gpg: Detect duplicate keys with --add-recipients.

* g10/packet.h (struct pubkey_enc_list): Change to use a union to also
store symkey_enc data.  Adjust all users accordingly.
(struct pubkey_enc_info_item): New.
* g10/free-packet.c (free_pubkey_enc_list): New.
* g10/mainproc.c (release_list): Use it here.
* g10/decrypt.c (decrypt_message): and here.

* g10/encrypt.c (reencrypt_to_new_recipients): Record the used
pubkey_enc packets and pass them to write_pubkey_enc_from_list.
(write_pubkey_enc_from_list): Add arg restrict_pk_list and use it to
skip recipients already used.
--

GnuPG-bug-id: 1825

Note that we here already prepare to better handle symkey_enc packets.

1 files changed, 22 insertions, 3 deletions

diff --git a/g10/packet.h b/g10/packet.h
index 6b1be6fc8..52f9aef8f 100644
--- a/g10/packet.h
+++ b/g10/packet.h
@@ -166,17 +166,34 @@ typedef struct {
   /* Whether to hide the key id.  This value is not directly
      serialized.  */
   byte    throw_keyid;
-  /* The session key.  */
+  /* The encrypted session key.  */
   gcry_mpi_t     data[PUBKEY_MAX_NENC];
 } PKT_pubkey_enc;
 
 
-/* An object to build a list of public-key encrypted session key.  */
+/* An object to build a list of public-key and symkey encrypted
+ * session key.  Note that we use a dedicated uinion here instead of
+ * the usual PACKET type; this the need for extra allocations. */
 struct pubkey_enc_list
 {
   struct pubkey_enc_list *next;
   int result;
-  PKT_pubkey_enc d;
+  int u_sym;  /* Use the sym member.  */
+  union {
+    PKT_pubkey_enc pub;
+    PKT_symkey_enc sym;
+  } u;
+};
+
+
+/* An object to record some properties of a PKT_pubkey_enc packet.  */
+struct pubkey_enc_info_item
+{
+  struct pubkey_enc_info_item *next;
+  /* 3 fields copied from a PKT_pubkey_enc:  */
+  u32     keyid[2];
+  byte    version;
+  byte    pubkey_algo;
 };
 
 
@@ -945,6 +962,8 @@ PKT_public_key *copy_public_key( PKT_public_key *d, PKT_public_key *s );
 PKT_signature *copy_signature( PKT_signature *d, PKT_signature *s );
 PKT_user_id *scopy_user_id (PKT_user_id *sd );
 
+void free_pubkey_enc_list (struct pubkey_enc_list *pkenc_list);
+
 int cmp_public_keys( PKT_public_key *a, PKT_public_key *b );
 int cmp_signatures( PKT_signature *a, PKT_signature *b );
 int cmp_user_ids( PKT_user_id *a, PKT_user_id *b );