GNUnet  0.19.3
dnsparser.c File Reference

helper library to parse DNS packets. More...

#include "platform.h"
#include "gnunet_util_lib.h"
Include dependency graph for dnsparser.c:

Go to the source code of this file.

Functions

int GNUNET_DNSPARSER_check_label (const char *label)
 Check if a label in UTF-8 format can be coded into valid IDNA. More...
 
int GNUNET_DNSPARSER_check_name (const char *name)
 Check if a label in UTF-8 format can be coded into valid IDNA. More...
 
void GNUNET_DNSPARSER_free_soa (struct GNUNET_DNSPARSER_SoaRecord *soa)
 Free SOA information record. More...
 
void GNUNET_DNSPARSER_free_cert (struct GNUNET_DNSPARSER_CertRecord *cert)
 Free CERT information record. More...
 
void GNUNET_DNSPARSER_free_srv (struct GNUNET_DNSPARSER_SrvRecord *srv)
 Free SRV information record. More...
 
void GNUNET_DNSPARSER_free_mx (struct GNUNET_DNSPARSER_MxRecord *mx)
 Free MX information record. More...
 
void GNUNET_DNSPARSER_free_record (struct GNUNET_DNSPARSER_Record *r)
 Free the given DNS record. More...
 
static char * parse_name (const char *udp_payload, size_t udp_payload_length, size_t *off, unsigned int depth)
 Parse name inside of a DNS query or record. More...
 
char * GNUNET_DNSPARSER_parse_name (const char *udp_payload, size_t udp_payload_length, size_t *off)
 Parse name inside of a DNS query or record. More...
 
int GNUNET_DNSPARSER_parse_query (const char *udp_payload, size_t udp_payload_length, size_t *off, struct GNUNET_DNSPARSER_Query *q)
 Parse a DNS query entry. More...
 
struct GNUNET_DNSPARSER_SoaRecordGNUNET_DNSPARSER_parse_soa (const char *udp_payload, size_t udp_payload_length, size_t *off)
 Parse a DNS SOA record. More...
 
struct GNUNET_DNSPARSER_MxRecordGNUNET_DNSPARSER_parse_mx (const char *udp_payload, size_t udp_payload_length, size_t *off)
 Parse a DNS MX record. More...
 
struct GNUNET_DNSPARSER_SrvRecordGNUNET_DNSPARSER_parse_srv (const char *udp_payload, size_t udp_payload_length, size_t *off)
 Parse a DNS SRV record. More...
 
struct GNUNET_DNSPARSER_CertRecordGNUNET_DNSPARSER_parse_cert (const char *udp_payload, size_t udp_payload_length, size_t *off)
 Parse a DNS CERT record. More...
 
int GNUNET_DNSPARSER_parse_record (const char *udp_payload, size_t udp_payload_length, size_t *off, struct GNUNET_DNSPARSER_Record *r)
 Parse a DNS record entry. More...
 
struct GNUNET_DNSPARSER_PacketGNUNET_DNSPARSER_parse (const char *udp_payload, size_t udp_payload_length)
 Parse a UDP payload of a DNS packet in to a nice struct for further processing and manipulation. More...
 
struct GNUNET_DNSPARSER_RecordGNUNET_DNSPARSER_duplicate_record (const struct GNUNET_DNSPARSER_Record *r)
 Duplicate (deep-copy) the given DNS record. More...
 
struct GNUNET_DNSPARSER_SoaRecordGNUNET_DNSPARSER_duplicate_soa_record (const struct GNUNET_DNSPARSER_SoaRecord *r)
 Duplicate (deep-copy) the given DNS record. More...
 
struct GNUNET_DNSPARSER_CertRecordGNUNET_DNSPARSER_duplicate_cert_record (const struct GNUNET_DNSPARSER_CertRecord *r)
 Duplicate (deep-copy) the given DNS record. More...
 
struct GNUNET_DNSPARSER_MxRecordGNUNET_DNSPARSER_duplicate_mx_record (const struct GNUNET_DNSPARSER_MxRecord *r)
 Duplicate (deep-copy) the given DNS record. More...
 
struct GNUNET_DNSPARSER_SrvRecordGNUNET_DNSPARSER_duplicate_srv_record (const struct GNUNET_DNSPARSER_SrvRecord *r)
 Duplicate (deep-copy) the given DNS record. More...
 
