src/network/getnameinfo.c

   1 #include <netdb.h>
   2 #include <limits.h>
   3 #include <string.h>
   4 #include <stdio.h>
   5 #include <sys/socket.h>
   6 #include <netinet/in.h>
   7 #include <arpa/inet.h>
   8 #include <net/if.h>
   9 #include <ctype.h>
  10 #include "lookup.h"
  11 #include "stdio_impl.h"
  12
  13 int __dns_parse(const unsigned char *, int, int (*)(void *, int, const void *, int, const void *), void *);
  14 int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
  15 int __res_mkquery(int, const char *, int, int, const unsigned char *, int, const unsigned char*, unsigned char *, int);
  16 int __res_send(const unsigned char *, int, unsigned char *, int);
  17
  18 #define PTR_MAX (64 + sizeof ".in-addr.arpa")
  19 #define RR_PTR 12
  20
  21 static char *itoa(char *p, unsigned x) {
  22         p += 3*sizeof(int);
  23         *--p = 0;
  24         do {
  25                 *--p = '0' + x % 10;
  26                 x /= 10;
  27         } while (x);
  28         return p;
  29 }
  30
  31 static void mkptr4(char *s, const unsigned char *ip)
  32 {
  33         sprintf(s, "%d.%d.%d.%d.in-addr.arpa",
  34                 ip[3], ip[2], ip[1], ip[0]);
  35 }
  36
  37 static void mkptr6(char *s, const unsigned char *ip)
  38 {
  39         static const char xdigits[] = "0123456789abcdef";
  40         int i;
  41         for (i=15; i>=0; i--) {
  42                 *s++ = xdigits[ip[i]&15]; *s++ = '.';
  43                 *s++ = xdigits[ip[i]>>4]; *s++ = '.';
  44         }
  45         strcpy(s, "ip6.arpa");
  46 }
  47
  48 static void reverse_hosts(char *buf, const unsigned char *a, unsigned scopeid, int family)
  49 {
  50         char line[512], *p, *z;
  51         unsigned char _buf[1032], atmp[16];
  52         struct address iplit;
  53         FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
  54         if (!f) return;
  55         if (family == AF_INET) {
  56                 memcpy(atmp+12, a, 4);
  57                 memcpy(atmp, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
  58                 a = atmp;
  59         }
  60         while (fgets(line, sizeof line, f)) {
  61                 if ((p=strchr(line, '#'))) *p++='\n', *p=0;
  62
  63                 for (p=line; *p && !isspace(*p); p++);
  64                 *p++ = 0;
  65                 if (__lookup_ipliteral(&iplit, line, AF_UNSPEC)<=0)
  66                         continue;
  67
  68                 if (iplit.family == AF_INET) {
  69                         memcpy(iplit.addr+12, iplit.addr, 4);
  70                         memcpy(iplit.addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
  71                         iplit.scopeid = 0;
  72                 }
  73
  74                 if (memcmp(a, iplit.addr, 16) || iplit.scopeid != scopeid)
  75                         continue;
  76
  77                 for (; *p && isspace(*p); p++);
  78                 for (z=p; *z && !isspace(*z); z++);
  79                 *z = 0;
  80                 if (z-p < 256) {
  81                         memcpy(buf, p, z-p+1);
  82                         break;
  83                 }
  84         }
  85         __fclose_ca(f);
  86 }
  87
  88 static void reverse_services(char *buf, int port, int dgram)
  89 {
  90         unsigned long svport;
  91         char line[128], *p, *z;
  92         unsigned char _buf[1032];
  93         FILE _f, *f = __fopen_rb_ca("/etc/services", &_f, _buf, sizeof _buf);
  94         if (!f) return;
  95         while (fgets(line, sizeof line, f)) {
  96                 if ((p=strchr(line, '#'))) *p++='\n', *p=0;
  97
  98                 for (p=line; *p && !isspace(*p); p++);
  99                 if (!*p) continue;
 100                 *p++ = 0;
 101                 svport = strtoul(p, &z, 10);
 102
 103                 if (svport != port || z==p) continue;
 104                 if (dgram && strncmp(z, "/udp", 4)) continue;
 105                 if (!dgram && strncmp(z, "/tcp", 4)) continue;
 106                 if (p-line > 32) continue;
