net/http: use ASCII space trimming throughout

Security hardening against HTTP request smuggling. Thank you to ZeddYu
for reporting this issue.

Change-Id: I98bd9f8ffe58360fc3bca9dc5d9a106773e55373
Reviewed-on: https://go-review.googlesource.com/c/go/+/231419
Reviewed-by: Katie Hockman <katie@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/cgi/host.go

@@ -21,6 +21,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/textproto"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -276,8 +277,8 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 			continue
 		}
 		header, val := parts[0], parts[1]
-		header = strings.TrimSpace(header)
-		val = strings.TrimSpace(val)
+		header = textproto.TrimString(header)
+		val = textproto.TrimString(val)
 		switch {
 		case header == "Status":
 			if len(val) < 3 {

src/net/http/cookie.go

@@ -7,6 +7,7 @@ package http
 import (
 	"log"
 	"net"
+	"net/textproto"
 	"strconv"
 	"strings"
 	"time"
@@ -60,11 +61,11 @@ func readSetCookies(h Header) []*Cookie {
 	}
 	cookies := make([]*Cookie, 0, cookieCount)
 	for _, line := range h["Set-Cookie"] {
-		parts := strings.Split(strings.TrimSpace(line), ";")
+		parts := strings.Split(textproto.TrimString(line), ";")
 		if len(parts) == 1 && parts[0] == "" {
 			continue
 		}
-		parts[0] = strings.TrimSpace(parts[0])
+		parts[0] = textproto.TrimString(parts[0])
 		j := strings.Index(parts[0], "=")
 		if j < 0 {
 			continue
@@ -83,7 +84,7 @@ func readSetCookies(h Header) []*Cookie {
 			Raw:   line,
 		}
 		for i := 1; i < len(parts); i++ {
-			parts[i] = strings.TrimSpace(parts[i])
+			parts[i] = textproto.TrimString(parts[i])
 			if len(parts[i]) == 0 {
 				continue
 			}
@@ -242,7 +243,7 @@ func readCookies(h Header, filter string) []*Cookie {
 
 	cookies := make([]*Cookie, 0, len(lines)+strings.Count(lines[0], ";"))
 	for _, line := range lines {
-		line = strings.TrimSpace(line)
+		line = textproto.TrimString(line)
 
 		var part string
 		for len(line) > 0 { // continue since we have rest
@@ -251,7 +252,7 @@ func readCookies(h Header, filter string) []*Cookie {
 			} else {
 				part, line = line, ""
 			}
-			part = strings.TrimSpace(part)
+			part = textproto.TrimString(part)
 			if len(part) == 0 {
 				continue
 			}

src/net/http/fs.go

@@ -756,7 +756,7 @@ func parseRange(s string, size int64) ([]httpRange, error) {
 	var ranges []httpRange
 	noOverlap := false
 	for _, ra := range strings.Split(s[len(b):], ",") {
-		ra = strings.TrimSpace(ra)
+		ra = textproto.TrimString(ra)
 		if ra == "" {
 			continue
 		}
@@ -764,7 +764,7 @@ func parseRange(s string, size int64) ([]httpRange, error) {
 		if i < 0 {
 			return nil, errors.New("invalid range")
 		}
-		start, end := strings.TrimSpace(ra[:i]), strings.TrimSpace(ra[i+1:])
+		start, end := textproto.TrimString(ra[:i]), textproto.TrimString(ra[i+1:])
 		var r httpRange
 		if start == "" {
 			// If no start is specified, end specifies the

src/net/http/httptest/recorder.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"net/textproto"
 	"strconv"
 	"strings"
 
@@ -221,7 +222,7 @@ func (rw *ResponseRecorder) Result() *http.Response {
 // This a modified version of same function found in net/http/transfer.go. This
 // one just ignores an invalid header.
 func parseContentLength(cl string) int64 {
-	cl = strings.TrimSpace(cl)
+	cl = textproto.TrimString(cl)
 	if cl == "" {
 		return -1
 	}

src/net/http/httputil/reverseproxy.go

@@ -13,6 +13,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/textproto"
 	"net/url"
 	"strings"
 	"sync"
@@ -387,7 +388,7 @@ func shouldPanicOnCopyError(req *http.Request) bool {
 func removeConnectionHeaders(h http.Header) {
 	for _, f := range h["Connection"] {
 		for _, sf := range strings.Split(f, ",") {
-			if sf = strings.TrimSpace(sf); sf != "" {
+			if sf = textproto.TrimString(sf); sf != "" {
 				h.Del(sf)
 			}
 		}

src/net/http/transfer.go

@@ -660,9 +660,9 @@ func fixLength(isResponse bool, status int, requestMethod string, header Header,
 		// Content-Length headers if they differ in value.
 		// If there are dups of the value, remove the dups.
 		// See Issue 16490.
-		first := strings.TrimSpace(contentLens[0])
+		first := textproto.TrimString(contentLens[0])
 		for _, ct := range contentLens[1:] {
-			if first != strings.TrimSpace(ct) {
+			if first != textproto.TrimString(ct) {
 				return 0, fmt.Errorf("http: message cannot contain multiple Content-Length headers; got %q", contentLens)
 			}
 		}
@@ -701,7 +701,7 @@ func fixLength(isResponse bool, status int, requestMethod string, header Header,
 	// Logic based on Content-Length
 	var cl string
 	if len(contentLens) == 1 {
-		cl = strings.TrimSpace(contentLens[0])
+		cl = textproto.TrimString(contentLens[0])
 	}
 	if cl != "" {
 		n, err := parseContentLength(cl)
@@ -1032,7 +1032,7 @@ func (bl bodyLocked) Read(p []byte) (n int, err error) {
 // parseContentLength trims whitespace from s and returns -1 if no value
 // is set, or the value if it's >= 0.
 func parseContentLength(cl string) (int64, error) {
-	cl = strings.TrimSpace(cl)
+	cl = textproto.TrimString(cl)
 	if cl == "" {
 		return -1, nil
 	}