1 files changed, 71 insertions, 0 deletions
diff --git a/src/dnsstub/dns_txt.c b/src/dnsstub/dns_txt.c
new file mode 100644
index 0000000..3c54773
--- /dev/null
+++ b/src/dnsstub/dns_txt.c
@@ -0,0 +1,71 @@
+#include "stralloc.h"
+#include "uint_t.h"
+#include "byte.h"
+#include "dnsresolv.h"
+
+/**
+  * @file dns_txt.c
+  * @authors djb, fefe, feh
+  * @ref ucspi-tcp
+  * @brief DNS text query (txt)
+  */
+
+int dns_txt_packet(stralloc *out,const char *buf,unsigned int len)
+{
+  unsigned int pos;
+  char header[12];
+  uint16 numanswers;
+  uint16 datalen;
+  char ch;
+  unsigned int txtlen;
+  int i;
+  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_TXT))
+      if (byte_equal(header + 2,2,DNS_C_IN)) {
+        if (pos + datalen > len) return DNS_ERR;
+        txtlen = (unsigned char) buf[pos];
+        for (i = 1; i < datalen; ++i) {
+          ch = buf[pos + i];
+          if (i == txtlen + 1)     // next label
+            txtlen += (unsigned char) ch + 1;
+          else {
+            if (ch < 32) ch = '?';
+            if (ch > 126) ch = '?';
+            if (!stralloc_append(out,&ch)) return DNS_MEM;
+          }
+        }
+      }
+    pos += datalen;
+    ++ranswers;
+    if (numanswers) if (!stralloc_append(out,"\n")) return DNS_MEM;
+  }
+
+  return ranswers;
+}
+
+static char *q = 0;
+
+int dns_txt(stralloc *out,const stralloc *fqdn)
+{
+  int rc; 
+
+  if (dns_domain_fromdot(&q,fqdn->s,fqdn->len) <= 0) return DNS_ERR;
+  if (dns_resolve(q,DNS_T_TXT) < 0) return DNS_ERR;
+  if ((rc = dns_txt_packet(out,dns_resolve_tx.packet,dns_resolve_tx.packetlen)) < 0) return DNS_ERR;
+  dns_transmit_free(&dns_resolve_tx);
+  dns_domain_free(&q);
+
+  return rc;
+}