From 5539fecb9915aea812c65d52183eba339b9c82e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E9=80=9A=E6=B4=B2?= <zhangsongcui3371@sina.com>
Date: Fri, 14 Jun 2024 11:17:45 +0800
Subject: [PATCH] LocalIP: detect MTU

---
 src/detection/localip/localip.h         |  1 +
 src/detection/localip/localip_linux.c   | 14 ++++++++++++++
 src/detection/localip/localip_windows.c |  6 +++++-
 src/modules/localip/localip.c           |  1 +
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/detection/localip/localip.h b/src/detection/localip/localip.h
index fe50575ad..4b4162604 100644
--- a/src/detection/localip/localip.h
+++ b/src/detection/localip/localip.h
@@ -8,6 +8,7 @@ typedef struct FFLocalIpResult
     FFstrbuf ipv4;
     FFstrbuf ipv6;
     FFstrbuf mac;
+    int32_t mtu;
     bool defaultRoute;
 } FFLocalIpResult;
 
diff --git a/src/detection/localip/localip_linux.c b/src/detection/localip/localip_linux.c
index 9c23b987f..0a8e3a05d 100644
--- a/src/detection/localip/localip_linux.c
+++ b/src/detection/localip/localip_linux.c
@@ -10,6 +10,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <stdio.h>
+#include <sys/ioctl.h>
 
 #if defined(__FreeBSD__) || defined(__APPLE__)
 #include <net/if_dl.h>
@@ -35,6 +36,7 @@ static void addNewIp(FFlist* list, const char* name, const char* addr, int type,
         ffStrbufInit(&ip->ipv6);
         ffStrbufInit(&ip->mac);
         ip->defaultRoute = defaultRoute;
+        ip->mtu = -1;
     }
 
     switch (type)
@@ -160,5 +162,17 @@ const char* ffDetectLocalIps(const FFLocalIpOptions* options, FFlist* results)
 
     if (ifAddrStruct) freeifaddrs(ifAddrStruct);
 
+    FF_AUTO_CLOSE_FD int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sockfd > 0)
+    {
+        FF_LIST_FOR_EACH(FFLocalIpResult, iface, *results)
+        {
+            struct ifreq ifr = {};
+            strncpy(ifr.ifr_name, iface->name.chars, IFNAMSIZ - 1);
+            if (ioctl(sockfd, SIOCGIFMTU, &ifr) == 0)
+                iface->mtu = ifr.ifr_mtu;
+        }
+    }
+
     return NULL;
 }
diff --git a/src/detection/localip/localip_windows.c b/src/detection/localip/localip_windows.c
index 0650ae54a..8ac766660 100644
--- a/src/detection/localip/localip_windows.c
+++ b/src/detection/localip/localip_windows.c
@@ -18,10 +18,11 @@ static void addNewIp(FFlist* list, const char* name, const char* addr, int type,
         ffStrbufInit(&ip->ipv6);
         ffStrbufInit(&ip->mac);
         ip->defaultRoute = defaultRoute;
+        ip->mtu = -1;
     }
     else
     {
-        ip = ffListGet(list, list->length - 1);
+        ip = FF_LIST_GET(FFLocalIpResult, *list, list->length - 1);
     }
 
     switch (type)
@@ -147,6 +148,9 @@ const char* ffDetectLocalIps(const FFLocalIpOptions* options, FFlist* results)
                 if (typesToAdd == 0) break;
             }
         }
+
+        if (!newIp)
+            FF_LIST_GET(FFLocalIpResult, *results, results->length - 1)->mtu = (int32_t) adapter->Mtu;
     }
 
     return NULL;
diff --git a/src/modules/localip/localip.c b/src/modules/localip/localip.c
index 28aa7d4d3..53bed6363 100644
--- a/src/modules/localip/localip.c
+++ b/src/modules/localip/localip.c
@@ -373,6 +373,7 @@ void ffGenerateLocalIpJsonResult(FF_MAYBE_UNUSED FFLocalIpOptions* options, yyjs
         yyjson_mut_obj_add_strbuf(doc, obj, "ipv6", &ip->ipv6);
         yyjson_mut_obj_add_strbuf(doc, obj, "mac", &ip->mac);
         yyjson_mut_obj_add_strbuf(doc, obj, "name", &ip->name);
+        yyjson_mut_obj_add_int(doc, obj, "mtu", ip->mtu);
     }
 
     FF_LIST_FOR_EACH(FFLocalIpResult, ip, results)