Upgrade net package from Go 1.21.4 to Go 1.26.2

Backport upstream Go standard library changes to TinyGo's net package.

Unmodified files (18) replaced directly from Go 1.26.2 source.
Modified files (22) merged via 3-way diff, preserving all TinyGo
netdev adaptations, TINYGO markers, and embedded-device constraints.

Notable upstream changes included:
- net/http: cookie handling improvements, fs enhancements,
  reverse proxy updates, chunked encoding fixes
- net/http: ServeMux routing and pattern matching updates
- net: IP parsing and MAC address handling improvements
- Various doc link syntax modernization (e.g. [Dial], [Buffers])

TinyGo-only files (netdev.go, tlssock.go) unchanged.
All TINYGO comment markers preserved.

http/client.go

@@ -1,4 +1,4 @@
-// TINYGO: The following is copied and modified from Go 1.21.4 official implementation.
+// TINYGO: The following is copied and modified from Go 1.26.2 official implementation.
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -27,34 +27,33 @@ import (
 	"golang.org/x/net/http/httpguts"
 )
 
-// A Client is an HTTP client. Its zero value (DefaultClient) is a
-// usable client that uses DefaultTransport.
+// A Client is an HTTP client. Its zero value ([DefaultClient]) is a
+// usable client that uses [DefaultTransport].
 //
-// The Client's Transport typically has internal state (cached TCP
+// The [Client.Transport] typically has internal state (cached TCP
 // connections), so Clients should be reused instead of created as
 // needed. Clients are safe for concurrent use by multiple goroutines.
 //
-// A Client is higher-level than a RoundTripper (such as Transport)
+// A Client is higher-level than a [RoundTripper] (such as [Transport])
 // and additionally handles HTTP details such as cookies and
 // redirects.
 //
 // When following redirects, the Client will forward all headers set on the
-// initial Request except:
+// initial [Request] except:
 //
-// • when forwarding sensitive headers like "Authorization",
-// "WWW-Authenticate", and "Cookie" to untrusted targets.
-// These headers will be ignored when following a redirect to a domain
-// that is not a subdomain match or exact match of the initial domain.
-// For example, a redirect from "foo.com" to either "foo.com" or "sub.foo.com"
-// will forward the sensitive headers, but a redirect to "bar.com" will not.
-//
-// • when forwarding the "Cookie" header with a non-nil cookie Jar.
-// Since each redirect may mutate the state of the cookie jar,
-// a redirect may possibly alter a cookie set in the initial request.
-// When forwarding the "Cookie" header, any mutated cookies will be omitted,
-// with the expectation that the Jar will insert those mutated cookies
-// with the updated values (assuming the origin matches).
-// If Jar is nil, the initial cookies are forwarded without change.
+//   - when forwarding sensitive headers like "Authorization",
+//     "WWW-Authenticate", and "Cookie" to untrusted targets.
+//     These headers will be ignored when following a redirect to a domain
+//     that is not a subdomain match or exact match of the initial domain.
+//     For example, a redirect from "foo.com" to either "foo.com" or "sub.foo.com"
+//     will forward the sensitive headers, but a redirect to "bar.com" will not.
+//   - when forwarding the "Cookie" header with a non-nil cookie Jar.
+//     Since each redirect may mutate the state of the cookie jar,
+//     a redirect may possibly alter a cookie set in the initial request.
+//     When forwarding the "Cookie" header, any mutated cookies will be omitted,
+//     with the expectation that the Jar will insert those mutated cookies
+//     with the updated values (assuming the origin matches).
+//     If Jar is nil, the initial cookies are forwarded without change.
 type Client struct {
 	// Transport specifies the mechanism by which individual
 	// HTTP requests are made.
@@ -106,11 +105,11 @@ type Client struct {
 	Timeout time.Duration
 }
 
-// DefaultClient is the default Client and is used by Get, Head, and Post.
+// DefaultClient is the default [Client] and is used by [Get], [Head], and [Post].
 var DefaultClient = &Client{}
 
 // RoundTripper is an interface representing the ability to execute a
-// single HTTP transaction, obtaining the Response for a given Request.
+// single HTTP transaction, obtaining the [Response] for a given [Request].
 //
 // A RoundTripper must be safe for concurrent use by multiple
 // goroutines.
@@ -144,8 +143,13 @@ type RoundTripper interface {
 
