3 files changed, 80 insertions, 0 deletions
diff --git a/vespalib/src/apps/vespa-validate-hostname/.gitignore b/vespalib/src/apps/vespa-validate-hostname/.gitignore
new file mode 100644
index 00000000000..9d95e867f73
--- /dev/null
+++ b/vespalib/src/apps/vespa-validate-hostname/.gitignore
@@ -0,0 +1 @@
+/vespa-validate-hostname
diff --git a/vespalib/src/apps/vespa-validate-hostname/CMakeLists.txt b/vespalib/src/apps/vespa-validate-hostname/CMakeLists.txt
new file mode 100644
index 00000000000..7ffa7d763ec
--- /dev/null
+++ b/vespalib/src/apps/vespa-validate-hostname/CMakeLists.txt
@@ -0,0 +1,9 @@
+# Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+vespa_add_executable(vespalib_vespa-validate-hostname_app
+    SOURCES
+    validate_hostname.cpp
+    OUTPUT_NAME vespa-validate-hostname
+    INSTALL bin
+    DEPENDS
+    vespalib
+)
diff --git a/vespalib/src/apps/vespa-validate-hostname/validate_hostname.cpp b/vespalib/src/apps/vespa-validate-hostname/validate_hostname.cpp
new file mode 100644
index 00000000000..da4907d4c91
--- /dev/null
+++ b/vespalib/src/apps/vespa-validate-hostname/validate_hostname.cpp
@@ -0,0 +1,70 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <vespa/vespalib/net/socket_address.h>
+#include <vespa/vespalib/stllike/string.h>
+#include <set>
+
+using vespalib::SocketAddress;
+
+std::set<vespalib::string> make_ip_set() {
+    std::set<vespalib::string> result;
+    for (const auto &addr: SocketAddress::get_interfaces()) {
+        result.insert(addr.ip_address());
+    }
+    return result;
+}
+
+vespalib::string normalize(const vespalib::string &hostname) {
+    vespalib::string canon_name = SocketAddress::normalize(hostname);
+    if (canon_name != hostname) {
+        fprintf(stderr, "warning: host name (%s) is not canonical (canonical host name: %s)\n",
+                hostname.c_str(), canon_name.c_str());
+    }
+    return canon_name;
+}
+
+void check_reverse(const vespalib::string &hostname, const SocketAddress &addr) {
+    std::set<vespalib::string> seen({hostname});
+    vespalib::string reverse = addr.reverse_lookup();
+    for (size_t i = 0; !reverse.empty() && (i < 10); ++i) {
+        if (seen.count(reverse) == 0) {
+            seen.insert(reverse);
+            fprintf(stderr, "warning: conflicting reverse lookup: %s->%s->%s\n",
+                    hostname.c_str(), addr.ip_address().c_str(), reverse.c_str());
+        }
+        reverse = addr.reverse_lookup();
+    }
+}
+
+int usage(const char *self) {
+    fprintf(stderr, "usage: %s <hostname>\n", self);
+    return 1;
+}
+
+int main(int argc, char **argv) {
+    if (argc != 2) {
+        return usage(argv[0]);
+    }
+    bool valid = true;
+    auto my_ip_set = make_ip_set();
+    vespalib::string hostname = normalize(argv[1]);
+    auto addr_list = SocketAddress::resolve(80, hostname.c_str());
+    if (addr_list.empty()) {
+        valid = false;
+        fprintf(stderr, "ERROR: host name (%s) could not be resolved\n",
+                hostname.c_str());
+    }
+    for (const SocketAddress &addr: addr_list) {
+        vespalib::string ip_addr = addr.ip_address();
+        if (my_ip_set.count(ip_addr) == 0) {
+            valid = false;
+            fprintf(stderr, "ERROR: host name (%s) resolves to ip address not owned by this host (%s)\n",
+                    hostname.c_str(), ip_addr.c_str());
+        } else {
+            check_reverse(hostname, addr);
+        }
+    }
+    return valid ? 0 : 1;
+}