support interface names in config as well as raw ips

Main.cc

@@ -115,14 +115,28 @@ void populate_state_from_config(shared_ptr<ServerState> s,
   } catch (const out_of_range&) { }
 
   auto local_address_str = d.at("LocalAddress")->as_string();
-  s->local_address = address_for_string(local_address_str.c_str());
-  s->all_addresses.emplace(s->local_address);
-  log(INFO, "added local address: %s", local_address_str.c_str());
+  try {
+    s->local_address = s->all_addresses.at(local_address_str);
+    string addr_str = string_for_address(s->local_address);
+    log(INFO, "added local address: %s (%s)", addr_str.c_str(),
+        local_address_str.c_str());
+  } catch (const out_of_range&) {
+    s->local_address = address_for_string(local_address_str.c_str());
+    log(INFO, "added local address: %s", local_address_str.c_str());
+  }
+  s->all_addresses.emplace("<local>", s->local_address);
 
   auto external_address_str = d.at("ExternalAddress")->as_string();
-  s->external_address = address_for_string(external_address_str.c_str());
-  s->all_addresses.emplace(s->external_address);
-  log(INFO, "added external address: %s", external_address_str.c_str());
+  try {
+    s->external_address = s->all_addresses.at(external_address_str);
+    string addr_str = string_for_address(s->external_address);
+    log(INFO, "added external address: %s (%s)", addr_str.c_str(),
+        external_address_str.c_str());
+  } catch (const out_of_range&) {
+    s->external_address = address_for_string(external_address_str.c_str());
+    log(INFO, "added external address: %s", external_address_str.c_str());
+  }
+  s->all_addresses.emplace("<external>", s->external_address);
 
   try {
     s->run_dns_server = d.at("RunDNSServer")->as_bool();
@@ -193,10 +207,10 @@ int main(int argc, char* argv[]) {
   shared_ptr<struct event_base> base(event_base_new(), event_base_free);
 
   log(INFO, "reading network addresses");
-  state->all_addresses = get_local_address_list();
-  for (uint32_t addr : state->all_addresses) {
-    string addr_str = string_for_address(addr);
-    log(INFO, "found address: %s", addr_str.c_str());
+  state->all_addresses = get_local_addresses();
+  for (const auto& it : state->all_addresses) {
+    string addr_str = string_for_address(it.second);
+    log(INFO, "found interface: %s = %s", it.first.c_str(), addr_str.c_str());
   }
 
   log(INFO, "loading configuration");

NetworkAddresses.cc

@@ -44,7 +44,7 @@ uint32_t resolve_address(const char* address) {
   return bswap32(res_sin->sin_addr.s_addr);
 }
 
-set<uint32_t> get_local_address_list() {
+map<string, uint32_t> get_local_addresses() {
   struct ifaddrs* ifa_raw;
   if (getifaddrs(&ifa_raw)) {
     auto s = string_for_error(errno);
@@ -53,7 +53,7 @@ set<uint32_t> get_local_address_list() {
 
   unique_ptr<struct ifaddrs, void(*)(struct ifaddrs*)> ifa(ifa_raw, freeifaddrs);
 
-  set<uint32_t> ret;
+  map<string, uint32_t> ret;
   for (struct ifaddrs* i = ifa.get(); i; i = i->ifa_next) {
     if (!i->ifa_addr) {
       continue;
@@ -64,7 +64,7 @@ set<uint32_t> get_local_address_list() {
       continue;
     }
 
-    ret.emplace(bswap32(sin->sin_addr.s_addr));
+    ret.emplace(i->ifa_name, bswap32(sin->sin_addr.s_addr));
   }
 
   return ret;

NetworkAddresses.hh

@@ -3,7 +3,7 @@
 #include <netinet/in.h>
 #include <stdint.h>
 
-#include <set>
+#include <map>
 #include <string>
 
 
@@ -12,7 +12,7 @@
 // it's easier
 
 uint32_t resolve_address(const char* address);
-std::set<uint32_t> get_local_address_list();
+std::map<std::string, uint32_t> get_local_addresses();
 uint32_t get_connected_address(int fd);
 bool is_local_address(uint32_t daddr);
 bool is_local_address(const sockaddr_storage& daddr);

ServerState.hh

@@ -52,7 +52,7 @@ struct ServerState {
   std::map<int64_t, std::shared_ptr<Lobby>> id_to_lobby;
   std::atomic<int32_t> next_lobby_id;
 
-  std::set<uint32_t> all_addresses;
+  std::map<std::string, uint32_t> all_addresses;
   uint32_t local_address;
   uint32_t external_address;
 

system/config.json

@@ -3,10 +3,10 @@
 
   // Server's name (maximum 16 characters)
   "ServerName": "Alexandria",
-  // Address to connect local clients to
+  // Address to connect local clients to (IP address or interface name)
   "LocalAddress": "192.168.0.5",
-  // Address to connect external clients to
-  "ExternalAddress": "10.0.1.6",
+  // Address to connect external clients to (IP address or interface name)
+  "ExternalAddress": "en0",
   // Set to false to disable the DNS server
   "RunDNSServer": true,
   // By default, the interactive shell runs if stdin is a terminal, and doesn't