1From 798bfb5e984845a27874d1a244686db6e384d7b8 Mon Sep 17 00:00:00 2001
2From: Nate Karstens <nate.karstens@garmin.com>
3Date: Thu, 13 Jul 2017 09:00:00 -0500
4Subject: [PATCH 04/11] Use list for changed interfaces
5
6Uses a linked list to store the index of changed network interfaces
7instead of a bitfield. This allows for network interfaces with an
8index greater than 31 (an index of 36 was seen on Android).
9
10Upstream-Status: Submitted [dts@apple.com]
11
12Signed-off-by: Nate Karstens <nate.karstens@garmin.com>
13---
14 mDNSPosix/mDNSPosix.c | 67 +++++++++++++++++++++++++++++++++----------
15 1 file changed, 52 insertions(+), 15 deletions(-)
16
17diff --git a/mDNSPosix/mDNSPosix.c b/mDNSPosix/mDNSPosix.c
18index 195d04b..bb883c1 100755
19--- a/mDNSPosix/mDNSPosix.c
20+++ b/mDNSPosix/mDNSPosix.c
21@@ -67,6 +67,14 @@ struct IfChangeRec
22 };
23 typedef struct IfChangeRec IfChangeRec;
24
25+// Used to build a list of network interface indices
26+struct NetworkInterfaceIndex
27+{
28+    int if_index;
29+    struct NetworkInterfaceIndex *Next;
30+};
31+typedef struct NetworkInterfaceIndex NetworkInterfaceIndex;
32+
33 // Note that static data is initialized to zero in (modern) C.
34 static PosixEventSource *gEventSources;             // linked list of PosixEventSource's
35 static sigset_t gEventSignalSet;                // Signals which event loop listens for
36@@ -1458,6 +1466,32 @@ mDNSlocal mStatus OpenIfNotifySocket(int *pFD)
37     return err;
38 }
39
40+mDNSlocal mDNSBool ListContainsInterfaceIndex(GenLinkedList *list, int if_index)
41+{
42+    NetworkInterfaceIndex *item;
43+
44+    for (item = (NetworkInterfaceIndex*)list->Head; item != NULL; item = item->Next)
45+    {
46+        if (if_index == item->if_index) return mDNStrue;
47+    }
48+
49+    return mDNSfalse;
50+}
51+
52+mDNSlocal void AddInterfaceIndexToList(GenLinkedList *list, int if_index)
53+{
54+    NetworkInterfaceIndex *item;
55+
56+    if (ListContainsInterfaceIndex(list, if_index)) return;
57+
58+    item = malloc(sizeof *item);
59+    if (item == NULL) return;
60+
61+    item->if_index = if_index;
62+    item->Next = NULL;
63+    AddToTail(list, item);
64+}
65+
66 #if MDNS_DEBUGMSGS
67 mDNSlocal void      PrintNetLinkMsg(const struct nlmsghdr *pNLMsg)
68 {
69@@ -1485,14 +1519,13 @@ mDNSlocal void      PrintNetLinkMsg(const struct nlmsghdr *pNLMsg)
70 }
71 #endif
72
73-mDNSlocal mDNSu32       ProcessRoutingNotification(int sd)
74+mDNSlocal void          ProcessRoutingNotification(int sd, GenLinkedList *changedInterfaces)
75 // Read through the messages on sd and if any indicate that any interface records should
76 // be torn down and rebuilt, return affected indices as a bitmask. Otherwise return 0.
77 {
78     ssize_t readCount;
79     char buff[4096];
80     struct nlmsghdr         *pNLMsg = (struct nlmsghdr*) buff;
81-    mDNSu32 result = 0;
82
83     // The structure here is more complex than it really ought to be because,
84     // unfortunately, there's no good way to size a buffer in advance large
85@@ -1528,9 +1561,9 @@ mDNSlocal mDNSu32       ProcessRoutingNotification(int sd)
86
87         // Process the NetLink message
88         if (pNLMsg->nlmsg_type == RTM_GETLINK || pNLMsg->nlmsg_type == RTM_NEWLINK)
89-            result |= 1 << ((struct ifinfomsg*) NLMSG_DATA(pNLMsg))->ifi_index;
90+            AddInterfaceIndexToList(changedInterfaces, ((struct ifinfomsg*) NLMSG_DATA(pNLMsg))->ifi_index);
91         else if (pNLMsg->nlmsg_type == RTM_DELADDR || pNLMsg->nlmsg_type == RTM_NEWADDR)
92-            result |= 1 << ((struct ifaddrmsg*) NLMSG_DATA(pNLMsg))->ifa_index;
93+            AddInterfaceIndexToList(changedInterfaces, ((struct ifaddrmsg*) NLMSG_DATA(pNLMsg))->ifa_index);
94
95         // Advance pNLMsg to the next message in the buffer
96         if ((pNLMsg->nlmsg_flags & NLM_F_MULTI) != 0 && pNLMsg->nlmsg_type != NLMSG_DONE)
97@@ -1541,8 +1574,6 @@ mDNSlocal mDNSu32       ProcessRoutingNotification(int sd)
98         else
99             break;  // all done!
