cmd/swarm, swarm: cross-platform Content-Type detection (#17782)

- Mime types generator (Standard "mime" package rely on system-settings, see mime.osInitMime)
- Changed swarm/api.Upload:
    - simplify I/O throttling by semaphore primitive and use file name where possible
    - f.Close() must be called in Defer - otherwise panic or future added early return will cause leak of file descriptors
    - one error was suppressed

swarm/api/http/server_test.go

@@ -32,6 +32,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"path"
 	"strconv"
 	"strings"
 	"testing"
@@ -764,6 +765,16 @@ func testBzzTar(encrypted bool, t *testing.T) {
 	}
 	defer resp2.Body.Close()
 
+	if h := resp2.Header.Get("Content-Type"); h != "application/x-tar" {
+		t.Fatalf("Content-Type header expected: application/x-tar, got: %s", h)
+	}
+
+	expectedFileName := string(swarmHash) + ".tar"
+	expectedContentDisposition := fmt.Sprintf("inline; filename=\"%s\"", expectedFileName)
+	if h := resp2.Header.Get("Content-Disposition"); h != expectedContentDisposition {
+		t.Fatalf("Content-Disposition header expected: %s, got: %s", expectedContentDisposition, h)
+	}
+
 	file, err := ioutil.TempFile("", "swarm-downloaded-tarball")
 	if err != nil {
 		t.Fatal(err)
@@ -1099,7 +1110,7 @@ func TestModify(t *testing.T) {
 			res, body := httpDo(testCase.method, testCase.uri, reqBody, testCase.headers, testCase.verbose, t)
 
 			if res.StatusCode != testCase.expectedStatusCode {
-				t.Fatalf("expected status code %d but got %d", testCase.expectedStatusCode, res.StatusCode)
+				t.Fatalf("expected status code %d but got %d, %s", testCase.expectedStatusCode, res.StatusCode, body)
 			}
 			if testCase.assertResponseBody != "" && !strings.Contains(body, testCase.assertResponseBody) {
 				t.Log(body)
@@ -1210,19 +1221,25 @@ func TestBzzGetFileWithResolver(t *testing.T) {
 	hash := common.HexToHash(string(swarmHash))
 	resolver.hash = &hash
 	for _, v := range []struct {
-		addr               string
-		path               string
-		expectedStatusCode int
+		addr                string
+		path                string
+		expectedStatusCode  int
+		expectedContentType string
+		expectedFileName    string
 	}{
 		{
-			addr:               string(swarmHash),
-			path:               fileNames[0],
-			expectedStatusCode: http.StatusOK,
+			addr:                string(swarmHash),
+			path:                fileNames[0],
+			expectedStatusCode:  http.StatusOK,
+			expectedContentType: "text/plain",
+			expectedFileName:    path.Base(fileNames[0]),
 		},
 		{
-			addr:               "somebogusensname",
-			path:               fileNames[0],
-			expectedStatusCode: http.StatusOK,
+			addr:                "somebogusensname",
+			path:                fileNames[0],
+			expectedStatusCode:  http.StatusOK,
+			expectedContentType: "text/plain",
+			expectedFileName:    path.Base(fileNames[0]),
 		},
 	} {
 		req, err := http.NewRequest("GET", fmt.Sprintf(srv.URL+"/bzz:/%s/%s", v.addr, v.path), nil)
@@ -1237,6 +1254,16 @@ func TestBzzGetFileWithResolver(t *testing.T) {
 		if serverResponse.StatusCode != v.expectedStatusCode {
 			t.Fatalf("expected %d, got %d", v.expectedStatusCode, serverResponse.StatusCode)
 		}
+
+		if h := serverResponse.Header.Get("Content-Type"); h != v.expectedContentType {
+			t.Fatalf("Content-Type header expected: %s, got %s", v.expectedContentType, h)
+		}
+
+		expectedContentDisposition := fmt.Sprintf("inline; filename=\"%s\"", v.expectedFileName)
+		if h := serverResponse.Header.Get("Content-Disposition"); h != expectedContentDisposition {
+			t.Fatalf("Content-Disposition header expected: %s, got: %s", expectedContentDisposition, h)
+		}
+
 	}
 }