diff options
author | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 13:58:20 +0200 |
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committer | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 13:58:20 +0200 |
commit | 249866e3d1e11dc72eaa1305f4bb479ded92ef38 (patch) | |
tree | 7118c5f58e29fe61c100e4d067bb90ba8d52589e /src/dnsstub/dns_cname.c | |
parent | 96cf8dffe4f7b0b910f790066ae622dc429eb522 (diff) |
reorganized file structure
Moved c files into src/.
Corrected VERSION file.
Removed BUILD and FILES.
Diffstat (limited to 'src/dnsstub/dns_cname.c')
-rw-r--r-- | src/dnsstub/dns_cname.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/src/dnsstub/dns_cname.c b/src/dnsstub/dns_cname.c new file mode 100644 index 0000000..408949a --- /dev/null +++ b/src/dnsstub/dns_cname.c @@ -0,0 +1,59 @@ +#include "stralloc.h" +#include "uint_t.h" +#include "byte.h" +#include "ip.h" +#include "case.h" +#include "dnsresolv.h" + +/** + @file dns_cname.c + @author feh + @brief DNS cname lookup +*/ + +static char *q = 0; + +int dns_cname_packet(stralloc *out,const char *buf,unsigned int len) +{ + unsigned int pos; + char header[12]; + uint16 numanswers; + uint16 datalen; + int ranswers = 0; + + if (!stralloc_copys(out,"")) return DNS_MEM; + + pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return DNS_ERR; + uint16_unpack_big(header + 6,&numanswers); + pos = dns_packet_skipname(buf,len,pos); if (!pos) return DNS_ERR; + pos += 4; + + while (numanswers--) { + pos = dns_packet_skipname(buf,len,pos); if (!pos) return DNS_ERR; + pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return DNS_ERR; + uint16_unpack_big(header + 8,&datalen); + if (byte_equal(header,2,DNS_T_CNAME)) + if (byte_equal(header + 2,2,DNS_C_IN)) { + if (!dns_packet_getname(buf,len,pos,&q)) return DNS_ERR; + if (dns_domain_todot_cat(out,q) <= 0) return DNS_ERR; + } + pos += datalen; + ++ranswers; + } + + return ranswers; +} + +int dns_cname(stralloc *out,stralloc *fqdn) +{ + int rc; + + if (dns_domain_fromdot(&q,fqdn->s,fqdn->len) <= 0) return DNS_ERR; + if (dns_resolve(q,DNS_T_CNAME) < 0) return DNS_ERR; + if ((rc = dns_cname_packet(out,dns_resolve_tx.packet,dns_resolve_tx.packetlen)) < 0) return DNS_ERR; + dns_transmit_free(&dns_resolve_tx); + dns_domain_free(&q); + if (case_equals(out->s,fqdn->s)) rc = -6; // loop DNS_HARD + + return rc; +} |