cmd/go/internal/get: add GOINSECURE support

Adds support for the GOINSECURE environment variable to GOPATH mode.

Updates #37519.

Change-Id: Ibe3f52b7f30b1395edb000998905ee93abe6cada
GitHub-Last-Rev: e298c0009eb5eba537bb00185a8778d2aab696ba
GitHub-Pull-Request: golang/go#38628
Reviewed-on: https://go-review.googlesource.com/c/go/+/229758
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

3 files changed, 42 insertions, 8 deletions

diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index 98861c8a0d..8ad4f66d09 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -2172,7 +2172,10 @@
 // before resolving dependencies or building the code.
 //
 // The -insecure flag permits fetching from repositories and resolving
-// custom domains using insecure schemes such as HTTP. Use with caution.
+// custom domains using insecure schemes such as HTTP. Use with caution. The
+// GOINSECURE environment variable is usually a better alternative, since it
+// provides control over which modules may be retrieved using an insecure scheme.
+// See 'go help environment' for details.
 //
 // The -t flag instructs get to also download the packages required to build
 // the tests for the specified packages.
diff --git a/src/cmd/go/internal/get/get.go b/src/cmd/go/internal/get/get.go
index d1f032a167..d0be3fe1e7 100644
--- a/src/cmd/go/internal/get/get.go
+++ b/src/cmd/go/internal/get/get.go
@@ -43,7 +43,10 @@ The -fix flag instructs get to run the fix tool on the downloaded packages
 before resolving dependencies or building the code.
 
 The -insecure flag permits fetching from repositories and resolving
-custom domains using insecure schemes such as HTTP. Use with caution.
+custom domains using insecure schemes such as HTTP. Use with caution. The
+GOINSECURE environment variable is usually a better alternative, since it
+provides control over which modules may be retrieved using an insecure scheme.
+See 'go help environment' for details.
 
 The -t flag instructs get to also download the packages required to build
 the tests for the specified packages.
@@ -411,11 +414,6 @@ func downloadPackage(p *load.Package) error {
 		blindRepo      bool // set if the repo has unusual configuration
 	)
 
-	security := web.SecureOnly
-	if Insecure {
-		security = web.Insecure
-	}
-
 	// p can be either a real package, or a pseudo-package whose “import path” is
 	// actually a wildcard pattern.
 	// Trim the path at the element containing the first wildcard,
@@ -432,6 +430,10 @@ func downloadPackage(p *load.Package) error {
 	if err := module.CheckImportPath(importPrefix); err != nil {
 		return fmt.Errorf("%s: invalid import path: %v", p.ImportPath, err)
 	}
+	security := web.SecureOnly
+	if Insecure || module.MatchPrefixPatterns(cfg.GOINSECURE, importPrefix) {
+		security = web.Insecure
+	}
 
 	if p.Internal.Build.SrcRoot != "" {
 		// Directory exists. Look for checkout along path to src.
@@ -475,7 +477,7 @@ func downloadPackage(p *load.Package) error {
 		}
 		vcs, repo, rootPath = rr.vcs, rr.Repo, rr.Root
 	}
-	if !blindRepo && !vcs.isSecure(repo) && !Insecure {
+	if !blindRepo && !vcs.isSecure(repo) && security != web.Insecure {
 		return fmt.Errorf("cannot download, %v uses insecure protocol", repo)
 	}
 
diff --git a/src/cmd/go/testdata/script/get_insecure_env.txt b/src/cmd/go/testdata/script/get_insecure_env.txt
new file mode 100644
index 0000000000..8d88427c31
--- /dev/null
+++ b/src/cmd/go/testdata/script/get_insecure_env.txt
@@ -0,0 +1,29 @@
+[!net] skip
+[!exec:git] skip
+
+# GOPATH: Set up
+env GO111MODULE=off
+
+# GOPATH: Try go get -d of HTTP-only repo (should fail).
+! go get -d insecure.go-get-issue-15410.appspot.com/pkg/p
+
+# GOPATH: Try again with invalid GOINSECURE (should fail).
+env GOINSECURE=insecure.go-get-issue-15410.appspot.com/pkg/q
+! go get -d insecure.go-get-issue-15410.appspot.com/pkg/p
+
+# GOPATH: Try with correct GOINSECURE (should succeed).
+env GOINSECURE=insecure.go-get-issue-15410.appspot.com/pkg/p
+go get -d insecure.go-get-issue-15410.appspot.com/pkg/p
+
+# GOPATH: Try updating without GOINSECURE (should fail).
+env GOINSECURE=
+! go get -d -u -f insecure.go-get-issue-15410.appspot.com/pkg/p
+
+# GOPATH: Try updating with GOINSECURE glob (should succeed).
+env GOINSECURE=*.go-get-*.appspot.com
+go get -d -u -f insecure.go-get-issue-15410.appspot.com/pkg/p
+
+# GOPATH: Try updating with GOINSECURE base URL (should succeed).
+env GOINSECURE=insecure.go-get-issue-15410.appspot.com
+go get -d -u -f insecure.go-get-issue-15410.appspot.com/pkg/p
+