void GNUNET_DNSPARSER_free_packet (struct GNUNET_DNSPARSER_Packet *p)
 Free memory taken by a packet. More...
 
int GNUNET_DNSPARSER_builder_add_name (char *dst, size_t dst_len, size_t *off, const char *name)
 Add a DNS name to the UDP packet at the given location, converting the name to IDNA notation as necessary. More...
 
int GNUNET_DNSPARSER_builder_add_query (char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_Query *query)
 Add a DNS query to the UDP packet at the given location. More...
 
int GNUNET_DNSPARSER_builder_add_mx (char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_MxRecord *mx)
 Add an MX record to the UDP packet at the given location. More...
 
int GNUNET_DNSPARSER_builder_add_cert (char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_CertRecord *cert)
 Add a CERT record to the UDP packet at the given location. More...
 
int GNUNET_DNSPARSER_builder_add_soa (char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_SoaRecord *soa)
 Add an SOA record to the UDP packet at the given location. More...
 
int GNUNET_DNSPARSER_builder_add_srv (char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_SrvRecord *srv)
 Add an SRV record to the UDP packet at the given location. More...
 
static int add_record (char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_Record *record)
 Add a DNS record to the UDP packet at the given location. More...
 
int GNUNET_DNSPARSER_pack (const struct GNUNET_DNSPARSER_Packet *p, uint16_t max, char **buf, size_t *buf_length)
 Given a DNS packet p, generate the corresponding UDP payload. More...
 
char * GNUNET_DNSPARSER_bin_to_hex (const void *data, size_t data_size)
 Convert a block of binary data to HEX. More...
 
size_t GNUNET_DNSPARSER_hex_to_bin (const char *hex, void *data)
 Convert a HEX string to block of binary data. More...
 

Detailed Description

helper library to parse DNS packets.

Author
Philipp Toelke
Christian Grothoff

Definition in file dnsparser.c.

Function Documentation

◆ parse_name()

static char* parse_name ( const char *  udp_payload,
size_t  udp_payload_length,
size_t *  off,
unsigned int  depth 
)
static

Parse name inside of a DNS query or record.

Parameters
udp_payloadentire UDP payload
udp_payload_lengthlength of udp_payload
offpointer to the offset of the name to parse in the udp_payload (to be incremented by the size of the name)
depthcurrent depth of our recursion (to prevent stack overflow)
Returns
name as 0-terminated C string on success, NULL if the payload is malformed

Definition at line 214 of file dnsparser.c.

