Fix #80706: mail(): Headers after Bcc headers may be ignored

We need to handle the case where a CRLF after a Bcc header is not the
beginning of a folding marker, because in that case the Bcc header was
not the last "thing".

Closes GH-6666.

NEWS

@@ -2,6 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 2021, PHP 7.4.16
 
+- Core:
+  . Fixed #80706 (mail(): Headers after Bcc headers may be ignored). (cmb)
+
 - MySQLi:
   . Fixed bug #74779 (x() and y() truncating floats to integers). (cmb)
 

ext/standard/tests/mail/bug80706.phpt

@@ -0,0 +1,76 @@
+--TEST--
+Bug #72964 (White space not unfolded for CC/Bcc headers)
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY !== 'Windows') die('skip Windows only test');
+if (getenv("SKIP_SLOW_TESTS")) die('skip slow test');
+require_once __DIR__ . '/mail_skipif.inc';
+?>
+--INI--
+SMTP=localhost
+smtp_port=25
+--FILE--
+<?php
+require_once __DIR__ . '/mail_include.inc';
+
+function find_and_delete_message($username, $subject) {
+    global $default_mailbox, $password;
+
+    $imap_stream = imap_open($default_mailbox, $username, $password);
+    if ($imap_stream === false) {
+        die("Cannot connect to IMAP server $server: " . imap_last_error() . "\n");
+    }
+
+    $found = false;
+    $repeat_count = 20; // we will repeat a max of 20 times
+    while (!$found && $repeat_count > 0) {
+        // sleep for a while to allow msg to be delivered
+        sleep(1);
+
+        $num_messages = imap_check($imap_stream)->Nmsgs;
+        for ($i = $num_messages; $i > 0; $i--) {
+            $info = imap_headerinfo($imap_stream, $i);
+            if ($info->subject === $subject) {
+                $header = imap_fetchheader($imap_stream, $i);
+                echo "X-Mailer header found: ";
+                var_dump(strpos($header, 'X-Mailer: bug80706') !== false);
+                imap_delete($imap_stream, $i);
+                $found = true;
+                break;
+            }
+        }
+        $repeat_count--;
+    }
+
+    imap_close($imap_stream, CL_EXPUNGE);
+    return $found;
+}
+
+$to = "{$users[1]}@$domain";
+$subject = bin2hex(random_bytes(16));
+$message = 'hello';
+$headers = "From: webmaster@example.com\r\n"
+    . "Bcc: {$users[2]}@$domain\r\n"
+    . "X-Mailer: bug80706";
+
+$res = mail($to, $subject, $message, $headers);
+if ($res !== true) {
+	die("TEST FAILED : Unable to send test email\n");
+} else {
+	echo "Message sent OK\n";
+}
+
+foreach ([$users[1], $users[2]] as $user) {
+    if (!find_and_delete_message("$user@$domain", $subject)) {
+        echo "TEST FAILED: email not delivered\n";
+    } else {
+        echo "TEST PASSED: Message sent and deleted OK\n";
+    }
+}
+?>
+--EXPECT--
+Message sent OK
+X-Mailer header found: bool(true)
+TEST PASSED: Message sent and deleted OK
+X-Mailer header found: bool(true)
+TEST PASSED: Message sent and deleted OK

win32/sendmail.c

@@ -526,7 +526,7 @@ static int SendText(char *RPath, char *Subject, char *mailTo, char *mailCc, char
 				   header we know it was the last thing. */
 				pos2 = pos1;
 			} else {
-				char *pos3 = NULL;
+				char *pos3 = pos2;
 				while (pos2[2] == ' ' || pos2[2] == '\t') {
 					pos3 = strstr(pos2 + 2, "\r\n");
 					if (pos3 != NULL) {