Provided by: libunbound-dev_1.4.22-1ubuntu4_amd64 bug


       libunbound,  unbound.h,  ub_ctx,  ub_result,  ub_callback_t, ub_ctx_create, ub_ctx_delete,
       ub_ctx_set_option, ub_ctx_get_option,  ub_ctx_config,  ub_ctx_set_fwd,  ub_ctx_resolvconf,
       ub_ctx_hosts,   ub_ctx_add_ta,  ub_ctx_add_ta_file,  ub_ctx_trustedkeys,  ub_ctx_debugout,
       ub_ctx_debuglevel,  ub_ctx_async,  ub_poll,  ub_wait,   ub_fd,   ub_process,   ub_resolve,
       ub_resolve_async,   ub_cancel,   ub_resolve_free,  ub_strerror,  ub_ctx_print_local_zones,
       ub_ctx_zone_add, ub_ctx_zone_remove, ub_ctx_data_add,  ub_ctx_data_remove  -  Unbound  DNS
       validating resolver 1.4.22 functions.


       #include <unbound.h>

       struct ub_ctx * ub_ctx_create(void);

       void ub_ctx_delete(struct ub_ctx* ctx);

       int ub_ctx_set_option(struct ub_ctx* ctx, char* opt, char* val);

       int ub_ctx_get_option(struct ub_ctx* ctx, char* opt, char** val);

       int ub_ctx_config(struct ub_ctx* ctx, char* fname);

       int ub_ctx_set_fwd(struct ub_ctx* ctx, char* addr);

       int ub_ctx_resolvconf(struct ub_ctx* ctx, char* fname);

       int ub_ctx_hosts(struct ub_ctx* ctx, char* fname);

       int ub_ctx_add_ta(struct ub_ctx* ctx, char* ta);

       int ub_ctx_add_ta_file(struct ub_ctx* ctx, char* fname);

       int ub_ctx_trustedkeys(struct ub_ctx* ctx, char* fname);

       int ub_ctx_debugout(struct ub_ctx* ctx, FILE* out);

       int ub_ctx_debuglevel(struct ub_ctx* ctx, int d);

       int ub_ctx_async(struct ub_ctx* ctx, int dothread);

       int ub_poll(struct ub_ctx* ctx);

       int ub_wait(struct ub_ctx* ctx);

       int ub_fd(struct ub_ctx* ctx);

       int ub_process(struct ub_ctx* ctx);

       int ub_resolve(struct ub_ctx* ctx, char* name,
                  int rrtype, int rrclass, struct ub_result** result);

       int ub_resolve_async(struct ub_ctx* ctx, char* name,
                        int rrtype, int rrclass, void* mydata,
                        ub_callback_t callback, int* async_id);

       int ub_cancel(struct ub_ctx* ctx, int async_id);

       void ub_resolve_free(struct ub_result* result);

       const char * ub_strerror(int err);

       int ub_ctx_print_local_zones(struct ub_ctx* ctx);

       int ub_ctx_zone_add(struct ub_ctx* ctx, char* zone_name, char* zone_type);

       int ub_ctx_zone_remove(struct ub_ctx* ctx, char* zone_name);

       int ub_ctx_data_add(struct ub_ctx* ctx, char* data);

       int ub_ctx_data_remove(struct ub_ctx* ctx, char* data);


       Unbound  is  an implementation of a DNS resolver, that does caching and DNSSEC validation.
       This is the library API, for using the -lunbound library.  The server daemon is  described
       in  unbound(8).   The  library can be used to convert hostnames to ip addresses, and back,
       and obtain other information from the DNS. The library performs public-key  validation  of
       results with DNSSEC.

       The  library uses a variable of type struct ub_ctx to keep context between calls. The user
       must maintain it, creating it with ub_ctx_create and deleting it with  ub_ctx_delete.   It
       can  be  created  and  deleted  at  any  time.  Creating  it  anew  removes  any  previous
       configuration (such as trusted keys) and clears any cached results.

       The functions are thread-safe, and a context an be used in a threaded (as  well  as  in  a
       non-threaded)  environment. Also resolution (and validation) can be performed blocking and
       non-blocking  (also  called  asynchronous).   The  async  method  returns  from  the  call
       immediately, so that processing can go on, while the results become available later.

       The functions are discussed in turn below.


              Create   a   new   context,   initialised  with  defaults.   The  information  from
              /etc/resolv.conf and /etc/hosts is not utilised by default.  Use  ub_ctx_resolvconf
              and  ub_ctx_hosts  to  read  them.  Before you call this, use the openssl functions
              CRYPTO_set_id_callback  and  CRYPTO_set_locking_callback  to  set  up   asyncronous
              operation  if  you  use lib openssl (the application calls these functions once for

              Delete validation context and free associated resources.  Outstanding async queries
              are killed and callbacks are not called for them.

              A  power-user  interface  that  lets you specify one of the options from the config
              file format, see unbound.conf(5). Not all options are relevant. For  some  specific
              options, such as adding trust anchors, special routines exist. Pass the option name
              with the trailing ':'.

              A power-user interface that gets an option value.  Some options cannot  be  gotten,
              and  others return a newline separated list.  Pass the option name without trailing
              ':'.  The returned value must be free(2)d by the caller.

              A  power-user  interface  that  lets  you  specify  an  unbound  config  file,  see
              unbound.conf(5), which is read for configuration. Not all options are relevant. For
              some specific options, such as adding trust anchors, special routines exist.

