radius: convert identifiers to hex strings before sending them to Radius server

src/lib/dhcpsrv/radius_host_data_source.cc

@@ -178,7 +178,23 @@ RadiusHostDataSource::getAll(const Host::IdentifierType& identifier_type,
     HostPtr host;
     int res;
     VALUE_PAIR 	*send = NULL, *received;
-    if (rc_avpair_add(rh, &send, PW_USER_NAME, identifier_begin, identifier_len, 0) == NULL)
+    // Convert binary identifier (DUID or MAC address) to an hexadecimal
+    // string, with each byte separated by a colon.
+    std::stringstream tmp;
+    tmp << std::hex;
+    bool delim = false;
+    for (int i = 0; i < identifier_len; ++i) {
+        if (delim) {
+            tmp << ":";
+        }
+        tmp << std::setw(2) << std::setfill('0') << static_cast<unsigned int>(identifier_begin[i]);
+        delim = true;
+    }
+    // Necessary because of variable lifetime, see https://stackoverflow.com/a/1374485/4113356
+    const std::string tmp2 = tmp.str();
+    const char* identifier_hex = tmp2.c_str();
+    // Build radius request
+    if (rc_avpair_add(rh, &send, PW_USER_NAME, identifier_hex, -1, 0) == NULL)
         isc_throw(isc::Exception, "Failed to set username");
 
     res = rc_auth(rh, 0, send, &received, NULL);
@@ -187,7 +203,7 @@ RadiusHostDataSource::getAll(const Host::IdentifierType& identifier_type,
         char name[128];
         char value[128];
 
-        fprintf(stderr, "\"%s\" RADIUS Authentication OK\n", identifier_begin);
+        fprintf(stderr, "\"%s\" RADIUS Authentication OK\n", identifier_hex);
 
         /* print the known attributes in the reply */
         while(vp != NULL) {
@@ -202,7 +218,7 @@ RadiusHostDataSource::getAll(const Host::IdentifierType& identifier_type,
                             SubnetID(), asiolink::IOAddress("10.42.42.42")));
         result.push_back(host);
     } else {
-        fprintf(stderr, "\"%s\" RADIUS Authentication failure (RC=%i)\n", identifier_begin, res);
+        fprintf(stderr, "\"%s\" RADIUS Authentication failure (RC=%i)\n", identifier_hex, res);
     }
 
     return (result);