toolman.org/net/peercredlistener

peercredlistener

import "toolman.org/net/peercredlistener"

• Install
• Overview
• Index
• Subdirectories

Install

    go get toolman.org/net/peercredlistener

Overview

Package peercredlistener provides PeerCredListener and supporting functions.

PeerCredListener is a net.Listener implementation leveraging features of Linux based, Unix domain sockets to garner the PID, UID, and GID of the client side connection.

PeerCredListener is intended for use cases where a unix-domain server needs to reliably identify the process on the client side of each connection. By itself, peercredlistener provides support for simple socket connections. Additional support for gRPC over unix-domain sockets is available with the subordinate package toolman.org/net/peercredlistener/pclcreds.

A simple, unix-domain server can be written similar to the following:

// Create a new PeerCredListener listening on socketName
lsnr, err := peercredlistener.New(ctx, socketName)
if err != nil {
    return err
}

// Wait for and accept an incoming connection
conn, err := lsnr.AcceptPeerCred()
if err != nil {
    return err
}

// conn.Ucred has fields Pid, Uid and Gid
fmt.Printf("Client PID=%d UID=%d\n", conn.Ucred.Pid, conn.Ucred.Uid)

NOTE: This package does not work with IP connections or on operating systems other than Linux.

Index

• Constants
• type PeerCredConn
• type PeerCredListener
  • func New(ctx context.Context, addr string) (*PeerCredListener, error)
  • func (pcl *PeerCredListener) Accept() (net.Conn, error)
  • func (pcl *PeerCredListener) AcceptPeerCred() (*PeerCredConn, error)

Package files

listener.go

Constants

const ErrAddrInUse = unix.EADDRINUSE

ErrAddrInUse is a convenience wrapper around the Posix errno value for EADDRINUSE.

type PeerCredConn

type PeerCredConn struct {
    Ucred *unix.Ucred
    net.Conn
}

PeerCredConn is a net.Conn containing the process credentials for the client side of a Unix domain socket connection.

type PeerCredListener

type PeerCredListener struct {
    net.Listener
}

PeerCredListener is an implementation of net.Listener that extracts the identity (i.e. pid, uid, gid) from the connection's client process. This information is then made available through the Ucred member of the *PeerCredConn returned by AcceptPeerCred or Accept (after a type assertion).

func New

func New(ctx context.Context, addr string) (*PeerCredListener, error)

New returns a new PeerCredListener listening on the Unix domain socket addr.

func (*PeerCredListener) Accept

func (pcl *PeerCredListener) Accept() (net.Conn, error)

Accept is a convenience wrapper around AcceptPeerCred allowing PeerCredListener callers that utilize net.Listener to function as expected. The returned net.Conn is a *PeerCredConn which may be accessed through a type assertion. See AcceptPeerCred for details on possible error conditions.

Accept contributes to implementing the net.Listener interface.

func (*PeerCredListener) AcceptPeerCred

func (pcl *PeerCredListener) AcceptPeerCred() (*PeerCredConn, error)

AcceptPeerCred accepts a connection from the receiver's listener returning a *PeerCredConn containing the process credentials for the client. If the underlying Accept fails or if process credentials cannot be extracted, AcceptPeerCred returns nil and an error.