refactor: Split large main file

pem_io.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"bytes"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+	"os"
+)
+
+func decodeCrlBytes(content []byte) ([]byte, error) {
+	if !bytes.Contains(content, []byte("BEGIN")) {
+		return content, nil
+	}
+	block, rest := pem.Decode(content)
+	if block == nil {
+		return nil, fmt.Errorf("crl pem block could not be decoded")
+	}
+	if len(bytes.TrimSpace(rest)) > 0 {
+		return nil, fmt.Errorf("crl file contains trailing data")
+	}
+	return block.Bytes, nil
+}
+
+func loadCrlFromFile(path string) (*x509.RevocationList, error) {
+	content, readError := os.ReadFile(path)
+	if readError != nil {
+		return nil, readError
+	}
+	derBytes, decodeError := decodeCrlBytes(content)
+	if decodeError != nil {
+		return nil, fmt.Errorf("%s: %w", path, decodeError)
+	}
+	return x509.ParseRevocationList(derBytes)
+}
+
+func loadCertificateFromFile(path string) (*x509.Certificate, error) {
+	content, readError := os.ReadFile(path)
+	if readError != nil {
+		return nil, readError
+	}
+	block, rest := pem.Decode(content)
+	if block == nil {
+		return nil, fmt.Errorf("%s: certificate pem block could not be decoded", path)
+	}
+	if len(bytes.TrimSpace(rest)) > 0 {
+		return nil, fmt.Errorf("%s: certificate file contains trailing data", path)
+	}
+	return x509.ParseCertificate(block.Bytes)
+}