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authorJannis Hoffmann <jannis@fehcom.de>2024-07-09 13:58:20 +0200
committerJannis Hoffmann <jannis@fehcom.de>2024-07-09 13:58:20 +0200
commit249866e3d1e11dc72eaa1305f4bb479ded92ef38 (patch)
tree7118c5f58e29fe61c100e4d067bb90ba8d52589e /src/dnsstub/dns_cname.c
parent96cf8dffe4f7b0b910f790066ae622dc429eb522 (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.c59
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;
+}