9p.c

来自「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」· C语言 代码 · 共 1,175 行 · 第 1/2 页

	if(!fileIsDir(fid->file)){
		vtSetError("not a directory");
		goto error;
	}
	if(permFid(fid, PermW) <= 0)
		goto error;
	if(!validFileName(m->t.name))
		goto error;
	if(strcmp(fid->uid, uidnoworld) == 0){
		vtSetError(EPermission);
		goto error;
	}

	omode = m->t.mode & OMODE;
	open = 0;

	if(omode == OREAD || omode == ORDWR || omode == OEXEC)
		open |= FidORead;
	if(omode == OWRITE || omode == ORDWR)
		open |= FidOWrite;
	if((open & (FidOWrite|FidORead)) == 0){
		vtSetError("unknown mode");
		goto error;
	}
	if(m->t.perm & DMDIR){
		if((m->t.mode & (ORCLOSE|OTRUNC)) || (open & FidOWrite)){
			vtSetError("illegal mode");
			goto error;
		}
		if(m->t.perm & DMAPPEND){
			vtSetError("illegal perm");
			goto error;
		}
	}

	mode = fileGetMode(fid->file);
	perm = m->t.perm;
	if(m->t.perm & DMDIR)
		perm &= ~0777|(mode & 0777);
	else
		perm &= ~0666|(mode & 0666);
	mode = perm & 0777;
	if(m->t.perm & DMDIR)
		mode |= ModeDir;
	if(m->t.perm & DMAPPEND)
		mode |= ModeAppend;
	if(m->t.perm & DMEXCL)
		mode |= ModeExclusive;
	if(m->t.perm & DMTMP)
		mode |= ModeTemporary;

	if((file = fileCreate(fid->file, m->t.name, mode, fid->uid)) == nil){
		fidPut(fid);
		return 0;
	}
	fileDecRef(fid->file);

	fid->qid.vers = fileGetMcount(file);
	fid->qid.path = fileGetId(file);
	fid->file = file;
	mode = fileGetMode(fid->file);
	if(mode & ModeDir)
		fid->qid.type = QTDIR;
	else
		fid->qid.type = QTFILE;
	if(mode & ModeAppend)
		fid->qid.type |= QTAPPEND;
	if(mode & ModeExclusive){
		fid->qid.type |= QTEXCL;
		assert(exclAlloc(fid) != 0);
	}
	if(m->t.mode & ORCLOSE)
		open |= FidORclose;
	fid->open = open;

	m->r.qid = fid->qid;
	m->r.iounit = m->con->msize-IOHDRSZ;

	fidPut(fid);
	return 1;

error:
	fidPut(fid);
	return 0;
}

static int
rTopen(Msg* m)
{
	Fid *fid;
	int isdir, mode, omode, open, rofs;

	if((fid = fidGet(m->con, m->t.fid, FidFWlock)) == nil)
		return 0;
	if(fid->open){
		vtSetError("fid open for I/O");
		goto error;
	}

	isdir = fileIsDir(fid->file);
	open = 0;
	rofs = fileIsRoFs(fid->file) || !groupWriteMember(fid->uname);

	if(m->t.mode & ORCLOSE){
		if(isdir){
			vtSetError("is a directory");
			goto error;
		}
		if(rofs){
			vtSetError("read-only filesystem");
			goto error;
		}
		if(permParent(fid, PermW) <= 0)
			goto error;

		open |= FidORclose;
	}

	omode = m->t.mode & OMODE;
	if(omode == OREAD || omode == ORDWR){
		if(permFid(fid, PermR) <= 0)
			goto error;
		open |= FidORead;
	}
	if(omode == OWRITE || omode == ORDWR || (m->t.mode & OTRUNC)){
		if(isdir){
			vtSetError("is a directory");
			goto error;
		}
		if(rofs){
			vtSetError("read-only filesystem");
			goto error;
		}
		if(permFid(fid, PermW) <= 0)
			goto error;
		open |= FidOWrite;
	}
	if(omode == OEXEC){
		if(isdir){
			vtSetError("is a directory");
			goto error;
		}
		if(permFid(fid, PermX) <= 0)
			goto error;
		open |= FidORead;
	}
	if((open & (FidOWrite|FidORead)) == 0){
		vtSetError("unknown mode");
		goto error;
	}

	mode = fileGetMode(fid->file);
	if((mode & ModeExclusive) && exclAlloc(fid) == 0)
		goto error;

