expose fewer internals in packages, for easier software reuse

- prometheus is now behind an interface, they aren't dependencies for the
  reusable components anymore.
- some dependencies have been inverted: instead of packages importing a main
  package to get configuration, the main package now sets configuration in
  these packages. that means fewer internals are pulled in.
- some functions now have new parameters for values that were retrieved from
  package "mox-".

moxio/decode.go

@@ -1,27 +0,0 @@
-package moxio
-
-import (
-	"io"
-	"strings"
-
-	"golang.org/x/text/encoding/ianaindex"
-)
-
-// DecodeReader returns a reader that reads from r, decoding as charset. If
-// charset is empty, us-ascii, utf-8 or unknown, the original reader is
-// returned and no decoding takes place.
-func DecodeReader(charset string, r io.Reader) io.Reader {
-	switch strings.ToLower(charset) {
-	case "", "us-ascii", "utf-8":
-		return r
-	}
-	enc, _ := ianaindex.MIME.Encoding(charset)
-	if enc == nil {
-		enc, _ = ianaindex.IANA.Encoding(charset)
-	}
-	// todo: ianaindex doesn't know all encodings, e.g. gb2312. should we transform them, with which code?
-	if enc == nil {
-		return r
-	}
-	return enc.NewDecoder().Reader(r)
-}

moxio/decode_test.go

@@ -1,24 +0,0 @@
-package moxio
-
-import (
-	"io"
-	"strings"
-	"testing"
-)
-
-func TestDecodeReader(t *testing.T) {
-	check := func(charset, input, output string) {
-		t.Helper()
-		buf, err := io.ReadAll(DecodeReader(charset, strings.NewReader(input)))
-		tcheckf(t, err, "decode")
-		if string(buf) != output {
-			t.Fatalf("decoding %q with charset %q, got %q, expected %q", input, charset, buf, output)
-		}
-	}
-
-	check("", "☺", "☺")         // No decoding.
-	check("us-ascii", "☺", "☺") // No decoding.
-	check("utf-8", "☺", "☺")
-	check("iso-8859-1", string([]byte{0xa9}), "©")
-	check("iso-8859-5", string([]byte{0xd0}), "а")
-}

moxio/tlsinfo.go

@@ -0,0 +1,29 @@
+package moxio
+
+import (
+	"crypto/tls"
+	"fmt"
+)
+
+// TLSInfo returns human-readable strings about the TLS connection, for use in
+// logging.
+func TLSInfo(conn *tls.Conn) (version, ciphersuite string) {
+	st := conn.ConnectionState()
+
+	versions := map[uint16]string{
+		tls.VersionTLS10: "TLS1.0",
+		tls.VersionTLS11: "TLS1.1",
+		tls.VersionTLS12: "TLS1.2",
+		tls.VersionTLS13: "TLS1.3",
+	}
+
+	v, ok := versions[st.Version]
+	if ok {
+		version = v
+	} else {
+		version = fmt.Sprintf("TLS %x", st.Version)
+	}
+
+	ciphersuite = tls.CipherSuiteName(st.CipherSuite)
+	return
+}