src/network/getnameinfo.c

   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                 if (!*p) continue;
  62                 *p++ = 0;
  63                 if (__lookup_ipliteral(&iplit, line, AF_UNSPEC)<=0)
  64                         continue;
  65
  66                 if (iplit.family == AF_INET) {
  67                         memcpy(iplit.addr+12, iplit.addr, 4);
  68                         memcpy(iplit.addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
  69                         iplit.scopeid = 0;
  70                 }
  71
  72                 if (memcmp(a, iplit.addr, 16) || iplit.scopeid != scopeid)
  73                         continue;
  74
  75                 for (; *p && isspace(*p); p++);
  76                 for (z=p; *z && !isspace(*z); z++);
  77                 *z = 0;
  78                 if (z-p < 256) {
  79                         memcpy(buf, p, z-p+1);
  80                         break;
  81                 }
  82         }
  83         __fclose_ca(f);
  84 }
  85
  86 static void reverse_services(char *buf, int port, int dgram)
  87 {
  88         unsigned long svport;
  89         char line[128], *p, *z;
  90         unsigned char _buf[1032];
  91         FILE _f, *f = __fopen_rb_ca("/etc/services", &_f, _buf, sizeof _buf);
  92         if (!f) return;
  93         while (fgets(line, sizeof line, f)) {
  94                 if ((p=strchr(line, '#'))) *p++='\n', *p=0;
  95
  96                 for (p=line; *p && !isspace(*p); p++);
  97                 if (!*p) continue;
  98                 *p++ = 0;
  99                 svport = strtoul(p, &z, 10);
 100
 101                 if (svport != port || z==p) continue;
 102                 if (dgram && strncmp(z, "/udp", 4)) continue;
 103                 if (!dgram && strncmp(z, "/tcp", 4)) continue;
 104                 if (p-line > 32) continue;
 105
 106                 memcpy(buf, line, p-line);
 107                 break;
 108         }
 109         __fclose_ca(f);
 110 }
 111
 112 static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet, int plen)
 113 {
 114         if (rr != RR_PTR) return 0;
 115         if (__dn_expand(packet, (const unsigned char *)packet + plen,
 116             data, c, 256) <= 0)
 117                 *(char *)c = 0;
 118         return 0;
 119
 120 }
 121
 122 int getnameinfo(const struct sockaddr *restrict sa, socklen_t sl,
 123         char *restrict node, socklen_t nodelen,
 124         char *restrict serv, socklen_t servlen,
 125         int flags)
 126 {
 127         char ptr[PTR_MAX];
 128         char buf[256], num[3*sizeof(int)+1];
 129         int af = sa->sa_family;
 130         unsigned char *a;
 131         unsigned scopeid;
 132
 133         switch (af) {
 134         case AF_INET:
 135                 a = (void *)&((struct sockaddr_in *)sa)->sin_addr;
 136                 if (sl < sizeof(struct sockaddr_in)) return EAI_FAMILY;
 137                 mkptr4(ptr, a);
 138                 scopeid = 0;
 139                 break;
 140         case AF_INET6:
 141                 a = (void *)&((struct sockaddr_in6 *)sa)->sin6_addr;
 142                 if (sl < sizeof(struct sockaddr_in6)) return EAI_FAMILY;
 143                 if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12))
 144                         mkptr6(ptr, a);
 145                 else
 146                         mkptr4(ptr, a+12);
 147                 scopeid = ((struct sockaddr_in6 *)sa)->sin6_scope_id;
 148                 break;
 149         default:
 150                 return EAI_FAMILY;
 151         }
 152
 153         if (node && nodelen) {
 154                 buf[0] = 0;
 155                 if (!(flags & NI_NUMERICHOST)) {
 156                         reverse_hosts(buf, a, scopeid, af);
 157                 }
 158                 if (!*buf && !(flags & NI_NUMERICHOST)) {
 159                         unsigned char query[18+PTR_MAX], reply[512];
 160                         int qlen = __res_mkquery(0, ptr, 1, RR_PTR,
 161                                 0, 0, 0, query, sizeof query);
 162                         query[3] = 0; /* don't need AD flag */
 163                         int rlen = __res_send(query, qlen, reply, sizeof reply);
 164                         buf[0] = 0;
 165                         if (rlen > 0)
 166                                 __dns_parse(reply, rlen, dns_parse_callback, buf);
 167                 }
 168                 if (!*buf) {
 169                         if (flags & NI_NAMEREQD) return EAI_NONAME;
 170                         inet_ntop(af, a, buf, sizeof buf);
 171                         if (scopeid) {
 172                                 char *p = 0, tmp[IF_NAMESIZE+1];
 173                                 if (!(flags & NI_NUMERICSCOPE) &&
 174                                     (IN6_IS_ADDR_LINKLOCAL(a) ||
 175                                      IN6_IS_ADDR_MC_LINKLOCAL(a)))
 176                                         p = if_indextoname(scopeid, tmp+1);
 177                                 if (!p)
 178                                         p = itoa(num, scopeid);
 179                                 *--p = '%';
 180                                 strcat(buf, p);
 181                         }
 182                 }
 183                 if (strlen(buf) >= nodelen) return EAI_OVERFLOW;
 184                 strcpy(node, buf);
 185         }
 186
 187         if (serv && servlen) {
 188                 char *p = buf;
 189                 int port = ntohs(((struct sockaddr_in *)sa)->sin_port);
 190                 buf[0] = 0;
 191                 if (!(flags & NI_NUMERICSERV))
 192                         reverse_services(buf, port, flags & NI_DGRAM);
 193                 if (!*p)
 194                         p = itoa(num, port);
 195                 if (strlen(p) >= servlen)
 196                         return EAI_OVERFLOW;
 197                 strcpy(serv, p);
 198         }
 199
 200         return 0;
 201 }