cmd: start linting fixes.

cmd/stealchain-server/main.go

@@ -8,7 +8,6 @@ import (
 	"encoding/pem"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"os"
 
@@ -46,18 +45,18 @@ func main() {
 		os.Exit(1)
 	}
 	cfg.Certificates = append(cfg.Certificates, cert)
-	if sysRoot != "" {
-		pemList, err := ioutil.ReadFile(sysRoot)
-		die.If(err)
+ if sysRoot != "" {
+        pemList, err := os.ReadFile(sysRoot)
+        die.If(err)
 
-		roots := x509.NewCertPool()
-		if !roots.AppendCertsFromPEM(pemList) {
-			fmt.Printf("[!] no valid roots found")
-			roots = nil
-		}
+        roots := x509.NewCertPool()
+        if !roots.AppendCertsFromPEM(pemList) {
+            fmt.Printf("[!] no valid roots found")
+            roots = nil
+        }
 
-		cfg.RootCAs = roots
-	}
+        cfg.RootCAs = roots
+    }
 
 	l, err := net.Listen("tcp", listenAddr)
 	if err != nil {
@@ -65,42 +64,46 @@ func main() {
 		os.Exit(1)
 	}
 
-	for {
-		conn, err := l.Accept()
-		if err != nil {
-			fmt.Println(err.Error())
-		}
-
-		raddr := conn.RemoteAddr()
-		tconn := tls.Server(conn, cfg)
-		err = tconn.Handshake()
-		if err != nil {
-			fmt.Printf("[+] %v: failed to complete handshake: %v\n", raddr, err)
-			continue
-		}
-		cs := tconn.ConnectionState()
-		if len(cs.PeerCertificates) == 0 {
-			fmt.Printf("[+] %v: no chain presented\n", raddr)
-			continue
-		}
-
-		var chain []byte
-		for _, cert := range cs.PeerCertificates {
-			p := &pem.Block{
-				Type:  "CERTIFICATE",
-				Bytes: cert.Raw,
-			}
-			chain = append(chain, pem.EncodeToMemory(p)...)
-		}
-
-		var nonce [16]byte
-		_, err = rand.Read(nonce[:])
-		if err != nil {
-			panic(err)
-		}
-		fname := fmt.Sprintf("%v-%v.pem", raddr, hex.EncodeToString(nonce[:]))
-		err = ioutil.WriteFile(fname, chain, 0644)
-		die.If(err)
-		fmt.Printf("%v: [+] wrote %v.\n", raddr, fname)
-	}
+    for {
+        conn, err := l.Accept()
+        if err != nil {
+            fmt.Println(err.Error())
+            continue
+        }
+        handleConn(conn, cfg)
+    }
+}
+
+// handleConn performs a TLS handshake, extracts the peer chain, and writes it to a file.
+func handleConn(conn net.Conn, cfg *tls.Config) {
+    defer conn.Close()
+    raddr := conn.RemoteAddr()
+    tconn := tls.Server(conn, cfg)
+    if err := tconn.Handshake(); err != nil {
+        fmt.Printf("[+] %v: failed to complete handshake: %v\n", raddr, err)
+        return
+    }
+    cs := tconn.ConnectionState()
+    if len(cs.PeerCertificates) == 0 {
+        fmt.Printf("[+] %v: no chain presented\n", raddr)
+        return
+    }
+
+    var chain []byte
+    for _, cert := range cs.PeerCertificates {
+        p := &pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw}
+        chain = append(chain, pem.EncodeToMemory(p)...)
+    }
+
+    var nonce [16]byte
+    if _, err := rand.Read(nonce[:]); err != nil {
+        fmt.Printf("[+] %v: failed to generate filename nonce: %v\n", raddr, err)
+        return
+    }
+    fname := fmt.Sprintf("%v-%v.pem", raddr, hex.EncodeToString(nonce[:]))
+    if err := os.WriteFile(fname, chain, 0o644); err != nil {
+        fmt.Printf("[+] %v: failed to write %v: %v\n", raddr, fname, err)
+        return
+    }
+    fmt.Printf("%v: [+] wrote %v.\n", raddr, fname)
 }