TheArchive/tailscale
1
0
Fork 0
mirror of https://github.com/tailscale/tailscale.git synced 2024-11-25 19:15:34 +00:00
Code Issues Packages Projects Releases Wiki Activity

net/netstat: document the Windows netstat code a bit more

Browse Source 
And defensively bound allocation.

Updates tailscale/corp#8878

Change-Id: Iaa07479ea2ea28ee1ac3326ab025046d6d785b00
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2023-01-27 10:02:16 -08:00 committed by Brad Fitzpatrick
parent 8c20da2568
commit 2fc8de485c
1 changed files with 29 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
net/netstat/netstat_windows.go
View File

@ -20,6 +20,13 @@
// OSMetadata includes any additional OS-specific information that may be
// obtained during the retrieval of a given Entry.
type OSMetadata interface {
// GetModule returns the entry's module name.
//
// It returns ("", nil) if no entry is found. As of 2023-01-27, any returned
// error is silently discarded by its sole caller in portlist_windows.go and
// treated equivalently as returning ("", nil), but this may change in the
// future. An error should only be returned in casees that are worthy of
// being logged at least.
GetModule() (string, error)
}
@ -224,7 +231,13 @@ type moduleInfoConstraint interface {
_MIB_TCPROW_OWNER_MODULE | _MIB_TCP6ROW_OWNER_MODULE
}
// moduleInfo may return "", nil indicating a successful call but with empty data
// moduleInfo implements OSMetadata.GetModule. It calls
// getOwnerModuleFromTcpEntry or getOwnerModuleFromTcp6Entry.
//
// See
// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getownermodulefromtcpentry
//
// It may return "", nil indicating a successful call but with empty data.
func moduleInfo[entryType moduleInfoConstraint](entry *entryType, proc *windows.LazyProc) (string, error) {
var buf []byte
var desiredLen uint32
@ -241,28 +254,36 @@ func moduleInfo[entryType moduleInfoConstraint](entry *entryType, proc *windows.
if err == windows.ERROR_SUCCESS {
break
}
if err == windows.ERROR_NOT_FOUND {
return "", nil
}
if err != windows.ERROR_INSUFFICIENT_BUFFER {
return "", err
}
if desiredLen > 1<<20 {
// Sanity check before allocating too much.
return "", nil
}
buf = make([]byte, desiredLen)
addr = unsafe.Pointer(&buf[0])
}
basicInfo := (*_TCPIP_OWNER_MODULE_BASIC_INFO)(addr)
// GetOwnerModuleFromTcp*Entry is apparently using nil as an empty result
// under certain circumstances, so we check all the things.
if basicInfo == nil || basicInfo.moduleName == nil {
if addr == nil {
// GetOwnerModuleFromTcp*Entry can apparently return ERROR_SUCCESS
// (NO_ERROR) on the first call without the usual first
// ERROR_INSUFFICIENT_BUFFER result. Windows said success, so interpret
// that was sucessfully not having data.
return "", nil
}
basicInfo := (*_TCPIP_OWNER_MODULE_BASIC_INFO)(addr)
return windows.UTF16PtrToString(basicInfo.moduleName), nil
}
// GetModule implements OSMetadata.
func (m *_MIB_TCPROW_OWNER_MODULE) GetModule() (string, error) {
return moduleInfo(m, getOwnerModuleFromTcpEntry)
}
// GetModule implements OSMetadata.
func (m *_MIB_TCP6ROW_OWNER_MODULE) GetModule() (string, error) {
return moduleInfo(m, getOwnerModuleFromTcp6Entry)
}