Fix build breaks on Plan9 and Solaris.

README.md

@@ -40,11 +40,16 @@ Pull requests for other OSs happily considered!
 
 ## Versions
 
+### v1.0.13
+
++ Add tools/check-cross-compile.sh to check that the code compiles for various OSs.
++ Fix compilation errors exposed by tools/check-cross-compile.sh.
+
 ### v1.0.12
 
 + If there are multiple default gateways, Windows now returns the gateway with the lowest metric.
 + Fix solaris build break. (In theory, IDK how to test this easily.)
-+ upgrade to golang 1.21
++ Upgrade to golang 1.21
 + Upgrade golang.org/x/net version, makes dependabot happy. Probably was not any actual security
   issue because gateway doesn't use any of the APIs of golang.org/x/net that had security issues.
 

gateway.go

@@ -13,10 +13,10 @@ type ErrNoGateway struct{}
 // ErrCantParse is returned if the route table is garbage.
 type ErrCantParse struct{}
 
-// ErrNotImpemented is returned if your operating system
+// ErrNotImplemented is returned if your operating system
 // is not supported by this package. Please raise an issue
 // to request support.
-type ErrNotImpemented struct{}
+type ErrNotImplemented struct{}
 
 // ErrInvalidRouteFileFormat is returned if the format
 // of /proc/net/route is unexpected on Linux systems.
@@ -33,7 +33,7 @@ func (*ErrCantParse) Error() string {
 	return "can't parse route table"
 }
 
-func (*ErrNotImpemented) Error() string {
+func (*ErrNotImplemented) Error() string {
 	return "not implemented for OS: " + runtime.GOOS
 }
 

gatewayForBSDs.go

@@ -1,4 +1,4 @@
-//go:build darwin || dragonfly || freebsd || netbsd || openbsd || solaris
+//go:build darwin || dragonfly || freebsd || netbsd || openbsd
 
 package gateway
 

gateway_solaris.go

@@ -5,10 +5,16 @@ package gateway
 
 import (
 	"net"
+	"os/exec"
 )
 
+func readNetstat() ([]byte, error) {
+	routeCmd := exec.Command("netstat", "-rn")
+	return routeCmd.CombinedOutput()
+}
+
 func discoverGatewayOSSpecific() (ip net.IP, err error) {
-	bytes, err = readNetstat()
+	bytes, err := readNetstat()
 	if err != nil {
 		return nil, err
 	}
@@ -17,7 +23,7 @@ func discoverGatewayOSSpecific() (ip net.IP, err error) {
 }
 
 func discoverGatewayInterfaceOSSpecific() (ip net.IP, err error) {
-	bytes, err = readNetstat()
+	bytes, err := readNetstat()
 	if err != nil {
 		return nil, err
 	}

gateway_unimplemented.go

@@ -8,9 +8,9 @@ import (
 )
 
 func discoverGatewayOSSpecific() (ip net.IP, err error) {
-	return ip, errNotImplemented
+	return ip, &ErrNotImplemented{}
 }
 
 func discoverGatewayInterfaceOSSpecific() (ip net.IP, err error) {
-	return nil, errNotImplemented
+	return nil, &ErrNotImplemented{}
 }

tools/check-cross-compile.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+
+TOP_DIR=${SCRIPT_DIR}/..
+
+cd ${TOP_DIR}
+
+# Check that tests pass on local os / architecture.
+
+go test ./...
+
+# Check that the library builds on all supported OSs.
+#
+# Note that "plan9" is in this list to test gateway_unimplemented.go
+for os in "darwin" "dragonfly" "freebsd" "netbsd" "openbsd" "plan9" "solaris" "windows"
+do
+    GOOS=${os} GOARCH=amd64 go build
+done