Use caddy's certmagic library for extensible/robust ACME handling (#14177)

* use certmagic for more extensible/robust ACME cert handling

* accept TOS based on config option

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>

vendor/golang.org/x/net/ipv6/sys_ssmreq.go

@@ -0,0 +1,54 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build aix darwin freebsd linux solaris zos
+
+package ipv6
+
+import (
+	"net"
+	"unsafe"
+
+	"golang.org/x/net/internal/socket"
+)
+
+var compatFreeBSD32 bool // 386 emulation on amd64
+
+func (so *sockOpt) setGroupReq(c *socket.Conn, ifi *net.Interface, grp net.IP) error {
+	var gr groupReq
+	if ifi != nil {
+		gr.Interface = uint32(ifi.Index)
+	}
+	gr.setGroup(grp)
+	var b []byte
+	if compatFreeBSD32 {
+		var d [sizeofGroupReq + 4]byte
+		s := (*[sizeofGroupReq]byte)(unsafe.Pointer(&gr))
+		copy(d[:4], s[:4])
+		copy(d[8:], s[4:])
+		b = d[:]
+	} else {
+		b = (*[sizeofGroupReq]byte)(unsafe.Pointer(&gr))[:sizeofGroupReq]
+	}
+	return so.Set(c, b)
+}
+
+func (so *sockOpt) setGroupSourceReq(c *socket.Conn, ifi *net.Interface, grp, src net.IP) error {
+	var gsr groupSourceReq
+	if ifi != nil {
+		gsr.Interface = uint32(ifi.Index)
+	}
+	gsr.setSourceGroup(grp, src)
+	var b []byte
+	if compatFreeBSD32 {
+		var d [sizeofGroupSourceReq + 4]byte
+		s := (*[sizeofGroupSourceReq]byte)(unsafe.Pointer(&gsr))
+		copy(d[:4], s[:4])
+		copy(d[8:], s[4:])
+		b = d[:]
+	} else {
+		b = (*[sizeofGroupSourceReq]byte)(unsafe.Pointer(&gsr))[:sizeofGroupSourceReq]
+	}
+	return so.Set(c, b)
+}