One student asked me how to read options.
That bothers me! A graduate student in CS should not need to ask that.

OK, some help.

1. If (HLEN == 5) 
   There are no options. just read the 5 lines and do your thing.

2. If (HLEN > 5)
   There are options.
   Read the first 5 lines, do your thing. Then:
   Loop:
Read the next octet. 
(i) If this is 1 it is No-Op and the next octet is the first octet of the
next option.
Else (ii) If this is 0 it is EoO and ...
Else (iii) If this 137 it is the first octet of a SSR option. In that case 
read the next octet: the Length octet. That gives L. Read the next L-2 
octets. This completes reading the SSR option. Handle it. 
Compute how many option octets you have read thus far. If it equals
HLEN*4 - 20, you are done with reading options. If it is less than 
HLEN*4 - 20, you must read the next option. 
Else (iv) If it is 7 it is the first octet of a RR option. (similar) etc.
Until you are done with the option. Than: check how many option octets you
read. If it equals
HLEN*4 - 20, you are done with reading options. If it is less than 
HLEN*4 - 20, you must read the next option. (Do the loop again).

Teun Ott.

Warning:
There are always HLEN lines of input for a packet. That I will never do
wrong. It is conceivable I will have other errors in my input, so you can
not read (L-2) more octets after reading L, etc. 
I do not greatly care you report that kind of things correctly, but 
make sure your program recovers and does the next packet right.