From 979c1cfbe8880e302d5a73df47f4efc3d34ee416 Mon Sep 17 00:00:00 2001 From: Antonio Ojea Date: Wed, 11 Dec 2024 15:03:59 +0000 Subject: [PATCH] net: avoid unnecessary interface lookup fetching all interface addresses 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 Commit-Queue: Ian Lance Taylor LUCI-TryBot-Result: Go LUCI Auto-Submit: Ian Lance Taylor --- src/net/interface_linux.go | 21 +++------------------ 1 file changed, 3 insertions(+), 18 deletions(-) diff --git a/src/net/interface_linux.go b/src/net/interface_linux.go index 9112ecc854..7856dae8fc 100644 --- a/src/net/interface_linux.go +++ b/src/net/interface_linux.go @@ -129,22 +129,14 @@ func interfaceAddrTable(ifi *Interface) ([]Addr, error) { if err != nil { return nil, os.NewSyscallError("parsenetlinkmessage", err) } - var ift []Interface - if ifi == nil { - var err error - ift, err = interfaceTable(0) - if err != nil { - return nil, err - } - } - ifat, err := addrTable(ift, ifi, msgs) + ifat, err := addrTable(ifi, msgs) if err != nil { return nil, err } 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 loop: for _, m := range msgs { @@ -153,14 +145,7 @@ loop: break loop case syscall.RTM_NEWADDR: ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0])) - if len(ift) != 0 || 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 - } - } + if ifi == nil || ifi.Index == int(ifam.Index) { attrs, err := syscall.ParseNetlinkRouteAttr(&m) if err != nil { return nil, os.NewSyscallError("parsenetlinkrouteattr", err) -- 2.48.1