#include <stdio.h>#include <netdb.h>#include <sys/types.h>#include <netinet/in.h>#include <arpa/nameser.h>#include <resolv.h>#include <errno.h>extern int res_query();extern int res_search();extern int errno;extern int h_errno;#include "ip.h"#include "ipalloc.h"#include "fmt.h"#include "alloc.h"#include "str.h"#include "stralloc.h"#include "dns.h"#include "case.h"static unsigned short getshort(c) unsigned char *c;{ unsigned short u; u = c[0]; return (u << 8) + c[1]; }static union { HEADER hdr; unsigned char buf[PACKETSZ]; } response;static int responselen;static unsigned char *responseend;static unsigned char *responsepos;static int numanswers;static char name[MAXDNAME];static struct ip_address ip;unsigned short pref;static stralloc glue = {0};static int (*lookup)() = res_query;static int resolve(domain,type)stralloc *domain;int type;{ int n; int i; errno = 0; if (!stralloc_copy(&glue,domain)) return DNS_MEM; if (!stralloc_0(&glue)) return DNS_MEM; responselen = lookup(glue.s,C_IN,type,response.buf,sizeof(response)); if (responselen <= 0)  {   if (errno == ECONNREFUSED) return DNS_SOFT;   if (h_errno == TRY_AGAIN) return DNS_SOFT;   return DNS_HARD;  } if (responselen >= sizeof(response))   responselen = sizeof(response); responseend = response.buf + responselen; responsepos = response.buf + sizeof(HEADER); n = ntohs(response.hdr.qdcount); while (n-- > 0)  {   i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME);   if (i < 0) return DNS_SOFT;   responsepos += i;   i = responseend - responsepos;   if (i < QFIXEDSZ) return DNS_SOFT;   responsepos += QFIXEDSZ;  } numanswers = ntohs(response.hdr.ancount); return 0;}static int findname(wanttype)int wanttype;{ unsigned short rrtype; unsigned short rrdlen; int i; if (numanswers <= 0) return 2; --numanswers; if (responsepos == responseend) return DNS_SOFT; i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); if (i < 0) return DNS_SOFT; responsepos += i; i = responseend - responsepos; if (i < 4 + 3 * 2) return DNS_SOFT;    rrtype = getshort(responsepos); rrdlen = getshort(responsepos + 8); responsepos += 10; if (rrtype == wanttype)  {   if (dn_expand(response.buf,responseend,responsepos,name,MAXDNAME) < 0)     return DNS_SOFT;   responsepos += rrdlen;   return 1;  }    responsepos += rrdlen; return 0;}static int findip(wanttype)int wanttype;{ unsigned short rrtype; unsigned short rrdlen; int i; if (numanswers <= 0) return 2; --numanswers; if (responsepos == responseend) return DNS_SOFT; i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); if (i < 0) return DNS_SOFT; responsepos += i; i = responseend - responsepos; if (i < 4 + 3 * 2) return DNS_SOFT;    rrtype = getshort(responsepos); rrdlen = getshort(responsepos + 8); responsepos += 10; if (rrtype == wanttype)  {   if (rrdlen < 4)     return DNS_SOFT;   ip.d[0] = responsepos[0];   ip.d[1] = responsepos[1];   ip.d[2] = responsepos[2];   ip.d[3] = responsepos[3];   responsepos += rrdlen;   return 1;  }    responsepos += rrdlen; return 0;}static int findmx(wanttype)int wanttype;{ unsigned short rrtype; unsigned short rrdlen; int i; if (numanswers <= 0) return 2; --numanswers; if (responsepos == responseend) return DNS_SOFT; i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); if (i < 0) return DNS_SOFT; responsepos += i; i = responseend - responsepos; if (i < 4 + 3 * 2) return DNS_SOFT;    rrtype = getshort(responsepos); rrdlen = getshort(responsepos + 8); responsepos += 10; if (rrtype == wanttype)  {   if (rrdlen < 3)     return DNS_SOFT;   pref = (responsepos[0] << 8) + responsepos[1];   if (dn_expand(response.buf,responseend,responsepos + 2,name,MAXDNAME) < 0)     return DNS_SOFT;   responsepos += rrdlen;   return 1;  }    responsepos += rrdlen; return 0;}void dns_init(flagsearch)int flagsearch;{ res_init(); if (flagsearch) lookup = res_search;}int dns_cname(sa)stralloc *sa;{ int r; int loop; for (loop = 0;loop < 10;++loop)  {   if (!sa->len) return loop;   if (sa->s[sa->len - 1] == ']') return loop;   if (sa->s[sa->len - 1] == '.') { --sa->len; continue; }   switch(resolve(sa,T_ANY))    {     case DNS_MEM: return DNS_MEM;     case DNS_SOFT: return DNS_SOFT;     case DNS_HARD: return loop;     default:       while ((r = findname(T_CNAME)) != 2)	{	 if (r == DNS_SOFT) return DNS_SOFT;	 if (r == 1)	  {	   if (!stralloc_copys(sa,name)) return DNS_MEM;	   break;	  }	}       if (r == 2) return loop;    }  } return DNS_HARD; /* alias loop */}#define FMT_IAA 40static int iaafmt(s,ip)char *s;struct ip_address *ip;{ unsigned int i; unsigned int len; len = 0; i = fmt_ulong(s,(unsigned long) ip->d[3]); len += i; if (s) s += i; i = fmt_str(s,"."); len += i; if (s) s += i; i = fmt_ulong(s,(unsigned long) ip->d[2]); len += i; if (s) s += i; i = fmt_str(s,"."); len += i; if (s) s += i; i = fmt_ulong(s,(unsigned long) ip->d[1]); len += i; if (s) s += i; i = fmt_str(s,"."); len += i; if (s) s += i; i = fmt_ulong(s,(unsigned long) ip->d[0]); len += i; if (s) s += i; i = fmt_str(s,".in-addr.arpa."); len += i; if (s) s += i; return len;}int dns_ptr(sa,ip)stralloc *sa;struct ip_address *ip;{ int r; if (!stralloc_ready(sa,iaafmt((char *) 0,ip))) return DNS_MEM; sa->len = iaafmt(sa->s,ip); switch(resolve(sa,T_PTR))  {   case DNS_MEM: return DNS_MEM;   case DNS_SOFT: return DNS_SOFT;   case DNS_HARD: return DNS_HARD;  } while ((r = findname(T_PTR)) != 2)  {   if (r == DNS_SOFT) return DNS_SOFT;   if (r == 1)    {     if (!stralloc_copys(sa,name)) return DNS_MEM;     return 0;    }  } return DNS_HARD;}static int dns_ipplus(ia,sa,pref)ipalloc *ia;stralloc *sa;int pref;{ int r; struct ip_mx ix; if (!stralloc_copy(&glue,sa)) return DNS_MEM; if (!stralloc_0(&glue)) return DNS_MEM; if (glue.s[0]) {   ix.pref = 0;   if (!glue.s[ip_scan(glue.s,&ix.ip)] || !glue.s[ip_scanbracket(glue.s,&ix.ip)])    {     if (!ipalloc_append(ia,&ix)) return DNS_MEM;     return 0;    } } switch(resolve(sa,T_A))  {   case DNS_MEM: return DNS_MEM;   case DNS_SOFT: return DNS_SOFT;   case DNS_HARD: return DNS_HARD;  } while ((r = findip(T_A)) != 2)  {   ix.ip = ip;   ix.pref = pref;   if (r == DNS_SOFT) return DNS_SOFT;   if (r == 1)     if (!ipalloc_append(ia,&ix)) return DNS_MEM;  } return 0;}int dns_ip(ia,sa)ipalloc *ia;stralloc *sa;{ if (!ipalloc_readyplus(ia,0)) return DNS_MEM; ia->len = 0; return dns_ipplus(ia,sa,0);}int dns_mxip(ia,sa,random)ipalloc *ia;stralloc *sa;unsigned long random;{ int r; struct mx { stralloc sa; unsigned short p; } *mx; struct ip_mx ix; int nummx; int i; int j; int flagsoft; if (!ipalloc_readyplus(ia,0)) return DNS_MEM; ia->len = 0; if (!stralloc_copy(&glue,sa)) return DNS_MEM; if (!stralloc_0(&glue)) return DNS_MEM; if (glue.s[0]) {   ix.pref = 0;   if (!glue.s[ip_scan(glue.s,&ix.ip)] || !glue.s[ip_scanbracket(glue.s,&ix.ip)])    {     if (!ipalloc_append(ia,&ix)) return DNS_MEM;     return 0;    } } switch(resolve(sa,T_MX))  {   case DNS_MEM: return DNS_MEM;   case DNS_SOFT: return DNS_SOFT;   case DNS_HARD: return dns_ip(ia,sa);  } mx = (struct mx *) alloc(numanswers * sizeof(struct mx)); if (!mx) return DNS_MEM; nummx = 0; while ((r = findmx(T_MX)) != 2)  {   if (r == DNS_SOFT) { alloc_free(mx); return DNS_SOFT; }   if (r == 1)    {     mx[nummx].p = pref;     mx[nummx].sa.s = 0;     if (!stralloc_copys(&mx[nummx].sa,name))      {       while (nummx > 0) alloc_free(mx[--nummx].sa.s);       alloc_free(mx); return DNS_MEM;      }     ++nummx;    }  } if (!nummx) return dns_ip(ia,sa); /* e.g., CNAME -> A */ flagsoft = 0; while (nummx > 0)  {   unsigned long numsame;   i = 0;   numsame = 1;   for (j = 1;j < nummx;++j)     if (mx[j].p < mx[i].p)      {       i = j;       numsame = 1;      }     else if (mx[j].p == mx[i].p)      {       ++numsame;       random = random * 69069 + 1;       if ((random / 2) < (2147483647 / numsame))         i = j;      }   switch(dns_ipplus(ia,&mx[i].sa,mx[i].p))    {     case DNS_MEM: case DNS_SOFT:       flagsoft = 1; break;    }   alloc_free(mx[i].sa.s);   mx[i] = mx[--nummx];  } alloc_free(mx); return flagsoft;}