Support the Charset: armor header for inline PGP. Closes #3039.

The header is defined as optional by RfC4880.

This is based on patch-1.5.9.tamo.pgp_charsetchack.1. We only support
reading this header and, if present, recode the PGP output from the
given charset to $charset if we find it valid; otherwise fall back to
UTF-8. Certain clients make use of the header when sending mail, so mutt
should respect it because some messages are otherwise unreadable.

The sending side is not touched, we unconditionally send UTF-8.

diff --git a/pgp.c b/pgp.c
index bc77229e8a39d6f98b3d727ba6180efa34067743..c03627f2155dd66146548259587b20a0eff902a9 100644 (file)
--- a/pgp.c
+++ b/pgp.c
@@ -264,6 +264,7 @@ int pgp_application_pgp_handler (BODY *m, STATE *s)
   short maybe_goodsig = 1;
   short have_any_sigs = 0;
 
+  char *gpgcharset = NULL;
   char body_charset[STRING];
   mutt_get_body_charset (body_charset, sizeof (body_charset), m);
 
@@ -331,6 +332,16 @@ int pgp_application_pgp_handler (BODY *m, STATE *s)
              && (mutt_strcmp ("-----END PGP SIGNATURE-----\n", buf) == 0
                  || mutt_strcmp ("-----END PGP PUBLIC KEY BLOCK-----\n",buf) == 0)))
          break;
+       /* remember optional Charset: armor header as defined by RfC4880 */
+       if (mutt_strncmp ("Charset: ", buf, 9) == 0)
+       {
+         size_t l = 0;
+         gpgcharset = safe_strdup (buf + 9);
+         if ((l = mutt_strlen (gpgcharset)) > 0 && gpgcharset[l-1] == '\n')
+           gpgcharset[l-1] = 0;
+         if (mutt_check_charset (gpgcharset, 0) < 0)
+           mutt_str_replace (&gpgcharset, "UTF-8");
+       }
       }
 
       /* leave tmpfp open in case we still need it - but flush it! */
@@ -418,9 +429,7 @@ int pgp_application_pgp_handler (BODY *m, STATE *s)
       }
       
       /*
-       * Now, copy cleartext to the screen.  NOTE - we expect that PGP
-       * outputs utf-8 cleartext.  This may not always be true, but it 
-       * seems to be a reasonable guess.
+       * Now, copy cleartext to the screen.
        */
 
       if(s->flags & M_DISPLAY)
@@ -443,9 +452,14 @@ int pgp_application_pgp_handler (BODY *m, STATE *s)
       {
        FGETCONV *fc;
        int c;
+       char *expected_charset = gpgcharset && *gpgcharset ? gpgcharset : "utf-8";
+
+       dprint(4,(debugfile,"pgp: recoding inline from [%s] to [%s]\n",
+                 expected_charset, Charset));
+
        rewind (pgpout);
        state_set_prefix (s);
-       fc = fgetconv_open (pgpout, "utf-8", Charset, 0);
+       fc = fgetconv_open (pgpout, expected_charset, Charset, M_ICONV_HOOK_FROM);
        while ((c = fgetconv (fc)) != EOF)
          state_prefix_putc (c, s);
        fgetconv_close (&fc);
@@ -495,7 +509,9 @@ out:
     safe_fclose (&pgpout);
     mutt_unlink (outfile);
   }
-  
+
+  FREE(&gpgcharset);
+
   if (needpass == -1)
   {
     state_attach_puts (_("[-- Error: could not find beginning of PGP message! --]\n\n"), s);