• A [10 points]: Construct a routine or object that takes as it's parameters: (1) IP address, (2) UDP port number, (3) a variable length string representing a stock symbol, (4) a variable length string representing the type of quote, either "ask" or "bid", (5) the time, in milliseconds, between each retransmission, and (6) the maximum number of times to retransmit before giving up. The routine or object should send quote queries to the IP address and UDP port until it receives a response or retransmits enough times and gives up. The time between each retransmission must be as given by the appropriate parameter. The format of a quote query and response are given below. The dollar value is the whole dollar value of the stock price. The 64th is the number of 64ths of a dollar in the stock price. This value must be between 0 and 63.

  
  Query:
  
  Bytes:    2      Var     1   Var  1
        +------+----------+-+------+-+
        |  0x1 |  symbol  |0| type |0|
        +------+----------+-+------+-+
  
  Response:
  
  Bytes:    2      Var     1   Var  1    2       1
        +------+----------+-+------+-+--------+------+
        |  0x2 |  symbol  |0| type |0| dollar | 64th |
        +------+----------+-+------+-+--------+------+
  
  Error:
  
  Bytes:    2      Var     1   Var  1      Var        1
        +------+----------+-+------+-+--------+------+-+
        |  0x3 |  symbol  |0| type |0| error message |0|
        +------+----------+-+------+-+--------+------+-+
  
  

  The routine or object must return whether a response was received or not and the dollar and 64th values of the response.
• B [10 points]: Take the routine or object above and construct a program that allows input of the listed parameters and displays information on whether a response was received or not and the price of the stock as included in the response. The output should be formatted nicely and readable.

• A [20 points]: Construct a routine or object that takes as parameters: (1) a variable length stock symbol string, and (2) a variable length string for the type of quote and randomly determines the stock price given some parameters and saved information. They are:
  • There should be a 10% chance that the stock symbol is not defined if the server has not seen the symbol before. If the symbol is not defined, then it will never be defined and all subsequent queries for it will not be defined.
  • For symbols that are defined, but have not been queried before, they have a random value between 5 and 20 dollars. The 64th value must also be random. This is the IPO price. The ask and bid prices are the same for an IPO.
  • For symbols that are defined, a stocks ask price may go up (50% chance) or down (50% chance) by up to 25% of the stocks previous value. In other words, the stocks new price will be anywhere between 75% of the previous value and 125% of the previous value.
  • For symbols that are defined, a stocks bid price may go up (50% chance) or down (50% chance) by up to 50% of the stocks previous value. In other words, the stocks new price will be anywhere between 50% of the previous value and 150% of the previous value.
  • Once a query is performed, the stocks price is saved as the last bid price (25% chance) or ask price (75% chance). In other words, the price of the stock is saved as the ask or bid price. The next query will determine new ask and bid prices and one of those two will be saved as the new stock price.
• B [20 points]: Construct a UDP server that listens on a UDP port for stock queries from Part 1. The routine or object should then consult the routine or object above to determine the stock ask or bid price and determine the information to send back to the stock quote client.

• A [15 points]: Construct a routine or object to read in a single IP packet from a file into a byte array.
• B [15 points]: Construct a routine or object to take a single IP packet in a byte array and decompose it into the IP header, TCP/UDP header, and data. For the IP/TCP/UDP headers, print out the following pieces of information:
  • Source and Destination IP Addresses
  • IP Header Length in bytes
  • TCP/UDP Source and Destination Ports
  • TCP Header Length in bytes
  • TCP Sequence Number
  • TCP Flags (U,P,R,A,S,F)
  • Length of Data in bytes
• C [10 points]: Take the routines or objects constructed in the above parts and construct an application that takes a given filename and parses the file into IP packets and prints out their contents. Files to be used for submission will be given later. Until then, use the files given below for testing:
  • ~cs268/sniff-Fa00-1.data
  • ~cs268/sniff-Fa00-2.data

Notes: Your submissions must at least compile before any credit will be given. Submissions that do not compile will not be graded. Submissions submitted after the due date will not be graded. All work must be your own original work. If you share code with others, you will be given a 0 for the assignment. This assignment set is worth 25% of your total grade.

Extra Credit