Merge pull request #1 from xNaCly/main

refactor: cache inode->pid lookup via map on function startup

Author: Intevel

linux-open-ports.go

@@ -7,12 +7,13 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"unicode"
 )
 
 type OpenPort struct {
 	Protocol string
 	Port     int
-	PID      int
+	PID      string
 }
 
 func GetOpenPorts() ([]OpenPort, error) {
@@ -24,6 +25,8 @@ func GetOpenPorts() ([]OpenPort, error) {
 		"udp": {"/proc/net/udp", "/proc/net/udp6"},
 	}
 
+	cachedInodePIDMap := inodePIDMap()
+
 	for protocol, files := range protocolFiles {
 		for _, filePath := range files {
 			file, err := os.Open(filePath)
@@ -54,7 +57,11 @@ func GetOpenPorts() ([]OpenPort, error) {
 					continue
 				}
 
-				pid := findPIDByInode(inode)
+				pid, ok := cachedInodePIDMap[inode]
+				if !ok {
+					continue
+				}
+
 				portKey := fmt.Sprintf("%s/%d", protocol, port)
 				if !uniquePorts[portKey] {
 					openPorts = append(openPorts, OpenPort{
@@ -71,33 +78,32 @@ func GetOpenPorts() ([]OpenPort, error) {
 	return openPorts, nil
 }
 
-func findPIDByInode(inode string) int {
+func inodePIDMap() map[string]string {
+	m := map[string]string{}
 	procDirs, _ := os.ReadDir("/proc")
 	for _, procDir := range procDirs {
-		if !procDir.IsDir() || !isNumeric(procDir.Name()) {
+		pid := procDir.Name()
+		if !procDir.IsDir() && !unicode.IsDigit(rune(pid[0])) {
 			continue
 		}
 
-		pid := procDir.Name()
 		fdDir := filepath.Join("/proc", pid, "fd")
 		fdFiles, err := os.ReadDir(fdDir)
 		if err != nil {
 			continue
 		}
 
 		for _, fdFile := range fdFiles {
-			fdPath := filepath.Join(fdDir, fdFile.Name())
-			link, err := os.Readlink(fdPath)
-			if err == nil && strings.Contains(link, fmt.Sprintf("socket:[%s]", inode)) {
-				pidInt, _ := strconv.Atoi(pid)
-				return pidInt
+			path := filepath.Join(fdDir, fdFile.Name())
+			linkName, err := os.Readlink(path)
+			if err != nil {
+				continue
+			}
+			if strings.Contains(linkName, "socket") {
+				inode := linkName[8 : len(linkName)-1]
+				m[inode] = pid
 			}
 		}
 	}
-	return -1
-}
-
-func isNumeric(s string) bool {
-	_, err := strconv.Atoi(s)
-	return err == nil
+	return m
 }