100     }
101-
102-    return result;
103 }
104
105 #else // USES_NETLINK
106@@ -1574,14 +1605,13 @@ mDNSlocal void      PrintRoutingSocketMsg(const struct ifa_msghdr *pRSMsg)
107 }
108 #endif
109
110-mDNSlocal mDNSu32       ProcessRoutingNotification(int sd)
111+mDNSlocal void          ProcessRoutingNotification(int sd, GenLinkedList *changedInterfaces)
112 // Read through the messages on sd and if any indicate that any interface records should
113 // be torn down and rebuilt, return affected indices as a bitmask. Otherwise return 0.
114 {
115     ssize_t readCount;
116     char buff[4096];
117     struct ifa_msghdr       *pRSMsg = (struct ifa_msghdr*) buff;
118-    mDNSu32 result = 0;
119
120     readCount = read(sd, buff, sizeof buff);
121     if (readCount < (ssize_t) sizeof(struct ifa_msghdr))
122@@ -1596,12 +1626,10 @@ mDNSlocal mDNSu32       ProcessRoutingNotification(int sd)
123         pRSMsg->ifam_type == RTM_IFINFO)
124     {
125         if (pRSMsg->ifam_type == RTM_IFINFO)
126-            result |= 1 << ((struct if_msghdr*) pRSMsg)->ifm_index;
127+            AddInterfaceIndexToList(changedInterfaces, ((struct if_msghdr*) pRSMsg)->ifm_index);
128         else
129-            result |= 1 << pRSMsg->ifam_index;
130+            AddInterfaceIndexToList(changedInterfaces, pRSMsg->ifam_index);
131     }
132-
133-    return result;
134 }
135
136 #endif // USES_NETLINK
137@@ -1611,7 +1639,8 @@ mDNSlocal void InterfaceChangeCallback(int fd, void *context)
138 {
139     IfChangeRec     *pChgRec = (IfChangeRec*) context;
140     fd_set readFDs;
141-    mDNSu32 changedInterfaces = 0;
142+    GenLinkedList changedInterfaces;
143+    NetworkInterfaceIndex *changedInterface;
144     struct timeval zeroTimeout = { 0, 0 };
145
146     (void)fd; // Unused
147@@ -1619,17 +1648,25 @@ mDNSlocal void InterfaceChangeCallback(int fd, void *context)
148     FD_ZERO(&readFDs);
149     FD_SET(pChgRec->NotifySD, &readFDs);
150
151+    InitLinkedList(&changedInterfaces, offsetof(NetworkInterfaceIndex, Next));
152+
153     do
154     {
155-        changedInterfaces |= ProcessRoutingNotification(pChgRec->NotifySD);
156+        ProcessRoutingNotification(pChgRec->NotifySD, &changedInterfaces);
157     }
158     while (0 < select(pChgRec->NotifySD + 1, &readFDs, (fd_set*) NULL, (fd_set*) NULL, &zeroTimeout));
159
160     // Currently we rebuild the entire interface list whenever any interface change is
161     // detected. If this ever proves to be a performance issue in a multi-homed
162     // configuration, more care should be paid to changedInterfaces.
163-    if (changedInterfaces)
164+    if (changedInterfaces.Head != NULL)
165         mDNSPlatformPosixRefreshInterfaceList(pChgRec->mDNS);
166+
167+    while ((changedInterface = (NetworkInterfaceIndex*)changedInterfaces.Head) != NULL)
168+    {
169+        RemoveFromList(&changedInterfaces, changedInterface);
170+        free(changedInterface);
171+    }
172 }
173
174 // Register with either a Routing Socket or RtNetLink to listen for interface changes.
175--
1762.20.1
177
178