* @file dns/dnsparser.c
* @brief helper library to parse DNS packets.
* @author Philipp Toelke
+ * @author Christian Grothoff
*/
-
#include "platform.h"
+#include "gnunet_util_lib.h"
#include "gnunet_dnsparser_lib.h"
+#include "dnsparser.h"
+
-// DNS-Stuff
-GNUNET_NETWORK_STRUCT_BEGIN
-struct dns_header
+/**
+ * Parse name inside of a DNS query or record.
+ *
+ * @param udp_payload entire UDP payload
+ * @param udp_payload_length length of udp_payload
+ * @param off pointer to the offset of the name to parse in the udp_payload (to be
+ * incremented by the size of the name)
+ * @param depth current depth of our recursion (to prevent stack overflow)
+ * @return name as 0-terminated C string on success, NULL if the payload is malformed
+ */
+static char *
+parse_name (const char *udp_payload,
+ size_t udp_payload_length,
+ size_t *off,
+ unsigned int depth)
{
- uint16_t id GNUNET_PACKED;
- struct GNUNET_DNSPARSER_Flags flags GNUNET_PACKED;
- uint16_t query_count GNUNET_PACKED; // number of questions
- uint16_t answer_rcount GNUNET_PACKED; // number of answers
- uint16_t authority_rcount GNUNET_PACKED; // number of authority-records
- uint16_t additional_rcount GNUNET_PACKED; // number of additional records
-};
-GNUNET_NETWORK_STRUCT_END
+ const uint8_t *input = (const uint8_t *) udp_payload;
+ char *ret;
+ char *tmp;
+ char *xstr;
+ uint8_t len;
+ size_t xoff;
+
+ ret = GNUNET_strdup ("");
+ while (1)
+ {
+ if (*off >= udp_payload_length)
+ goto error;
+ len = input[*off];
+ if (0 == len)
+ {
+ (*off)++;
+ break;
+ }
+ if (len < 64)
+ {
+ if (*off + 1 + len > udp_payload_length)
+ goto error;
+ GNUNET_asprintf (&tmp,
+ "%s%.*s.",
+ ret,
+ (int) len,
+ &udp_payload[*off + 1]);
+ GNUNET_free (ret);
+ ret = tmp;
+ *off += 1 + len;
+ }
+ else if ((64 | 128) == (len & (64 | 128)) )
+ {
+ if (depth > 32)
+ goto error; /* hard bound on stack to prevent "infinite" recursion, disallow! */
+ /* pointer to string */
+ if (*off + 1 > udp_payload_length)
+ goto error;
+ xoff = ((len - (64 | 128)) << 8) + input[*off+1];
+ xstr = parse_name (udp_payload,
+ udp_payload_length,
+ &xoff,
+ depth + 1);
+ if (NULL == xstr)
+ goto error;
+ GNUNET_asprintf (&tmp,
+ "%s%s.",
+ ret,
+ xstr);
+ GNUNET_free (ret);
+ GNUNET_free (xstr);
+ ret = tmp;
+ if (strlen (ret) > udp_payload_length)
+ goto error; /* we are looping (building an infinite string) */
+ *off += 2;
+ /* pointers always terminate names */
+ break;
+ }
+ else
+ {
+ /* neither pointer nor inline string, not supported... */
+ goto error;
+ }
+ }
+ if (0 < strlen(ret))
+ ret[strlen(ret)-1] = '\0'; /* eat tailing '.' */
+ return ret;
+ error:
+ GNUNET_free (ret);
+ return NULL;
+}
/**
size_t *off,
struct GNUNET_DNSPARSER_Query *q)
{
- return GNUNET_SYSERR;
+ char *name;
+ struct query_line ql;
+
+ name = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ if (NULL == name)
+ return GNUNET_SYSERR;
+ q->name = name;
+ if (*off + sizeof (struct query_line) > udp_payload_length)
+ return GNUNET_SYSERR;
+ memcpy (&ql, &udp_payload[*off], sizeof (ql));
+ *off += sizeof (ql);
+ q->type = ntohs (ql.type);
+ q->class = ntohs (ql.class);
+ return GNUNET_OK;
}
size_t *off,
