net: prefer /etc/hosts over DNS when no /etc/nsswitch.conf is present
Do not mimic glibc behavior if /etc/nsswitch.conf is missing. This will
will likely be missing on musl libc systems and glibc systems will likely
always have it, resulting in localhost lookup being done over DNS rather
than from /etc/hosts.
Do what makes most sense rather than making any assumption about the
libc.
Fixes #35305
Change-Id: I20bd7e24131bba8eaa39a20c8950fe552364784d
GitHub-Last-Rev: 119409839d37c8c7268f5f6db19c1789d9d96074
GitHub-Pull-Request: golang/go#39685
Reviewed-on: https://go-review.googlesource.com/c/go/+/238629
Run-TryBot: Dan Peterson <dpiddy@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Peterson <dpiddy@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
diff --git a/src/net/conf.go b/src/net/conf.go
index 5340847..f1bbfed 100644
--- a/src/net/conf.go
+++ b/src/net/conf.go
@@ -202,11 +202,6 @@
// illumos defaults to "nis [NOTFOUND=return] files"
return fallbackOrder
}
- if c.goos == "linux" {
- // glibc says the default is "dns [!UNAVAIL=return] files"
- // https://www.gnu.org/software/libc/manual/html_node/Notes-on-NSS-Configuration-File.html.
- return hostLookupDNSFiles
- }
return hostLookupFilesDNS
}
if nss.err != nil {
diff --git a/src/net/conf_test.go b/src/net/conf_test.go
index 4c21d56..1fe3cf4 100644
--- a/src/net/conf_test.go
+++ b/src/net/conf_test.go
@@ -170,8 +170,6 @@
},
hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupDNSFiles}},
},
- // glibc lacking an nsswitch.conf, per
- // https://www.gnu.org/software/libc/manual/html_node/Notes-on-NSS-Configuration-File.html
{
name: "linux_no_nsswitch.conf",
c: &conf{
@@ -179,7 +177,16 @@
nss: &nssConf{err: fs.ErrNotExist},
resolv: defaultResolvConf,
},
- hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupDNSFiles}},
+ hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupFilesDNS}},
+ },
+ {
+ name: "linux_empty_nsswitch.conf",
+ c: &conf{
+ goos: "linux",
+ nss: nssStr(""),
+ resolv: defaultResolvConf,
+ },
+ hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupFilesDNS}},
},
{
name: "files_mdns_dns",
