From 9683c297a74c07cf63f84a41f6ffa138a5adefca Mon Sep 17 00:00:00 2001
From: Kr328 <kr328app@outlook.com>
Date: Wed, 9 Mar 2022 13:41:50 +0800
Subject: [PATCH] Chore: add more details to process resolving (#2017)

---
 component/process/process_linux.go | 45 ++++++++++++------------------
 1 file changed, 18 insertions(+), 27 deletions(-)

diff --git a/component/process/process_linux.go b/component/process/process_linux.go
index 0ca42716..c718dc2f 100644
--- a/component/process/process_linux.go
+++ b/component/process/process_linux.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
-	"io"
 	"net"
 	"os"
 	"path"
@@ -27,17 +26,6 @@ var nativeEndian = func() binary.ByteOrder {
 	return binary.LittleEndian
 }()
 
-type (
-	SocketResolver      func(network string, ip net.IP, srcPort int) (inode, uid int, err error)
-	ProcessNameResolver func(inode, uid int) (name string, err error)
-)
-
-// export for android
-var (
-	DefaultSocketResolver      SocketResolver      = resolveSocketByNetlink
-	DefaultProcessNameResolver ProcessNameResolver = resolveProcessNameByProcSearch
-)
-
 const (
 	sizeOfSocketDiagRequest = syscall.SizeofNlMsghdr + 8 + 48
 	socketDiagByFamily      = 20
@@ -45,15 +33,15 @@ const (
 )
 
 func findProcessName(network string, ip net.IP, srcPort int) (string, error) {
-	inode, uid, err := DefaultSocketResolver(network, ip, srcPort)
+	inode, uid, err := resolveSocketByNetlink(network, ip, srcPort)
 	if err != nil {
 		return "", err
 	}
 
-	return DefaultProcessNameResolver(inode, uid)
+	return resolveProcessNameByProcSearch(inode, uid)
 }
 
-func resolveSocketByNetlink(network string, ip net.IP, srcPort int) (int, int, error) {
+func resolveSocketByNetlink(network string, ip net.IP, srcPort int) (int32, int32, error) {
 	var family byte
 	var protocol byte
 
@@ -76,7 +64,7 @@ func resolveSocketByNetlink(network string, ip net.IP, srcPort int) (int, int, e
 
 	socket, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_DGRAM, syscall.NETLINK_INET_DIAG)
 	if err != nil {
-		return 0, 0, err
+		return 0, 0, fmt.Errorf("dial netlink: %w", err)
 	}
 	defer syscall.Close(socket)
 
@@ -94,7 +82,7 @@ func resolveSocketByNetlink(network string, ip net.IP, srcPort int) (int, int, e
 	}
 
 	if _, err := syscall.Write(socket, req); err != nil {
-		return 0, 0, err
+		return 0, 0, fmt.Errorf("write request: %w", err)
 	}
 
 	rb := pool.Get(pool.RelayBufferSize)
@@ -102,24 +90,27 @@ func resolveSocketByNetlink(network string, ip net.IP, srcPort int) (int, int, e
 
 	n, err := syscall.Read(socket, rb)
 	if err != nil {
-		return 0, 0, err
+		return 0, 0, fmt.Errorf("read response: %w", err)
 	}
 
 	messages, err := syscall.ParseNetlinkMessage(rb[:n])
 	if err != nil {
-		return 0, 0, err
+		return 0, 0, fmt.Errorf("parse netlink message: %w", err)
 	} else if len(messages) == 0 {
-		return 0, 0, io.ErrUnexpectedEOF
+		return 0, 0, fmt.Errorf("unexcepted netlink response")
 	}
 
 	message := messages[0]
 	if message.Header.Type&syscall.NLMSG_ERROR != 0 {
-		return 0, 0, syscall.ESRCH
+		return 0, 0, fmt.Errorf("netlink message: NLMSG_ERROR")
 	}
 
 	uid, inode := unpackSocketDiagResponse(&messages[0])
+	if uid < 0 || inode < 0 {
+		return 0, 0, fmt.Errorf("invalid uid(%d) or inode(%d)", uid, inode)
+	}
 
-	return int(uid), int(inode), nil
+	return uid, inode, nil
 }
 
 func packSocketDiagRequest(family, protocol byte, source net.IP, sourcePort uint16) []byte {
@@ -157,20 +148,20 @@ func packSocketDiagRequest(family, protocol byte, source net.IP, sourcePort uint
 	return buf
 }
 
-func unpackSocketDiagResponse(msg *syscall.NetlinkMessage) (inode, uid uint32) {
+func unpackSocketDiagResponse(msg *syscall.NetlinkMessage) (inode, uid int32) {
 	if len(msg.Data) < 72 {
 		return 0, 0
 	}
 
 	data := msg.Data
 
-	uid = nativeEndian.Uint32(data[64:68])
-	inode = nativeEndian.Uint32(data[68:72])
+	uid = int32(nativeEndian.Uint32(data[64:68]))
+	inode = int32(nativeEndian.Uint32(data[68:72]))
 
 	return
 }
 
-func resolveProcessNameByProcSearch(inode, uid int) (string, error) {
+func resolveProcessNameByProcSearch(inode, uid int32) (string, error) {
 	files, err := os.ReadDir(pathProc)
 	if err != nil {
 		return "", err
@@ -217,7 +208,7 @@ func resolveProcessNameByProcSearch(inode, uid int) (string, error) {
 		}
 	}
 
-	return "", syscall.ESRCH
+	return "", fmt.Errorf("process of uid(%d),inode(%d) not found", uid, inode)
 }
 
 func splitCmdline(cmdline []byte) string {