From 084042b1a83874734960f358cd2c1d428b79bbe1 Mon Sep 17 00:00:00 2001
From: Nikhil Marathe <nsm.nikhil@gmail.com>
Date: Tue, 18 Sep 2012 19:23:22 +0530
Subject: [PATCH] Added network interfaces section

---
 code/Makefile          |  3 ++-
 code/interfaces/main.c | 33 +++++++++++++++++++++++++++++++++
 source/networking.rst  | 14 +++++++++++++-
 3 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 code/interfaces/main.c

diff --git a/code/Makefile b/code/Makefile
index 787ef25..9dcb868 100644
--- a/code/Makefile
+++ b/code/Makefile
@@ -19,7 +19,8 @@ examples=\
 	pipe-echo-server\
 	multi-echo-server\
 	tty\
-	tty-gravity
+	tty-gravity\
+	interfaces
 
 UV_PATH=$(shell pwd)/../libuv
 CFLAGS=-g -Wall -I$(UV_PATH)/include $(UV_PATH)/uv.a
diff --git a/code/interfaces/main.c b/code/interfaces/main.c
new file mode 100644
index 0000000..cac12c2
--- /dev/null
+++ b/code/interfaces/main.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include <uv.h>
+
+int main() {
+    char buf[512];
+    uv_interface_address_t *info;
+    int count, i;
+
+    uv_interface_addresses(&info, &count);
+    i = count;
+
+    printf("Number of interfaces: %d\n", count);
+    while (i--) {
+        uv_interface_address_t interface = info[i];
+
+        printf("Name: %s\n", interface.name);
+        printf("Internal? %s\n", interface.is_internal ? "Yes" : "No");
+        
+        if (interface.address.address4.sin_family == AF_INET) {
+            uv_ip4_name(&interface.address.address4, buf, sizeof(buf));
+            printf("IPv4 address: %s\n", buf);
+        }
+        else if (interface.address.address4.sin_family == AF_INET6) {
+            uv_ip6_name(&interface.address.address6, buf, sizeof(buf));
+            printf("IPv6 address: %s\n", buf);
+        }
+
+        printf("\n");
+    }
+
+    uv_free_interface_addresses(info, count);
+    return 0;
+}
diff --git a/source/networking.rst b/source/networking.rst
index da29a42..85c36c5 100644
--- a/source/networking.rst
+++ b/source/networking.rst
@@ -193,7 +193,19 @@ call ``uv_freeaddrinfo`` in the callback.
 Network interfaces
 ------------------
 
-TODO
+Information about the system's network interfaces can be obtained through libuv
+using ``uv_interface_addresses``. This simple program just prints out all the
+interface details so you get an idea of the fields that are available. This is
+useful to allow your service to bind to IP addresses when it starts.
+
+.. rubric:: interfaces/main.c
+.. literalinclude:: ../code/interfaces/main.c
+    :linenos:
+    :emphasize-lines: 9,17
+
+``is_internal`` is true for loopback interfaces. Note that if a physical
+interface has multiple IPv4/IPv6 addresses, the name will be reported multiple
+times, with each address being reported once.
 
 .. _c-ares: http://c-ares.haxx.se
 .. _getaddrinfo: http://www.kernel.org/doc/man-pages/online/pages/man3/getaddrinfo.3.html