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Diffstat (limited to 'lib/crypto/gpg/reader.go')
-rw-r--r--lib/crypto/gpg/reader.go165
1 files changed, 165 insertions, 0 deletions
diff --git a/lib/crypto/gpg/reader.go b/lib/crypto/gpg/reader.go
new file mode 100644
index 00000000..bf977ed4
--- /dev/null
+++ b/lib/crypto/gpg/reader.go
@@ -0,0 +1,165 @@
+// reader.go largerly mimics github.com/emersion/go-gpgmail, with changes made
+// to interface with the gpg package in aerc
+
+package gpg
+
+import (
+ "bufio"
+ "bytes"
+ "fmt"
+ "io"
+ "mime"
+ "strings"
+
+ "git.sr.ht/~rjarry/aerc/lib/crypto/gpg/gpgbin"
+ "git.sr.ht/~rjarry/aerc/models"
+ "github.com/emersion/go-message/textproto"
+)
+
+type Reader struct {
+ Header textproto.Header
+ MessageDetails *models.MessageDetails
+}
+
+func NewReader(h textproto.Header, body io.Reader) (*Reader, error) {
+ t, params, err := mime.ParseMediaType(h.Get("Content-Type"))
+ if err != nil {
+ return nil, err
+ }
+
+ if strings.EqualFold(t, "multipart/encrypted") && strings.EqualFold(params["protocol"], "application/pgp-encrypted") {
+ mr := textproto.NewMultipartReader(body, params["boundary"])
+ return newEncryptedReader(h, mr)
+ }
+ if strings.EqualFold(t, "multipart/signed") && strings.EqualFold(params["protocol"], "application/pgp-signature") {
+ micalg := params["micalg"]
+ mr := textproto.NewMultipartReader(body, params["boundary"])
+ return newSignedReader(h, mr, micalg)
+ }
+
+ var headerBuf bytes.Buffer
+ textproto.WriteHeader(&headerBuf, h)
+
+ return &Reader{
+ Header: h,
+ MessageDetails: &models.MessageDetails{
+ Body: io.MultiReader(&headerBuf, body),
+ },
+ }, nil
+}
+
+func Read(r io.Reader) (*Reader, error) {
+ br := bufio.NewReader(r)
+
+ h, err := textproto.ReadHeader(br)
+ if err != nil {
+ return nil, err
+ }
+ return NewReader(h, br)
+}
+
+func newEncryptedReader(h textproto.Header, mr *textproto.MultipartReader) (*Reader, error) {
+ p, err := mr.NextPart()
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read first part in multipart/encrypted message: %v", err)
+ }
+
+ t, _, err := mime.ParseMediaType(p.Header.Get("Content-Type"))
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to parse Content-Type of first part in multipart/encrypted message: %v", err)
+ }
+ if !strings.EqualFold(t, "application/pgp-encrypted") {
+ return nil, fmt.Errorf("gpgmail: first part in multipart/encrypted message has type %q, not application/pgp-encrypted", t)
+ }
+
+ metadata, err := textproto.ReadHeader(bufio.NewReader(p))
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to parse application/pgp-encrypted part: %v", err)
+ }
+ if s := metadata.Get("Version"); s != "1" {
+ return nil, fmt.Errorf("gpgmail: unsupported PGP/MIME version: %q", s)
+ }
+
+ p, err = mr.NextPart()
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read second part in multipart/encrypted message: %v", err)
+ }
+ t, _, err = mime.ParseMediaType(p.Header.Get("Content-Type"))
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to parse Content-Type of second part in multipart/encrypted message: %v", err)
+ }
+ if !strings.EqualFold(t, "application/octet-stream") {
+ return nil, fmt.Errorf("gpgmail: second part in multipart/encrypted message has type %q, not application/octet-stream", t)
+ }
+
+ md, err := gpgbin.Decrypt(p)
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read PGP message: %v", err)
+ }
+
+ cleartext := bufio.NewReader(md.Body)
+ cleartextHeader, err := textproto.ReadHeader(cleartext)
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read encrypted header: %v", err)
+ }
+
+ t, params, err := mime.ParseMediaType(cleartextHeader.Get("Content-Type"))
+ if err != nil {
+ return nil, err
+ }
+
+ if md.IsEncrypted && !md.IsSigned && strings.EqualFold(t, "multipart/signed") && strings.EqualFold(params["protocol"], "application/pgp-signature") {
+ // RFC 1847 encapsulation, see RFC 3156 section 6.1
+ micalg := params["micalg"]
+ mr := textproto.NewMultipartReader(cleartext, params["boundary"])
+ mds, err := newSignedReader(cleartextHeader, mr, micalg)
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read encapsulated multipart/signed message: %v", err)
+ }
+ mds.MessageDetails.IsEncrypted = md.IsEncrypted
+ mds.MessageDetails.DecryptedWith = md.DecryptedWith
+ mds.MessageDetails.DecryptedWithKeyId = md.DecryptedWithKeyId
+ return mds, nil
+ }
+
+ var headerBuf bytes.Buffer
+ textproto.WriteHeader(&headerBuf, cleartextHeader)
+ md.Body = io.MultiReader(&headerBuf, cleartext)
+
+ return &Reader{
+ Header: h,
+ MessageDetails: md,
+ }, nil
+}
+
+func newSignedReader(h textproto.Header, mr *textproto.MultipartReader, micalg string) (*Reader, error) {
+ micalg = strings.ToLower(micalg)
+ p, err := mr.NextPart()
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read signed part in multipart/signed message: %v", err)
+ }
+ var headerBuf bytes.Buffer
+ textproto.WriteHeader(&headerBuf, p.Header)
+ var msg bytes.Buffer
+ headerRdr := bytes.NewReader(headerBuf.Bytes())
+ fullMsg := io.MultiReader(headerRdr, p)
+ io.Copy(&msg, fullMsg)
+
+ sig, err := mr.NextPart()
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read pgp part in multipart/signed message: %v", err)
+ }
+
+ md, err := gpgbin.Verify(&msg, sig)
+ if err != nil {
+ return nil, fmt.Errorf("gpgmail: failed to read PGP message: %v", err)
+ }
+ if md.Micalg != micalg && md.SignatureError == "" {
+ md.SignatureError = "gpg: header hash does not match actual sig hash"
+ }
+
+ return &Reader{
+ Header: h,
+ MessageDetails: md,
+ }, nil
+}