From e7959c280c0361d2e448776d9ea11305e2f026bc Mon Sep 17 00:00:00 2001
From: Steve Holme <steve_holme@hotmail.com>
Date: Sat, 8 Feb 2020 00:14:57 +0000
Subject: smtp: Support UTF-8 based host names in the RCPT TO command

---
 lib/smtp.c              | 24 +++++++++++++++----
 tests/data/Makefile.inc |  1 +
 tests/data/test960      |  3 +++
 tests/data/test963      | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 85 insertions(+), 5 deletions(-)
 create mode 100644 tests/data/test963

diff --git a/lib/smtp.c b/lib/smtp.c
index 18c45afbe..1718cc2db 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -659,14 +659,28 @@ static CURLcode smtp_perform_rcpt_to(struct connectdata *conn)
   CURLcode result = CURLE_OK;
   struct Curl_easy *data = conn->data;
   struct SMTP *smtp = data->req.protop;
+  char *address = NULL;
+  struct hostname host = { NULL, NULL, NULL, NULL };
+
+  /* Parse the recipient mailbox 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,
+                              &address, &host);
+  if(result)
+    return result;
 
   /* Send the RCPT TO command */
-  if(smtp->rcpt->data[0] == '<')
-    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "RCPT TO:%s",
-                           smtp->rcpt->data);
+  if(host.name)
+    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "RCPT TO:<%s@%s>", address,
+                           host.name);
   else
-    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "RCPT TO:<%s>",
-                           smtp->rcpt->data);
+    /* An invalid mailbox was provided but we'll simply let the server worry
+       about that and reply with a 501 error */
+    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "RCPT TO:<%s>", address);
+
+  Curl_free_idnconverted_hostname(&host);
+  free(address);
+
   if(!result)
     state(conn, SMTP_RCPT);
 
diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
index 0f0192847..8d2ef14ce 100644
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -109,6 +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 \
 \
 test1000 test1001 test1002 test1003 test1004 test1005 test1006 test1007 \
 test1008 test1009 test1010 test1011 test1012 test1013 test1014 test1015 \
diff --git a/tests/data/test960 b/tests/data/test960
index d164aa83c..ac7ee5f5f 100644
--- a/tests/data/test960
+++ b/tests/data/test960
@@ -16,6 +16,9 @@ SMTP
 <server>
 smtp
 </server>
+<features>
+!idn
+</features>
 <setenv>
 LC_ALL=en_US.UTF-8
 LC_CTYPE=en_US.UTF-8
diff --git a/tests/data/test963 b/tests/data/test963
new file mode 100644
index 000000000..6328304c4
--- /dev/null
+++ b/tests/data/test963
@@ -0,0 +1,62 @@
+<testcase>
+<info>
+<keywords>
+SMTP
+IDN
+</keywords>
+</info>
+
+#
+# Server-side
+<reply>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+smtp
+</server>
+<features>
+idn
+</features>
+<setenv>
+LC_ALL=en_US.UTF-8
+LC_CTYPE=en_US.UTF-8
+</setenv>
+<precheck>
+perl -MI18N::Langinfo=langinfo,CODESET -e 'die "Needs a UTF-8 locale" if (lc(langinfo(CODESET())) ne "utf-8");'
+</precheck>
+ <name>
+SMTP without SMTPUTF8 support (IDN Enabked) - UTF-8 based recipient (host part only)
+ </name>
+<stdin>
+From: different
+To: another
+
+body
+</stdin>
+<command>
+smtp://%HOSTIP:%SMTPPORT/963 --mail-rcpt recipient@åäö.se --mail-from sender@example.com -T -
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol>
+EHLO 963
+MAIL FROM:<sender@example.com>
+RCPT TO:<recipient@xn--4cab6c.se>
+DATA
+QUIT
+</protocol>
+<upload>
+From: different
+To: another
+
+body
+.
+</upload>
+</verify>
+</testcase>
-- 
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