check_icmp: Automatically detect IP protocol

This patch automatically detects whether the protocol version is IPv4 or
IPv6

All credits to: https://github.com/ghciv6

Signed-off-by: Jacob Hansen <jhansen@op5.com>

1 files changed, 45 insertions, 26 deletions

diff --git a/plugins-root/check_icmp.c b/plugins-root/check_icmp.c
index 4c17d239..cab69fda 100644
--- a/plugins-root/check_icmp.c
+++ b/plugins-root/check_icmp.c
@@ -419,7 +419,7 @@ main(int argc, char **argv)
          * that before pointer magic (esp. on network data) */
         icmp_sockerrno = udp_sockerrno = tcp_sockerrno = sockets = 0;
 
-        address_family = AF_INET;
+        address_family = -1;
         int icmp_proto = IPPROTO_ICMP;
 
         /* get calling name the old-fashioned way for portability instead
@@ -526,12 +526,10 @@ main(int argc, char **argv)
                                 break;
                         case '4':
                                 address_family = AF_INET;
-                                icmp_proto = IPPROTO_ICMP;
                                 break;
                         case '6':
 #ifdef USE_IPV6
                                 address_family = AF_INET6;
-                                icmp_proto = IPPROTO_ICMPV6;
 #else
                                 usage (_("IPv6 support not available\n"));
 #endif
@@ -540,29 +538,6 @@ main(int argc, char **argv)
                 }
         }
 
-        if((icmp_sock = socket(address_family, SOCK_RAW, icmp_proto)) != -1)
-                sockets |= HAVE_ICMP;
-        else icmp_sockerrno = errno;
-
-        /* if((udp_sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) != -1) */
-        /*      sockets |= HAVE_UDP; */
-        /* else udp_sockerrno = errno; */
-
-        /* if((tcp_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) != -1) */
-        /*      sockets |= HAVE_TCP; */
-        /* else tcp_sockerrno = errno; */
-
-        /* now drop privileges (no effect if not setsuid or geteuid() == 0) */
-        if (setuid(getuid()) == -1) {
-                printf("ERROR: Failed to drop privileges\n");
-                return 1;
-        }
-
-#ifdef SO_TIMESTAMP
-        if(setsockopt(icmp_sock, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)))
-          if(debug) printf("Warning: no SO_TIMESTAMP support\n");
-#endif // SO_TIMESTAMP
-
         /* POSIXLY_CORRECT might break things, so unset it (the portable way) */
         environ = NULL;
 
@@ -593,6 +568,37 @@ main(int argc, char **argv)
                 exit(3);
         }
 
+        // add_target might change address_family
+        switch ( address_family ){
+                case AF_INET:   icmp_proto = IPPROTO_ICMP;
+                                break;
+                case AF_INET6:  icmp_proto = IPPROTO_ICMPV6;
+                                break;
+                default:        crash("Address family not supported");
+        }
+        if((icmp_sock = socket(address_family, SOCK_RAW, icmp_proto)) != -1)
+                sockets |= HAVE_ICMP;
+        else icmp_sockerrno = errno;
+
+        /* if((udp_sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) != -1) */
+        /*      sockets |= HAVE_UDP; */
+        /* else udp_sockerrno = errno; */
+
+        /* if((tcp_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) != -1) */
+        /*      sockets |= HAVE_TCP; */
+        /* else tcp_sockerrno = errno; */
+
+#ifdef SO_TIMESTAMP
+        if(setsockopt(icmp_sock, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)))
+          if(debug) printf("Warning: no SO_TIMESTAMP support\n");
+#endif // SO_TIMESTAMP
+
+        /* now drop privileges (no effect if not setsuid or geteuid() == 0) */
+        if (setuid(getuid()) == -1) {
+                printf("ERROR: Failed to drop privileges\n");
+                return 1;
+        }
+
         if(!sockets) {
                 if(icmp_sock == -1) {
                         errno = icmp_sockerrno;
@@ -1319,6 +1325,19 @@ add_target(char *arg)
         struct sockaddr_in6 *sin6;
 
         switch (address_family) {
+        case -1:
+                // -4 and -6 are not specified on cmdline
+                address_family = AF_INET;
+                sin = (struct sockaddr_in *)&ip;
+                result = inet_pton(address_family, arg, &sin->sin_addr);
+#ifdef USE_IPV6
+                if( result != 1 ){
+                        address_family = AF_INET6;
+                        sin6 = (struct sockaddr_in6 *)&ip;
+                        result = inet_pton(address_family, arg, &sin6->sin6_addr);
+                }
+#endif
+                break;
         case AF_INET:
                 sin = (struct sockaddr_in *)&ip;
                 result = inet_pton(address_family, arg, &sin->sin_addr);