struct GNUNET_DNSPARSER_Record *r)
{
- return GNUNET_SYSERR;
+ char *name;
+ struct record_line rl;
+ size_t old_off;
+ struct soa_data soa;
+ uint16_t mxpref;
+ uint16_t data_len;
+ struct srv_data srv;
+ char *ndup;
+ char *tok;
+
+ name = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ if (NULL == name)
+ return GNUNET_SYSERR;
+ r->name = name;
+ if (*off + sizeof (struct record_line) > udp_payload_length)
+ return GNUNET_SYSERR;
+ memcpy (&rl, &udp_payload[*off], sizeof (rl));
+ (*off) += sizeof (rl);
+ r->type = ntohs (rl.type);
+ r->class = ntohs (rl.class);
+ r->expiration_time = GNUNET_TIME_relative_to_absolute (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
+ ntohl (rl.ttl)));
+ data_len = ntohs (rl.data_len);
+ if (*off + data_len > udp_payload_length)
+ return GNUNET_SYSERR;
+ switch (r->type)
+ {
+ case GNUNET_DNSPARSER_TYPE_NS:
+ case GNUNET_DNSPARSER_TYPE_CNAME:
+ case GNUNET_DNSPARSER_TYPE_PTR:
+ old_off = *off;
+ r->data.hostname = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ if ( (NULL == r->data.hostname) ||
+ (old_off + data_len != *off) )
+ return GNUNET_SYSERR;
+ return GNUNET_OK;
+ case GNUNET_DNSPARSER_TYPE_SOA:
+ old_off = *off;
+ r->data.soa = GNUNET_malloc (sizeof (struct GNUNET_DNSPARSER_SoaRecord));
+ r->data.soa->mname = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ r->data.soa->rname = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ if ( (NULL == r->data.soa->mname) ||
+ (NULL == r->data.soa->rname) ||
+ (*off + sizeof (struct soa_data) > udp_payload_length) )
+ return GNUNET_SYSERR;
+ memcpy (&soa, &udp_payload[*off], sizeof (struct soa_data));
+ r->data.soa->serial = ntohl (soa.serial);
+ r->data.soa->refresh = ntohl (soa.refresh);
+ r->data.soa->retry = ntohl (soa.retry);
+ r->data.soa->expire = ntohl (soa.expire);
+ r->data.soa->minimum_ttl = ntohl (soa.minimum);
+ (*off) += sizeof (struct soa_data);
+ if (old_off + data_len != *off)
+ return GNUNET_SYSERR;
+ return GNUNET_OK;
+ case GNUNET_DNSPARSER_TYPE_MX:
+ old_off = *off;
+ if (*off + sizeof (uint16_t) > udp_payload_length)
+ return GNUNET_SYSERR;
+ memcpy (&mxpref, &udp_payload[*off], sizeof (uint16_t));
+ (*off) += sizeof (uint16_t);
+ r->data.mx = GNUNET_malloc (sizeof (struct GNUNET_DNSPARSER_MxRecord));
+ r->data.mx->preference = ntohs (mxpref);
+ r->data.mx->mxhost = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ if (old_off + data_len != *off)
+ return GNUNET_SYSERR;
+ return GNUNET_OK;
+ case GNUNET_DNSPARSER_TYPE_SRV:
+ if ('_' != *r->name)
+ return GNUNET_SYSERR; /* all valid srv names must start with "_" */
+ if (NULL == strstr (r->name, "._"))
+ return GNUNET_SYSERR; /* necessary string from "._$PROTO" not present */
+ old_off = *off;
+ if (*off + sizeof (struct srv_data) > udp_payload_length)
+ return GNUNET_SYSERR;
+ memcpy (&srv, &udp_payload[*off], sizeof (struct srv_data));
+ (*off) += sizeof (struct srv_data);
+ r->data.srv = GNUNET_malloc (sizeof (struct GNUNET_DNSPARSER_SrvRecord));
+ r->data.srv->priority = ntohs (srv.prio);
+ r->data.srv->weight = ntohs (srv.weight);
+ r->data.srv->port = ntohs (srv.port);
+ /* parse 'data.hostname' into components, which are
