5 files changed, 101 insertions, 7 deletions
diff --git a/src/cmd/go/internal/get/discovery.go b/src/cmd/go/internal/get/discovery.go
index b2918dbb4f..97aa1d7e8d 100644
--- a/src/cmd/go/internal/get/discovery.go
+++ b/src/cmd/go/internal/get/discovery.go
@@ -55,6 +55,13 @@ func parseMetaGoImports(r io.Reader) (imports []metaImport, err error) {
 			continue
 		}
 		if f := strings.Fields(attrValue(e.Attr, "content")); len(f) == 3 {
+			// Ignore VCS type "mod", which is new Go modules.
+			// This code is for old go get and must ignore the new mod lines.
+			// Otherwise matchGoImport will complain about two
+			// different metaImport lines for the same Prefix.
+			if f[1] == "mod" {
+				continue
+			}
 			imports = append(imports, metaImport{
 				Prefix:   f[0],
 				VCS:      f[1],
diff --git a/src/cmd/go/internal/get/get.go b/src/cmd/go/internal/get/get.go
index e5dda643e4..6495576ab4 100644
--- a/src/cmd/go/internal/get/get.go
+++ b/src/cmd/go/internal/get/get.go
@@ -210,7 +210,7 @@ var downloadRootCache = map[string]bool{}
 // download runs the download half of the get command
 // for the package named by the argument.
 func download(arg string, parent *load.Package, stk *load.ImportStack, mode int) {
-	if mode&load.UseVendor != 0 {
+	if mode&load.ResolveImport != 0 {
 		// Caller is responsible for expanding vendor paths.
 		panic("internal error: download mode has useVendor set")
 	}
@@ -218,7 +218,7 @@ func download(arg string, parent *load.Package, stk *load.ImportStack, mode int)
 		if parent == nil {
 			return load.LoadPackage(path, stk)
 		}
-		return load.LoadImport(path, parent.Dir, parent, stk, nil, mode)
+		return load.LoadImport(path, parent.Dir, parent, stk, nil, mode|load.ResolveModule)
 	}
 
 	p := load1(arg, mode)
@@ -347,12 +347,12 @@ func download(arg string, parent *load.Package, stk *load.ImportStack, mode int)
 				base.Errorf("%s", err)
 				continue
 			}
-			// If this is a test import, apply vendor lookup now.
-			// We cannot pass useVendor to download, because
+			// If this is a test import, apply module and vendor lookup now.
+			// We cannot pass ResolveImport to download, because
 			// download does caching based on the value of path,
 			// so it must be the fully qualified path already.
 			if i >= len(p.Imports) {
-				path = load.VendoredImportPath(p, path)
+				path = load.ResolveImportPath(p, path)
 			}
 			download(path, p, stk, 0)
 		}
diff --git a/src/cmd/go/internal/get/pkg_test.go b/src/cmd/go/internal/get/pkg_test.go
index b8937a57ec..1179d86693 100644
--- a/src/cmd/go/internal/get/pkg_test.go
+++ b/src/cmd/go/internal/get/pkg_test.go
@@ -48,6 +48,20 @@ var parseMetaGoImportsTests = []struct {
 		},
 	},
 	{
+		`<meta name="go-import" content="foo/bar git https://github.com/rsc/foo/bar">
+		<meta name="go-import" content="foo/bar mod http://github.com/rsc/baz/quux">`,
+		[]metaImport{
+			{"foo/bar", "git", "https://github.com/rsc/foo/bar"},
+		},
+	},
+	{
+		`<meta name="go-import" content="foo/bar mod http://github.com/rsc/baz/quux">
+		<meta name="go-import" content="foo/bar git https://github.com/rsc/foo/bar">`,
+		[]metaImport{
+			{"foo/bar", "git", "https://github.com/rsc/foo/bar"},
+		},
+	},
+	{
 		`<head>
 		<meta name="go-import" content="foo/bar git https://github.com/rsc/foo/bar">
 		</head>`,
diff --git a/src/cmd/go/internal/get/vcs.go b/src/cmd/go/internal/get/vcs.go
index 86d2e32efb..dcc7047211 100644
--- a/src/cmd/go/internal/get/vcs.go
+++ b/src/cmd/go/internal/get/vcs.go
@@ -767,8 +767,8 @@ func repoRootForImportDynamic(importPath string, security web.SecurityMode) (*re
 		}
 	}
 
-	if !strings.Contains(mmi.RepoRoot, "://") {
-		return nil, fmt.Errorf("%s: invalid repo root %q; no scheme", urlStr, mmi.RepoRoot)
+	if err := validateRepoRootScheme(mmi.RepoRoot); err != nil {
+		return nil, fmt.Errorf("%s: invalid repo root %q: %v", urlStr, mmi.RepoRoot, err)
 	}
 	rr := &repoRoot{
 		vcs:      vcsByCmd(mmi.VCS),
@@ -782,6 +782,36 @@ func repoRootForImportDynamic(importPath string, security web.SecurityMode) (*re
 	return rr, nil
 }
 
+// validateRepoRootScheme returns an error if repoRoot does not seem
+// to have a valid URL scheme. At this point we permit things that
+// aren't valid URLs, although later, if not using -insecure, we will
+// restrict repoRoots to be valid URLs. This is only because we've
+// historically permitted them, and people may depend on that.
+func validateRepoRootScheme(repoRoot string) error {
+	end := strings.Index(repoRoot, "://")
+	if end <= 0 {
+		return errors.New("no scheme")
+	}
+
+	// RFC 3986 section 3.1.
+	for i := 0; i < end; i++ {
+		c := repoRoot[i]
+		switch {
+		case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z':
+			// OK.
+		case '0' <= c && c <= '9' || c == '+' || c == '-' || c == '.':
+			// OK except at start.
+			if i == 0 {
+				return errors.New("invalid scheme")
+			}
+		default:
+			return errors.New("invalid scheme")
+		}
+	}
+
+	return nil
+}
+
 var fetchGroup singleflight.Group
 var (
 	fetchCacheMu sync.Mutex
diff --git a/src/cmd/go/internal/get/vcs_test.go b/src/cmd/go/internal/get/vcs_test.go
index 62d352ae57..31fa9ef430 100644
--- a/src/cmd/go/internal/get/vcs_test.go
+++ b/src/cmd/go/internal/get/vcs_test.go
@@ -390,3 +390,46 @@ func TestMatchGoImport(t *testing.T) {
 		}
 	}
 }
+
+func TestValidateRepoRootScheme(t *testing.T) {
+	tests := []struct {
+		root string
+		err  string
+	}{
+		{
+			root: "",
+			err:  "no scheme",
+		},
+		{
+			root: "http://",
+			err:  "",
+		},
+		{
+			root: "a://",
+			err:  "",
+		},
+		{
+			root: "a#://",
+			err:  "invalid scheme",
+		},
+		{
+			root: "-config://",
+			err:  "invalid scheme",
+		},
+	}
+
+	for _, test := range tests {
+		err := validateRepoRootScheme(test.root)
+		if err == nil {
+			if test.err != "" {
+				t.Errorf("validateRepoRootScheme(%q) = nil, want %q", test.root, test.err)
+			}
+		} else if test.err == "" {
+			if err != nil {
+				t.Errorf("validateRepoRootScheme(%q) = %q, want nil", test.root, test.err)
+			}
+		} else if err.Error() != test.err {
+			t.Errorf("validateRepoRootScheme(%q) = %q, want %q", test.root, err, test.err)
+		}
+	}
+}