              Set machine to forward DNS queries to, the caching resolver to  use.   IP4  or  IP6
              address.  Forwards  all  DNS  requests  to that machine, which is expected to run a
              recursive resolver. If the proxy is not DNSSEC capable, validation may fail. Can be
              called  several  times,  in that case the addresses are used as backup servers.  At
              this time it is only possible to set configuration  before  the  first  resolve  is

              By default the root servers are queried and full resolver mode is used, but you can
              use this call to read the list of nameservers  to  use  from  the  filename  given.
              Usually  "/etc/resolv.conf". Uses those nameservers as caching proxies.  If they do
              not support DNSSEC, validation may fail.   Only  nameservers  are  picked  up,  the
              searchdomain,  ndots  and other settings from resolv.conf(5) are ignored.  If fname
              NULL is  passed,  "/etc/resolv.conf"  is  used  (if  on  Windows,  the  system-wide
              configured  nameserver is picked instead).  At this time it is only possible to set
              configuration before the first resolve is done.

              Read list of hosts from the filename given.   Usually  "/etc/hosts".  When  queried
              for,  these  addresses  are  not  marked  DNSSEC  secure.  If fname NULL is passed,
              "/etc/hosts" is used (if on Windows, etc/hosts from WINDIR is picked instead).   At
              this  time  it  is  only  possible to set configuration before the first resolve is

              Add a trust anchor to the given context.  At this time it is only possible  to  add
              trusted  keys before the first resolve is done.  The format is a string, similar to
              the zone-file format, [domainname] [type] [rdata  contents].  Both  DS  and  DNSKEY
              records are accepted.

              Add  trust  anchors  to  the given context.  Pass name of a file with DS and DNSKEY
              records in zone file format.  At this time it is only possible to add trusted  keys
              before the first resolve is done.

              Add  trust anchors to the given context.  Pass the name of a bind-style config file
              with trusted-keys{}.  At this time it is only possible to add trusted  keys  before
              the first resolve is done.

              Set  debug  and  error log output to the given stream. Pass NULL to disable output.
              Default is stderr. File-names or using syslog can be enabled using config  options,
              this routine is for using your own stream.

              Set  debug  verbosity  for the context. Output is directed to stderr.  Higher debug
              level gives more output.

              Set a context behaviour for asynchronous action.  if set to true, enables threading
              and  a  call to ub_resolve_async creates a thread to handle work in the background.
              If false, a process is forked to handle work in the background.   Changes  to  this
              setting  after  ub_resolve_async  calls  have  been made have no effect (delete and
              re-create the context to change).

              Poll a context to see if it has any new results.  Do not poll in  a  loop,  instead
              extract  the fd below to poll for readiness, and then check, or wait using the wait
              routine.  Returns 0 if nothing to read, or nonzero if a result  is  available.   If
              nonzero, call ub_process to do callbacks.

              Wait for a context to finish with results. Calls ub_process after the wait for you.
              After the wait, there are no more outstanding asynchronous queries.

       ub_fd  Get file descriptor. Wait for it to become readable,  at  this  point  answers  are
              returned  from  the  asynchronous validating resolver.  Then call the ub_process to
              continue processing.

              Call this routine to continue processing results from the validating resolver (when
              the fd becomes readable).  Will perform necessary callbacks.

              Perform resolution and validation of the target name.  The name is a domain name in
              a zero terminated text string.  The rrtype and  rrclass  are  DNS  type  and  class
              codes.  The result structure is newly allocated with the resulting data.

              Perform  asynchronous resolution and validation of the target name.  Arguments mean
              the same as for ub_resolve except  no  data  is  returned  immediately,  instead  a
              callback is called later.  The callback receives a copy of the mydata pointer, that
              you can use to pass information to the callback. The callback type  is  a  function
              pointer to a function declared as

              void my_callback_function(void* my_arg, int err,
                                struct ub_result* result);

              The  async_id is returned so you can (at your option) decide to track it and cancel
              the request if needed.  If you pass a NULL pointer the async_id is not returned.

              Cancel an async query in progress.  This may return an error if the query does  not
              exist,  or  the  query is already being delivered, in that case you may still get a
              callback for the query.

              Free struct ub_result contents after use.

              Convert error value from one of the unbound library functions to a  human  readable

              Debug printout the local authority information to debug output.

              Add new zone to local authority info, like local-zone unbound.conf(5) statement.

              Delete zone from local authority info.

              Add  resource  record data to local authority info, like local-data unbound.conf(5)

              Delete local authority data from the name given.


       The result of the DNS resolution and validation  is  returned  as  struct  ub_result.  The
       result structure contains the following entries.

            struct ub_result {
                 char* qname; /* text string, original question */
                 int qtype;   /* type code asked for */
                 int qclass;  /* class code asked for */
                 char** data; /* array of rdata items, NULL terminated*/
                 int* len;    /* array with lengths of rdata items */
                 char* canonname; /* canonical name of result */
                 int rcode;   /* additional error code in case of no data */
                 void* answer_packet; /* full network format answer packet */
                 int answer_len; /* length of packet in octets */
                 int havedata; /* true if there is data */
                 int nxdomain; /* true if nodata because name does not exist */
                 int secure;  /* true if result is secure */
                 int bogus;   /* true if a security failure happened */
                 char* why_bogus; /* string with error if bogus */
                 int ttl;     /* number of seconds the result is valid */

       If  both secure and bogus are false, security was not enabled for the domain of the query.
       Else, they are not both true, one of them is true.


       Many routines return an error code. The value 0 (zero) denotes no  error  happened.  Other
       values  can  be  passed  to  ub_strerror  to  obtain a readable error string.  ub_strerror
       returns a zero terminated string.  ub_ctx_create  returns  NULL  on  an  error  (a  malloc
       failure).   ub_poll  returns  true  if some information may be available, false otherwise.
       ub_fd returns a file descriptor or -1 on error.


       unbound.conf(5), unbound(8).


       Unbound developers are mentioned in the CREDITS file in the distribution.