NFS v4 server in go

This package entails a server implementation for NFS v4 in pure go. It is heavily based on the works of https://github.com/smallfz/libnfs-go and allows to expose a virtual file system https://github.com/kuleuven/vfs over NFS v4.

Protocols v4.0, v4.1 and v4.2 are supported. RFC 7530, RFC 5661 and RFC 8276 are largely implemented. The current implementation has minimal server state, only a list of active clients is kept. No file locking is supported. The implemented authentication mechanism is AUTH_FLAVOR_UNIX, so that the client sends uid/gid/groups information to the server. It is possible to provide each user a different virtual file system.

The following operations are required by the RFCs but we didn't implement them:

• OP4_BACKCHANNEL_CTL
• OP4_BIND_CONN_TO_SESSION
• OP4_FREE_STATEID
• OP4_ILLEGAL
• OP4_LOCK
• OP4_LOCKT
• OP4_LOCKU
• OP4_SET_SSV
• OP4_TEST_STATEID

The following operations are optional by the RFCs and we didn't implement them:

• OP4_ALLOCATE
• OP4_CLONE
• OP4_COPY
• OP4_COPY_NOTIFY
• OP4_DEALLOCATE
• OP4_DELEGPURGE
• OP4_DELEGRETURN
• OP4_GETDEVICEINFO
• OP4_GET_DIR_DELEGATION
• OP4_IO_ADVISE
• OP4_LAYOUTCOMMIT
• OP4_LAYOUTERROR
• OP4_LAYOUTGET
• OP4_LAYOUTRETURN
• OP4_LAYOUTSTATS
• OP4_OFFLOAD_CANCEL
• OP4_OFFLOAD_STATUS
• OP4_OPENATTR
• OP4_READ_PLUS
• OP4_SEEK
• OP4_WANT_DELEGATION
• OP4_WRITE_SAME

Implementation details

• clock provides a global clock used whenever the current time is needed. It caches time.Now() since it is expensive to call frequently.
• logger provides a global logger that can be adapted for different logging needs.
• xdr handles decoding and encoding of the NFS protocol messages.
• msg contains the definitions of the NFS protocol messages.
• bufpool manages a pool of buffers for efficient memory allocation.
• clients manages the state of all NFS clients. A client can have one or multiple sessions. In case of NFS v4.0, we map a client ip to a single session.
• worker manages the combination of a session and user credentials, and maps it to a single virtual file system and state (open files). If a worker is idle for 5 minutes, it will be discarded and the virtual file system will be closed.

Usage

See cmd/nfs4go/example.go for an example exposing /srv over NFS v4.