common: Prepare for parsing mail sub-addresses.

* common/mbox-util.c (mailbox_from_userid): Add arg subaddress and
implement.  Change all callers to pass false for it.

* common/t-mbox-util.c (run_mbox_no_sub_test): New.
(run_filter): Add arg no_sub.
(main): Call new test and add option --no-sub.
--

Some stats: In the about 5300000 keys on the SKS servers we found 3055
unique mailboxes with a '+' in it.  After removing leading and
trailing '+' as well as multiple '+' (e.g. "c++" or "foo+bar+baz")
2697 were left which seem to be valid sub-addresses.

To filter mailboxes out from a line delimited list with
user-ids (e.g. an SQL output), the command

   t-mbox-util --verbose --filter

can be used; to output w/o sub-addresses add --no-sub.

GnuPG-bug-id: 4200
Signed-off-by: Werner Koch <[email protected]>

1 files changed, 28 insertions, 4 deletions

diff --git a/common/mbox-util.c b/common/mbox-util.c
index 76255ba38..a9086a3f5 100644
--- a/common/mbox-util.c
+++ b/common/mbox-util.c
@@ -173,11 +173,12 @@ is_valid_mailbox (const char *name)
 
 
 /* Return the mailbox (local-part@domain) form a standard user id.
-   All plain ASCII characters in the result are converted to
-   lowercase.  Caller must free the result.  Returns NULL if no valid
-   mailbox was found (or we are out of memory). */
+ * All plain ASCII characters in the result are converted to
+ * lowercase.  If SUBADDRESS is 1, '+' denoted sub-addresses are not
+ * included in the result.  Caller must free the result.  Returns NULL
+ * if no valid mailbox was found (or we are out of memory). */
 char *
-mailbox_from_userid (const char *userid)
+mailbox_from_userid (const char *userid, int subaddress)
 {
   const char *s, *s_end;
   size_t len;
@@ -226,6 +227,29 @@ mailbox_from_userid (const char *userid)
   else
     errno = EINVAL;
 
+  if (result && subaddress == 1)
+    {
+      char *atsign, *plus;
+
+      if ((atsign = strchr (result, '@')))
+        {
+          /* We consider a subaddress only if there is a single '+'
+           * in the local part and the '+' is not the first or last
+           * character.  */
+          *atsign = 0;
+          if ((plus = strchr (result, '+'))
+              && !strchr (plus+1, '+')
+              && result != plus
+              && plus[1] )
+            {
+              *atsign = '@';
+              memmove (plus, atsign, strlen (atsign)+1);
+            }
+          else
+            *atsign = '@';
+        }
+    }
+
   return result? ascii_strlwr (result): NULL;
 }