218 {
219  const uint8_t *input = (const uint8_t *) udp_payload;
220  char *ret;
221  char *tmp;
222  char *xstr;
223  uint8_t len;
224  size_t xoff;
225  char *utf8;
226  Idna_rc rc;
227 
228  ret = GNUNET_strdup ("");
229  while (1)
230  {
231  if (*off >= udp_payload_length)
232  {
233  GNUNET_break_op (0);
234  goto error;
235  }
236  len = input[*off];
237  if (0 == len)
238  {
239  (*off)++;
240  break;
241  }
242  if (len < 64)
243  {
244  if (*off + 1 + len > udp_payload_length)
245  {
246  GNUNET_break_op (0);
247  goto error;
248  }
249  GNUNET_asprintf (&tmp, "%.*s", (int) len, &udp_payload[*off + 1]);
250  if (IDNA_SUCCESS !=
251  (rc = idna_to_unicode_8z8z (tmp, &utf8, IDNA_ALLOW_UNASSIGNED)))
252  {
254  _ ("Failed to convert DNS IDNA name `%s' to UTF-8: %s\n"),
255  tmp,
256  idna_strerror (rc));
257  GNUNET_free (tmp);
258  GNUNET_asprintf (&tmp,
259  "%s%.*s.",
260  ret,
261  (int) len,
262  &udp_payload[*off + 1]);
263  }
264  else
265  {
266  GNUNET_free (tmp);
267  GNUNET_asprintf (&tmp, "%s%s.", ret, utf8);
268  free (utf8);
269  }
270  GNUNET_free (ret);
271  ret = tmp;
272  *off += 1 + len;
273  }
274  else if ((64 | 128) == (len & (64 | 128)))
275  {
276  if (depth > 32)
277  {
278  GNUNET_break_op (0);
279  goto error; /* hard bound on stack to prevent "infinite" recursion, disallow! */
280  }
281  /* pointer to string */
282  if (*off + 1 > udp_payload_length)
283  {
284  GNUNET_break_op (0);
285  goto error;
286  }
287  xoff = ((len - (64 | 128)) << 8) + input[*off + 1];
288  xstr = parse_name (udp_payload, udp_payload_length, &xoff, depth + 1);
289  if (NULL == xstr)
290  {
291  GNUNET_break_op (0);
292  goto error;
293  }
294  GNUNET_asprintf (&tmp, "%s%s.", ret, xstr);
295  GNUNET_free (ret);
296  GNUNET_free (xstr);
297  ret = tmp;
298  if (strlen (ret) > udp_payload_length)
299  {
300  GNUNET_break_op (0);
301  goto error; /* we are looping (building an infinite string) */
302  }
303  *off += 2;
304  /* pointers always terminate names */
305  break;
306  }
307  else
308  {
309  /* neither pointer nor inline string, not supported... */
310  GNUNET_break_op (0);
311  goto error;
312  }
313  }
314  if (0 < strlen (ret))
315  ret[strlen (ret) - 1] = '\0'; /* eat tailing '.' */
316  return ret;
317 error:
318  GNUNET_break_op (0);
319  GNUNET_free (ret);
320  return NULL;
321 }
static char * parse_name(const char *udp_payload, size_t udp_payload_length, size_t *off, unsigned int depth)
Parse name inside of a DNS query or record.
Definition: dnsparser.c:214
static int ret
Return value of the commandline.
Definition: gnunet-abd.c:81
uint16_t len
length of data (which is always a uint32_t, but presumably this can be used to specify that fewer byt...
#define GNUNET_log(kind,...)
#define GNUNET_break_op(cond)
Use this for assertion violations caused by other peers (i.e.
@ GNUNET_ERROR_TYPE_INFO
int int GNUNET_asprintf(char **buf, const char *format,...) __attribute__((format(printf
Like asprintf, just portable.
#define GNUNET_strdup(a)
Wrapper around GNUNET_xstrdup_.
#define GNUNET_free(ptr)
Wrapper around free.
#define _(String)
GNU gettext support macro.
Definition: platform.h:177

References _, GNUNET_asprintf(), GNUNET_break_op, GNUNET_ERROR_TYPE_INFO, GNUNET_free, GNUNET_log, GNUNET_strdup, len, and ret.

Referenced by GNUNET_DNSPARSER_parse_name().

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◆ add_record()

static int add_record ( char *  dst,
size_t  dst_len,
size_t *  off,
const struct GNUNET_DNSPARSER_Record record 
)
static

Add a DNS record to the UDP packet at the given location.

Parameters
dstwhere to write the query
dst_lennumber of bytes in dst
offpointer to offset where to write the query (increment by bytes used) must not be changed if there is an error
recordrecord to write
Returns
GNUNET_SYSERR if record is invalid GNUNET_NO if record did not fit GNUNET_OK if record was added to dst

Definition at line 1156 of file dnsparser.c.