+ "_$SERVICE._$PROTO.$DOMAIN_NAME" */
+ ndup = GNUNET_strdup (r->name);
+ tok = strtok (ndup, ".");
+ GNUNET_assert (NULL != tok);
+ GNUNET_assert ('_' == *tok);
+ r->data.srv->service = GNUNET_strdup (&tok[1]);
+ tok = strtok (NULL, ".");
+ if ( (NULL == tok) || ('_' != *tok) )
+ {
+ GNUNET_free (r->data.srv);
+ GNUNET_free (ndup);
+ return GNUNET_SYSERR;
+ }
+ r->data.srv->proto = GNUNET_strdup (&tok[1]);
+ tok = strtok (NULL, ".");
+ if (NULL == tok)
+ {
+ GNUNET_free (r->data.srv);
+ GNUNET_free (ndup);
+ return GNUNET_SYSERR;
+ }
+ r->data.srv->domain_name = GNUNET_strdup (tok);
+ GNUNET_free (ndup);
+ r->data.srv->target = parse_name (udp_payload,
+ udp_payload_length,
+ off, 0);
+ if (old_off + data_len != *off)
+ return GNUNET_SYSERR;
+ return GNUNET_OK;
+ default:
+ r->data.raw.data = GNUNET_malloc (data_len);
+ r->data.raw.data_len = data_len;
+ memcpy (r->data.raw.data, &udp_payload[*off], data_len);
+ break;
+ }
+ (*off) += data_len;
+ return GNUNET_OK;
}
-
/**
* Parse a UDP payload of a DNS packet in to a nice struct for further
* processing and manipulation.
size_t udp_payload_length)
{
struct GNUNET_DNSPARSER_Packet *p;
- const struct dns_header *dns;
+ const struct GNUNET_TUN_DnsHeader *dns;
size_t off;
unsigned int n;
unsigned int i;
- if (udp_payload_length < sizeof (struct dns_header))
+ if (udp_payload_length < sizeof (struct GNUNET_TUN_DnsHeader))
return NULL;
- dns = (const struct dns_header *) udp_payload;
- off = sizeof (struct dns_header);
+ dns = (const struct GNUNET_TUN_DnsHeader *) udp_payload;
+ off = sizeof (struct GNUNET_TUN_DnsHeader);
p = GNUNET_malloc (sizeof (struct GNUNET_DNSPARSER_Packet));
p->flags = dns->flags;
p->id = dns->id;
}
+/**
+ * Free SOA information record.
+ *
+ * @param soa record to free
+ */
+static void
+free_soa (struct GNUNET_DNSPARSER_SoaRecord *soa)
+{
+ if (NULL == soa)
+ return;
+ GNUNET_free_non_null (soa->mname);
+ GNUNET_free_non_null (soa->rname);
+ GNUNET_free (soa);
+}
+
+
+/**
+ * Free SRV information record.
+ *
+ * @param srv record to free
+ */
+static void
+free_srv (struct GNUNET_DNSPARSER_SrvRecord *srv)
+{
+ if (NULL == srv)
+ return;
+ GNUNET_free_non_null (srv->target);
+ GNUNET_free_non_null (srv->domain_name);
+ GNUNET_free_non_null (srv->proto);
+ GNUNET_free_non_null (srv->service);
+ GNUNET_free (srv);
+}
+
+
+/**
+ * Free MX information record.
+ *
+ * @param mx record to free
+ */
+static void
+free_mx (struct GNUNET_DNSPARSER_MxRecord *mx)
+{
+ if (NULL == mx)
+ return;
+ GNUNET_free_non_null (mx->mxhost);
+ GNUNET_free (mx);
+}
+
+
+static void
+free_record (struct GNUNET_DNSPARSER_Record *r)
+{
+ GNUNET_free_non_null (r->name);
+ switch (r->type)
+ {
+ case GNUNET_DNSPARSER_TYPE_MX:
+ free_mx (r->data.mx);
+ break;
+ case GNUNET_DNSPARSER_TYPE_SOA:
+ free_soa (r->data.soa);
+ break;
+ case GNUNET_DNSPARSER_TYPE_SRV:
+ free_srv (r->data.srv);
+ break;
+ case GNUNET_DNSPARSER_TYPE_NS:
+ case GNUNET_DNSPARSER_TYPE_CNAME:
+ case GNUNET_DNSPARSER_TYPE_PTR:
+ GNUNET_free_non_null (r->data.hostname);
+ break;
+ default:
+ GNUNET_free_non_null (r->data.raw.data);
+ break;
+ }
+}
+
+
/**
* Free memory taken by a packet.
