text: /* Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #ifndef __mod_h2__h2_util__
  #define __mod_h2__h2_util__
  
  #include <nghttp2/nghttp2.h>
  
  /*******************************************************************************
   * some debugging/format helpers
   ******************************************************************************/
  struct h2_request;
  struct nghttp2_frame;
  
  size_t h2_util_hex_dump(char *buffer, size_t maxlen,
                          const char *data, size_t datalen);
  
  size_t h2_util_header_print(char *buffer, size_t maxlen,
                              const char *name, size_t namelen,
                              const char *value, size_t valuelen);
  
  void h2_util_camel_case_header(char *s, size_t len);
  
  int h2_util_frame_print(const nghttp2_frame *frame, char *buffer, size_t maxlen);
  
  /*******************************************************************************
   * ihash - hash for structs with int identifier
   ******************************************************************************/
  typedef struct h2_ihash_t h2_ihash_t;
  typedef int h2_ihash_iter_t(void *ctx, void *val);
  
  /**
   * Create a hash for structures that have an identifying int member.
   * @param pool the pool to use
   * @param offset_of_int the offsetof() the int member in the struct
   */
  h2_ihash_t *h2_ihash_create(apr_pool_t *pool, size_t offset_of_int);
  
  size_t h2_ihash_count(h2_ihash_t *ih);
  int h2_ihash_empty(h2_ihash_t *ih);
  void *h2_ihash_get(h2_ihash_t *ih, int id);
  
  /**
   * Iterate over the hash members (without defined order) and invoke
   * fn for each member until 0 is returned.
   * @param ih the hash to iterate over
   * @param fn the function to invoke on each member
   * @param ctx user supplied data passed into each iteration call
   * @return 0 if one iteration returned 0, otherwise != 0
   */
  int h2_ihash_iter(h2_ihash_t *ih, h2_ihash_iter_t *fn, void *ctx);
  
  void h2_ihash_add(h2_ihash_t *ih, void *val);
  void h2_ihash_remove(h2_ihash_t *ih, int id);
  void h2_ihash_remove_val(h2_ihash_t *ih, void *val);
  void h2_ihash_clear(h2_ihash_t *ih);
  
  size_t h2_ihash_shift(h2_ihash_t *ih, void **buffer, size_t max);
  
  /*******************************************************************************
   * iqueue - sorted list of int with user defined ordering
   ******************************************************************************/
  typedef struct h2_iqueue {
      int *elts;
      int head;
      int nelts;
      int nalloc;
      apr_pool_t *pool;
  } h2_iqueue;
  
  /**
   * Comparator for two int to determine their order.
   *
   * @param i1 first int to compare
   * @param i2 second int to compare
   * @param ctx provided user data
   * @return value is the same as for strcmp() and has the effect:
   *    == 0: s1 and s2 are treated equal in ordering
   *     < 0: s1 should be sorted before s2
   *     > 0: s2 should be sorted before s1
   */
  typedef int h2_iq_cmp(int i1, int i2, void *ctx);
  
  /**
   * Allocate a new queue from the pool and initialize.
   * @param id the identifier of the queue
   * @param pool the memory pool
   */
  h2_iqueue *h2_iq_create(apr_pool_t *pool, int capacity);
  
  /**
   * Return != 0 iff there are no tasks in the queue.
   * @param q the queue to check
   */
  int h2_iq_empty(h2_iqueue *q);
  
  /**
   * Return the number of int in the queue.
   * @param q the queue to get size on
   */
  int h2_iq_count(h2_iqueue *q);
  
  /**
   * Add a stream id to the queue. 
   *
   * @param q the queue to append the id to
   * @param sid the stream id to add
   * @param cmp the comparator for sorting
   * @param ctx user data for comparator
   * @return != 0 iff id was not already there 
   */
  int h2_iq_add(h2_iqueue *q, int sid, h2_iq_cmp *cmp, void *ctx);
  
  /**
   * Append the id to the queue if not already present. 
   *
   * @param q the queue to append the id to
   * @param sid the id to append
   * @return != 0 iff id was not already there 
   */
  int h2_iq_append(h2_iqueue *q, int sid);
  
