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50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
23 years ago
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#include "stralloc.h"
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#include "byte.h"
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#include "uint16.h"
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#include "dns.h"
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static char *q = 0;
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int dns_mx_packet(stralloc *out,const char *buf,unsigned int len)
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{
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unsigned int pos;
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char header[12];
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char pref[2];
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uint16 numanswers;
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uint16 datalen;
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if (!stralloc_copys(out,"")) return -1;
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pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return -1;
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uint16_unpack_big(header + 6,&numanswers);
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pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
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pos += 4;
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while (numanswers--) {
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pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
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pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return -1;
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uint16_unpack_big(header + 8,&datalen);
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if (byte_equal(header,2,DNS_T_MX))
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if (byte_equal(header + 2,2,DNS_C_IN)) {
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if (!dns_packet_copy(buf,len,pos,pref,2)) return -1;
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if (!dns_packet_getname(buf,len,pos + 2,&q)) return -1;
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if (!stralloc_catb(out,pref,2)) return -1;
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if (!dns_domain_todot_cat(out,q)) return -1;
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if (!stralloc_0(out)) return -1;
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}
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pos += datalen;
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}
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return 0;
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}
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int dns_mx(stralloc *out,const stralloc *fqdn)
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{
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if (!dns_domain_fromdot(&q,fqdn->s,fqdn->len)) return -1;
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if (dns_resolve(q,DNS_T_MX) == -1) return -1;
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if (dns_mx_packet(out,dns_resolve_tx.packet,dns_resolve_tx.packetlen) == -1) return -1;
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dns_transmit_free(&dns_resolve_tx);
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dns_domain_free(&q);
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return 0;
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}
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