net: nfs: fix file handle length in NFSv3

The NFS protocol uses file handles to refer to file or directory.
In NFSv2 file handles have a fixed size of 32 bytes.
In NFSv3 file handles have a variable length up to 64 bytes. This is
also true for the MOUNT protocol. [1]
When the NFSv3 server replies with a file handle length > 32 bytes, U-Boot
only copies 32 bytes of that file handle and the next LOOKUP Call fails:

BIOS> nfs ${loadaddr} 192.168.1.51:/nfsroot/opos93dev-br/boot/Image
Using ethernet@428a0000 device
File transfer via NFS from server 192.168.1.51; our IP address is 192.168.1.133
Filename '/nfsroot/opos93dev-br/boot/Image'.
Load address: 0x80400000
Loading: *** ERROR: File lookup fail

done
BIOS>

Looking at this transfer in Wireshark, we can see that the server
replies with the following file handle:

    length: 36
    [hash (CRC-32): 0x230ac67b]
    FileHandle: 0100070101005e000000000091763911f87c449fa73c298552db19ba0c9f60002980cfd2

and U-Boot sends the following file handle in the next LOOKUP Call:

    length: 32
    [hash (CRC-32): 0x6314131b]
    FileHandle: 000000240100070101005e000000000091763911f87c449fa73c298552db19ba

Fix this by using a variable length file handle for dirfh.

[1] https://www.rfc-editor.org/rfc/rfc1813.html#page-106

Fixes: b0baca9 ("net: NFS: Add NFSv3 support")
Signed-off-by: Sébastien Szymanski <[email protected]>
Tested-by: Andrew Davis <[email protected]>

net/nfs.c

@@ -57,7 +57,8 @@ static int nfs_offset = -1;
 static int nfs_len;
 static const ulong nfs_timeout = CONFIG_NFS_TIMEOUT;
 
-static char dirfh[NFS_FHSIZE];	/* NFSv2 / NFSv3 file handle of directory */
+static char dirfh[NFS3_FHSIZE]; /* NFSv2 / NFSv3 file handle of directory */
+static unsigned int dirfh3_length; /* (variable) length of dirfh when NFSv3 */
 static char filefh[NFS3_FHSIZE]; /* NFSv2 / NFSv3 file handle */
 static unsigned int filefh3_length;	/* (variable) length of filefh when NFSv3 */
 
@@ -377,9 +378,9 @@ static void nfs_lookup_req(char *fname)
 
 		rpc_req(PROG_NFS, NFS_LOOKUP, data, len);
 	} else {  /* NFS_V3 */
-		*p++ = htonl(NFS_FHSIZE);	/* Dir handle length */
-		memcpy(p, dirfh, NFS_FHSIZE);
-		p += (NFS_FHSIZE / 4);
+		*p++ = htonl(dirfh3_length);	/* Dir handle length */
+		memcpy(p, dirfh, dirfh3_length);
+		p += (dirfh3_length / 4);
 		*p++ = htonl(fnamelen);
 		if (fnamelen & 3)
 			*(p + fnamelen / 4) = 0;
@@ -565,7 +566,14 @@ static int nfs_mount_reply(uchar *pkt, unsigned len)
 
 	fs_mounted = 1;
 	/*  NFSv2 and NFSv3 use same structure */
-	memcpy(dirfh, rpc_pkt.u.reply.data + 1, NFS_FHSIZE);
+	if (choosen_nfs_version != NFS_V3) {
+		memcpy(dirfh, rpc_pkt.u.reply.data + 1, NFS_FHSIZE);
+	} else {
+		dirfh3_length = ntohl(rpc_pkt.u.reply.data[1]);
+		if (dirfh3_length > NFS3_FHSIZE)
+			dirfh3_length  = NFS3_FHSIZE;
+		memcpy(dirfh, rpc_pkt.u.reply.data + 2, dirfh3_length);
+	}
 
 	return 0;
 }