1 files changed, 104 insertions, 0 deletions
diff --git a/contrib/sendmail/libsm/utf8_valid.c b/contrib/sendmail/libsm/utf8_valid.c
new file mode 100644
index 000000000000..3181eca907b9
--- /dev/null
+++ b/contrib/sendmail/libsm/utf8_valid.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2020 Proofpoint, Inc. and its suppliers.
+ *	All rights reserved.
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the sendmail distribution.
+ *
+ */
+
+#include <sm/gen.h>
+#include <sm/sendmail.h>
+#include <sm/ixlen.h>
+
+#if USE_EAI
+
+/*
+**  legal utf-8 byte sequence
+**  http://www.unicode.org/versions/Unicode6.0.0/ch03.pdf - page 94
+**
+**   Code Points        1st       2s       3s       4s
+**  U+0000..U+007F     00..7F
+**  U+0080..U+07FF     C2..DF   80..BF
+**  U+0800..U+0FFF     E0       A0..BF   80..BF
+**  U+1000..U+CFFF     E1..EC   80..BF   80..BF
+**  U+D000..U+D7FF     ED       80..9F   80..BF
+**  U+E000..U+FFFF     EE..EF   80..BF   80..BF
+**  U+10000..U+3FFFF   F0       90..BF   80..BF   80..BF
+**  U+40000..U+FFFFF   F1..F3   80..BF   80..BF   80..BF
+**  U+100000..U+10FFFF F4       80..8F   80..BF   80..BF
+*/
+
+/*
+**  based on
+**  https://github.com/lemire/fastvalidate-utf-8.git
+**  which is distributed under an MIT license (besides others).
+*/
+
+bool
+utf8_valid(b, length)
+	const char *b;
+	size_t length;
+{
+	const unsigned char *bytes;
+	size_t index;
+
+	bytes = (const unsigned char *)b;
+	index = 0;
+	while (true)
+	{
+		unsigned char byte1;
+
+		do { /* fast ASCII Path */
+			if (index >= length)
+				return true;
+			byte1 = bytes[index++];
+		} while (byte1 < 0x80);
+		if (byte1 < 0xE0)
+		{
+			/* Two-byte form. */
+			if (index == length)
+				return false;
+			if (byte1 < 0xC2 || bytes[index++] > 0xBF)
+				return false;
+		}
+		else if (byte1 < 0xF0)
+		{
+			/* Three-byte form. */
+			if (index + 1 >= length)
+				return false;
+			unsigned char byte2 = bytes[index++];
+			if (byte2 > 0xBF
+			    /* Overlong? 5 most significant bits must not all be zero. */
+			    || (byte1 == 0xE0 && byte2 < 0xA0)
+			    /* Check for illegal surrogate codepoints. */
+			    || (byte1 == 0xED && 0xA0 <= byte2)
+			    /* Third byte trailing-byte test. */
+			    || bytes[index++] > 0xBF)
+				return false;
+		}
+		else
+		{
+
+			/* Four-byte form. */
+			if (index + 2 >= length)
+				return false;
+			int byte2 = bytes[index++];
+			if (byte2 > 0xBF
+			    /* Check that 1 <= plane <= 16. Tricky optimized form of: */
+			    /* if (byte1 > (byte) 0xF4 */
+			    /*    || byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 */
+			    /*    || byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) */
+			    || (((byte1 << 28) + (byte2 - 0x90)) >> 30) != 0
+			    /* Third byte trailing-byte test */
+			    || bytes[index++] > 0xBF
+			    /* Fourth byte trailing-byte test */
+			    || bytes[index++] > 0xBF)
+				return false;
+		}
+	}
+	/* NOTREACHED */
+	return false;
+}
+#endif /* USE_EAI */