util: Add a function for converting IP bytes to strings

We need this for future work which turns netlink data into IP addresses.

Tested:
    Run through unit tests.

Change-Id: If078b28246509ca2ebd3bf7bab652b84258df0bd
Signed-off-by: William A. Kennington III <wak@google.com>

3 files changed, 66 insertions, 0 deletions

diff --git a/test/test_util.cpp b/test/test_util.cpp
index f536bd7..25953a1 100644
--- a/test/test_util.cpp
+++ b/test/test_util.cpp
@@ -1,5 +1,6 @@
 #include "util.hpp"
 
+#include <arpa/inet.h>
 #include <netinet/in.h>
 
 #include <cstddef>
@@ -44,6 +45,35 @@ TEST_F(TestUtil, MacToString)
     EXPECT_EQ("70:FF:84:09:35:09", mac_address::toString(mac2));
 }
 
+TEST_F(TestUtil, IpToString)
+{
+    struct in_addr ip1;
+    EXPECT_EQ(1, inet_pton(AF_INET, "192.168.10.1", &ip1));
+    EXPECT_EQ("192.168.10.1", toString(InAddrAny(ip1)));
+
+    struct in6_addr ip2;
+    EXPECT_EQ(1, inet_pton(AF_INET6, "fdd8:b5ad:9d93:94ee::2:1", &ip2));
+    EXPECT_EQ("fdd8:b5ad:9d93:94ee::2:1", toString(InAddrAny(ip2)));
+
+    InAddrAny ip3;
+    try
+    {
+        struct E
+        {
+            operator struct in6_addr()
+            {
+                throw 1;
+            }
+        };
+        ip3.emplace<struct in6_addr>(E());
+        EXPECT_TRUE(false);
+    }
+    catch (...)
+    {
+    }
+    EXPECT_THROW(toString(ip3), std::runtime_error);
+}
+
 TEST_F(TestUtil, IpValidation)
 {
     std::string ipaddress = "0.0.0.0";
diff --git a/util.cpp b/util.cpp
index 7aa4e2a..db164e6 100644
--- a/util.cpp
+++ b/util.cpp
@@ -14,6 +14,7 @@
 #include <list>
 #include <phosphor-logging/elog-errors.hpp>
 #include <phosphor-logging/log.hpp>
+#include <stdexcept>
 #include <string>
 #include <xyz/openbmc_project/Common/error.hpp>
 
@@ -203,6 +204,35 @@ std::string getNetworkID(int addressFamily, const std::string& ipaddress,
     return networkString;
 }
 
+std::string toString(const InAddrAny& addr)
+{
+    std::string ip;
+    if (std::holds_alternative<struct in_addr>(addr))
+    {
+        const auto& v = std::get<struct in_addr>(addr);
+        ip.resize(INET_ADDRSTRLEN);
+        if (inet_ntop(AF_INET, &v, ip.data(), ip.size()) == NULL)
+        {
+            throw std::runtime_error("Failed to convert IP4 to string");
+        }
+    }
+    else if (std::holds_alternative<struct in6_addr>(addr))
+    {
+        const auto& v = std::get<struct in6_addr>(addr);
+        ip.resize(INET6_ADDRSTRLEN);
+        if (inet_ntop(AF_INET6, &v, ip.data(), ip.size()) == NULL)
+        {
+            throw std::runtime_error("Failed to convert IP6 to string");
+        }
+    }
+    else
+    {
+        throw std::runtime_error("Invalid addr type");
+    }
+    ip.resize(strlen(ip.c_str()));
+    return ip;
+}
+
 bool isLinkLocalIP(const std::string& address)
 {
     return address.find(IPV4_PREFIX) == 0 || address.find(IPV6_PREFIX) == 0;
diff --git a/util.hpp b/util.hpp
index e01c744..537c6a0 100644
--- a/util.hpp
+++ b/util.hpp
@@ -93,6 +93,12 @@ constexpr auto timeSynchdService = "systemd-timesyncd.service";
  */
 uint8_t toCidr(int addressFamily, const std::string& mask);
 
+/* @brief converts the ip bytes into a string representation
+ * @param[in] addr - input ip address to convert.
+ * @returns String representation of the ip.
+ */
+std::string toString(const InAddrAny& addr);
+
 /* @brief converts the prefix into subnetmask.
  * @param[in] addressFamily - IP address family(AF_INET/AF_INET6).
  * @param[in] prefix - prefix length.