 // didTimeout is non-nil only if err != nil.
 func (c *Client) send(req *Request, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {
+	cookieURL := req.URL
+	if req.Host != "" {
+		cookieURL = cloneURL(cookieURL)
+		cookieURL.Host = req.Host
+	}
 	if c.Jar != nil {
-		for _, cookie := range c.Jar.Cookies(req.URL) {
+		for _, cookie := range c.Jar.Cookies(cookieURL) {
 			req.AddCookie(cookie)
 		}
 	}
@@ -155,7 +159,7 @@ func (c *Client) send(req *Request, deadline time.Time) (resp *Response, didTime
 	}
 	if c.Jar != nil {
 		if rc := resp.Cookies(); len(rc) > 0 {
-			c.Jar.SetCookies(req.URL, rc)
+			c.Jar.SetCookies(cookieURL, rc)
 		}
 	}
 	return resp, nil, nil
@@ -327,7 +331,7 @@ func basicAuth(username, password string) string {
 //
 // An error is returned if there were too many redirects or if there
 // was an HTTP protocol error. A non-2xx response doesn't cause an
-// error. Any returned error will be of type *url.Error. The url.Error
+// error. Any returned error will be of type [*url.Error]. The url.Error
 // value's Timeout method will report true if the request timed out.
 //
 // When err is nil, resp always contains a non-nil resp.Body.
@@ -335,10 +339,10 @@ func basicAuth(username, password string) string {
 //
 // Get is a wrapper around DefaultClient.Get.
 //
-// To make a request with custom headers, use NewRequest and
+// To make a request with custom headers, use [NewRequest] and
 // DefaultClient.Do.
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
+// To make a request with a specified context.Context, use [NewRequestWithContext]
 // and DefaultClient.Do.
 func Get(url string) (resp *Response, err error) {
 	return DefaultClient.Get(url)
@@ -346,7 +350,7 @@ func Get(url string) (resp *Response, err error) {
 
 // Get issues a GET to the specified URL. If the response is one of the
 // following redirect codes, Get follows the redirect after calling the
-// Client's CheckRedirect function:
+// [Client.CheckRedirect] function:
 //
 //	301 (Moved Permanently)
 //	302 (Found)
@@ -354,18 +358,18 @@ func Get(url string) (resp *Response, err error) {
 //	307 (Temporary Redirect)
 //	308 (Permanent Redirect)
 //
-// An error is returned if the Client's CheckRedirect function fails
+// An error is returned if the [Client.CheckRedirect] function fails
 // or if there was an HTTP protocol error. A non-2xx response doesn't
-// cause an error. Any returned error will be of type *url.Error. The
+// cause an error. Any returned error will be of type [*url.Error]. The
 // url.Error value's Timeout method will report true if the request
 // timed out.
 //
 // When err is nil, resp always contains a non-nil resp.Body.
 // Caller should close resp.Body when done reading from it.
 //
-// To make a request with custom headers, use NewRequest and Client.Do.
+// To make a request with custom headers, use [NewRequest] and [Client.Do].
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
+// To make a request with a specified context.Context, use [NewRequestWithContext]
 // and Client.Do.
 func (c *Client) Get(url string) (resp *Response, err error) {
 	req, err := NewRequest("GET", url, nil)
@@ -398,20 +402,21 @@ func urlErrorOp(method string) string {
 // connectivity problem). A non-2xx status code doesn't cause an
 // error.
 //
-// If the returned error is nil, the Response will contain a non-nil
+// If the returned error is nil, the [Response] will contain a non-nil
 // Body which the user is expected to close. If the Body is not both
-// read to EOF and closed, the Client's underlying RoundTripper
-// (typically Transport) may not be able to re-use a persistent TCP
+// read to EOF and closed, the [Client]'s underlying [RoundTripper]
+// (typically [Transport]) may not be able to re-use a persistent TCP
 // connection to the server for a subsequent "keep-alive" request.
 //
 // The request Body, if non-nil, will be closed by the underlying
-// Transport, even on errors.
+// Transport, even on errors. The Body may be closed asynchronously after
+// Do returns.
 //
 // On error, any Response can be ignored. A non-nil Response with a
 // non-nil error only occurs when CheckRedirect fails, and even then
-// the returned Response.Body is already closed.
+// the returned [Response.Body] is already closed.
 //
-// Generally Get, Post, or PostForm will be used instead of Do.
+// Generally [Get], [Post], or [PostForm] will be used instead of Do.
 //
 // If the server replies with a redirect, the Client first uses the
 // CheckRedirect function to determine whether the redirect should be
@@ -419,11 +424,11 @@ func urlErrorOp(method string) string {
 // subsequent requests to use HTTP method GET
 // (or HEAD if the original request was HEAD), with no body.
 // A 307 or 308 redirect preserves the original HTTP method and body,
-// provided that the Request.GetBody function is defined.
-// The NewRequest function automatically sets GetBody for common
+// provided that the [Request.GetBody] function is defined.
+// The [NewRequest] function automatically sets GetBody for common
 // standard library body types.
 //
-// Any returned error will be of type *url.Error. The url.Error
+// Any returned error will be of type [*url.Error]. The url.Error
 // value's Timeout method will report true if the request timed out.
 func (c *Client) Do(req *Request) (*Response, error) {
 	if c.Transport != nil {
@@ -441,6 +446,7 @@ func (c *Client) do(req *Request) (retres *Response, reterr error) {
 			Err: errors.New("http: nil Request.URL"),
 		}
 	}
+	_ = *c // panic early if c is nil; see go.dev/issue/53521
 