 107
 108                 memcpy(buf, line, p-line);
 109                 break;
 110         }
 111         __fclose_ca(f);
 112 }
 113
 114 static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
 115 {
 116         if (rr != RR_PTR) return 0;
 117         if (__dn_expand(packet, (const unsigned char *)packet + 512,
 118             data, c, 256) <= 0)
 119                 *(char *)c = 0;
 120         return 0;
 121
 122 }
 123
 124 int getnameinfo(const struct sockaddr *restrict sa, socklen_t sl,
 125         char *restrict node, socklen_t nodelen,
 126         char *restrict serv, socklen_t servlen,
 127         int flags)
 128 {
 129         char ptr[PTR_MAX];
 130         char buf[256], num[3*sizeof(int)+1];
 131         int af = sa->sa_family;
 132         unsigned char *a;
 133         unsigned scopeid;
 134
 135         switch (af) {
 136         case AF_INET:
 137                 a = (void *)&((struct sockaddr_in *)sa)->sin_addr;
 138                 if (sl < sizeof(struct sockaddr_in)) return EAI_FAMILY;
 139                 mkptr4(ptr, a);
 140                 scopeid = 0;
 141                 break;
 142         case AF_INET6:
 143                 a = (void *)&((struct sockaddr_in6 *)sa)->sin6_addr;
 144                 if (sl < sizeof(struct sockaddr_in6)) return EAI_FAMILY;
 145                 if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12))
 146                         mkptr6(ptr, a);
 147                 else
 148                         mkptr4(ptr, a+12);
 149                 scopeid = ((struct sockaddr_in6 *)sa)->sin6_scope_id;
 150                 break;
 151         default:
 152                 return EAI_FAMILY;
 153         }
 154
 155         if (node && nodelen) {
 156                 buf[0] = 0;
 157                 if (!(flags & NI_NUMERICHOST)) {
 158                         reverse_hosts(buf, a, scopeid, af);
 159                 }
 160                 if (!*buf && !(flags & NI_NUMERICHOST)) {
 161                         unsigned char query[18+PTR_MAX], reply[512];
 162                         int qlen = __res_mkquery(0, ptr, 1, RR_PTR,
 163                                 0, 0, 0, query, sizeof query);
 164                         int rlen = __res_send(query, qlen, reply, sizeof reply);
 165                         buf[0] = 0;
 166                         if (rlen > 0)
 167                                 __dns_parse(reply, rlen, dns_parse_callback, buf);
 168                 }
 169                 if (!*buf) {
 170                         if (flags & NI_NAMEREQD) return EAI_NONAME;
 171                         inet_ntop(af, a, buf, sizeof buf);
 172                         if (scopeid) {
 173                                 char *p = 0, tmp[IF_NAMESIZE+1];
 174                                 if (!(flags & NI_NUMERICSCOPE) &&
 175                                     (IN6_IS_ADDR_LINKLOCAL(a) ||
 176                                      IN6_IS_ADDR_MC_LINKLOCAL(a)))
 177                                         p = if_indextoname(scopeid, tmp+1);
 178                                 if (!p)
 179                                         p = itoa(num, scopeid);
 180                                 *--p = '%';
 181                                 strcat(buf, p);
 182                         }
 183                 }
 184                 if (strlen(buf) >= nodelen) return EAI_OVERFLOW;
 185                 strcpy(node, buf);
 186         }
 187
 188         if (serv && servlen) {
 189                 char *p = buf;
 190                 int port = ntohs(((struct sockaddr_in *)sa)->sin_port);
 191                 buf[0] = 0;
 192                 if (!(flags & NI_NUMERICSERV))
 193                         reverse_services(buf, port, flags & NI_DGRAM);
 194                 if (!*p)
 195                         p = itoa(num, port);
 196                 if (strlen(p) >= servlen)
 197                         return EAI_OVERFLOW;
 198                 strcpy(serv, p);
 199         }
 200
 201         return 0;
 202 }