1160 {
1161  int ret;
1162  size_t start;
1163  size_t pos;
1164  struct GNUNET_TUN_DnsRecordLine rl;
1165 
1166  start = *off;
1168  dst_len
1169  - sizeof(
1170  struct GNUNET_TUN_DnsRecordLine),
1171  off,
1172  record->name);
1173  if (GNUNET_OK != ret)
1174  return ret;
1175  /* '*off' is now the position where we will need to write the record line */
1176 
1177  pos = *off + sizeof(struct GNUNET_TUN_DnsRecordLine);
1178  switch (record->type)
1179  {
1181  ret = GNUNET_DNSPARSER_builder_add_mx (dst, dst_len, &pos, record->data.mx);
1182  break;
1183 
1185  ret =
1186  GNUNET_DNSPARSER_builder_add_cert (dst, dst_len, &pos, record->data.cert);
1187  break;
1188 
1190  ret =
1191  GNUNET_DNSPARSER_builder_add_soa (dst, dst_len, &pos, record->data.soa);
1192  break;
1193 
1198  dst_len,
1199  &pos,
1200  record->data.hostname);
1201  break;
1202 
1204  ret =
1205  GNUNET_DNSPARSER_builder_add_srv (dst, dst_len, &pos, record->data.srv);
1206  break;
1207 
1208  default:
1209  if (pos + record->data.raw.data_len > dst_len)
1210  {
1211  ret = GNUNET_NO;
1212  break;
1213  }
1214  GNUNET_memcpy (&dst[pos], record->data.raw.data, record->data.raw.data_len);
1215  pos += record->data.raw.data_len;
1216  ret = GNUNET_OK;
1217  break;
1218  }
1219  if (GNUNET_OK != ret)
1220  {
1221  *off = start;
1222  return GNUNET_NO;
1223  }
1224 
1225  if (pos - (*off + sizeof(struct GNUNET_TUN_DnsRecordLine)) > UINT16_MAX)
1226  {
1227  /* record data too long */
1228  *off = start;
1229  return GNUNET_NO;
1230  }
1231  rl.type = htons (record->type);
1232  rl.dns_traffic_class = htons (record->dns_traffic_class);
1233  rl.ttl = htonl (
1235  / 1000LL / 1000LL); /* in seconds */
1236  rl.data_len = htons (
1237  (uint16_t) (pos - (*off + sizeof(struct GNUNET_TUN_DnsRecordLine))));
1238  GNUNET_memcpy (&dst[*off], &rl, sizeof(struct GNUNET_TUN_DnsRecordLine));
1239  *off = pos;
1240  return GNUNET_OK;
1241 }
static int start
Set if we are to start default services (including ARM).
Definition: gnunet-arm.c:39
static void record(void *cls, size_t data_size, const void *data)
Process recorded audio data.
int GNUNET_DNSPARSER_builder_add_name(char *dst, size_t dst_len, size_t *off, const char *name)
Add a DNS name to the UDP packet at the given location, converting the name to IDNA notation as neces...
Definition: dnsparser.c:889
int GNUNET_DNSPARSER_builder_add_cert(char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_CertRecord *cert)
Add a CERT record to the UDP packet at the given location.
Definition: dnsparser.c:1032
#define GNUNET_DNSPARSER_TYPE_SRV
#define GNUNET_DNSPARSER_TYPE_SOA
#define GNUNET_DNSPARSER_TYPE_CERT
#define GNUNET_DNSPARSER_TYPE_PTR
#define GNUNET_DNSPARSER_TYPE_NS
int GNUNET_DNSPARSER_builder_add_soa(char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_SoaRecord *soa)
Add an SOA record to the UDP packet at the given location.
Definition: dnsparser.c:1079
#define GNUNET_DNSPARSER_TYPE_CNAME
int GNUNET_DNSPARSER_builder_add_mx(char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_MxRecord *mx)
Add an MX record to the UDP packet at the given location.
Definition: dnsparser.c:1003
int GNUNET_DNSPARSER_builder_add_srv(char *dst, size_t dst_len, size_t *off, const struct GNUNET_DNSPARSER_SrvRecord *srv)
Add an SRV record to the UDP packet at the given location.
Definition: dnsparser.c:1120
#define GNUNET_DNSPARSER_TYPE_MX
#define GNUNET_memcpy(dst, src, n)
Call memcpy() but check for n being 0 first.
@ GNUNET_OK
@ GNUNET_NO
struct GNUNET_TIME_Relative GNUNET_TIME_absolute_get_remaining(struct GNUNET_TIME_Absolute future)
Given a timestamp in the future, how much time remains until then?
Definition: time.c:405
uint64_t rel_value_us
The actual value.
General DNS record prefix.

References GNUNET_TUN_DnsRecordLine::data_len, GNUNET_TUN_DnsRecordLine::dns_traffic_class, GNUNET_DNSPARSER_builder_add_cert(), GNUNET_DNSPARSER_builder_add_mx(), GNUNET_DNSPARSER_builder_add_name(), GNUNET_DNSPARSER_builder_add_soa(), GNUNET_DNSPARSER_builder_add_srv(), GNUNET_DNSPARSER_TYPE_CERT, GNUNET_DNSPARSER_TYPE_CNAME, GNUNET_DNSPARSER_TYPE_MX, GNUNET_DNSPARSER_TYPE_NS, GNUNET_DNSPARSER_TYPE_PTR, GNUNET_DNSPARSER_TYPE_SOA, GNUNET_DNSPARSER_TYPE_SRV, GNUNET_memcpy, GNUNET_NO, GNUNET_OK, GNUNET_TIME_absolute_get_remaining(), record(), GNUNET_TIME_Relative::rel_value_us, ret, start, GNUNET_TUN_DnsRecordLine::ttl, and GNUNET_TUN_DnsRecordLine::type.

Referenced by GNUNET_DNSPARSER_pack().

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