 	var err error
 	var didTimeout func() bool
@@ -465,17 +471,17 @@ func (c *Client) do(req *Request) (retres *Response, reterr error) {
 //
 // Caller should close resp.Body when done reading from it.
 //
-// If the provided body is an io.Closer, it is closed after the
+// If the provided body is an [io.Closer], it is closed after the
 // request.
 //
 // Post is a wrapper around DefaultClient.Post.
 //
-// To set custom headers, use NewRequest and DefaultClient.Do.
+// To set custom headers, use [NewRequest] and DefaultClient.Do.
 //
-// See the Client.Do method documentation for details on how redirects
+// See the [Client.Do] method documentation for details on how redirects
 // are handled.
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
+// To make a request with a specified context.Context, use [NewRequestWithContext]
 // and DefaultClient.Do.
 func Post(url, contentType string, body io.Reader) (resp *Response, err error) {
 	return DefaultClient.Post(url, contentType, body)
@@ -485,15 +491,15 @@ func Post(url, contentType string, body io.Reader) (resp *Response, err error) {
 //
 // Caller should close resp.Body when done reading from it.
 //
-// If the provided body is an io.Closer, it is closed after the
+// If the provided body is an [io.Closer], it is closed after the
 // request.
 //
-// To set custom headers, use NewRequest and Client.Do.
+// To set custom headers, use [NewRequest] and [Client.Do].
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
-// and Client.Do.
+// To make a request with a specified context.Context, use [NewRequestWithContext]
+// and [Client.Do].
 //
-// See the Client.Do method documentation for details on how redirects
+// See the [Client.Do] method documentation for details on how redirects
 // are handled.
 func (c *Client) Post(url, contentType string, body io.Reader) (resp *Response, err error) {
 	req, err := NewRequest("POST", url, body)
@@ -508,17 +514,17 @@ func (c *Client) Post(url, contentType string, body io.Reader) (resp *Response,
 // values URL-encoded as the request body.
 //
 // The Content-Type header is set to application/x-www-form-urlencoded.
-// To set other headers, use NewRequest and DefaultClient.Do.
+// To set other headers, use [NewRequest] and DefaultClient.Do.
 //
 // When err is nil, resp always contains a non-nil resp.Body.
 // Caller should close resp.Body when done reading from it.
 //
 // PostForm is a wrapper around DefaultClient.PostForm.
 //
-// See the Client.Do method documentation for details on how redirects
+// See the [Client.Do] method documentation for details on how redirects
 // are handled.
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
+// To make a request with a specified [context.Context], use [NewRequestWithContext]
 // and DefaultClient.Do.
 func PostForm(url string, data url.Values) (resp *Response, err error) {
 	return DefaultClient.PostForm(url, data)
@@ -528,15 +534,15 @@ func PostForm(url string, data url.Values) (resp *Response, err error) {
 // with data's keys and values URL-encoded as the request body.
 //
 // The Content-Type header is set to application/x-www-form-urlencoded.
-// To set other headers, use NewRequest and Client.Do.
+// To set other headers, use [NewRequest] and [Client.Do].
 //
 // When err is nil, resp always contains a non-nil resp.Body.
 // Caller should close resp.Body when done reading from it.
 //
-// See the Client.Do method documentation for details on how redirects
+// See the [Client.Do] method documentation for details on how redirects
 // are handled.
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
+// To make a request with a specified context.Context, use [NewRequestWithContext]
 // and Client.Do.
 func (c *Client) PostForm(url string, data url.Values) (resp *Response, err error) {
 	return c.Post(url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
@@ -554,7 +560,7 @@ func (c *Client) PostForm(url string, data url.Values) (resp *Response, err erro
 //
 // Head is a wrapper around DefaultClient.Head.
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
+// To make a request with a specified [context.Context], use [NewRequestWithContext]
 // and DefaultClient.Do.
 func Head(url string) (resp *Response, err error) {
 	return DefaultClient.Head(url)
@@ -562,7 +568,7 @@ func Head(url string) (resp *Response, err error) {
 
 // Head issues a HEAD to the specified URL. If the response is one of the
 // following redirect codes, Head follows the redirect after calling the
-// Client's CheckRedirect function:
+// [Client.CheckRedirect] function:
 //
 //	301 (Moved Permanently)
 //	302 (Found)
@@ -570,8 +576,8 @@ func Head(url string) (resp *Response, err error) {
 //	307 (Temporary Redirect)
 //	308 (Permanent Redirect)
 //
-// To make a request with a specified context.Context, use NewRequestWithContext
-// and Client.Do.
+// To make a request with a specified [context.Context], use [NewRequestWithContext]
+// and [Client.Do].
 func (c *Client) Head(url string) (resp *Response, err error) {
 	req, err := NewRequest("HEAD", url, nil)
 	if err != nil {