From 34a1ffb05f3cf8efb8781627c95fffe89a1e86a1 Mon Sep 17 00:00:00 2001
From: Steve Holme <steve_holme@hotmail.com>
Date: Sun, 9 Feb 2020 16:41:34 +0000
Subject: smtp: Support the SMTPUTF8 extension for the EXPN command

Simply notify the server we support the SMTPUTF8 extension if it does.
---
 lib/smtp.c              | 25 ++++++++++++++++---------
 tests/data/Makefile.inc |  2 +-
 tests/data/test969      | 50 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 10 deletions(-)
 create mode 100644 tests/data/test969

diff --git a/lib/smtp.c b/lib/smtp.c
index 362e8eae9..b3b1e83ed 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -487,16 +487,16 @@ static CURLcode smtp_perform_command(struct connectdata *conn)
   struct SMTP *smtp = data->req.protop;
 
   if(smtp->rcpt) {
+    /* We notify the server we are sending UTF-8 data if a) it supports the
+       SMTPUTF8 extension and b) The mailbox contains UTF-8 charaacters, in
+       either the local address or host name parts. This is regardless of
+       whether the host name is encoded using IDN ACE */
+    bool utf8 = FALSE;
+
     if((!smtp->custom) || (!smtp->custom[0])) {
       char *address = NULL;
       struct hostname host = { NULL, NULL, NULL, NULL };
 
-      /* We notify the server we are sending UTF-8 data if a) it supports the
-         SMTPUTF8 extension and b) The mailbox contains UTF-8 charaacters, in
-         either the local address or host name parts. This is regardless of
-         whether the host name is encoded using IDN ACE */
-      bool utf8 = FALSE;
-
       /* Parse the mailbox to verify into the local address and host name
          parts, converting the host name to an IDN A-label if necessary */
       result = smtp_parse_address(conn, smtp->rcpt->data,
@@ -521,10 +521,17 @@ static CURLcode smtp_perform_command(struct connectdata *conn)
       Curl_free_idnconverted_hostname(&host);
       free(address);
     }
-    else
+    else {
+      /* Establish whether we should report that we support SMTPUTF8 for EXPN
+         commands to the server as per RFC-6531 sect. 3.1 point 6 */
+      utf8 = (conn->proto.smtpc.utf8_supported) &&
+             (!strcmp(smtp->custom, "EXPN"));
+
       /* Send the custom recipient based command such as the EXPN command */
-      result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s %s", smtp->custom,
-                             smtp->rcpt->data);
+      result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s %s%s", smtp->custom,
+                             smtp->rcpt->data,
+                             utf8 ? " SMTPUTF8" : "");
+    }
   }
   else
     /* Send the non-recipient based command such as HELP */
diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
index 9b9f8e485..d07d2885a 100644
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -109,7 +109,7 @@ test927 test928 test929 test930 test931 test932 test933 test934 test935 \
 test936 test937 test938 test939 test940 test941 test942 test943 test944 \
 test945 test946 test947 test948 test949 test950 test951 test952 test953 \
 test954 test955 test956 test957 test958 test959 test960 test961 test962 \
-test963 test964 test965 test966 test967 test968 \
+test963 test964 test965 test966 test967 test968 test969 \
 \
 test1000 test1001 test1002 test1003 test1004 test1005 test1006 test1007 \
 test1008 test1009 test1010 test1011 test1012 test1013 test1014 test1015 \
diff --git a/tests/data/test969 b/tests/data/test969
new file mode 100644
index 000000000..0df81d325
--- /dev/null
+++ b/tests/data/test969
@@ -0,0 +1,50 @@
+<testcase>
+<info>
+<keywords>
+SMTP
+EXPN
+CUSTOMREQUEST
+IDN
+</keywords>
+</info>
+
+#
+# Server-side
+<reply>
+<servercmd>
+CAPA SMTPUTF8
+</servercmd>
+<data>
+250-Joe Smith <joe.smith@example.com>
+250-Harry Smith <harry.smith@example.com>
+250 Melvin Smith <melvin.smith@example.com>
+</data>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+smtp
+</server>
+<features>
+idn
+</features>
+ <name>
+SMTP mailing list EXPN (CUSTOMREQUEST) with SMTPUTF8 support
+ </name>
+ <command>
+smtp://%HOSTIP:%SMTPPORT/969 --mail-rcpt Friends -X EXPN
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol>
+EHLO 969
+EXPN Friends SMTPUTF8
+QUIT
+</protocol>
+</verify>
+</testcase>
-- 
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