net/http/httputil: DumpRequest dumps Content-Length if set in header

Fixes #7215

Change-Id: I108171ef18cac66d0dc11ce3553c26fc49529807
Reviewed-on: https://go-review.googlesource.com/21790
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/httputil/dump.go

@@ -163,7 +163,6 @@ func valueOrDefault(value, def string) string {
 
 var reqWriteExcludeHeaderDump = map[string]bool{
 	"Host":              true, // not in Header map anyway
-	"Content-Length":    true,
 	"Transfer-Encoding": true,
 	"Trailer":           true,
 }

src/net/http/httputil/dump_test.go

@@ -122,6 +122,10 @@ var dumpTests = []dumpTest{
 				Host:   "post.tld",
 				Path:   "/",
 			},
+			Header: http.Header{
+				"Content-Length": []string{"8193"},
+			},
+
 			ContentLength: 8193,
 			ProtoMajor:    1,
 			ProtoMinor:    1,
@@ -135,6 +139,10 @@ var dumpTests = []dumpTest{
 			"Content-Length: 8193\r\n" +
 			"Accept-Encoding: gzip\r\n\r\n" +
 			strings.Repeat("a", 8193),
+		WantDump: "POST / HTTP/1.1\r\n" +
+			"Host: post.tld\r\n" +
+			"Content-Length: 8193\r\n\r\n" +
+			strings.Repeat("a", 8193),
 	},
 
 	{
@@ -144,6 +152,38 @@ var dumpTests = []dumpTest{
 		WantDump: "GET http://foo.com/ HTTP/1.1\r\n" +
 			"User-Agent: blah\r\n\r\n",
 	},
+
+	// Issue #7215. DumpRequest should return the "Content-Length" when set
+	{
+		Req: *mustReadRequest("POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 3\r\n" +
+			"\r\nkey1=name1&key2=name2"),
+		WantDump: "POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 3\r\n" +
+			"\r\nkey",
+	},
+
+	// Issue #7215. DumpRequest should return the "Content-Length" in ReadRequest
+	{
+		Req: *mustReadRequest("POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 0\r\n" +
+			"\r\nkey1=name1&key2=name2"),
+		WantDump: "POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 0\r\n\r\n",
+	},
+
+	// Issue #7215. DumpRequest should not return the "Content-Length" if unset
+	{
+		Req: *mustReadRequest("POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"\r\nkey1=name1&key2=name2"),
+		WantDump: "POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n\r\n",
+	},
 }
 
 func TestDumpRequest(t *testing.T) {

src/net/http/httputil/example_test.go

@@ -47,7 +47,7 @@ func ExampleDumpRequest() {
 	fmt.Printf("%s", b)
 
 	// Output:
-	// "POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
+	// "POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nContent-Length: 75\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
 }
 
 func ExampleDumpRequestOut() {