From a88301a8d21ae864a4c56745f4b0ab8c4cd0d03a Mon Sep 17 00:00:00 2001
From: Michal Sojka <sojkam1@fel.cvut.cz>
Date: Thu, 28 May 2009 00:56:03 +0200
Subject: [PATCH] Added handling of FORB_EXTERNAL_IP environment variable

This variable specifies the IP address of some local interface, which FORB
announces for contacting by others.
---
 src/proto_inet.c | 53 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 44 insertions(+), 9 deletions(-)

diff --git a/src/proto_inet.c b/src/proto_inet.c
index 5cef70d..32a45c8 100644
--- a/src/proto_inet.c
+++ b/src/proto_inet.c
@@ -60,6 +60,7 @@
 #include <unistd.h>
 #include <forb/config.h>
 #include "discovery.h"
+#include <stdlib.h>
 #include "iop.h" /* FIXME: Sending hello should be handled in IOP layer */
 
 /**
@@ -442,7 +443,6 @@ size_t inet_addr2str(char *dest, size_t maxlen, const void *addr)
 
 #include <fcb.h>
 #include <fcb_contact_info.h>
-#include <stdlib.h>
 
 static void inet_register_cb(forb_port_t *port)
 {
@@ -479,7 +479,19 @@ int get_local_address(int sock, struct in_addr *addr)
 {
 	struct ifconf  ifc;
 	struct ifreq   *ifr, req[MAX_INTERFACES];
+	char *env;
+	bool loopback = false;
+	int ret;
+	struct in_addr env_addr;
 	
+	env = getenv("FORB_EXTERNAL_IP");
+	if (env) {
+		if (inet_aton(env, &env_addr) == 0) {
+			ul_logerr("Cannot convert FORB_EXTERNAL_IP\n");
+			errno = EINVAL;
+			return -1;
+		}
+	}
 
 	ifc.ifc_len = sizeof(req);
 	ifc.ifc_req = req;
@@ -489,13 +501,32 @@ int get_local_address(int sock, struct in_addr *addr)
 	for (ifr = req; ifr < &req[MAX_INTERFACES]; ifr++) {
 		struct sockaddr_in ia;
 		memcpy(&ia, &ifr->ifr_addr, sizeof(ia));
-		ioctl(sock, SIOCGIFFLAGS, ifr);
-		if ((ifr->ifr_flags & IFF_UP) && !(ifr->ifr_flags & IFF_LOOPBACK)) {
-			*addr = ia.sin_addr;
-			return 0;
+		ret = ioctl(sock, SIOCGIFFLAGS, ifr);
+		if ((ret == 0) && (ifr->ifr_flags & IFF_UP)) {
+			if (env && env_addr.s_addr == ia.sin_addr.s_addr) {
+				*addr = env_addr;
+				return 0;
+			}
+			if (!(ifr->ifr_flags & IFF_LOOPBACK)) {
+				if (!env) {
+					*addr = ia.sin_addr;
+					return 0;
+				}
+			} else {
+				*addr = ia.sin_addr;
+				loopback = true;
+			}
 		}
 	}
-	return -1;
+	if (env) {
+		ul_logerr("FORB_EXTERNAL_IP doesn't match local interface\n");
+		errno = ENODEV;
+		return -1;
+	}
+	if (loopback)
+		return 0;
+	else
+		return -1;
 }
 
 /** 
@@ -539,6 +570,7 @@ forb_inet_port_init(struct forb_port_desc *port_desc, struct in_addr listen_on,
 
 	setnonblocking(port_priv->udp_socket);
 
+#ifndef CONFIG_FORB_PROTO_INET_DEFAULT
 	struct ip_mreq mreq;
 	inet_aton(MCAST_ADDR, &port_priv->multicast_addr);
 	mreq.imr_multiaddr = port_priv->multicast_addr;
@@ -547,6 +579,7 @@ forb_inet_port_init(struct forb_port_desc *port_desc, struct in_addr listen_on,
 			 IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
 	if (ret)
 		goto err_close_udp;
+#endif
 
 	addr.sin_family = AF_INET;
 	addr.sin_port = htons(MCAST_PORT);
@@ -593,9 +626,11 @@ forb_inet_port_init(struct forb_port_desc *port_desc, struct in_addr listen_on,
 	}
 
 	port_priv->addr.port = addr.sin_port;
-	if (listen_on.s_addr == INADDR_ANY)
-		get_local_address(port_priv->listen_socket, &port_priv->addr.addr);
-	else
+	if (listen_on.s_addr == INADDR_ANY) {
+		if (get_local_address(port_priv->listen_socket, &port_priv->addr.addr)) {
+			goto err_close_listen;
+		}
+	} else
 		port_priv->addr.addr = listen_on;
 
 	/* Initialize epoll descriptor */
-- 
2.39.2