*
GNUNET_free_non_null (p->queries[i].name);
GNUNET_free_non_null (p->queries);
for (i=0;i<p->num_answers;i++)
- {
- GNUNET_free_non_null (p->answers[i].name);
- GNUNET_free_non_null (p->answers[i].data);
- }
+ free_record (&p->answers[i]);
GNUNET_free_non_null (p->answers);
for (i=0;i<p->num_authority_records;i++)
- {
- GNUNET_free_non_null (p->authority_records[i].name);
- GNUNET_free_non_null (p->authority_records[i].data);
- }
+ free_record (&p->authority_records[i]);
GNUNET_free_non_null (p->authority_records);
for (i=0;i<p->num_additional_records;i++)
- {
- GNUNET_free_non_null (p->additional_records[i].name);
- GNUNET_free_non_null (p->additional_records[i].data);
- }
+ free_record (&p->additional_records[i]);
GNUNET_free_non_null (p->additional_records);
GNUNET_free (p);
}
+/* ********************** DNS packet assembly code **************** */
+
+
/**
- * Given a DNS packet, generate the corresponding UDP payload.
+ * Add a DNS name to the UDP packet at the given location.
*
- * @param p packet to pack
- * @param buf set to a buffer with the packed message
- * @param buf_length set to the length of buf
- * @return GNUNET_SYSERR if 'p' is invalid
- * GNUNET_NO if 'p' was truncated (but there is still a result in 'buf')
- * GNUNET_OK if 'p' was packed completely into '*buf'
+ * @param dst where to write the name
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the name (increment by bytes used)
+ * must not be changed if there is an error
+ * @param name name to write
+ * @return GNUNET_SYSERR if 'name' is invalid
+ * GNUNET_NO if 'name' did not fit
+ * GNUNET_OK if 'name' was added to 'dst'
*/
-int
-GNUNET_DNSPARSER_pack (struct GNUNET_DNSPARSER_Packet *p,
- char **buf,
- size_t *buf_length)
+static int
+add_name (char *dst,
+ size_t dst_len,
+ size_t *off,
+ const char *name)
{
- // FIXME: not implemented
- GNUNET_break (0);
- return GNUNET_SYSERR;
+ const char *dot;
+ size_t start;
+ size_t pos;
+ size_t len;
+
+ if (NULL == name)
+ return GNUNET_SYSERR;
+ start = *off;
+ if (start + strlen (name) + 2 > dst_len)
+ return GNUNET_NO;
+ pos = start;
+ do
+ {
+ dot = strchr (name, '.');
+ if (NULL == dot)
+ len = strlen (name);
+ else
+ len = dot - name;
+ if ( (len >= 64) || (len == 0) )
+ return GNUNET_NO; /* segment too long or empty */
+ dst[pos++] = (char) (uint8_t) len;
+ memcpy (&dst[pos], name, len);
+ pos += len;
+ name += len + 1; /* also skip dot */
+ }
+ while (NULL != dot);
+ dst[pos++] = '\0'; /* terminator */
+ *off = pos;
+ return GNUNET_OK;
}
-
-
-/* legacy code follows */
-
/**
- * Parse a name from DNS to a normal .-delimited, 0-terminated string.
+ * Add a DNS query to the UDP packet at the given location.
*
- * @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)
+ * @param dst where to write the query
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the query (increment by bytes used)
+ * must not be changed if there is an error
+ * @param query query to write
+ * @return GNUNET_SYSERR if 'query' is invalid
+ * GNUNET_NO if 'query' did not fit
+ * GNUNET_OK if 'query' was added to 'dst'
*/
-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;
+static int
+add_query (char *dst,
+ size_t dst_len,
+ size_t *off,
+ const struct GNUNET_DNSPARSER_Query *query)
+{
+ int ret;
+ struct query_line ql;
+
+ ret = add_name (dst, dst_len - sizeof (struct query_line), off, query->name);
+ if (ret != GNUNET_OK)
+ return ret;
+ ql.type = htons (query->type);
+ ql.class = htons (query->class);
+ memcpy (&dst[*off], &ql, sizeof (ql));
+ (*off) += sizeof (ql);
+ return GNUNET_OK;
}
-/*}}}*/
/**
- * Parse a complete DNS-Record from raw DNS-data to a struct dns_record
+ * Add an MX record to the UDP packet at the given location.
