1 files changed, 127 insertions, 0 deletions
diff --git a/src/libs6dns/s6dns_analyze_packet.c b/src/libs6dns/s6dns_analyze_packet.c
new file mode 100644
index 0000000..57a5ce5
--- /dev/null
+++ b/src/libs6dns/s6dns_analyze_packet.c
@@ -0,0 +1,127 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <skalibs/error.h>
+#include <skalibs/uint16.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/genwrite.h>
+#include <skalibs/fmtscan.h>
+#include <s6-dns/s6dns-constants.h>
+#include <s6-dns/s6dns-domain.h>
+#include <s6-dns/s6dns-message.h>
+#include <s6-dns/s6dns-analyze.h>
+
+#define add(s) if ((*gp->put)(gp->target, (s), str_len(s)) < 0) return 0
+#define addfmt(n) if ((*gp->put)(gp->target, fmt, uint_fmt(fmt, (n))) < 0) return 0
+#define addfmt16(n) if ((*gp->put)(gp->target, fmt, uint16_fmt(fmt, (n))) < 0) return 0
+
+int s6dns_analyze_packet (genwrite_t *gp, char const *packet, unsigned int packetlen, int rec)
+{
+  s6dns_message_header_t h ;
+  s6dns_message_counts_t counts ;
+  unsigned int pos ;
+  unsigned int section ;
+  char fmt[UINT_FMT] ;
+  if (!s6dns_message_parse_init(&h, &counts, packet, packetlen, &pos))
+    return 0 ;
+
+  addfmt(packetlen) ;
+  add(" bytes, ") ;
+  addfmt16(counts.qd) ;
+  add("+") ;
+  addfmt16(counts.an) ;
+  add("+") ;
+  addfmt16(counts.ns) ;
+  add("+") ;
+  addfmt16(counts.nr) ;
+  add(" records") ;
+  if (h.qr) add(", response") ;
+  if (h.opcode)
+  {
+    add(", weird op (") ;
+    addfmt(h.opcode) ;
+    add(")") ;
+  }
+  if (h.aa) add(", authoritative") ;
+  if (h.tc) add(", truncated") ;
+  if (h.rd)
+  {
+    add(", ") ;
+    if (!rec) add("weird ") ;
+    add("rd") ;
+  }
+  if (h.ra)
+  {
+    add(", ") ;
+    if (!rec) add("weird ") ;
+    add("ra") ;
+  }
+  switch (h.rcode)
+  {
+    case 0 : add(", noerror") ; break ;
+    case 1 : add(", fmterror") ; break ;
+    case 2 : add(", servfail") ; break ;
+    case 3 : add(", nxdomain") ; break ;
+    case 4 : add(", notimpl") ; break ;
+    case 5 : add(", refused") ; break ;
+    default:
+    {
+      add(", weird rcode (") ;
+      addfmt(h.rcode) ;
+      add(")") ;
+    }
+  }
+  if (h.z)
+  {
+    add(", weird z (") ;
+    addfmt(h.z) ;
+    add(")") ;
+  }
+  add("\n") ;
+
+  for (;;)
+  {
+    s6dns_domain_t d ;
+    char buf[257] ;
+    unsigned int len ;
+    uint16 qtype ;
+    uint16 qclass ;
+    section = s6dns_message_counts_next(&counts) ;
+    if (section != 1) break ;
+    add("query: ") ;
+    if (!s6dns_message_get_domain(&d, packet, packetlen, &pos)) return 0 ;
+    len = s6dns_domain_tostring(buf, 255, &d) ;
+    if (!len) return 0 ;
+    buf[len++] = '\n' ; buf[len++] = 0 ;
+    if (pos + 4 > packetlen) return (errno = EPROTO, 0) ;
+    uint16_unpack_big(packet + pos, &qtype) ; pos += 2 ;
+    uint16_unpack_big(packet + pos, &qclass) ; pos += 2 ;
+    if (qclass != S6DNS_C_IN)
+    {
+      add("weird class (") ;
+      addfmt16(qclass) ;
+      add(") - ") ;
+    }
+    addfmt16(qtype) ;
+    add(" ") ;
+    add(buf) ;
+  }
+
+  while (section)
+  {
+    static char const *intro[3] = { "answer: ", "authority: ", "additional: " } ;
+    s6dns_message_rr_t rr ;
+    if (!s6dns_message_parse_getrr(&rr, packet, packetlen, &pos)) return 0 ;
+    add(intro[section-2]) ;
+    if (rr.rclass != S6DNS_C_IN)
+    {
+      add("weird class (") ;
+      addfmt16(rr.rclass) ;
+      add("), not attempting to analyze record\n") ;
+    }
+    else if (!s6dns_analyze_record(gp, &rr, packet, packetlen, pos)) return 0 ;
+    section = s6dns_message_parse_next(&counts, &rr, packet, packetlen, &pos) ;
+  }
+
+  return 1 ;
+}