;
	case Qdata:
	case Qctl:
		p = &proto[PROTO(c->qid)];
		lock(&p->l);
		cv = p->conv[CONV(c->qid)];
		lock(&cv->r.lk);
		if((perm & (cv->perm>>6)) != perm) {
			if(strcmp(up->user, cv->owner) != 0 ||
		 	  (perm & cv->perm) != perm) {
				unlock(&cv->r.lk);
				unlock(&p->l);
				error(Eperm);
			}
		}
		cv->r.ref++;
		if(cv->r.ref == 1) {
			memmove(cv->owner, up->user, KNAMELEN);
			cv->perm = 0660;
		}
		unlock(&cv->r.lk);
		unlock(&p->l);
		break;
	case Qlisten:
		p = &proto[PROTO(c->qid)];
		lcv = p->conv[CONV(c->qid)];
		sfd = so_accept(lcv->sfd, &raddr, &rport);
		cv = protoclone(p, up->user, sfd);
		if(cv == 0) {
			close(sfd);
			error(Enodev);
		}
		cv->raddr = raddr;
		cv->rport = rport;
		setladdr(cv);
		cv->state = "Established";
		c->qid.path = QID(p->x, cv->x, Qctl);
		break;
	}
	c->mode = openmode(omode);
	c->flag |= COPEN;
	c->offset = 0;
	return c;
}

void
ipclose(Chan *c)
{
	Conv *cc;

	switch(TYPE(c->qid)) {
	case Qcs:
		csclose(c);
		break;
	case Qdata:
	case Qctl:
		if((c->flag & COPEN) == 0)
			break;
		cc = proto[PROTO(c->qid)].conv[CONV(c->qid)];
		if(decref(&cc->r) != 0)
			break;
		strcpy(cc->owner, "network");
		cc->perm = 0666;
		cc->state = "Closed";
		cc->laddr = 0;
		cc->raddr = 0;
		cc->lport = 0;
		cc->rport = 0;
		close(cc->sfd);
		break;
	}
}

long
ipread(Chan *ch, void *a, long n, vlong offset)
{
	int r;
	Conv *c;
	Proto *x;
	uchar ip[4];
	char buf[128], *p;

/*print("ipread %s %lux\n", c2name(ch), (long)ch->qid.path);*/
	p = a;
	switch(TYPE(ch->qid)) {
	default:
		error(Eperm);
	case Qcs:
		return csread(ch, a, n, offset);
	case Qprotodir:
	case Qtopdir:
	case Qconvdir:
		return devdirread(ch, a, n, 0, 0, ipgen);
	case Qctl:
		sprint(buf, "%d", CONV(ch->qid));
		return readstr(offset, p, n, buf);
	case Qremote:
		c = proto[PROTO(ch->qid)].conv[CONV(ch->qid)];
		hnputl(ip, c->raddr);
		sprint(buf, "%I!%d\n", ip, c->rport);
		return readstr(offset, p, n, buf);
	case Qlocal:
		c = proto[PROTO(ch->qid)].conv[CONV(ch->qid)];
		hnputl(ip, c->laddr);
		sprint(buf, "%I!%d\n", ip, c->lport);
		return readstr(offset, p, n, buf);
	case Qstatus:
		x = &proto[PROTO(ch->qid)];
		c = x->conv[CONV(ch->qid)];
		sprint(buf, "%s/%d %d %s \n",
			c->p->name, c->x, c->r.ref, c->state);
		return readstr(offset, p, n, buf);
	case Qdata:
		c = proto[PROTO(ch->qid)].conv[CONV(ch->qid)];
		r = so_recv(c->sfd, a, n, 0);
		if(r < 0){
			oserrstr();
			nexterror();
		}
		return r;
	}
}

static void
setladdr(Conv *c)
{
	so_getsockname(c->sfd, &c->laddr, &c->lport);
}

static void
setlport(Conv *c)
{
	if(c->restricted == 0 && c->lport == 0)
		return;

	so_bind(c->sfd, c->restricted, c->lport);
}

static void
setladdrport(Conv *c, char *str)
{
	char *p, addr[4];

	p = strchr(str, '!');
	if(p == 0) {
		p = str;
		c->laddr = 0;
	}
	else {
		*p++ = 0;
		parseip(addr, str);
		c->laddr = nhgetl((uchar*)addr);
	}
	if(*p == '*')
		c->lport = 0;
	else
		c->lport = atoi(p);

	setlport(c);
}

static char*
setraddrport(Conv *c, char *str)
{
	char *p, addr[4];

	p = strchr(str, '!');
	if(p == 0)
		return "malformed address";
	*p++ = 0;
	parseip(addr, str);
	c->raddr = nhgetl((uchar*)addr);
	c->rport = atoi(p);
	p = strchr(p, '!');
	if(p) {
		if(strcmp(p, "!r") == 0)
			c->restricted = 1;
	}
	return 0;
}

long
ipwrite(Chan *ch, void *a, long n, vlong offset)
{
	Conv *c;
	Proto *x;
	int r, nf;
	char *p, *fields[3], buf[128];

	switch(TYPE(ch->qid)) {
	default:
		error(Eperm);
	case Qcs:
		return cswrite(ch, a, n, offset);
	case Qctl:
		x = &proto[PROTO(ch->qid)];
		c = x->conv[CONV(ch->qid)];
		if(n > sizeof(buf)-1)
			n = sizeof(buf)-1;
		memmove(buf, a, n);
		buf[n] = '\0';

		nf = tokenize(buf, fields, 3);
		if(strcmp(fields[0], "connect") == 0){
			switch(nf) {
			default:
				error("bad args to connect");
			case 2: