client: add GetHostUser for u@host and .ssh/config

Since 2017 cpu used $USER as the user. Now that it supports
ssh, it needs better processing.

Add GetHostUser, which takes a string in [user@]host form,
and returns a host and user name as follows:
if user@host form, return the host and user.

Look up the host in .ssh/config; if found, and
there is a UserName record, return that UserName

Otherwise return host and $USER.

If a host entry is found in .ssh/config, the
HostName from that entry is used.

This means that code that used GetHost should start using
GetHostUser.

Signed-off-by: Ron Minnich <[email protected]>

client/fns.go

@@ -200,6 +200,30 @@ func GetHostName(host string) string {
 	return host
 }
 
+// GetHostUser gets the user and host name. In ssh syntax, these can
+// be in one string, or defined in .ssh/config, or (for user), as
+// $USER. Given that just about anything can be valid, and errors
+// will be caught in other places, it does not return an error.
+// Also, experimentally, in the name@host form, name overrides
+// any use name that might be in .ssh/config. Host, on the other hand,
+// is always determined from .ssh/config. The host name
+// is also pulled from .ssh/config; calls to GetHostName
+// can be replaced as needed, but that's for the future.
+func GetHostUser(n string) (host, user string) {
+	if u, h, ok := strings.Cut(n, "@"); ok {
+		host, user = GetHostName(h), u
+		return
+	}
+	// Perhaps a user name is found in .ssh/config
+	if cp := config.Get(n, "User"); len(cp) != 0 {
+		host, user = GetHostName(n), cp
+		return
+	}
+	// Last try: the environment.
+	host, user = GetHostName(n), os.Getenv("USER")
+	return
+}
+
 // GetPort gets a port. It verifies that the port fits in 16-bit space.
 // The rules here are messy, since config.Get will return "22" if
 // there is no entry in .ssh/config. 22 is not allowed. So in the case

client/fns_test.go

@@ -6,6 +6,7 @@ package client
 
 import (
 	"errors"
+	"os"
 	"path"
 	"strconv"
 	"strings"
@@ -124,3 +125,26 @@ func TestUserKeyConfigWithDisablePrivateKey(t *testing.T) {
 		t.Fatalf("cmd.config.Auth: got %v, want []", cmd.config.Auth)
 	}
 }
+
+// test getting a user and host.
+// In a better world, the sshconfig package would let us test our own
+// ssh config, but that package hardwires the path and provides no way to change it.
+func TestUserHost(t *testing.T) {
+	type test struct {
+		name string
+		hn   string
+		host string
+		user string
+	}
+	var tests = []test{
+		{name: "a@b", hn: "a@b", host: "b", user: "a"},
+	}
+	if user, ok := os.LookupEnv("USER"); ok {
+		tests = append(tests, test{name: "host with $USER", hn: "a", host: "a", user: user})
+	}
+	for _, tt := range tests {
+		if h, u := GetHostUser(tt.hn); h != tt.host || u != tt.user {
+			t.Errorf("%s:GetHostUser(%q): (%q,%q) != (%q,%q)", tt.name, tt.hn, h, u, tt.host, tt.user)
+		}
+	}
+}

go.mod

@@ -35,7 +35,6 @@ require (
 	github.com/miekg/dns v1.1.55 // indirect
 	github.com/pierrec/lz4/v4 v4.1.18 // indirect
 	github.com/rasky/go-xdr v0.0.0-20170124162913-1a41d1a06c93 // indirect
-	github.com/stretchr/testify v1.9.0 // indirect
 	github.com/tklauser/go-sysconf v0.3.11 // indirect
 	github.com/tklauser/numcpus v0.6.1 // indirect
 	github.com/u-root/uio v0.0.0-20230305220412-3e8cd9d6bf63 // indirect

go.sum

@@ -4,25 +4,19 @@ github.com/brutella/dnssd v1.2.9 h1:eUqO0qXZAMaFN4W4Ms1AAO/OtAbNoh9U87GAlN+1FCs=
 github.com/brutella/dnssd v1.2.9/go.mod h1:yZ+GHHbGhtp5yJeKTnppdFGiy6OhiPoxs0WHW1KUcFA=
 github.com/creack/pty v1.1.18 h1:n56/Zwd5o6whRC5PMGretI4IdRLlmBXYNjScPaBgsbY=
 github.com/creack/pty v1.1.18/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
-github.com/cyphar/filepath-securejoin v0.2.4 h1:Ugdm7cg7i6ZK6x3xDF1oEu1nfkyfH53EtKeQYTC3kyg=
-github.com/cyphar/filepath-securejoin v0.2.4/go.mod h1:aPGpWjXOXUn2NCNjFvBE6aRxGGx79pTxQpKOJNYHHl4=
 github.com/cyphar/filepath-securejoin v0.2.5 h1:6iR5tXJ/e6tJZzzdMc1km3Sa7RRIVBKAK32O2s7AYfo=
 github.com/cyphar/filepath-securejoin v0.2.5/go.mod h1:aPGpWjXOXUn2NCNjFvBE6aRxGGx79pTxQpKOJNYHHl4=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/gliderlabs/ssh v0.3.5 h1:OcaySEmAQJgyYcArR+gGGTHCyE7nvhEMTlYY+Dp8CpY=
 github.com/gliderlabs/ssh v0.3.5/go.mod h1:8XB4KraRrX39qHhT6yxPsHedjA08I/uBVwj4xC+/+z4=
-github.com/go-git/go-billy/v5 v5.5.0 h1:yEY4yhzCDuMGSv83oGxiBotRzhwhNr8VZyphhiu+mTU=
-github.com/go-git/go-billy/v5 v5.5.0/go.mod h1:hmexnoNsr2SJU1Ju67OaNz5ASJY3+sHgFRpCtpDCKow=
 github.com/go-git/go-billy/v5 v5.5.1-0.20240514075308-8f1b719cb6a2 h1:vWpyklHBOaIWDj1n3s/6M7rfLFDBXXbT1jrNOtBVo7Y=
 github.com/go-git/go-billy/v5 v5.5.1-0.20240514075308-8f1b719cb6a2/go.mod h1:7u9KSvLbAYN7/p0U+SsuzbbMuqCAk7MYkPI8l2+71s4=
 github.com/go-ole/go-ole v1.2.6 h1:/Fpf6oFPoeFik9ty7siob0G6Ke8QvQEuVcuChpwXzpY=
 github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
 github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
-github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/goexpect v0.0.0-20191001010744-5b6988669ffa h1:PMkmJA8ju9DjqAJjIzrBdrmhuuPsoNnNLYgKQBopWL0=
 github.com/google/goterm v0.0.0-20200907032337-555d40f16ae2 h1:CVuJwN34x4xM2aT4sIKhmeib40NeBPhRihNjQmpJsA4=
 github.com/google/uuid v1.5.0 h1:1p67kYwdtXjb0gL0BPiP1Av9wiZPo5A8z2cWkTZ+eyU=
@@ -49,25 +43,17 @@ github.com/mdlayher/vsock v1.2.1 h1:pC1mTJTvjo1r9n9fbm7S1j04rCgCzhCOS5DY0zqHlnQ=
 github.com/mdlayher/vsock v1.2.1/go.mod h1:NRfCibel++DgeMD8z/hP+PPTjlNJsdPOmxcnENvE+SE=
 github.com/miekg/dns v1.1.55 h1:GoQ4hpsj0nFLYe+bWiCToyrBEJXkQfOOIvFGFy0lEgo=
 github.com/miekg/dns v1.1.55/go.mod h1:uInx36IzPl7FYnDcMeVWxj9byh7DutNykX4G9Sj60FY=
-github.com/onsi/gomega v1.27.10 h1:naR28SdDFlqrG6kScpT8VWpu1xWY5nJRCF3XaYyBjhI=
 github.com/onsi/gomega v1.33.1 h1:dsYjIxxSR755MDmKVsaFQTE22ChNBcuuTWgkUDSubOk=
 github.com/pierrec/lz4/v4 v4.1.14/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
 github.com/pierrec/lz4/v4 v4.1.18 h1:xaKrnTkyoqfh1YItXl56+6KJNVYWlEEPuAQW9xsplYQ=
 github.com/pierrec/lz4/v4 v4.1.18/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rasky/go-xdr v0.0.0-20170124162913-1a41d1a06c93 h1:UVArwN/wkKjMVhh2EQGC0tEc1+FqiLlvYXY5mQ2f8Wg=
 github.com/rasky/go-xdr v0.0.0-20170124162913-1a41d1a06c93/go.mod h1:Nfe4efndBz4TibWycNE+lqyJZiMX4ycx+QKV8Ta0f/o=
 github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M=
 github.com/shirou/gopsutil v3.21.11+incompatible h1:+1+c1VGhc88SSonWP6foOcLhvnKlUeu/erjjvaPEYiI=
