nfs.c

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	id = rpc_id++;
	buf.u.call.id = htonl(id);
	buf.u.call.type = htonl(MSG_CALL);
	buf.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
	buf.u.call.prog = htonl(PROG_NFS);
	buf.u.call.vers = htonl(2);	/* nfsd is version 2 */
	buf.u.call.proc = htonl(NFS_READLINK);
	p = rpc_add_credentials((long *)buf.u.call.data);
	memcpy(p, nfh, NFS_FHSIZE);
	p += (NFS_FHSIZE / 4);
	for (retries = 0; retries < MAX_RPC_RETRIES; retries++) {
		long timeout = rfc2131_sleep_interval(TIMEOUT, retries);
		udp_transmit(arptable[server].ipaddr.s_addr, sport, port,
			(char *)p - (char *)&buf, &buf);
		if (await_reply(await_rpc, sport, &id, timeout)) {
			rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
			if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
			    rpc->u.reply.astatus || rpc->u.reply.data[0]) {
				rpc_printerror(rpc);
				if (rpc->u.reply.rstatus) {
					/* RPC failed, no verifier, data[0] */
					return -9999;
				}
				if (rpc->u.reply.astatus) {
					/* RPC couldn't decode parameters */
					return -9998;
				}
				return -ntohl(rpc->u.reply.data[0]);
			} else {
				// It *is* a link.
				// If it's a relative link, append everything to dirname, filename TOO!
				retries = strlen ( (char *)(&(rpc->u.reply.data[2]) ));
				if ( *((char *)(&(rpc->u.reply.data[2]))) != '/' ) {
					path[pathlen++] = '/';
					while ( ( retries + pathlen ) > 298 ) {
						retries--;
					}
					if ( retries > 0 ) {
						memcpy(path + pathlen, &(rpc->u.reply.data[2]), retries + 1);
					} else { retries = 0; }
					path[pathlen + retries] = 0;
				} else {
					// Else make it the only path.
					if ( retries > 298 ) { retries = 298; }
					memcpy ( path, &(rpc->u.reply.data[2]), retries + 1 );
					path[retries] = 0;
				}
				return 0;
			}
		}
	}
	return -1;
}
/**************************************************************************
NFS_LOOKUP - Lookup Pathname
**************************************************************************/
static int nfs_lookup(int server, int port, char *fh, char *path, char *nfh,
	int sport)
{
	struct rpc_t buf, *rpc;
	unsigned long id;
	long *p;
	int retries;
	int pathlen = strlen(path);

	id = rpc_id++;
	buf.u.call.id = htonl(id);
	buf.u.call.type = htonl(MSG_CALL);
	buf.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
	buf.u.call.prog = htonl(PROG_NFS);
	buf.u.call.vers = htonl(2);	/* nfsd is version 2 */
	buf.u.call.proc = htonl(NFS_LOOKUP);
	p = rpc_add_credentials((long *)buf.u.call.data);
	memcpy(p, fh, NFS_FHSIZE);
	p += (NFS_FHSIZE / 4);
	*p++ = htonl(pathlen);
	if (pathlen & 3) {
		*(p + pathlen / 4) = 0;	/* add zero padding */
	}
	memcpy(p, path, pathlen);
	p += (pathlen + 3) / 4;
	for (retries = 0; retries < MAX_RPC_RETRIES; retries++) {
		long timeout = rfc2131_sleep_interval(TIMEOUT, retries);
		udp_transmit(arptable[server].ipaddr.s_addr, sport, port,
			(char *)p - (char *)&buf, &buf);
		if (await_reply(await_rpc, sport, &id, timeout)) {
			rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
			if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
			    rpc->u.reply.astatus || rpc->u.reply.data[0]) {
				rpc_printerror(rpc);
				if (rpc->u.reply.rstatus) {
					/* RPC failed, no verifier, data[0] */
					return -9999;
				}
				if (rpc->u.reply.astatus) {
					/* RPC couldn't decode parameters */
					return -9998;
				}
				return -ntohl(rpc->u.reply.data[0]);
			} else {
				memcpy(nfh, rpc->u.reply.data + 1, NFS_FHSIZE);
				return 0;
			}
		}
	}
	return -1;
}

/**************************************************************************
NFS_READ - Read File on NFS Server
**************************************************************************/
static int nfs_read(int server, int port, char *fh, int offset, int len,
		    int sport)
{
	struct rpc_t buf, *rpc;
	unsigned long id;
	int retries;
	long *p;

	static int tokens=0;
	/*
	 * Try to implement something similar to a window protocol in
	 * terms of response to losses. On successful receive, increment
	 * the number of tokens by 1 (cap at 256). On failure, halve it.
	 * When the number of tokens is >= 2, use a very short timeout.
	 */

	id = rpc_id++;
	buf.u.call.id = htonl(id);
	buf.u.call.type = htonl(MSG_CALL);
	buf.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
	buf.u.call.prog = htonl(PROG_NFS);
	buf.u.call.vers = htonl(2);	/* nfsd is version 2 */
	buf.u.call.proc = htonl(NFS_READ);
	p = rpc_add_credentials((long *)buf.u.call.data);
	memcpy(p, fh, NFS_FHSIZE);
	p += NFS_FHSIZE / 4;
	*p++ = htonl(offset);
	*p++ = htonl(len);
	*p++ = 0;		/* unused parameter */
	for (retries = 0; retries < MAX_RPC_RETRIES; retries++) {
		long timeout = rfc2131_sleep_interval(TIMEOUT, retries);
		if (tokens >= 2)
			timeout = TICKS_PER_SEC/2;

		udp_transmit(arptable[server].ipaddr.s_addr, sport, port,
			(char *)p - (char *)&buf, &buf);
		if (await_reply(await_rpc, sport, &id, timeout)) {
			if (tokens < 256)
				tokens++;
			rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
			if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
			    rpc->u.reply.astatus || rpc->u.reply.data[0]) {
				rpc_printerror(rpc);
				if (rpc->u.reply.rstatus) {
					/* RPC failed, no verifier, data[0] */
					return -9999;
				}
				if (rpc->u.reply.astatus) {
					/* RPC couldn't decode parameters */
					return -9998;
				}
				return -ntohl(rpc->u.reply.data[0]);
			} else {
				return 0;
			}
		} else
			tokens >>= 1;
	}
	return -1;
}

/**************************************************************************
NFS - Download extended BOOTP data, or kernel image from NFS server
**************************************************************************/
int nfs(const char *name, int (*fnc)(unsigned char *, unsigned int, unsigned int, int))
{
	static int recursion = 0;
	int sport;
	int err, namelen = strlen(name);
	char dirname[300], *fname;
	char dirfh[NFS_FHSIZE];		/* file handle of directory */
	char filefh[NFS_FHSIZE];	/* file handle of kernel image */
	unsigned int block;
	int rlen, size, offs, len;
	struct rpc_t *rpc;

	rx_qdrain();

	sport = oport++;
	if (oport > START_OPORT+OPORT_SWEEP) {
		oport = START_OPORT;
	}
	if ( name != dirname ) {
		memcpy(dirname, name, namelen + 1);
	}
	recursion = 0;
nfssymlink:
	if ( recursion > NFS_MAXLINKDEPTH ) {
		printf ( "\nRecursion: More than %d symlinks followed. Abort.\n", NFS_MAXLINKDEPTH );
		return	0;
	}
	recursion++;
	fname = dirname + (namelen - 1);
	while (fname >= dirname) {
		if (*fname == '/') {
			*fname = '\0';
			fname++;
			break;
		}
		fname--;
	}
	if (fname < dirname) {
		printf("can't parse file name %s\n", name);
		return 0;
	}

	if (mount_port == -1) {
		mount_port = rpc_lookup(ARP_SERVER, PROG_MOUNT, 1, sport);
	}
	if (nfs_port == -1) {
		nfs_port = rpc_lookup(ARP_SERVER, PROG_NFS, 2, sport);
	}
	if (nfs_port == -1 || mount_port == -1) {
		printf("can't get nfs/mount ports from portmapper\n");
		return 0;
	}


	err = nfs_mount(ARP_SERVER, mount_port, dirname, dirfh, sport);
	if (err) {
		printf("mounting %s: ", dirname);
		nfs_printerror(err);
		/* just to be sure... */
		nfs_umountall(ARP_SERVER);
		return 0;
	}

	err = nfs_lookup(ARP_SERVER, nfs_port, dirfh, fname, filefh, sport);
	if (err) {
		printf("looking up %s: ", fname);
		nfs_printerror(err);
		nfs_umountall(ARP_SERVER);
		return 0;
	}

	offs = 0;
	block = 1;	/* blocks are numbered starting from 1 */
	size = -1;	/* will be set properly with the first reply */
	len = NFS_READ_SIZE;	/* first request is always full size */
	do {
		err = nfs_read(ARP_SERVER, nfs_port, filefh, offs, len, sport);
                if ((err <= -NFSERR_ISDIR)&&(err >= -NFSERR_INVAL) && (offs == 0)) {
			// An error occured. NFS servers tend to sending
			// errors 21 / 22 when symlink instead of real file
			// is requested. So check if it's a symlink!
			block = nfs_readlink(ARP_SERVER, nfs_port, dirfh, dirname,
			                filefh, sport);
			if ( 0 == block ) {
				printf("\nLoading symlink:%s ..",dirname);
				goto nfssymlink;
			}
			nfs_printerror(err);
			nfs_umountall(ARP_SERVER);
			return 0;
		}
		if (err) {
			printf("reading at offset %d: ", offs);
			nfs_printerror(err);
			nfs_umountall(ARP_SERVER);
			return 0;
		}

		rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];

		/* size must be found out early to allow EOF detection */
		if (size == -1) {
			size = ntohl(rpc->u.reply.data[6]);
		}
		rlen = ntohl(rpc->u.reply.data[18]);
		if (rlen > len) {
			rlen = len;	/* shouldn't happen...  */
		}

		err = fnc((char *)&rpc->u.reply.data[19], block, rlen,
			(offs+rlen == size));
		if (err <= 0) {
			nfs_umountall(ARP_SERVER);
			return err;
		}

		block++;
		offs += rlen;
		/* last request is done with matching requested read size */
		if (size-offs < NFS_READ_SIZE) {
			len = size-offs;
		}
	} while (len != 0);
	/* len == 0 means that all the file has been read */
	return 1;
}

#endif	/* DOWNLOAD_PROTO_NFS */