unix: add sockaddr and defines for PPPoE sockets.

`sockaddr_pppox` is a packed struct, which godefs doesn't understand.
So, I had to do the byte packing by hand instead.

Change-Id: Ib92cf43f8ae0729a0af043c4241063911c95e6bf
GitHub-Last-Rev: 8982dec099594064d3892f3fa05bb7b5989cec6d
GitHub-Pull-Request: golang/sys#23
Reviewed-on: https://go-review.googlesource.com/c/149757
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

unix/linux/types.go

@@ -48,6 +48,7 @@ package unix
 #include <sys/wait.h>
 #include <linux/filter.h>
 #include <linux/icmpv6.h>
+#include <linux/if_pppox.h>
 #include <linux/keyctl.h>
 #include <linux/netfilter/nf_tables.h>
 #include <linux/netfilter/nfnetlink.h>
@@ -168,6 +169,7 @@ union sockaddr_all {
 	struct sockaddr_un s4;
 	struct sockaddr_ll s5;
 	struct sockaddr_nl s6;
+	struct sockaddr_pppox s7;
 };
 
 struct sockaddr_any {
@@ -432,6 +434,8 @@ type RawSockaddrVM C.struct_sockaddr_vm
 
 type RawSockaddrXDP C.struct_sockaddr_xdp
 
+type RawSockaddrPPPoX [C.sizeof_struct_sockaddr_pppox]byte
+
 type RawSockaddr C.struct_sockaddr
 
 type RawSockaddrAny C.struct_sockaddr_any
@@ -480,6 +484,7 @@ const (
 	SizeofSockaddrALG       = C.sizeof_struct_sockaddr_alg
 	SizeofSockaddrVM        = C.sizeof_struct_sockaddr_vm
 	SizeofSockaddrXDP       = C.sizeof_struct_sockaddr_xdp
+	SizeofSockaddrPPPoX     = C.sizeof_struct_sockaddr_pppox
 	SizeofLinger            = C.sizeof_struct_linger
 	SizeofIovec             = C.sizeof_struct_iovec
 	SizeofIPMreq            = C.sizeof_struct_ip_mreq

unix/syscall_linux.go

@@ -12,6 +12,8 @@
 package unix
 
 import (
+	"encoding/binary"
+	"net"
 	"syscall"
 	"unsafe"
 )
@@ -710,6 +712,51 @@ func (sa *SockaddrXDP) sockaddr() (unsafe.Pointer, _Socklen, error) {
 	return unsafe.Pointer(&sa.raw), SizeofSockaddrXDP, nil
 }
 
+// This constant mirrors the #define of PX_PROTO_OE in
+// linux/if_pppox.h. We're defining this by hand here instead of
+// autogenerating through mkerrors.sh because including
+// linux/if_pppox.h causes some declaration conflicts with other
+// includes (linux/if_pppox.h includes linux/in.h, which conflicts
+// with netinet/in.h). Given that we only need a single zero constant
+// out of that file, it's cleaner to just define it by hand here.
+const px_proto_oe = 0
+
+type SockaddrPPPoE struct {
+	SID    uint16
+	Remote net.HardwareAddr
+	Dev    string
+	raw    RawSockaddrPPPoX
+}
+
+func (sa *SockaddrPPPoE) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if len(sa.Remote) != 6 {
+		return nil, 0, EINVAL
+	}
+	if len(sa.Dev) > IFNAMSIZ-1 {
+		return nil, 0, EINVAL
+	}
+
+	*(*uint16)(unsafe.Pointer(&sa.raw[0])) = AF_PPPOX
+	// This next field is in host-endian byte order. We can't use the
+	// same unsafe pointer cast as above, because this value is not
+	// 32-bit aligned and some architectures don't allow unaligned
+	// access.
+	//
+	// However, the value of px_proto_oe is 0, so we can use
+	// encoding/binary helpers to write the bytes without worrying
+	// about the ordering.
+	binary.BigEndian.PutUint32(sa.raw[2:6], px_proto_oe)
+	// This field is deliberately big-endian, unlike the previous
+	// one. The kernel expects SID to be in network byte order.
+	binary.BigEndian.PutUint16(sa.raw[6:8], sa.SID)
+	copy(sa.raw[8:14], sa.Remote)
+	for i := 14; i < 14+IFNAMSIZ; i++ {
+		sa.raw[i] = 0
+	}
+	copy(sa.raw[14:], sa.Dev)
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrPPPoX, nil
+}
+
 func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
 	switch rsa.Addr.Family {
 	case AF_NETLINK:
@@ -820,6 +867,22 @@ func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
 			SharedUmemFD: pp.Shared_umem_fd,
 		}
 		return sa, nil
+	case AF_PPPOX:
+		pp := (*RawSockaddrPPPoX)(unsafe.Pointer(rsa))
+		if binary.BigEndian.Uint32(pp[2:6]) != px_proto_oe {
+			return nil, EINVAL
+		}
+		sa := &SockaddrPPPoE{
+			SID:    binary.BigEndian.Uint16(pp[6:8]),
+			Remote: net.HardwareAddr(pp[8:14]),
+		}
+		for i := 14; i < 14+IFNAMSIZ; i++ {
+			if pp[i] == 0 {
+				sa.Dev = string(pp[14:i])
+				break
+			}
+		}
+		return sa, nil
 	}
 	return nil, EAFNOSUPPORT
 }

unix/ztypes_linux_386.go

@@ -286,6 +286,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -421,6 +423,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x8
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_amd64.go

@@ -288,6 +288,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -425,6 +427,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_arm.go

@@ -289,6 +289,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]uint8
@@ -424,6 +426,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x8
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_arm64.go

@@ -289,6 +289,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -426,6 +428,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_mips.go

@@ -287,6 +287,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -422,6 +424,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x8
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_mips64.go

@@ -289,6 +289,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -426,6 +428,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_mips64le.go

@@ -289,6 +289,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -426,6 +428,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_mipsle.go

@@ -287,6 +287,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -422,6 +424,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x8
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_ppc64.go

@@ -290,6 +290,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]uint8
@@ -427,6 +429,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_ppc64le.go

@@ -290,6 +290,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]uint8
@@ -427,6 +429,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_riscv64.go

@@ -289,6 +289,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]uint8
@@ -426,6 +428,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8

unix/ztypes_linux_s390x.go

@@ -288,6 +288,8 @@ type RawSockaddrXDP struct {
 	Shared_umem_fd uint32
 }
 
+type RawSockaddrPPPoX [0x1e]byte
+
 type RawSockaddr struct {
 	Family uint16
 	Data   [14]int8
@@ -425,6 +427,7 @@ const (
 	SizeofSockaddrALG       = 0x58
 	SizeofSockaddrVM        = 0x10
 	SizeofSockaddrXDP       = 0x10
+	SizeofSockaddrPPPoX     = 0x1e
 	SizeofLinger            = 0x8
 	SizeofIovec             = 0x10
 	SizeofIPMreq            = 0x8