*
- * @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)
+ * @param dst where to write the mx record
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the mx information (increment by bytes used);
+ * can also change if there was an error
+ * @param mx mx information to write
+ * @return GNUNET_SYSERR if 'mx' is invalid
+ * GNUNET_NO if 'mx' did not fit
+ * GNUNET_OK if 'mx' was added to 'dst'
*/
-static unsigned short
-parse_dns_record (unsigned char *data, /*{{{ */
- struct dns_record **dst, unsigned short count,
- unsigned short idx)
+static int
+add_mx (char *dst,
+ size_t dst_len,
+ size_t *off,
+ const struct GNUNET_DNSPARSER_MxRecord *mx)
{
- int i;
- unsigned short _idx;
+ uint16_t mxpref;
+
+ if (*off + sizeof (uint16_t) > dst_len)
+ return GNUNET_NO;
+ mxpref = htons (mx->preference);
+ memcpy (&dst[*off], &mxpref, sizeof (mxpref));
+ (*off) += sizeof (mxpref);
+ return add_name (dst, dst_len, off, mx->mxhost);
+}
- 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
+ * Add an SOA record to the UDP packet at the given location.
+ *
+ * @param dst where to write the SOA record
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the SOA information (increment by bytes used)
+ * can also change if there was an error
+ * @param soa SOA information to write
+ * @return GNUNET_SYSERR if 'soa' is invalid
+ * GNUNET_NO if 'soa' did not fit
+ * GNUNET_OK if 'soa' was added to 'dst'
*/
-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. */
+static int
+add_soa (char *dst,
+ size_t dst_len,
+ size_t *off,
+ const struct GNUNET_DNSPARSER_SoaRecord *soa)
+{
+ struct soa_data sd;
+ int ret;
+
+ if ( (GNUNET_OK != (ret = add_name (dst,
+ dst_len,
+ off,
+ soa->mname))) ||
+ (GNUNET_OK != (ret = add_name (dst,
+ dst_len,
+ off,
+ soa->rname)) ) )
+ return ret;
+ if (*off + sizeof (struct soa_data) > dst_len)
+ return GNUNET_NO;
+ sd.serial = htonl (soa->serial);
+ sd.refresh = htonl (soa->refresh);
+ sd.retry = htonl (soa->retry);
+ sd.expire = htonl (soa->expire);
+ sd.minimum = htonl (soa->minimum_ttl);
+ memcpy (&dst[*off], &sd, sizeof (sd));
+ (*off) += sizeof (sd);
+ return GNUNET_OK;
+}
- _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);
+/**
+ * Add an SRV record to the UDP packet at the given location.
+ *
+ * @param dst where to write the SRV record
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the SRV information (increment by bytes used)
+ * can also change if there was an error
+ * @param srv SRV information to write
+ * @return GNUNET_SYSERR if 'srv' is invalid
+ * GNUNET_NO if 'srv' did not fit
+ * GNUNET_OK if 'srv' was added to 'dst'
+ */
+static int
+add_srv (char *dst,
+ size_t dst_len,
+ size_t *off,
+ const struct GNUNET_DNSPARSER_SrvRecord *srv)
+{
+ struct srv_data sd;
+ int ret;
+
+ if (*off + sizeof (struct srv_data) > dst_len)
+ return GNUNET_NO;
+ sd.prio = htons (srv->priority);
+ sd.weight = htons (srv->weight);
+ sd.port = htons (srv->port);
+ memcpy (&dst[*off], &sd, sizeof (sd));
+ (*off) += sizeof (sd);
+ if (GNUNET_OK != (ret = add_name (dst,
+ dst_len,
+ off,
+ srv->target)))
+ return ret;
+ return GNUNET_OK;
+}
- 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)
+/**
+ * Add a DNS record to the UDP packet at the given location.
