1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
/*
* File: util.c
* Author: Andy Sayler
* Modified: Shiv Mishra
* Project: CSCI 3753 Programming Assignment 5
* Create Date: 2012/02/01
* Modify Date: 2012/02/01
* Modify Date: 2016/09/26
* Description:
* This file contains declarations of utility functions for
* Programming Assignment 5.
*
*/
#include "util.h"
int dnslookup(const char *hostname, char *firstIPstr, int maxSize) {
/* Local vars */
struct addrinfo *headresult = NULL;
struct addrinfo *result = NULL;
struct sockaddr_in *ipv4sock = NULL;
struct in_addr *ipv4addr = NULL;
char ipv4str[INET_ADDRSTRLEN];
char ipstr[INET6_ADDRSTRLEN];
int addrError = 0;
/* DEBUG: Print Hostname*/
#ifdef UTIL_DEBUG
fprintf(stderr, "%s\n", hostname);
#endif
/* Lookup Hostname */
addrError = getaddrinfo(hostname, NULL, NULL, &headresult);
if (addrError) {
fprintf(stderr, "Error looking up Address: %s\n", gai_strerror(addrError));
return UTIL_FAILURE;
}
/* Loop Through result Linked List */
for (result = headresult; result != NULL; result = result->ai_next) {
/* Extract IP Address and Convert to String */
if (result->ai_addr->sa_family == AF_INET) {
/* IPv4 Address Handling */
ipv4sock = (struct sockaddr_in *)(result->ai_addr);
ipv4addr = &(ipv4sock->sin_addr);
if (!inet_ntop(result->ai_family, ipv4addr, ipv4str, sizeof(ipv4str))) {
perror("Error Converting IP to String");
return UTIL_FAILURE;
}
#ifdef UTIL_DEBUG
fprintf(stdout, "%s\n", ipv4str);
#endif
strncpy(ipstr, ipv4str, sizeof(ipstr));
ipstr[sizeof(ipstr) - 1] = '\0';
} else if (result->ai_addr->sa_family == AF_INET6) {
/* IPv6 Handling */
#ifdef UTIL_DEBUG
fprintf(stdout, "IPv6 Address: Not Handled\n");
#endif
strncpy(ipstr, "UNHANDELED", sizeof(ipstr));
ipstr[sizeof(ipstr) - 1] = '\0';
} else {
/* Unhandlded Protocol Handling */
#ifdef UTIL_DEBUG
fprintf(stdout, "Unknown Protocol: Not Handled\n");
#endif
strncpy(ipstr, "UNHANDELED", sizeof(ipstr));
ipstr[sizeof(ipstr) - 1] = '\0';
}
/* Save First IP Address */
if (result == headresult) {
strncpy(firstIPstr, ipstr, maxSize);
firstIPstr[maxSize - 1] = '\0';
}
}
/* Cleanup */
freeaddrinfo(headresult);
return UTIL_SUCCESS;
}
|