1 files changed, 300 insertions, 0 deletions

diff --git a/src/dns/dnsparser.c b/src/dns/dnsparser.c
new file mode 100644
index 000000000..6921f0d34
--- /dev/null
+++ b/src/dns/dnsparser.c
@@ -0,0 +1,300 @@
+#include "platform.h"
+#include "gnunet_dnsparser_lib.h"
+
+/**
+ * Parse a name from DNS to a normal .-delimited, 0-terminated string.
+ *
+ * @param d The destination of the name. Should have at least 255 bytes allocated.
+ * @param src The DNS-Packet
+ * @param idx The offset inside the Packet from which on the name should be read
+ * @returns The offset of the first unparsed byte (the byte right behind the name)
+ */
+static unsigned int
+parse_dns_name (char *d, const unsigned char *src, unsigned short idx)
+{                               /*{{{ */
+  char *dest = d;
+
+  int len = src[idx++];
+
+  while (len != 0)
+  {
+    if (len & 0xC0)
+    {                           /* Compressed name, offset in this and the next octet */
+      unsigned short offset = ((len & 0x3F) << 8) | src[idx++];
+
+      parse_dns_name (dest, src, offset - 12);  /* 12 for the Header of the DNS-Packet, idx starts at 0 which is 12 bytes from the start of the packet */
+      return idx;
+    }
+    memcpy (dest, src + idx, len);
+    idx += len;
+    dest += len;
+    *dest = '.';
+    dest++;
+    len = src[idx++];
+  };
+  *dest = 0;
+
+  return idx;
+}
+
+/*}}}*/
+
+/**
+ * Parse a complete DNS-Record from raw DNS-data to a struct dns_record
+ *
+ * @param data The DNS-data
+ * @param dst Pointer to count pointers; individual pointers will be allocated
+ * @param count Number of records to parse
+ * @param idx The offset inside the Packet from which on the name should be read
+ * @returns The offset of the first unparsed byte (the byte right behind the last record)
+ */
+static unsigned short
+parse_dns_record (unsigned char *data,  /*{{{ */
+                  struct dns_record **dst, unsigned short count,
+                  unsigned short idx)
+{
+  int i;
+  unsigned short _idx;
+
+  for (i = 0; i < count; i++)
+  {
+    dst[i] = GNUNET_malloc (sizeof (struct dns_record));
+    dst[i]->name = alloca (255);        // see RFC1035, no name can be longer than this.
+    char *name = dst[i]->name;
+
+    _idx = parse_dns_name (name, data, idx);
+    dst[i]->namelen = _idx - idx;
+
+    dst[i]->name = GNUNET_malloc (dst[i]->namelen);
+    memcpy (dst[i]->name, name, dst[i]->namelen);
+
+    idx = _idx;
+
+    dst[i]->type = *((unsigned short *) (data + idx));
+    idx += 2;
+    dst[i]->class = *((unsigned short *) (data + idx));
+    idx += 2;
+    dst[i]->ttl = *((unsigned int *) (data + idx));
+    idx += 4;
+    dst[i]->data_len = *((unsigned short *) (data + idx));
+    idx += 2;
+    dst[i]->data = GNUNET_malloc (ntohs (dst[i]->data_len));
+    memcpy (dst[i]->data, data + idx, ntohs (dst[i]->data_len));
+    idx += ntohs (dst[i]->data_len);
+  }
+  return idx;
+}                               /*}}} */
+
+/**
+ * Parse a raw DNS-Packet into an usable struct
+ */
+struct dns_pkt_parsed *
+parse_dns_packet (struct dns_pkt *pkt)
+{                               /*{{{ */
+  struct dns_pkt_parsed *ppkt = GNUNET_malloc (sizeof (struct dns_pkt_parsed));
+
+  memcpy (&ppkt->s, &pkt->s, sizeof pkt->s);
