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113 lines
2.2 KiB
Go
113 lines
2.2 KiB
Go
// +build linux,cgo
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package obfssh
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/*
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <netinet/in.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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// the RPI toolchain does not have this macro
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#ifndef IP6T_SO_ORIGINAL_DST
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#define IP6T_SO_ORIGINAL_DST 80
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#endif
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int get_original_dst4(int fd, void *addr);
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int get_original_dst6(int fd, void *addr);
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unsigned short _ntohs(unsigned short a);
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int get_original_dst4(int fd, void *addr){
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int ret;
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int l = sizeof(struct sockaddr_in);
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ret = getsockopt(fd, SOL_IP, SO_ORIGINAL_DST,
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(struct sockaddr_in *)addr, &l);
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return ret;
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}
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int get_original_dst6(int fd, void *addr){
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int ret;
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int l = sizeof(struct sockaddr_in6);
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ret = getsockopt(fd, SOL_IPV6, IP6T_SO_ORIGINAL_DST,
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(struct sockaddr_in6 *)addr, &l);
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return ret;
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}
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unsigned short _ntohs(unsigned short a) {
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return ntohs(a);
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}
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*/
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import "C"
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import (
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"fmt"
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//"log"
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"net"
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"syscall"
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"unsafe"
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)
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func getOriginDst(c net.Conn) (net.Addr, error) {
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var addr net.Addr
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var err error
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if _, ok := c.(*net.TCPConn); !ok {
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return nil, fmt.Errorf("only tcp socket supported")
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}
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ip := c.LocalAddr().(*net.TCPAddr).IP
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if ip.To4() != nil { // ipv4
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addr, err = getOriginDst4(c)
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} else {
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addr, err = getOriginDst6(c)
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}
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return addr, err
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}
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func getOriginDst4(c net.Conn) (net.Addr, error) {
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c1 := c.(*net.TCPConn)
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f, _ := c1.File()
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defer f.Close()
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var addr4 syscall.RawSockaddrInet4
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ret := C.get_original_dst4(C.int(f.Fd()), unsafe.Pointer(&addr4))
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if int(ret) != 0 {
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return nil, fmt.Errorf("ipv4 getsockopt SO_ORIGINAL_DST return %v", int(ret))
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}
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port := int(C._ntohs(C.ushort(addr4.Port)))
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ip := net.IP(addr4.Addr[0:])
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return &net.TCPAddr{IP: ip, Port: port}, nil
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}
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func getOriginDst6(c net.Conn) (net.Addr, error) {
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c1 := c.(*net.TCPConn)
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f, _ := c1.File()
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defer f.Close()
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var addr6 syscall.RawSockaddrInet6
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ret := C.get_original_dst6(C.int(f.Fd()), unsafe.Pointer(&addr6))
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if int(ret) != 0 {
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return nil, fmt.Errorf("ipv6 getsockopt IP6T_ORIGINAL_DST return %v", int(ret))
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}
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port := int(C._ntohs(C.ushort(addr6.Port)))
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ip := net.IP(addr6.Addr[0:])
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return &net.TCPAddr{IP: ip, Port: port}, nil
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}
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