+ *
+ * @param dst where to write the query
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the query (increment by bytes used)
+ * must not be changed if there is an error
+ * @param record record to write
+ * @return GNUNET_SYSERR if 'record' is invalid
+ * GNUNET_NO if 'record' did not fit
+ * GNUNET_OK if 'record' was added to 'dst'
+ */
+static int
+add_record (char *dst,
+ size_t dst_len,
+ size_t *off,
+ const struct GNUNET_DNSPARSER_Record *record)
{
- char *b = dest;
- char cnt = 0;
-
- dest++;
- while (*src != 0)
- {
- while (*src != '.' && *src != 0)
+ int ret;
+ size_t start;
+ size_t pos;
+ struct record_line rl;
+ char *name;
+
+ start = *off;
+ /* for SRV records, we can create the name from the details
+ of the record if needed */
+ name = record->name;
+ if ( (GNUNET_DNSPARSER_TYPE_SRV == record->type) &&
+ (NULL == name) )
+ GNUNET_asprintf (&name,
+ "_%s._%s.%s",
+ record->data.srv->service,
+ record->data.srv->proto,
+ record->data.srv->domain_name);
+ ret = add_name (dst, dst_len - sizeof (struct record_line), off, name);
+ if (name != record->name)
+ GNUNET_free (name);
+ if (GNUNET_OK != ret)
+ return ret;
+ /* '*off' is now the position where we will need to write the record line */
+
+ pos = *off + sizeof (struct record_line);
+ switch (record->type)
+ {
+ case GNUNET_DNSPARSER_TYPE_MX:
+ ret = add_mx (dst, dst_len, &pos, record->data.mx);
+ break;
+ case GNUNET_DNSPARSER_TYPE_SOA:
+ ret = add_soa (dst, dst_len, &pos, record->data.soa);
+ break;
+ case GNUNET_DNSPARSER_TYPE_NS:
+ case GNUNET_DNSPARSER_TYPE_CNAME:
+ case GNUNET_DNSPARSER_TYPE_PTR:
+ ret = add_name (dst, dst_len, &pos, record->data.hostname);
+ break;
+ case GNUNET_DNSPARSER_TYPE_SRV:
+ ret = add_srv (dst, dst_len, &pos, record->data.srv);
+ break;
+ default:
+ if (pos + record->data.raw.data_len > dst_len)
{
- *dest = *src;
- src++;
- dest++;
- cnt++;
+ ret = GNUNET_NO;
+ break;
}
- *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);
+ memcpy (&dst[pos], record->data.raw.data, record->data.raw.data_len);
+ pos += record->data.raw.data_len;
+ ret = GNUNET_OK;
+ break;
}
-
- for (i = 0; i < ntohs (ppkt->s.ancount); i++)
+ if (GNUNET_OK != ret)
{
- 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;
+ *off = start;
+ return GNUNET_NO;
}
- for (i = 0; i < ntohs (ppkt->s.nscount); i++)
+ if (pos - (*off + sizeof (struct record_line)) > UINT16_MAX)
{
- 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;
+ /* record data too long */
+ *off = start;
+ return GNUNET_NO;
}
-
- 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;
+ rl.type = htons (record->type);
+ rl.class = htons (record->class);
+ rl.ttl = htonl (GNUNET_TIME_absolute_get_remaining (record->expiration_time).rel_value / 1000); /* in seconds */
+ rl.data_len = htons ((uint16_t) (pos - (*off + sizeof (struct record_line))));
+ memcpy (&dst[*off], &rl, sizeof (struct record_line));
+ *off = pos;
+ return GNUNET_OK;
}
-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++)
+/**
+ * Given a DNS packet, generate the corresponding UDP payload.
+ * Note that we do not attempt to pack the strings with pointers
+ * as this would complicate the code and this is about being
+ * simple and secure, not fast, fancy and broken like bind.