	/*
	 * Everything checks out, try to commit any changes.
	 */
	if((m->t.mode & OTRUNC) && !(mode & ModeAppend))
		if(!fileTruncate(fid->file, fid->uid))
			goto error;

	if(isdir && fid->db != nil){
		dirBufFree(fid->db);
		fid->db = nil;
	}

	fid->qid.vers = fileGetMcount(fid->file);
	m->r.qid = fid->qid;
	m->r.iounit = m->con->msize-IOHDRSZ;

	fid->open = open;

	fidPut(fid);
	return 1;

error:
	if(fid->excl != nil)
		exclFree(fid);
	fidPut(fid);
	return 0;
}

static int
rTwalk(Msg* m)
{
	Qid qid;
	Fcall *r, *t;
	int nwname, wlock;
	File *file, *nfile;
	Fid *fid, *ofid, *nfid;

	t = &m->t;
	if(t->fid == t->newfid)
		wlock = FidFWlock;
	else
		wlock = 0;

	/*
	 * The file identified by t->fid must be valid in the
	 * current session and must not have been opened for I/O
	 * by an open or create message.
	 */
	if((ofid = fidGet(m->con, t->fid, wlock)) == nil)
		return 0;
	if(ofid->open){
		vtSetError("file open for I/O");
		fidPut(ofid);
		return 0;
	}

	/*
	 * If newfid is not the same as fid, allocate a new file;
	 * a side effect is checking newfid is not already in use (error);
	 * if there are no names to walk this will be equivalent to a
	 * simple 'clone' operation.
	 * It's a no-op if newfid is the same as fid and t->nwname is 0.
	 */
	nfid = nil;
	if(t->fid != t->newfid){
		nfid = fidGet(m->con, t->newfid, FidFWlock|FidFCreate);
		if(nfid == nil){
			vtSetError("fid in use");
			fidPut(ofid);
			return 0;
		}
		nfid->open = ofid->open & ~FidORclose;
		nfid->file = fileIncRef(ofid->file);
		nfid->qid = ofid->qid;
		nfid->uid = vtStrDup(ofid->uid);
		nfid->uname = vtStrDup(ofid->uname);
		nfid->fsys = fsysIncRef(ofid->fsys);
		fid = nfid;
	}
	else
		fid = ofid;

	r = &m->r;
	r->nwqid = 0;

	if(t->nwname == 0){
		if(nfid != nil)
			fidPut(nfid);
		fidPut(ofid);

		return 1;
	}

	file = fid->file;
	fileIncRef(file);
	qid = fid->qid;

	for(nwname = 0; nwname < t->nwname; nwname++){
		/*
		 * Walked elements must represent a directory and
		 * the implied user must have permission to search
		 * the directory.  Walking .. is always allowed, so that
		 * you can't walk into a directory and then not be able
		 * to walk out of it.
		 */
		if(!(qid.type & QTDIR)){
			vtSetError("not a directory");
			break;
		}
		switch(permFile(file, fid, PermX)){
		case 1:
			break;
		case 0:
			if(strcmp(t->wname[nwname], "..") == 0)
				break;
		case -1:
			goto Out;
		}
		if((nfile = fileWalk(file, t->wname[nwname])) == nil)
			break;
		fileDecRef(file);
		file = nfile;
		qid.type = QTFILE;
		if(fileIsDir(file))
			qid.type = QTDIR;
		qid.vers = fileGetMcount(file);
		qid.path = fileGetId(file);
		r->wqid[r->nwqid++] = qid;
	}

