Events: Socket creation after getaddrinfo and IPv4 and IPv6 packet capture

Issue: Currently, the socket creation is done
prior to getaddrinfo function being invoked. This
can cause mismatch in the protocol and address
families of the created socket and the result
of the getaddrinfo api. Also, the glustereventsd
UDP server by default only captures IPv4 packets
hence IPv6 packets are not even captured.

Code Changes:
1. Modified the socket creation in such a way that
the parameters taken in are dependent upon the
result of the getaddrinfo function.
2. Created a subclass for adding address family
in glustereventsd.py for both AF_INET and AF_INET6.
3. Modified addresses in the eventsapiconf.py.in

Reasoning behind the approach:
1. If we are using getaddrinfo function then
socket creation should happen only after we
check if we received back valid addresses.
Hence socket creation should come after the call
to getaddrinfo
2. The listening server which pushes the events
to the webhook has to listen for both IPv4
and IPv6 messages as we would not be sure as to
what address family is picked in _gf_event.

Fixes: #1377
Change-Id: I568dcd1a977c8832f0fef981e1f81cac7043c760
Signed-off-by: srijan-sivakumar <ssivakum@redhat.com>
(cherry picked from commit 7c309928591deb8d0188793677958226ac03897a)

3 files changed, 49 insertions, 15 deletions

diff --git a/events/src/eventsapiconf.py.in b/events/src/eventsapiconf.py.in
index 76b5954d325..700093bee60 100644
--- a/events/src/eventsapiconf.py.in
+++ b/events/src/eventsapiconf.py.in
@@ -28,6 +28,8 @@ def get_glusterd_workdir():
     return glusterd_workdir
 
 SERVER_ADDRESS = "0.0.0.0"
+SERVER_ADDRESSv4 = "0.0.0.0"
+SERVER_ADDRESSv6 = "::1"
 DEFAULT_CONFIG_FILE = "@SYSCONF_DIR@/glusterfs/eventsconfig.json"
 CUSTOM_CONFIG_FILE_TO_SYNC = "/events/config.json"
 CUSTOM_CONFIG_FILE = get_glusterd_workdir() + CUSTOM_CONFIG_FILE_TO_SYNC
diff --git a/events/src/glustereventsd.py b/events/src/glustereventsd.py
index c4c7b65e332..341a3b60947 100644
--- a/events/src/glustereventsd.py
+++ b/events/src/glustereventsd.py
@@ -13,6 +13,7 @@
 from __future__ import print_function
 import sys
 import signal
+import threading
 try:
     import socketserver
 except ImportError:
@@ -23,10 +24,17 @@ from argparse import ArgumentParser, RawDescriptionHelpFormatter
 from eventtypes import all_events
 import handlers
 import utils
-from eventsapiconf import SERVER_ADDRESS, PID_FILE
+from eventsapiconf import SERVER_ADDRESSv4, SERVER_ADDRESSv6, PID_FILE
 from eventsapiconf import AUTO_BOOL_ATTRIBUTES, AUTO_INT_ATTRIBUTES
 from utils import logger, PidFile, PidFileLockFailed, boolify
 
+# Subclass so that specifically IPv4 packets are captured
+class UDPServerv4(socketserver.ThreadingUDPServer):
+    address_family = socket.AF_INET
+
+# Subclass so that specifically IPv6 packets are captured
+class UDPServerv6(socketserver.ThreadingUDPServer):
+    address_family = socket.AF_INET6
 
 class GlusterEventsRequestHandler(socketserver.BaseRequestHandler):
 
@@ -89,6 +97,10 @@ def signal_handler_sigusr2(sig, frame):
     utils.restart_webhook_pool()
 
 
+def UDP_server_thread(sock):
+    sock.serve_forever()
+
+
 def init_event_server():
     utils.setup_logger()
     utils.load_all()
@@ -99,15 +111,26 @@ def init_event_server():
         sys.stderr.write("Unable to get Port details from Config\n")
         sys.exit(1)
 
-    # Start the Eventing Server, UDP Server
+    # Creating the Eventing Server, UDP Server for IPv4 packets
+    try:
+        serverv4 = UDPServerv4((SERVER_ADDRESSv4, port),
+                   GlusterEventsRequestHandler)
+    except socket.error as e:
+        sys.stderr.write("Failed to start Eventsd for IPv4: {0}\n".format(e))
+        sys.exit(1)
+    # Creating the Eventing Server, UDP Server for IPv6 packets
     try:
-        server = socketserver.ThreadingUDPServer(
-            (SERVER_ADDRESS, port),
-            GlusterEventsRequestHandler)
+        serverv6 = UDPServerv6((SERVER_ADDRESSv6, port),
+                   GlusterEventsRequestHandler)
     except socket.error as e:
-        sys.stderr.write("Failed to start Eventsd: {0}\n".format(e))
+        sys.stderr.write("Failed to start Eventsd for IPv6: {0}\n".format(e))
         sys.exit(1)
-    server.serve_forever()
+    server_thread1 = threading.Thread(target=UDP_server_thread,
+                     args=(serverv4,))
+    server_thread2 = threading.Thread(target=UDP_server_thread,
+                     args=(serverv6,))
+    server_thread1.start()
+    server_thread2.start()
 
 
 def get_args():
diff --git a/libglusterfs/src/events.c b/libglusterfs/src/events.c
index 6d1e3836477..b397f413bb9 100644
--- a/libglusterfs/src/events.c
+++ b/libglusterfs/src/events.c
@@ -51,13 +51,6 @@ _gf_event(eventtypes_t event, const char *fmt, ...)
         goto out;
     }
 
-    /* Initialize UDP socket */
-    sock = socket(AF_INET, SOCK_DGRAM, 0);
-    if (sock < 0) {
-        ret = EVENT_ERROR_SOCKET;
-        goto out;
-    }
-
     if (ctx) {
         volfile_server_transport = ctx->cmd_args.volfile_server_transport;
     }
@@ -66,7 +59,6 @@ _gf_event(eventtypes_t event, const char *fmt, ...)
     }
 
     /* host = NULL returns localhost */
-    host = NULL;
     if (ctx && ctx->cmd_args.volfile_server &&
         (strcmp(volfile_server_transport, "unix"))) {
         /* If it is client code then volfile_server is set
@@ -84,6 +76,23 @@ _gf_event(eventtypes_t event, const char *fmt, ...)
         goto out;
     }
 
+    // iterate over the result and break when socket creation is success.
+    for (; result != NULL; result = result->ai_next) {
+        sock = socket(result->ai_family, result->ai_socktype,
+                      result->ai_protocol);
+        if (sock != -1) {
+            break;
+        }
+    }
+    /*
+     * If none of the addrinfo structures lead to a successful socket
+     * creation, socket creation has failed.
+     */
+    if (sock < 0) {
+        ret = EVENT_ERROR_SOCKET;
+        goto out;
+    }
+
     va_start(arguments, fmt);
     ret = gf_vasprintf(&msg, fmt, arguments);
     va_end(arguments);