Linux: refactor broken TPACKET_V3 detection.

Extracted to a separate function and using sscanf
for version parsing to make it easier to follow.

diff --git a/pcap-linux.c b/pcap-linux.c
index f9fe8ac6cfab897ab6e03028c7ecc12d4995312a..94e65473aa5447b3838bd33ffcf3f8c7722a233c 100644 (file)
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -1227,6 +1227,44 @@ static void      pcap_cleanup_linux( pcap_t *handle )
        pcap_cleanup_live_common(handle);
 }
 
+#ifdef HAVE_TPACKET3
+/*
+ * Some versions of TPACKET_V3 have annoying bugs/misfeatures
+ * around which we have to work.  Determine if we have those
+ * problems or not.
+ * 3.19 is the first release with a fixed version of
+ * TPACKET_V3.  We treat anything before that as
+ * not having a fixed version; that may really mean
+ * it has *no* version.
+ */
+static int has_broken_tpacket_v3(void)
+{
+       struct utsname utsname;
+       const char *release;
+       long major, minor;
+       int matches, verlen;
+
+       /* No version information, assume broken. */
+       if (uname(&utsname) == -1)
+               return 1;
+       release = utsname.release;
+
+       /* A malformed version, ditto. */
+       matches = sscanf(release, "%ld.%ld%n", &major, &minor, &verlen);
+       if (matches != 2)
+               return 1;
+       if (release[verlen] != '.' && release[verlen] != '\0')
+               return 1;
+
+       /* OK, a fixed version. */
+       if (major > 3 || (major == 3 && minor >= 19))
+               return 0;
+
+       /* Too old :( */
+       return 1;
+}
+#endif
+
 /*
  * Set the timeout to be used in poll() with memory-mapped packet capture.
  */
@@ -1234,45 +1272,7 @@ static void
 set_poll_timeout(struct pcap_linux *handlep)
 {
 #ifdef HAVE_TPACKET3
-       struct utsname utsname;
-       char *version_component, *endp;
-       long major, minor;
-       int broken_tpacket_v3 = 1;
-
-       /*
-        * Some versions of TPACKET_V3 have annoying bugs/misfeatures
-        * around which we have to work.  Determine if we have those
-        * problems or not.
-        */
-       if (uname(&utsname) == 0) {
-               /*
-                * 3.19 is the first release with a fixed version of
-                * TPACKET_V3.  We treat anything before that as
-                * not haveing a fixed version; that may really mean
-                * it has *no* version.
-                */
-               version_component = utsname.release;
-               major = strtol(version_component, &endp, 10);
-               if (endp != version_component && *endp == '.') {
-                       /*
-                        * OK, that was a valid major version.
-                        * Get the minor version.
-                        */
-                       version_component = endp + 1;
-                       minor = strtol(version_component, &endp, 10);
-                       if (endp != version_component &&
-                           (*endp == '.' || *endp == '\0')) {
-                               /*
-                                * OK, that was a valid minor version.
-                                * Is this 3.19 or newer?
-                                */
-                               if (major >= 4 || (major == 3 && minor >= 19)) {
-                                       /* Yes. TPACKET_V3 works correctly. */
-                                       broken_tpacket_v3 = 0;
-                               }
-                       }
-               }
-       }
+       int broken_tpacket_v3 = has_broken_tpacket_v3();
 #endif
        if (handlep->timeout == 0) {
 #ifdef HAVE_TPACKET3