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net: avoid unnecessary interface lookup fetching all interface addresses

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InterfaceAddrs returns a list of the system's unicast interface addresses.

In order to do so, the function reuses the existing helpers and
list first all addresses with the netlink call RTM_GETADDR, then
all interfaces with RTM_GETLINK, and later it merge both lists
(each address references an interface).

However, the list of interfaces and addresses are obtained at
different times and there can be inconsistencies and, if an
address references an interface that is not present in the list
of interfaces, the function fails with an error.

Since the function InterfaceAddress is only about the system
addresses, there is no need to list all the interfaces, and we can
obtain the list of addresses directly from the netlink call RTM_GETADDR.
There is no need to correlate this list with the list of interfaces, as
the OS is the source of truth and should be the one providing the
consistency between addresses and interfaces.

Fixes #51934

Change-Id: I3b816e8146b1c07fdfe1bf6af338f001ef75734f
Reviewed-on: https://go-review.googlesource.com/c/go/+/635196
Reviewed-by: Ian Lance Taylor <iant@google.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
This commit is contained in:
Antonio Ojea 2024-12-11 15:03:59 +00:00 • committed by Gopher Robot
parent e424d78c3d
commit 979c1cfbe8
1 changed files with 3 additions and 18 deletions
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21
src/net/interface_linux.go
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@ -129,22 +129,14 @@ func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
if err != nil { if err != nil {
return nil, os.NewSyscallError("parsenetlinkmessage", err) return nil, os.NewSyscallError("parsenetlinkmessage", err)
} }
var ift []Interface ifat, err := addrTable(ifi, msgs)
if ifi == nil {
var err error
ift, err = interfaceTable(0)
if err != nil {
return nil, err
}
}
ifat, err := addrTable(ift, ifi, msgs)
if err != nil { if err != nil {
return nil, err return nil, err
} }
return ifat, nil return ifat, nil
} }
func addrTable(ift []Interface, ifi *Interface, msgs []syscall.NetlinkMessage) ([]Addr, error) { func addrTable(ifi *Interface, msgs []syscall.NetlinkMessage) ([]Addr, error) {
var ifat []Addr var ifat []Addr
loop: loop:
for _, m := range msgs { for _, m := range msgs {
@ -153,14 +145,7 @@ loop:
break loop break loop
case syscall.RTM_NEWADDR: case syscall.RTM_NEWADDR:
ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0])) ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0]))
if len(ift) != 0 || ifi.Index == int(ifam.Index) { if ifi == nil || ifi.Index == int(ifam.Index) {
if len(ift) != 0 {
var err error
ifi, err = interfaceByIndex(ift, int(ifam.Index))
if err != nil {
return nil, err
}
}
attrs, err := syscall.ParseNetlinkRouteAttr(&m) attrs, err := syscall.ParseNetlinkRouteAttr(&m)
if err != nil { if err != nil {
return nil, os.NewSyscallError("parsenetlinkrouteattr", err) return nil, os.NewSyscallError("parsenetlinkrouteattr", err)