+
+  unsigned short qdcount = ntohs (ppkt->s.qdcount);
+  unsigned short ancount = ntohs (ppkt->s.ancount);
+  unsigned short nscount = ntohs (ppkt->s.nscount);
+  unsigned short arcount = ntohs (ppkt->s.arcount);
+
+  ppkt->queries = GNUNET_malloc (qdcount * sizeof (struct dns_query *));
+  ppkt->answers = GNUNET_malloc (ancount * sizeof (struct dns_record *));
+  ppkt->nameservers = GNUNET_malloc (nscount * sizeof (struct dns_record *));
+  ppkt->additional = GNUNET_malloc (arcount * sizeof (struct dns_record *));
+
+  unsigned short idx = 0, _idx; /* This keeps track how far we have parsed the data */
+
+  /* Parse the Query */
+  int i;
+
+  for (i = 0; i < qdcount; i++)
+  {                             /*{{{ */
+    ppkt->queries[i] = GNUNET_malloc (sizeof (struct dns_query));
+    char *name = alloca (255);  /* see RFC1035, it can't be more than this. */
+
+    _idx = parse_dns_name (name, pkt->data, idx);
+    ppkt->queries[i]->namelen = _idx - idx;
+    idx = _idx;
+
+    ppkt->queries[i]->name = GNUNET_malloc (ppkt->queries[i]->namelen);
+    memcpy (ppkt->queries[i]->name, name, ppkt->queries[i]->namelen);
+
+    ppkt->queries[i]->qtype = *((unsigned short *) (pkt->data + idx));
+    idx += 2;
+    ppkt->queries[i]->qclass = *((unsigned short *) (pkt->data + idx));
+    idx += 2;
+  }
+  /*}}} */
+  idx = parse_dns_record (pkt->data, ppkt->answers, ancount, idx);
+  idx = parse_dns_record (pkt->data, ppkt->nameservers, nscount, idx);
+  idx = parse_dns_record (pkt->data, ppkt->additional, arcount, idx);
+  return ppkt;
+}                               /*}}} */
+
+static void
+unparse_dns_name (char *dest, char *src, size_t len)
+{
+  char *b = dest;
+  char cnt = 0;
+
+  dest++;
+  while (*src != 0)
+  {
+    while (*src != '.' && *src != 0)
+    {
+      *dest = *src;
+      src++;
+      dest++;
+      cnt++;
+    }
+    *b = cnt;
+    cnt = 0;
+    b = dest;
+    dest++;
+    src++;
+  }
+  *b = 0;
+}
+
+struct dns_pkt *
+unparse_dns_packet (struct dns_pkt_parsed *ppkt)
+{
+  size_t size = sizeof (struct dns_pkt) - 1;
+  int i;
+
+  for (i = 0; i < ntohs (ppkt->s.qdcount); i++)
+    size += ppkt->queries[i]->namelen + 1;
+
+  for (i = 0; i < ntohs (ppkt->s.ancount); i++)
+  {
+    size += ppkt->answers[i]->namelen + 1;
+    size += ppkt->answers[i]->data_len;
+  }
+  for (i = 0; i < ntohs (ppkt->s.nscount); i++)
+  {
+    size += ppkt->nameservers[i]->namelen + 1;
+    size += ppkt->nameservers[i]->data_len;
+  }
+  for (i = 0; i < ntohs (ppkt->s.arcount); i++)
+  {
+    size += ppkt->additional[i]->namelen + 1;
+    size += ppkt->additional[i]->data_len;
+  }
+
+  size +=
+      4 * ntohs (ppkt->s.qdcount) + 10 * (ntohs (ppkt->s.ancount) +
+                                          ntohs (ppkt->s.arcount) +
+                                          ntohs (ppkt->s.nscount));
+
+  struct dns_pkt *pkt = GNUNET_malloc (size);
+  char *pkt_c = (char *) pkt;
+
+  memcpy (&pkt->s, &ppkt->s, sizeof ppkt->s);
+  size_t idx = sizeof ppkt->s;
+
+  for (i = 0; i < ntohs (ppkt->s.qdcount); i++)
+  {
+    unparse_dns_name (&pkt_c[idx], ppkt->queries[i]->name,
+                      ppkt->queries[i]->namelen);
+    idx += ppkt->queries[i]->namelen;
