1. The following C program named server.c is to run a server-side application that can connect and receive data from a specific client application.

1. (1)________________(comment about lines 2 to 6)
2. #include
3. #include
4. #include
5. #include
6. #include
8. (2)_________________(comment about lines 9 to 10)
9. #define SERVER_PORT 3490
10. #define MAX_BUF_LEN 100
12. int main(void)
13. {
14. int sockfd; (3)________________(comment about line 14)
16. (4)________________(comment about lines 17 to 18)
17. struct sockaddr_in srv_info;
18. struct sockaddr_in clnt_info;
20. int addr_len, numbytes; (5)________________(comment about line 20)
21. char buf[MAX_BUF_LEN]; (6)________________(comment about line 21)
23. (7)________________(comment about lines 24 to 28)
24. if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
25. {
26. perror("Socket creation error.");
27. exit(1);
28. }
30. (8)________________(comment about lines 31 to 34)
31. srv_info.sin_family = AF_INET;
32. srv_info.sin_addr.s_addr = INADDR_ANY;
33. srv_info.sin_port = htons(SERVER_PORT);
34. memset(&srv_info, 0, sizeof(srv_info));
36. (9)________________(comment about lines 37 to 41)
37. if(bind(sockfd,(struct sockaddr *)&srv_info, sizeof(struct sockaddr)) == -1)
38. {
39. perror("Bind error.");
40. exit(1);
41. }
43. while (1)
44. {
45. addr_len = sizeof(struct sockaddr);
47. (10)________________(comment about lines 48 to 53)
48. if ((numbytes=recvfrom(sockfd, buf, MAX_BUF_LEN-1, 0, (struct sockaddr *)&clnt_info, &addr_len)) == -1)
49. {
50. perror("Receiving error.");
51. exit(1);
52. }
53. buf[numbytes] = '\0';
55. (11)________________(comment about lines 56 to 60)
56. if ((numbytes=sendto(sockfd, "Your message is received ", 26, 0, (struct sockaddr *)&clnt_info, sizeof(struct sockaddr))) == -1)
57. {
58. perror("Sending error.");
59. exit(1);
60. }
62. printf("Type ctrl-C to exit server ");
63. }
65. close(sockfd); (12)________________(comment about line 65)
67. return 0;
68. }

Please read the program code and try to explain the program by writing down appropriate comments to describe each different part of the program code (highlighted in yellow color above).