1 /*
2 * socktoa - return a numeric host name from a sockaddr_storage structure
3 */
4 #include <config.h>
5 #include <sys/types.h>
6 #ifdef HAVE_SYS_SOCKET_H
7 #include <sys/socket.h>
8 #endif
9 #ifdef HAVE_NETINET_IN_H
10 #include <netinet/in.h>
11 #endif
12
13 #include <arpa/inet.h>
14
15 #include <stdio.h>
16
17 #include "ntp_fp.h"
18 #include "lib_strbuf.h"
19 #include "ntp_stdlib.h"
20 #include "ntp.h"
21 #include "ntp_debug.h"
22
23
24 const char *
socktohost(const sockaddr_u * sock)25 socktohost(
26 const sockaddr_u *sock
27 )
28 {
29 const char svc[] = "ntp";
30 char * pbuf;
31 char * pliar;
32 int gni_flags;
33 struct addrinfo hints;
34 struct addrinfo * alist;
35 struct addrinfo * ai;
36 sockaddr_u addr;
37 size_t octets;
38 int a_info;
39 int saved_errno;
40
41 saved_errno = socket_errno();
42
43 /* reverse the address to purported DNS name */
44 LIB_GETBUF(pbuf);
45 gni_flags = NI_DGRAM | NI_NAMEREQD;
46 if (getnameinfo(&sock->sa, SOCKLEN(sock), pbuf, LIB_BUFLENGTH,
47 NULL, 0, gni_flags)) {
48 errno = saved_errno;
49 return stoa(sock); /* use address */
50 }
51
52 TRACE(1, ("%s reversed to %s\n", stoa(sock), pbuf));
53
54 /*
55 * Resolve the reversed name and make sure the reversed address
56 * is among the results.
57 */
58 ZERO(hints);
59 hints.ai_family = AF(sock);
60 hints.ai_protocol = IPPROTO_UDP;
61 hints.ai_socktype = SOCK_DGRAM;
62 hints.ai_flags = 0;
63 alist = NULL;
64
65 a_info = getaddrinfo(pbuf, svc, &hints, &alist);
66 if (a_info == EAI_NONAME
67 #ifdef EAI_NODATA
68 || a_info == EAI_NODATA
69 #endif
70 ) {
71 hints.ai_flags = AI_CANONNAME;
72 #ifdef AI_ADDRCONFIG
73 hints.ai_flags |= AI_ADDRCONFIG;
74 #endif
75 a_info = getaddrinfo(pbuf, svc, &hints, &alist);
76 }
77 #ifdef AI_ADDRCONFIG
78 /* Some older implementations don't like AI_ADDRCONFIG. */
79 if (a_info == EAI_BADFLAGS) {
80 hints.ai_flags &= ~AI_ADDRCONFIG;
81 a_info = getaddrinfo(pbuf, svc, &hints, &alist);
82 }
83 #endif
84 if (a_info)
85 goto forward_fail;
86
87 INSIST(alist != NULL);
88
89 for (ai = alist; ai != NULL; ai = ai->ai_next) {
90 /*
91 * Make a convenience sockaddr_u copy from ai->ai_addr
92 * because casting from sockaddr * to sockaddr_u * is
93 * risking alignment problems on platforms where
94 * sockaddr_u has stricter alignment than sockaddr,
95 * such as sparc.
96 */
97 ZERO_SOCK(&addr);
98 octets = min(sizeof(addr), ai->ai_addrlen);
99 memcpy(&addr, ai->ai_addr, octets);
100 if (SOCK_EQ(sock, &addr))
101 break;
102 }
103 freeaddrinfo(alist);
104
105 if (ai != NULL) {
106 errno = saved_errno;
107 return pbuf; /* forward check passed */
108 }
109
110 forward_fail:
111 TRACE(1, ("%s forward check lookup fail: %s\n", pbuf,
112 gai_strerror(a_info)));
113 LIB_GETBUF(pliar);
114 snprintf(pliar, LIB_BUFLENGTH, "%s (%s)", stoa(sock), pbuf);
115
116 errno = saved_errno;
117 return pliar;
118 }
119