+ *
+ * @param p packet to pack
+ * @param max maximum allowed size for the resulting UDP payload
+ * @param buf set to a buffer with the packed message
+ * @param buf_length set to the length of buf
+ * @return GNUNET_SYSERR if 'p' is invalid
+ * GNUNET_NO if 'p' was truncated (but there is still a result in 'buf')
+ * GNUNET_OK if 'p' was packed completely into '*buf'
+ */
+int
+GNUNET_DNSPARSER_pack (const struct GNUNET_DNSPARSER_Packet *p,
+ uint16_t max,
+ char **buf,
+ size_t *buf_length)
+{
+ struct GNUNET_TUN_DnsHeader dns;
+ size_t off;
+ char tmp[max];
+ unsigned int i;
+ int ret;
+ int trc;
+
+ if ( (p->num_queries > UINT16_MAX) ||
+ (p->num_answers > UINT16_MAX) ||
+ (p->num_authority_records > UINT16_MAX) ||
+ (p->num_additional_records > UINT16_MAX) )
+ return GNUNET_SYSERR;
+ dns.id = p->id;
+ dns.flags = p->flags;
+ dns.query_count = htons (p->num_queries);
+ dns.answer_rcount = htons (p->num_answers);
+ dns.authority_rcount = htons (p->num_authority_records);
+ dns.additional_rcount = htons (p->num_additional_records);
+
+ off = sizeof (struct GNUNET_TUN_DnsHeader);
+ trc = GNUNET_NO;
+ for (i=0;i<p->num_queries;i++)
{
- GNUNET_free (ppkt->queries[i]->name);
- GNUNET_free (ppkt->queries[i]);
+ ret = add_query (tmp, sizeof (tmp), &off, &p->queries[i]);
+ if (GNUNET_SYSERR == ret)
+ return GNUNET_SYSERR;
+ if (GNUNET_NO == ret)
+ {
+ dns.query_count = htons ((uint16_t) (i-1));
+ trc = GNUNET_YES;
+ break;
+ }
}
- GNUNET_free (ppkt->queries);
- for (i = 0; i < ancount; i++)
+ for (i=0;i<p->num_answers;i++)
{
- GNUNET_free (ppkt->answers[i]->name);
- GNUNET_free (ppkt->answers[i]->data);
- GNUNET_free (ppkt->answers[i]);
+ ret = add_record (tmp, sizeof (tmp), &off, &p->answers[i]);
+ if (GNUNET_SYSERR == ret)
+ return GNUNET_SYSERR;
+ if (GNUNET_NO == ret)
+ {
+ dns.answer_rcount = htons ((uint16_t) (i-1));
+ trc = GNUNET_YES;
+ break;
+ }
}
- GNUNET_free (ppkt->answers);
- for (i = 0; i < nscount; i++)
+ for (i=0;i<p->num_authority_records;i++)
{
- GNUNET_free (ppkt->nameservers[i]->name);
- GNUNET_free (ppkt->nameservers[i]->data);
- GNUNET_free (ppkt->nameservers[i]);
+ ret = add_record (tmp, sizeof (tmp), &off, &p->authority_records[i]);
+ if (GNUNET_SYSERR == ret)
+ return GNUNET_SYSERR;
+ if (GNUNET_NO == ret)
+ {
+ dns.authority_rcount = htons ((uint16_t) (i-1));
+ trc = GNUNET_YES;
+ break;
+ }
}
- GNUNET_free (ppkt->nameservers);
- for (i = 0; i < arcount; i++)
+ for (i=0;i<p->num_additional_records;i++)
{
- GNUNET_free (ppkt->additional[i]->name);
- GNUNET_free (ppkt->additional[i]->data);
- GNUNET_free (ppkt->additional[i]);
+ ret = add_record (tmp, sizeof (tmp), &off, &p->additional_records[i]);
+ if (GNUNET_SYSERR == ret)
+ return GNUNET_SYSERR;
+ if (GNUNET_NO == ret)
+ {
+ dns.additional_rcount = htons (i-1);
+ trc = GNUNET_YES;
+ break;
+ }
}
- GNUNET_free (ppkt->additional);
- GNUNET_free (ppkt);
+
+ if (GNUNET_YES == trc)
+ dns.flags.message_truncated = 1;
+ memcpy (tmp, &dns, sizeof (struct GNUNET_TUN_DnsHeader));
+
+ *buf = GNUNET_malloc (off);
+ *buf_length = off;
+ memcpy (*buf, tmp, off);
+ if (GNUNET_YES == trc)
+ return GNUNET_NO;
+ return GNUNET_OK;
}
+
+/* end of dnsparser.c */
projects / oweals / gnunet.git / blobdiff