getnameinfo.c raw
1 #include <netdb.h>
2 #include <limits.h>
3 #include <string.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <sys/socket.h>
7 #include <netinet/in.h>
8 #include <arpa/inet.h>
9 #include <net/if.h>
10 #include <ctype.h>
11 #include <resolv.h>
12 #include "lookup.h"
13 #include "stdio_impl.h"
14
15 #define PTR_MAX (64 + sizeof ".in-addr.arpa")
16 #define RR_PTR 12
17
18 static char *itoa(char *p, unsigned x) {
19 p += 3*sizeof(int);
20 *--p = 0;
21 do {
22 *--p = '0' + x % 10;
23 x /= 10;
24 } while (x);
25 return p;
26 }
27
28 static void mkptr4(char *s, const unsigned char *ip)
29 {
30 sprintf(s, "%d.%d.%d.%d.in-addr.arpa",
31 ip[3], ip[2], ip[1], ip[0]);
32 }
33
34 static void mkptr6(char *s, const unsigned char *ip)
35 {
36 static const char xdigits[] = "0123456789abcdef";
37 int i;
38 for (i=15; i>=0; i--) {
39 *s++ = xdigits[ip[i]&15]; *s++ = '.';
40 *s++ = xdigits[ip[i]>>4]; *s++ = '.';
41 }
42 strcpy(s, "ip6.arpa");
43 }
44
45 static void reverse_hosts(char *buf, const unsigned char *a, unsigned scopeid, int family)
46 {
47 char line[512], *p, *z;
48 unsigned char _buf[1032], atmp[16];
49 struct address iplit;
50 FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
51 if (!f) return;
52 if (family == AF_INET) {
53 memcpy(atmp+12, a, 4);
54 memcpy(atmp, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
55 a = atmp;
56 }
57 while (fgets(line, sizeof line, f)) {
58 if ((p=strchr(line, '#'))) *p++='\n', *p=0;
59
60 for (p=line; *p && !isspace(*p); p++);
61 *p++ = 0;
62 if (__lookup_ipliteral(&iplit, line, AF_UNSPEC)<=0)
63 continue;
64
65 if (iplit.family == AF_INET) {
66 memcpy(iplit.addr+12, iplit.addr, 4);
67 memcpy(iplit.addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
68 iplit.scopeid = 0;
69 }
70
71 if (memcmp(a, iplit.addr, 16) || iplit.scopeid != scopeid)
72 continue;
73
74 for (; *p && isspace(*p); p++);
75 for (z=p; *z && !isspace(*z); z++);
76 *z = 0;
77 if (z-p < 256) {
78 memcpy(buf, p, z-p+1);
79 break;
80 }
81 }
82 __fclose_ca(f);
83 }
84
85 static void reverse_services(char *buf, int port, int dgram)
86 {
87 unsigned long svport;
88 char line[128], *p, *z;
89 unsigned char _buf[1032];
90 FILE _f, *f = __fopen_rb_ca("/etc/services", &_f, _buf, sizeof _buf);
91 if (!f) return;
92 while (fgets(line, sizeof line, f)) {
93 if ((p=strchr(line, '#'))) *p++='\n', *p=0;
94
95 for (p=line; *p && !isspace(*p); p++);
96 if (!*p) continue;
97 *p++ = 0;
98 svport = strtoul(p, &z, 10);
99
100 if (svport != port || z==p) continue;
101 if (dgram && strncmp(z, "/udp", 4)) continue;
102 if (!dgram && strncmp(z, "/tcp", 4)) continue;
103 if (p-line > 32) continue;
104
105 memcpy(buf, line, p-line);
106 break;
107 }
108 __fclose_ca(f);
109 }
110
111 static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
112 {
113 if (rr != RR_PTR) return 0;
114 if (__dn_expand(packet, (const unsigned char *)packet + 512,
115 data, c, 256) <= 0)
116 *(char *)c = 0;
117 return 0;
118
119 }
120
121 int getnameinfo(const struct sockaddr *restrict sa, socklen_t sl,
122 char *restrict node, socklen_t nodelen,
123 char *restrict serv, socklen_t servlen,
124 int flags)
125 {
126 char ptr[PTR_MAX];
127 char buf[256], num[3*sizeof(int)+1];
128 int af = sa->sa_family;
129 unsigned char *a;
130 unsigned scopeid;
131
132 switch (af) {
133 case AF_INET:
134 a = (void *)&((struct sockaddr_in *)sa)->sin_addr;
135 if (sl < sizeof(struct sockaddr_in)) return EAI_FAMILY;
136 mkptr4(ptr, a);
137 scopeid = 0;
138 break;
139 case AF_INET6:
140 a = (void *)&((struct sockaddr_in6 *)sa)->sin6_addr;
141 if (sl < sizeof(struct sockaddr_in6)) return EAI_FAMILY;
142 if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12))
143 mkptr6(ptr, a);
144 else
145 mkptr4(ptr, a+12);
146 scopeid = ((struct sockaddr_in6 *)sa)->sin6_scope_id;
147 break;
148 default:
149 return EAI_FAMILY;
150 }
151
152 if (node && nodelen) {
153 buf[0] = 0;
154 if (!(flags & NI_NUMERICHOST)) {
155 reverse_hosts(buf, a, scopeid, af);
156 }
157 if (!*buf && !(flags & NI_NUMERICHOST)) {
158 unsigned char query[18+PTR_MAX], reply[512];
159 int qlen = __res_mkquery(0, ptr, 1, RR_PTR,
160 0, 0, 0, query, sizeof query);
161 query[3] = 0; /* don't need AD flag */
162 int rlen = __res_send(query, qlen, reply, sizeof reply);
163 buf[0] = 0;
164 if (rlen > 0)
165 __dns_parse(reply, rlen, dns_parse_callback, buf);
166 }
167 if (!*buf) {
168 if (flags & NI_NAMEREQD) return EAI_NONAME;
169 inet_ntop(af, a, buf, sizeof buf);
170 if (scopeid) {
171 char *p = 0, tmp[IF_NAMESIZE+1];
172 if (!(flags & NI_NUMERICSCOPE) &&
173 (IN6_IS_ADDR_LINKLOCAL(a) ||
174 IN6_IS_ADDR_MC_LINKLOCAL(a)))
175 p = if_indextoname(scopeid, tmp+1);
176 if (!p)
177 p = itoa(num, scopeid);
178 *--p = '%';
179 strcat(buf, p);
180 }
181 }
182 if (strlen(buf) >= nodelen) return EAI_OVERFLOW;
183 strcpy(node, buf);
184 }
185
186 if (serv && servlen) {
187 char *p = buf;
188 int port = ntohs(((struct sockaddr_in *)sa)->sin_port);
189 buf[0] = 0;
190 if (!(flags & NI_NUMERICSERV))
191 reverse_services(buf, port, flags & NI_DGRAM);
192 if (!*p)
193 p = itoa(num, port);
194 if (strlen(p) >= servlen)
195 return EAI_OVERFLOW;
196 strcpy(serv, p);
197 }
198
199 return 0;
200 }
201