add dns_tlsa(...) and dnstlsa utility

1 files changed, 41 insertions, 0 deletions

diff --git a/dns.c b/dns.c
index bed2bd2..b4d106c 100644
--- a/dns.c
+++ b/dns.c
@@ -418,3 +418,44 @@ unsigned long random;
  alloc_free(mx);
  return flagsoft;
 }
+
+int dns_tlsa(stralloc *out, const stralloc *fqdn)
+{
+  int ranswers = 0;
+
+  switch(resolve(fqdn, T_TLSA))
+  {
+    case DNS_MEM: return DNS_MEM;
+    case DNS_SOFT: return DNS_SOFT;
+    case DNS_HARD: return DNS_HARD;
+  }
+
+  if (!stralloc_copys(out,"")) return DNS_MEM;
+  while(numanswers-- > 0) {
+    int i;
+    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;
+
+    unsigned short rrtype = getshort(responsepos);
+    unsigned short rrdlen = getshort(responsepos + 8);
+    responsepos += 10; // skip dns header
+    if (responsepos + rrdlen > responseend) return DNS_HARD;
+
+    if (rrtype == T_TLSA)
+    {
+      unsigned char rrlen[2] = { rrdlen >> 8, rrdlen & 0xFF };
+      stralloc_catb(out, rrlen, 2);
+      if (!stralloc_catb(out, responsepos, rrdlen)) return DNS_MEM;
+      ++ranswers;
+    }
+
+    responsepos += rrdlen;
+  }
+  return ranswers;
+}