+    struct dns_query_line *d = (struct dns_query_line *) &pkt_c[idx];
+
+    d->class = ppkt->queries[i]->qclass;
+    d->type = ppkt->queries[i]->qtype;
+    idx += sizeof (struct dns_query_line);
+  }
+
+  for (i = 0; i < ntohs (ppkt->s.ancount); i++)
+  {
+    unparse_dns_name (&pkt_c[idx], ppkt->answers[i]->name,
+                      ppkt->answers[i]->namelen);
+    idx += ppkt->answers[i]->namelen;
+    struct dns_record_line *r = (struct dns_record_line *) &pkt_c[idx];
+
+    r->type = ppkt->answers[i]->type;
+    r->class = ppkt->answers[i]->class;
+    r->ttl = ppkt->answers[i]->ttl;
+    r->data_len = ppkt->answers[i]->data_len;
+    idx += sizeof (struct dns_record_line);
+    memcpy (&r->data, ppkt->answers[i]->data, ppkt->answers[i]->data_len);
+    idx += ppkt->answers[i]->data_len;
+  }
+
+  for (i = 0; i < ntohs (ppkt->s.nscount); i++)
+  {
+    unparse_dns_name (&pkt_c[idx], ppkt->nameservers[i]->name,
+                      ppkt->nameservers[i]->namelen);
+    idx += ppkt->nameservers[i]->namelen;
+    struct dns_record_line *r = (struct dns_record_line *) &pkt_c[idx];
+
+    r->type = ppkt->nameservers[i]->type;
+    r->class = ppkt->nameservers[i]->class;
+    r->ttl = ppkt->nameservers[i]->ttl;
+    r->data_len = ppkt->nameservers[i]->data_len;
+    idx += sizeof (struct dns_record_line);
+    memcpy (&r->data, ppkt->nameservers[i]->data,
+            ppkt->nameservers[i]->data_len);
+    idx += ppkt->nameservers[i]->data_len;
+  }
+
+  for (i = 0; i < ntohs (ppkt->s.arcount); i++)
+  {
+    unparse_dns_name (&pkt_c[idx], ppkt->additional[i]->name,
+                      ppkt->additional[i]->namelen);
+    idx += ppkt->additional[i]->namelen;
+    struct dns_record_line *r = (struct dns_record_line *) &pkt_c[idx];
+
+    r->type = ppkt->additional[i]->type;
+    r->class = ppkt->additional[i]->class;
+    r->ttl = ppkt->additional[i]->ttl;
+    r->data_len = ppkt->additional[i]->data_len;
+    idx += sizeof (struct dns_record_line);
+    memcpy (&r->data, ppkt->additional[i]->data, ppkt->additional[i]->data_len);
+    idx += ppkt->additional[i]->data_len;
+  }
+
+  return pkt;
+}
+
+void
+free_parsed_dns_packet (struct dns_pkt_parsed *ppkt)
+{
+  unsigned short qdcount = ntohs (ppkt->s.qdcount);
+  unsigned short ancount = ntohs (ppkt->s.ancount);
+  unsigned short nscount = ntohs (ppkt->s.nscount);
+  unsigned short arcount = ntohs (ppkt->s.arcount);
+
+  int i;
+
+  for (i = 0; i < qdcount; i++)
+  {
+    GNUNET_free (ppkt->queries[i]->name);
+    GNUNET_free (ppkt->queries[i]);
+  }
+  GNUNET_free (ppkt->queries);
+  for (i = 0; i < ancount; i++)
+  {
+    GNUNET_free (ppkt->answers[i]->name);
+    GNUNET_free (ppkt->answers[i]->data);
+    GNUNET_free (ppkt->answers[i]);
+  }
+  GNUNET_free (ppkt->answers);
+  for (i = 0; i < nscount; i++)
+  {
+    GNUNET_free (ppkt->nameservers[i]->name);
+    GNUNET_free (ppkt->nameservers[i]->data);
+    GNUNET_free (ppkt->nameservers[i]);
+  }
+  GNUNET_free (ppkt->nameservers);
+  for (i = 0; i < arcount; i++)
+  {
+    GNUNET_free (ppkt->additional[i]->name);
+    GNUNET_free (ppkt->additional[i]->data);
+    GNUNET_free (ppkt->additional[i]);
+  }
+  GNUNET_free (ppkt->additional);
+  GNUNET_free (ppkt);
+}