| 22.1 | In Figure 22.18, why are there two calls to printf? |
| 22.2 | Can dg_send_recv (Figures 22.8 and 22.9) ever return 0? |
| 22.3 | Recode dg_send_recv to use select and its timer instead of using alarm, SIGALRM, sigsetjmp, and siglongjmp. |
| 22.4 | How can an IPv4 server guarantee that the source address of its reply equals the destination address of the client's request (e.g., functionality similar to that provided by the IPV6_PKTINFO socket option)? |
| 22.5 | The main function in Section 22.6 is protocol-dependent on IPv4. Recode it to be protocolindependent. Require the user to specify one or two command-line arguments, the first being an optional IP address (e.g., 0.0.0.0 or 0::0) and the second being a required port number. Then call udp_client just to obtain the address family, port number, and length of the socket address structure.What happens if you call udp_client, as suggested, without specifying a hostname argument because udp_client does not specify the AI_PASSIVE hint to getaddrinfo? |
| Figure 22.6 to an echo server across the Internet after modifying the RTT functions to print each RTT. Also, modify the dg_send_recv function to print each received sequence number. Plot the resulting RTTs along with the estimators for the RTT and its mean deviation. |
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