From e43d699973eb3207f1f7948d5d8cbb71106a7ec1 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Thu, 31 Oct 2019 12:52:18 +0100
Subject: [PATCH] util: add functions for printing and parsing hexadecimal data

---
 keys.c           | 16 ++--------------
 test/unit/util.c | 15 +++++++++++++++
 util.c           | 39 +++++++++++++++++++++++++++++++++++++++
 util.h           |  7 +++++++
 4 files changed, 63 insertions(+), 14 deletions(-)

diff --git a/keys.c b/keys.c
index 1305e82..1fa2215 100644
--- a/keys.c
+++ b/keys.c
@@ -159,25 +159,13 @@ determine_hash_delay(uint32_t key_id)
 static int
 decode_key(char *key)
 {
-  int i, j, len = strlen(key);
-  char buf[3], *p;
+  int len = strlen(key);
 
   if (!strncmp(key, "ASCII:", 6)) {
     memmove(key, key + 6, len - 6);
     return len - 6;
   } else if (!strncmp(key, "HEX:", 4)) {
-    if ((len - 4) % 2)
-      return 0;
-
-    for (i = 0, j = 4; j + 1 < len; i++, j += 2) {
-      buf[0] = key[j], buf[1] = key[j + 1], buf[2] = '\0';
-      key[i] = strtol(buf, &p, 16);
-
-      if (p != buf + 2)
-        return 0;
-    }
-
-    return i;
+    return UTI_HexToBytes(key + 4, key, len);
   } else {
     /* assume ASCII */
     return len;
diff --git a/test/unit/util.c b/test/unit/util.c
index af9e90c..824f3a8 100644
--- a/test/unit/util.c
+++ b/test/unit/util.c
@@ -318,4 +318,19 @@ void test_unit(void) {
   TEST_CHECK(UTI_RemoveFile(NULL, "testfile", NULL));
   TEST_CHECK(stat("testfile", &st) < 0);
   TEST_CHECK(!UTI_RemoveFile(NULL, "testfile", NULL));
+
+  assert(sizeof (buf) >= 16);
+  TEST_CHECK(UTI_HexToBytes("", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("0", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF0", buf, 8) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF0", buf, sizeof (buf)) == 9);
+  TEST_CHECK(memcmp(buf, "\x00\x12\x34\x56\x78\x9A\xBC\xDE\xF0", 9) == 0);
+  memcpy(buf, "AB123456780001", 15);
+  TEST_CHECK(UTI_HexToBytes(buf, buf, sizeof (buf)) == 7);
+  TEST_CHECK(memcmp(buf, "\xAB\x12\x34\x56\x78\x00\x01", 7) == 0);
+
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 7, buf, 14) == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 7, buf, 15) == 1);
+  TEST_CHECK(strcmp(buf, "AB123456780001") == 0);
 }
diff --git a/util.c b/util.c
index 0e605ac..ec3ea60 100644
--- a/util.c
+++ b/util.c
@@ -1361,3 +1361,42 @@ UTI_GetRandomBytes(void *buf, unsigned int len)
   UTI_GetRandomBytesUrandom(buf, len);
 #endif
 }
+
+/* ================================================== */
+
+int
+UTI_BytesToHex(const void *buf, unsigned int buf_len, char *hex, unsigned int hex_len)
+{
+  unsigned int i, l;
+
+  for (i = l = 0; i < buf_len; i++, l += 2) {
+    if (l + 2 >= hex_len ||
+        snprintf(hex + l, hex_len - l, "%02hhX", ((const char *)buf)[i]) != 2)
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+unsigned int
+UTI_HexToBytes(const char *hex, void *buf, unsigned int len)
+{
+  char *p, byte[3];
+  unsigned int i;
+
+  for (i = 0; i < len && *hex != '\0'; i++) {
+    byte[0] = *hex++;
+    if (*hex == '\0')
+      return 0;
+    byte[1] = *hex++;
+    byte[2] = '\0';
+    ((char *)buf)[i] = strtol(byte, &p, 16);
+
+    if (p != byte + 2)
+      return 0;
+  }
+
+  return *hex == '\0' ? i : 0;
+}
diff --git a/util.h b/util.h
index f0cc141..6f0db5c 100644
--- a/util.h
+++ b/util.h
@@ -205,6 +205,13 @@ extern void UTI_GetRandomBytesUrandom(void *buf, unsigned int len);
    generating long-term keys */
 extern void UTI_GetRandomBytes(void *buf, unsigned int len);
 
+/* Print data in hexadecimal format */
+extern int UTI_BytesToHex(const void *buf, unsigned int buf_len, char *hex, unsigned int hex_len);
+
+/* Parse a string containing data in hexadecimal format.  In-place conversion
+   is supported. */
+extern unsigned int UTI_HexToBytes(const char *hex, void *buf, unsigned int len);
+
 /* Macros to get maximum and minimum of two values */
 #ifdef MAX
 #undef MAX