feat: add gpg integration

This commit adds gpg system integration. This is done through two new
packages: gpgbin, which handles the system calls and parsing; and gpg
which is mostly a copy of emersion/go-pgpmail with modifications to
interface with package gpgbin. gpg includes tests for many cases, and
by it's nature also tests package gpgbin. I separated these in case an
external dependency is ever used for the gpg sys-calls/parsing (IE we
mirror how go-pgpmail+openpgp currently are dependencies)

Two new config options are introduced:
* pgp-provider. If it is not explicitly set to "gpg", aerc will default to
it's internal pgp provider
* pgp-key-id: (Optionally) specify a key by short or long keyId

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/crypto/gpg/gpgbin/decrypt.go b/lib/crypto/gpg/gpgbin/decrypt.go
new file mode 100644
index 0000000..4b8d8f2
--- /dev/null
+++ b/lib/crypto/gpg/gpgbin/decrypt.go
@@ -0,0 +1,34 @@
+package gpgbin
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+
+	"git.sr.ht/~rjarry/aerc/models"
+)
+
+// Decrypt runs gpg --decrypt on the contents of r. If the packet is signed,
+// the signature is also verified
+func Decrypt(r io.Reader) (*models.MessageDetails, error) {
+	md := new(models.MessageDetails)
+	orig, err := ioutil.ReadAll(r)
+	if err != nil {
+		return md, err
+	}
+	args := []string{"--decrypt"}
+	g := newGpg(bytes.NewReader(orig), args)
+	err = g.cmd.Run()
+	if err != nil {
+		err = parseError(g.stderr.String())
+		switch GPGErrors[err.Error()] {
+		case ERROR_NO_PGP_DATA_FOUND:
+			md.Body = bytes.NewReader(orig)
+			return md, nil
+		default:
+		}
+	}
+	outRdr := bytes.NewReader(g.stdout.Bytes())
+	parse(outRdr, md)
+	return md, nil
+}