	if(nwname == t->nwname){
		/*
		 * Walked all elements. Update the target fid
		 * from the temporary qid used during the walk,
		 * and tidy up.
		 */
		fid->qid = r->wqid[r->nwqid-1];
		fileDecRef(fid->file);
		fid->file = file;

		if(nfid != nil)
			fidPut(nfid);

		fidPut(ofid);
		return 1;
	}

Out:
	/*
	 * Didn't walk all elements, 'clunk' nfid if it exists
	 * and leave fid untouched.
	 * It's not an error if some of the elements were walked OK.
	 */
	fileDecRef(file);
	if(nfid != nil)
		fidClunk(nfid);

	fidPut(ofid);
	if(nwname == 0)
		return 0;
	return 1;
}

static int
rTflush(Msg* m)
{
	if(m->t.oldtag != NOTAG)
		msgFlush(m);
	return 1;
}

static void
parseAname(char *aname, char **fsname, char **path)
{
	char *s;

	if(aname && aname[0])
		s = vtStrDup(aname);
	else
		s = vtStrDup("main/active");
	*fsname = s;
	if((*path = strchr(s, '/')) != nil)
		*(*path)++ = '\0';
	else
		*path = "";
}

/*
 * Check remote IP address against /mnt/ipok.
 * Sources.cs.bell-labs.com uses this to disallow
 * network connections from Sudan, Libya, etc., 
 * following U.S. cryptography export regulations.
 */
static int
conIPCheck(Con* con)
{
	char ok[256], *p;
	int fd;

	if(con->flags&ConIPCheck){
		if(con->remote[0] == 0){
			vtSetError("cannot verify unknown remote address");
			return 0;
		}
		if(access("/mnt/ipok/ok", AEXIST) < 0){
			/* mount closes the fd on success */
			if((fd = open("/srv/ipok", ORDWR)) >= 0 
			&& mount(fd, -1, "/mnt/ipok", MREPL, "") < 0)
				close(fd);
			if(access("/mnt/ipok/ok", AEXIST) < 0){
				vtSetError("cannot verify remote address");
				return 0;
			}
		}
		snprint(ok, sizeof ok, "/mnt/ipok/ok/%s", con->remote);
		if((p = strchr(ok, '!')) != nil)
			*p = 0;
		if(access(ok, AEXIST) < 0){
			vtSetError("restricted remote address");
			return 0;
		}
	}
	return 1;
}

static int
rTattach(Msg* m)
{
	Fid *fid;
	Fsys *fsys;
	char *fsname, *path;

	if((fid = fidGet(m->con, m->t.fid, FidFWlock|FidFCreate)) == nil)
		return 0;

	parseAname(m->t.aname, &fsname, &path);
	if((fsys = fsysGet(fsname)) == nil){
		fidClunk(fid);
		vtMemFree(fsname);
		return 0;
	}
	fid->fsys = fsys;

	if(m->t.uname[0] != '\0')
		fid->uname = vtStrDup(m->t.uname);
	else
		fid->uname = vtStrDup(unamenone);

	if((fid->con->flags&ConIPCheck) && !conIPCheck(fid->con)){
		consPrint("reject %s from %s: %R\n", fid->uname, fid->con->remote);
		fidClunk(fid);
		vtMemFree(fsname);
		return 0;
	}
	if(fsysNoAuthCheck(fsys) || (m->con->flags&ConNoAuthCheck)){
		if((fid->uid = uidByUname(fid->uname)) == nil)
			fid->uid = vtStrDup(unamenone);
	}
	else if(!authCheck(&m->t, fid, fsys)){
		fidClunk(fid);
		vtMemFree(fsname);
		return 0;
	}

	fsysFsRlock(fsys);
	if((fid->file = fsysGetRoot(fsys, path)) == nil){
		fsysFsRUnlock(fsys);
		fidClunk(fid);
		vtMemFree(fsname);
		return 0;
	}
	fsysFsRUnlock(fsys);
	vtMemFree(fsname);

	fid->qid = (Qid){fileGetId(fid->file), 0, QTDIR};
	m->r.qid = fid->qid;

