libgo/go/net/cgo_unix.go

   1 // Copyright 2011 The Go Authors.  All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build !netgo
   6 // +build darwin dragonfly freebsd linux netbsd openbsd
   7
   8 package net
   9
  10 /*
  11 #include <sys/types.h>
  12 #include <sys/socket.h>
  13 #include <netinet/in.h>
  14 #include <netdb.h>
  15 #include <stdlib.h>
  16 #include <unistd.h>
  17 #include <string.h>
  18 */
  19
  20 import (
  21         "syscall"
  22         "unsafe"
  23 )
  24
  25 //extern getaddrinfo
  26 func libc_getaddrinfo(node *byte, service *byte, hints *syscall.Addrinfo, res **syscall.Addrinfo) int
  27
  28 //extern freeaddrinfo
  29 func libc_freeaddrinfo(res *syscall.Addrinfo)
  30
  31 //extern gai_strerror
  32 func libc_gai_strerror(errcode int) *byte
  33
  34 // bytePtrToString takes a NUL-terminated array of bytes and convert
  35 // it to a Go string.
  36 func bytePtrToString(p *byte) string {
  37         a := (*[10000]byte)(unsafe.Pointer(p))
  38         i := 0
  39         for a[i] != 0 {
  40                 i++
  41         }
  42         return string(a[:i])
  43 }
  44
  45 func cgoLookupHost(name string) (addrs []string, err error, completed bool) {
  46         ip, err, completed := cgoLookupIP(name)
  47         for _, p := range ip {
  48                 addrs = append(addrs, p.String())
  49         }
  50         return
  51 }
  52
  53 func cgoLookupPort(net, service string) (port int, err error, completed bool) {
  54         acquireThread()
  55         defer releaseThread()
  56
  57         var res *syscall.Addrinfo
  58         var hints syscall.Addrinfo
  59
  60         switch net {
  61         case "":
  62                 // no hints
  63         case "tcp", "tcp4", "tcp6":
  64                 hints.Ai_socktype = syscall.SOCK_STREAM
  65                 hints.Ai_protocol = syscall.IPPROTO_TCP
  66         case "udp", "udp4", "udp6":
  67                 hints.Ai_socktype = syscall.SOCK_DGRAM
  68                 hints.Ai_protocol = syscall.IPPROTO_UDP
  69         default:
  70                 return 0, UnknownNetworkError(net), true
  71         }
  72         if len(net) >= 4 {
  73                 switch net[3] {
  74                 case '4':
  75                         hints.Ai_family = syscall.AF_INET
  76                 case '6':
  77                         hints.Ai_family = syscall.AF_INET6
  78                 }
  79         }
  80
  81         s := syscall.StringBytePtr(service)
  82         syscall.Entersyscall()
  83         gerrno := libc_getaddrinfo(nil, s, &hints, &res)
  84         syscall.Exitsyscall()
  85         if gerrno == 0 {
  86                 defer libc_freeaddrinfo(res)
  87                 for r := res; r != nil; r = r.Ai_next {
  88                         switch r.Ai_family {
  89                         default:
  90                                 continue
  91                         case syscall.AF_INET:
  92                                 sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
  93                                 p := (*[2]byte)(unsafe.Pointer(&sa.Port))
  94                                 return int(p[0])<<8 | int(p[1]), nil, true
  95                         case syscall.AF_INET6:
  96                                 sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
  97                                 p := (*[2]byte)(unsafe.Pointer(&sa.Port))
  98                                 return int(p[0])<<8 | int(p[1]), nil, true
  99                         }
 100                 }
 101         }
 102         return 0, &AddrError{"unknown port", net + "/" + service}, true
 103 }
 104
 105 func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
 106         acquireThread()
 107         defer releaseThread()
 108
 109         var res *syscall.Addrinfo
 110         var hints syscall.Addrinfo
 111
 112         hints.Ai_flags = int32(cgoAddrInfoFlags())
 113         hints.Ai_socktype = syscall.SOCK_STREAM
 114
 115         h := syscall.StringBytePtr(name)
 116         syscall.Entersyscall()
 117         gerrno := libc_getaddrinfo(h, nil, &hints, &res)
 118         syscall.Exitsyscall()
 119         if gerrno != 0 {
 120                 var str string
 121                 if gerrno == syscall.EAI_NONAME {
 122                         str = noSuchHost
 123                 } else if gerrno == syscall.EAI_SYSTEM {
 124                         errno := syscall.GetErrno()
 125                         if errno == 0 {
 126                                 // err should not be nil, but sometimes getaddrinfo returns
 127                                 // gerrno == C.EAI_SYSTEM with err == nil on Linux.
 128                                 // The report claims that it happens when we have too many
 129                                 // open files, so use syscall.EMFILE (too many open files in system).
 130                                 // Most system calls would return ENFILE (too many open files),
 131                                 // so at the least EMFILE should be easy to recognize if this
 132                                 // comes up again. golang.org/issue/6232.
 133                                 errno = syscall.EMFILE
 134                         }
 135                         str = errno.Error()
 136                 } else {
 137                         str = bytePtrToString(libc_gai_strerror(gerrno))
 138                 }
 139                 return nil, "", &DNSError{Err: str, Name: name}, true
 140         }
 141         defer libc_freeaddrinfo(res)
 142         if res != nil {
 143                 cname = bytePtrToString((*byte)(unsafe.Pointer(res.Ai_canonname)))
 144                 if cname == "" {
 145                         cname = name
 146                 }
 147                 if len(cname) > 0 && cname[len(cname)-1] != '.' {
 148                         cname += "."
 149                 }
 150         }
 151         for r := res; r != nil; r = r.Ai_next {
 152                 // We only asked for SOCK_STREAM, but check anyhow.
 153                 if r.Ai_socktype != syscall.SOCK_STREAM {
 154                         continue
 155                 }
 156                 switch r.Ai_family {
 157                 default:
 158                         continue
 159                 case syscall.AF_INET:
 160                         sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
 161                         addrs = append(addrs, copyIP(sa.Addr[:]))
 162                 case syscall.AF_INET6:
 163                         sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
 164                         addrs = append(addrs, copyIP(sa.Addr[:]))
 165                 }
 166         }
 167         return addrs, cname, nil, true
 168 }
 169
 170 func cgoLookupIP(name string) (addrs []IP, err error, completed bool) {
 171         addrs, _, err, completed = cgoLookupIPCNAME(name)
 172         return
 173 }
 174
 175 func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
 176         _, cname, err, completed = cgoLookupIPCNAME(name)
 177         return
 178 }
 179
 180 func copyIP(x IP) IP {
 181         if len(x) < 16 {
 182                 return x.To16()
 183         }
 184         y := make(IP, len(x))
 185         copy(y, x)
 186         return y
 187 }