func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
var res *C.struct_addrinfo
var hints C.struct_addrinfo
// NOTE(rsc): In theory there are approximately balanced
// arguments for and against including AI_ADDRCONFIG
// in the flags (it includes IPv4 results only on IPv4 systems,
// and similarly for IPv6), but in practice setting it causes
// getaddrinfo to return the wrong canonical name on Linux.
// So definitely leave it out.
hints.ai_flags = (C.AI_ALL | C.AI_V4MAPPED | C.AI_CANONNAME) & cgoAddrInfoMask()
h := C.CString(name)
defer C.free(unsafe.Pointer(h))
gerrno, err := C.getaddrinfo(h, nil, &hints, &res)
if gerrno != 0 {
var str string
if gerrno == C.EAI_NONAME {
str = noSuchHost
} else if gerrno == C.EAI_SYSTEM {
str = err.Error()
} else {
str = C.GoString(C.gai_strerror(gerrno))
}
return nil, "", &DNSError{Err: str, Name: name}, true
}
defer C.freeaddrinfo(res)
if res != nil {
cname = C.GoString(res.ai_canonname)
if cname == "" {
cname = name
}
if len(cname) > 0 && cname[len(cname)-1] != '.' {
cname += "."
}
}
for r := res; r != nil; r = r.ai_next {
// Everything comes back twice, once for UDP and once for TCP.
if r.ai_socktype != C.SOCK_STREAM {
continue
}
switch r.ai_family {
default:
continue
case C.AF_INET:
sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.ai_addr))
addrs = append(addrs, copyIP(sa.Addr[:]))
case C.AF_INET6:
sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.ai_addr))
addrs = append(addrs, copyIP(sa.Addr[:]))
}
}
return addrs, cname, nil, true
}
func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
acquireThread()
defer releaseThread()
var res *C.struct_addrinfo
var hints C.struct_addrinfo
hints.ai_flags = cgoAddrInfoFlags()
hints.ai_socktype = C.SOCK_STREAM
h := C.CString(name)
defer C.free(unsafe.Pointer(h))
gerrno, err := C.getaddrinfo(h, nil, &hints, &res)
if gerrno != 0 {
var str string
if gerrno == C.EAI_NONAME {
str = noSuchHost
} else if gerrno == C.EAI_SYSTEM {
str = err.Error()
} else {
str = C.GoString(C.gai_strerror(gerrno))
}
return nil, "", &DNSError{Err: str, Name: name}, true
}
defer C.freeaddrinfo(res)
if res != nil {
cname = C.GoString(res.ai_canonname)
if cname == "" {
cname = name
}
if len(cname) > 0 && cname[len(cname)-1] != '.' {
cname += "."
}
}
for r := res; r != nil; r = r.ai_next {
// We only asked for SOCK_STREAM, but check anyhow.
if r.ai_socktype != C.SOCK_STREAM {
continue
}
switch r.ai_family {
default:
continue
case C.AF_INET:
sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.ai_addr))
addrs = append(addrs, copyIP(sa.Addr[:]))
case C.AF_INET6:
sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.ai_addr))
addrs = append(addrs, copyIP(sa.Addr[:]))
}
}
return addrs, cname, nil, true
}
func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, completed bool) {
acquireThread()
defer releaseThread()
var res *C.struct_addrinfo
var hints C.struct_addrinfo
hints.ai_flags = cgoAddrInfoFlags()
hints.ai_socktype = C.SOCK_STREAM
h := C.CString(name)
defer C.free(unsafe.Pointer(h))
gerrno, err := C.getaddrinfo(h, nil, &hints, &res)
if gerrno != 0 {
var str string
if gerrno == C.EAI_NONAME {
str = noSuchHost
} else if gerrno == C.EAI_SYSTEM {
if err == nil {
// err should not be nil, but sometimes getaddrinfo returns
// gerrno == C.EAI_SYSTEM with err == nil on Linux.
// The report claims that it happens when we have too many
// open files, so use syscall.EMFILE (too many open files in system).
// Most system calls would return ENFILE (too many open files),
// so at the least EMFILE should be easy to recognize if this
// comes up again. golang.org/issue/6232.
err = syscall.EMFILE
}
str = err.Error()
} else {
str = C.GoString(C.gai_strerror(gerrno))
}
return nil, "", &DNSError{Err: str, Name: name}, true
}
defer C.freeaddrinfo(res)
if res != nil {
cname = C.GoString(res.ai_canonname)
if cname == "" {
cname = name
}
if len(cname) > 0 && cname[len(cname)-1] != '.' {
cname += "."
}
}
for r := res; r != nil; r = r.ai_next {
// We only asked for SOCK_STREAM, but check anyhow.
if r.ai_socktype != C.SOCK_STREAM {
continue
}
switch r.ai_family {
default:
continue
case C.AF_INET:
sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.ai_addr))
addr := IPAddr{IP: copyIP(sa.Addr[:])}
addrs = append(addrs, addr)
case C.AF_INET6:
sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.ai_addr))
addr := IPAddr{IP: copyIP(sa.Addr[:]), Zone: zoneToString(int(sa.Scope_id))}
addrs = append(addrs, addr)
}
}
return addrs, cname, nil, true
}