	fidPut(fid);
	return 1;
}

static int
rTauth(Msg* m)
{
	int afd;
	Con *con;
	Fid *afid;
	Fsys *fsys;
	char *fsname, *path;

	parseAname(m->t.aname, &fsname, &path);
	if((fsys = fsysGet(fsname)) == nil){
		vtMemFree(fsname);
		return 0;
	}
	vtMemFree(fsname);

	if(fsysNoAuthCheck(fsys) || (m->con->flags&ConNoAuthCheck)){
		m->con->aok = 1;
		vtSetError("authentication disabled");
		fsysPut(fsys);
		return 0;
	}
	if(strcmp(m->t.uname, unamenone) == 0){
		vtSetError("user 'none' requires no authentication");
		fsysPut(fsys);
		return 0;
	}

	con = m->con;
	if((afid = fidGet(con, m->t.afid, FidFWlock|FidFCreate)) == nil){
		fsysPut(fsys);
		return 0;
	}
	afid->fsys = fsys;

	if((afd = open("/mnt/factotum/rpc", ORDWR)) < 0){
		vtSetError("can't open \"/mnt/factotum/rpc\"");
		fidClunk(afid);
		return 0;
	}
	if((afid->rpc = auth_allocrpc(afd)) == nil){
		close(afd);
		vtSetError("can't auth_allocrpc");
		fidClunk(afid);
		return 0;
	}
	if(auth_rpc(afid->rpc, "start", "proto=p9any role=server", 23) != ARok){
		vtSetError("can't auth_rpc");
		fidClunk(afid);
		return 0;
	}

	afid->open = FidOWrite|FidORead;
	afid->qid.type = QTAUTH;
	afid->qid.path = m->t.afid;
	afid->uname = vtStrDup(m->t.uname);

	m->r.qid = afid->qid;

	fidPut(afid);
	return 1;
}

static int
rTversion(Msg* m)
{
	int v;
	Con *con;
	Fcall *r, *t;

	t = &m->t;
	r = &m->r;
	con = m->con;

	vtLock(con->lock);
	if(con->state != ConInit){
		vtUnlock(con->lock);
		vtSetError("Tversion: down");
		return 0;
	}
	con->state = ConNew;

	/*
	 * Release the karma of past lives and suffering.
	 * Should this be done before or after checking the
	 * validity of the Tversion?
	 */
	fidClunkAll(con);

	if(t->tag != NOTAG){
		vtUnlock(con->lock);
		vtSetError("Tversion: invalid tag");
		return 0;
	}

	if(t->msize < 256){
		vtUnlock(con->lock);
		vtSetError("Tversion: message size too small");
		return 0;
	}
	if(t->msize < con->msize)
		r->msize = t->msize;
	else
		r->msize = con->msize;

	r->version = "unknown";
	if(t->version[0] == '9' && t->version[1] == 'P'){
		/*
		 * Currently, the only defined version
		 * is "9P2000"; ignore any later versions.
          	 */
		v = strtol(&t->version[2], 0, 10);
		if(v >= 2000){
			r->version = VERSION9P;
			con->msize = r->msize;
			con->state = ConUp;
		}
		else if(strcmp(t->version, "9PEoF") == 0){
			r->version = "9PEoF";
			con->msize = r->msize;
			con->state = ConMoribund;

			/*
			 * Don't want to attempt to write this
			 * message as the connection may be already
			 * closed.
			 */
			m->state = MsgF;
		}
	}
	vtUnlock(con->lock);

	return 1;
}

int (*rFcall[Tmax])(Msg*) = {
	[Tversion]	= rTversion,
	[Tauth]		= rTauth,
	[Tattach]	= rTattach,
	[Tflush]	= rTflush,
	[Twalk]		= rTwalk,
	[Topen]		= rTopen,
	[Tcreate]	= rTcreate,
	[Tread]		= rTread,
	[Twrite]	= rTwrite,
	[Tclunk]	= rTclunk,
	[Tremove]	= rTremove,
	[Tstat]		= rTstat,
	[Twstat]	= rTwstat,
};