util: Fix mac truncation (openbmc#58)

We don't want to allow MACs to be silently truncated. Change-Id: I1d2771c481bccb30e957b829fd1db1e4db0dc051 Signed-off-by: William A. Kennington III <[email protected]> Co-authored-by: William A. Kennington III <[email protected]>
eddiejames · Feb 21, 2023 · 363a2ad · 363a2ad
1 parent 2067354
commit 363a2ad
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Showing 3 changed files with 42 additions and 10 deletions.
diff --git a/src/util.cpp b/src/util.cpp
@@ -10,6 +10,7 @@
 
 #include <algorithm>
 #include <cctype>
+#include <charconv>
 #include <cstdlib>
 #include <cstring>
 #include <filesystem>
@@ -23,6 +24,7 @@
 #include <stdexcept>
 #include <stdplus/raw.hpp>
 #include <string>
+#include <string_view>
 #include <variant>
 #include <xyz/openbmc_project/Common/error.hpp>
 
@@ -633,14 +635,41 @@ ether_addr getfromInventory(sdbusplus::bus::bus& bus,
     return fromString(std::get<std::string>(value));
 }
 
-ether_addr fromString(const char* str)
+uint8_t decodeHex(std::string_view str)
 {
-    struct ether_addr* mac = ether_aton(str);
-    if (mac == nullptr)
+    uint8_t ret;
+    auto res = std::from_chars(str.begin(), str.end(), ret, 16);
+    if (res.ptr != str.end() || res.ec != std::errc())
     {
-        throw std::invalid_argument("Invalid MAC Address");
+        throw std::invalid_argument("Not hex");
     }
-    return *mac;
+    return ret;
+}
+ether_addr fromString(std::string_view str)
+{
+    ether_addr ret;
+    if (str.size() == 12 && str.find(":") == str.npos)
+    {
+        for (size_t i = 0; i < 6; ++i)
+        {
+            ret.ether_addr_octet[i] = decodeHex(str.substr(i * 2, 2));
+        }
+    }
+    else
+    {
+        for (size_t i = 0; i < 5; ++i)
+        {
+            auto loc = str.find(":");
+            ret.ether_addr_octet[i] = decodeHex(str.substr(0, loc));
+            str.remove_prefix(loc == str.npos ? str.size() : loc + 1);
+            if (str.empty())
+            {
+                throw std::invalid_argument("Missing mac data");
+            }
+        }
+        ret.ether_addr_octet[5] = decodeHex(str);
+    }
+    return ret;
 }
 
 std::string toString(const ether_addr& mac)

diff --git a/src/util.hpp b/src/util.hpp
@@ -44,11 +44,7 @@ ether_addr getfromInventory(sdbusplus::bus::bus& bus,
  *  @returns A mac address in network byte order
  *  @throws std::runtime_error for bad mac
  */
-ether_addr fromString(const char* str);
-inline ether_addr fromString(const std::string& str)
-{
-    return fromString(str.c_str());
-}
+ether_addr fromString(std::string_view str);
 
 /** @brief Converts the given mac address bytes into a string
  *  @param[in] mac - The mac address

diff --git a/test/test_util.cpp b/test/test_util.cpp
@@ -268,6 +268,13 @@ TEST(MacFromString, Bad)
 {
     EXPECT_THROW(fromString("0x:00:00:00:00:00"), std::invalid_argument);
     EXPECT_THROW(fromString("00:00:00:00:00"), std::invalid_argument);
+    EXPECT_THROW(fromString("00:00:00:00:00:"), std::invalid_argument);
+    EXPECT_THROW(fromString("00:00:00:00::00"), std::invalid_argument);
+    EXPECT_THROW(fromString(":00:00:00:00:00"), std::invalid_argument);
+    EXPECT_THROW(fromString("00::00:00:00:00"), std::invalid_argument);
+    EXPECT_THROW(fromString(":::::"), std::invalid_argument);
+    EXPECT_THROW(fromString("00:0:0:0:0"), std::invalid_argument);
+    EXPECT_THROW(fromString("00:00:00:00:00:00:00"), std::invalid_argument);
     EXPECT_THROW(fromString(""), std::invalid_argument);
 }