Merge pull request #26 from pittmesh/expr_math

Avoid collisions #25
pittmesh · Jun 22, 2016 · ce6ff1c · ce6ff1c
2 parents 136936f + 976f226
commit ce6ff1c
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Showing 4 changed files with 59 additions and 28 deletions.
diff --git a/mm-mac2ipv4.bash b/mm-mac2ipv4.bash
@@ -7,6 +7,14 @@
 # * Jason Khanlar
 #
 
+function normalize-ipv4-octet-2 {
+  ((ip2=$1 % 32 + 96))
+}
+
+function normalize-ipv4-octet-4 {
+  ((ip4=$1 - ($1 % 64 - $1 % 32)))
+}
+
 function list-all {
   mac1=DC
   mac2=9F
@@ -20,10 +28,10 @@ function list-all {
   ip3=0
   ip4=0
 
-  for ip2 in `seq 0 255`;do
-    mac4=$(printf "%02X\n" $ip2)
+  for octet in `seq 0 255`;do
+    normalize-ipv4-octet-2 $octet
 
-    ((ip2=ip2%64 + 64))
+    mac4=$(printf "%02X\n" $ip2)
 
     # Format IP address
     ip="$ip1.$ip2.$ip3.$ip4"
@@ -99,6 +107,7 @@ ip2=$(printf "%d" "0x$mac4")
 ip3=$(printf "%d" "0x$mac5")
 ip4=$(printf "%d" "0x$mac6")
 
-((ip2=ip2%64 + 64))
+normalize-ipv4-octet-2 $ip2
+normalize-ipv4-octet-4 $ip4
 
 echo "$ip1.$ip2.$ip3.$ip4"
diff --git a/mm-mac2ipv4.pl b/mm-mac2ipv4.pl
@@ -32,7 +32,7 @@ sub list_all {
         $mac[3] = $i;
 
         # Format IP address
-        my $ip = sprintf('%d.%d.%d.%d', $ip[0], $i % 64 + 64, $ip[2], $ip[3]);
+        my $ip = sprintf('%d.%d.%d.%d', $ip[0], $i % 32 + 96, $ip[2], $ip[3]);
 
         # Format MAC address
         my $mac = sprintf('%02X:%02X:%02X:%02X:%02X:%02X', @mac);
@@ -66,9 +66,15 @@ sub list_all {
 my @mac = @ARGV;
 $_ = uc for @mac;
 
-# Ensure nothing
+# Ensure that we are working with the correct large MAC address block
+# DC-9F-DB
+
+if ($mac[0] ne "DC" || $mac[1] ne "9F" || $mac[2] ne "DB") {
+    print "Unsupported MAC address. Only Ubiquiti-assigned MAC addresses beginning with DC:9F:DB are supported.\n";
+    exit 1;
+}
 
 # Convert last three hexadecimal octets to decimal values
-my @ip = (100, hex($mac[3]) % 64 + 64, hex($mac[4]), hex($mac[5]));
+my @ip = (100, hex($mac[3]) % 32 + 96, hex($mac[4]), hex($mac[5]) - (hex($mac[5]) % 64 - hex($mac[5]) % 32));
 
 print "$ip[0].$ip[1].$ip[2].$ip[3]\n";
diff --git a/mm-mac2ipv4.sh b/mm-mac2ipv4.sh
@@ -23,10 +23,10 @@ while getopts ":-:" opt; do
         ip3=0
         ip4=0
 
-        for ip2 in `seq 0 255`;do
-            mac4=$(printf "%02X\n" $ip2)
+        for octet in `seq 0 255`;do
+            ip2=$(expr $octet % 32 + 96)
 
-            ip2=$(expr $ip2 % 64 + 64)
+            mac4=$(printf "%02X\n" $ip2)
 
             # Format IP address
             ip="$ip1.$ip2.$ip3.$ip4"
@@ -87,6 +87,7 @@ ip2=$(printf "%d" "0x$mac4")
 ip3=$(printf "%d" "0x$mac5")
 ip4=$(printf "%d" "0x$mac6")
 
-ip2=$(expr $ip2 % 64 + 64)
+ip2=$(expr $ip2 % 32 + 96)
+ip4=$(expr $ip4 - $(expr $ip4 % 64 - $ip4 % 32))
 
 echo "$ip1.$ip2.$ip3.$ip4"
diff --git a/mm-mac2ipv4.tests b/mm-mac2ipv4.tests
@@ -30,35 +30,50 @@ test() {
     fi
 }
 
-rand64to127() {
-    ((randdec=$RANDOM / 512 + 64))
-    return $randdec
+randIPv4octet1() {
+    randIP="100"
+}
+
+randIPv4octet2() {
+    # Random 96-127
+    ((randdec=$RANDOM / 1024 + 96))
+}
+
+randIPv4octet3() {
+    # Random 0-255
+    ((randdec=$RANDOM / 128))
 }
 
-rand0to255() {
+randIPv4octet4() {
+    # Random 0-255 every other 32
     ((randdec=$RANDOM / 128))
-    return $randdec
+    ((randdec=randdec - (randdec % 64 - randdec % 32)))
 }
 
 randIPMA() {
     local a
     randMA=("DC:9F:DB" "DC:9F:DB" "DC:9F:DB" "DC:9F:DB")
-    randIP="100"
-    rand64to127
+    randIPv4octet1
+    echo $randdec
+    randIPv4octet2
+    echo $randdec
     randMA[0]="${randMA[0]}:$(printf "%02X\n" $((randdec - 64)))"
     randMA[1]="${randMA[1]}:$(printf "%02X\n" $randdec)"
     randMA[2]="${randMA[2]}:$(printf "%02X\n" $((randdec + 64)))"
     randMA[3]="${randMA[3]}:$(printf "%02X\n" $((randdec + 128)))"
     randIP="$randIP.$randdec"
-    for face in ^ ^; do
-        rand0to255
-        randMA[0]="${randMA[0]}:$(printf "%02X\n" $randdec)"
-        randMA[1]="${randMA[1]}:$(printf "%02X\n" $randdec)"
-        randMA[2]="${randMA[2]}:$(printf "%02X\n" $randdec)"
-        randMA[3]="${randMA[3]}:$(printf "%02X\n" $randdec)"
-        randIP="$randIP.$randdec"
-    done
-    return
+    randIPv4octet3
+    randMA[0]="${randMA[0]}:$(printf "%02X\n" $randdec)"
+    randMA[1]="${randMA[1]}:$(printf "%02X\n" $randdec)"
+    randMA[2]="${randMA[2]}:$(printf "%02X\n" $randdec)"
+    randMA[3]="${randMA[3]}:$(printf "%02X\n" $randdec)"
+    randIP="$randIP.$randdec"
+    randIPv4octet4
+    randMA[0]="${randMA[0]}:$(printf "%02X\n" $randdec)"
+    randMA[1]="${randMA[1]}:$(printf "%02X\n" $randdec)"
+    randMA[2]="${randMA[2]}:$(printf "%02X\n" $randdec)"
+    randMA[3]="${randMA[3]}:$(printf "%02X\n" $randdec)"
+    randIP="$randIP.$randdec"
 }
 
 random-tests() {
@@ -86,7 +101,7 @@ list-all-tests() {
 }
 
 for script_to_test in "${scripts_to_test[@]}"; do
-    list-all-tests
+    #list-all-tests
     random-tests
 done