 github.com/shirou/gopsutil v3.21.11+incompatible/go.mod h1:5b4v6he4MtMOwMlS0TUMTu2PcXUg8+E1lC7eC3UO/RA=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
-github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
-github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/tklauser/go-sysconf v0.3.11 h1:89WgdJhk5SNwJfu+GKyYveZ4IaJ7xAkecBo+KdJV0CM=
 github.com/tklauser/go-sysconf v0.3.11/go.mod h1:GqXfhXY3kiPa0nAXPDIQIWzJbMCB7AmcWpGR8lSZfqI=
 github.com/tklauser/numcpus v0.6.0/go.mod h1:FEZLMke0lhOUG6w2JadTzp0a+Nl8PF/GFkQ5UVIcaL4=
@@ -92,8 +78,6 @@ github.com/willscott/go-nfs-client v0.0.0-20240104095149-b44639837b00/go.mod h1:
 github.com/yusufpapurcu/wmi v1.2.3 h1:E1ctvB7uKFMOJw3fdOW32DwGE9I7t++CRUEMKvFoFiw=
 github.com/yusufpapurcu/wmi v1.2.3/go.mod h1:SBZ9tNy3G9/m5Oi98Zks0QjeHVDvuK0qfxQmPyzfmi0=
 golang.org/x/crypto v0.0.0-20220826181053-bd7e27e6170d/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
-golang.org/x/crypto v0.21.0 h1:X31++rzVUdKhX5sWmSOFZxx8UW/ldWx55cbf08iNAMA=
-golang.org/x/crypto v0.21.0/go.mod h1:0BP7YvVV9gBbVKyeTG0Gyn+gZm94bibOW5BjDEYAOMs=
 golang.org/x/crypto v0.22.0 h1:g1v0xeRhjcugydODzvb3mEM9SQ0HGp9s/nh3COQ/C30=
 golang.org/x/crypto v0.22.0/go.mod h1:vr6Su+7cTlO45qkww3VDJlzDn0ctJvRgYbC2NvXHt+M=
 golang.org/x/exp v0.0.0-20230810033253-352e893a4cad h1:g0bG7Z4uG+OgH2QDODnjp6ggkk1bJDsINcuWmJN1iJU=
@@ -102,8 +86,6 @@ golang.org/x/mod v0.12.0 h1:rmsUpXtvNzj340zd98LZ4KntptpfRHwpFOHG188oHXc=
 golang.org/x/mod v0.12.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20220826154423-83b083e8dc8b/go.mod h1:YDH+HFinaLZZlnHAfSS6ZXJJ9M9t4Dl22yv3iI2vPwk=
-golang.org/x/net v0.23.0 h1:7EYJ93RZ9vYSZAIb2x3lnuvqO5zneoD6IvWjuhfxjTs=
-golang.org/x/net v0.23.0/go.mod h1:JKghWKKOSdJwpW2GEx0Ja7fmaKnMsbu+MWVZTokSYmg=
 golang.org/x/net v0.24.0 h1:1PcaxkF854Fu3+lvBIx5SYn9wRlBzzcnHZSiaFFAb0w=
 golang.org/x/net v0.24.0/go.mod h1:2Q7sJY5mzlzWjKtYUEXSlBWCdyaioyXzRB2RtU8KVE8=
 golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
@@ -119,15 +101,11 @@ golang.org/x/sys v0.0.0-20220728004956-3c1f35247d10/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220825204002-c680a09ffe64/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
-golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.0.0-20220722155259-a9ba230a4035/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/term v0.18.0 h1:FcHjZXDMxI8mM3nwhX9HlKop4C0YQvCVCdwYl2wOtE8=
-golang.org/x/term v0.18.0/go.mod h1:ILwASektA3OnRv7amZ1xhE/KTR+u50pbXfZ03+6Nx58=
 golang.org/x/term v0.19.0 h1:+ThwsDv+tYfnJFhF4L8jITxu1tdTWRTZpdsWgEgjL6Q=
 golang.org/x/term v0.19.0/go.mod h1:2CuTdWZ7KHSQwUzKva0cbMg6q2DMI3Mmxp+gKJbskEk=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
@@ -139,8 +117,5 @@ golang.org/x/tools v0.12.0/go.mod h1:Sc0INKfu04TlqNoRA1hgpFZbhYXHPr4V5DzpSBTPqQM
 google.golang.org/grpc v1.56.3 h1:8I4C0Yq1EjstUzUJzpcRVbuYA2mODtEmpWiQoN/b2nc=
 google.golang.org/grpc v1.56.3/go.mod h1:I9bI3vqKfayGqPUAwGdOSu7kt6oIJLixfffKrpXqQ9s=
 google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=