  /**
   * Remove the stream id from the queue. Return != 0 iff task
   * was found in queue.
   * @param q the task queue
   * @param sid the stream id to remove
   * @return != 0 iff task was found in queue
   */
  int h2_iq_remove(h2_iqueue *q, int sid);
  
  /**
   * Remove all entries in the queue.
   */
  void h2_iq_clear(h2_iqueue *q);
  
  /**
   * Sort the stream idqueue again. Call if the task ordering
   * has changed.
   *
   * @param q the queue to sort
   * @param cmp the comparator for sorting
   * @param ctx user data for the comparator 
   */
  void h2_iq_sort(h2_iqueue *q, h2_iq_cmp *cmp, void *ctx);
  
  /**
   * Get the first id from the queue or 0 if the queue is empty. 
   * The id is being removed.
   *
   * @param q the queue to get the first id from
   * @return the first id of the queue, 0 if empty
   */
  int h2_iq_shift(h2_iqueue *q);
  
  /**
   * Get the first max ids from the queue. All these ids will be removed.
   *
   * @param q the queue to get the first task from
   * @param pint the int array to receive the values
   * @param max the maximum number of ids to shift
   * @return the actual number of ids shifted
   */
  size_t h2_iq_mshift(h2_iqueue *q, int *pint, size_t max);
  
  /**
   * Determine if int is in the queue already
   *
   * @parm q the queue
   * @param sid the integer id to check for
   * @return != 0 iff sid is already in the queue
   */
  int h2_iq_contains(h2_iqueue *q, int sid);
  
  /*******************************************************************************
   * FIFO queue (void* elements)
   ******************************************************************************/
  
  /**
   * A thread-safe FIFO queue with some extra bells and whistles, if you
   * do not need anything special, better use 'apr_queue'.
   */
  typedef struct h2_fifo h2_fifo;
  
  /**
   * Create a FIFO queue that can hold up to capacity elements. Elements can
   * appear several times.
   */
  apr_status_t h2_fifo_create(h2_fifo **pfifo, apr_pool_t *pool, int capacity);
  
  /**
   * Create a FIFO set that can hold up to capacity elements. Elements only
   * appear once. Pushing an element already present does not change the
   * queue and is successful.
   */
  apr_status_t h2_fifo_set_create(h2_fifo **pfifo, apr_pool_t *pool, int capacity);
  
  apr_status_t h2_fifo_term(h2_fifo *fifo);
  
  int h2_fifo_count(h2_fifo *fifo);
  
  /**
   * Push en element into the queue. Blocks if there is no capacity left.
   * 
   * @param fifo the FIFO queue
   * @param elem the element to push
   * @return APR_SUCCESS on push, APR_EAGAIN on try_push on a full queue,
   *         APR_EEXIST when in set mode and elem already there.
   */
  apr_status_t h2_fifo_push(h2_fifo *fifo, void *elem);
  apr_status_t h2_fifo_try_push(h2_fifo *fifo, void *elem);
  
  apr_status_t h2_fifo_pull(h2_fifo *fifo, void **pelem);
  apr_status_t h2_fifo_try_pull(h2_fifo *fifo, void **pelem);
  
  typedef enum {
      H2_FIFO_OP_PULL,   /* pull the element from the queue, ie discard it */
      H2_FIFO_OP_REPUSH, /* pull and immediately re-push it */
  } h2_fifo_op_t;
  
  typedef h2_fifo_op_t h2_fifo_peek_fn(void *head, void *ctx);
  
  /**
   * Call given function on the head of the queue, once it exists, and
   * perform the returned operation on it. The queue will hold its lock during
   * this time, so no other operations on the queue are possible.
   * @param fifo the queue to peek at
   * @param fn   the function to call on the head, once available
   * @param ctx  context to pass in call to function
   */
  apr_status_t h2_fifo_peek(h2_fifo *fifo, h2_fifo_peek_fn *fn, void *ctx);
  
  /**
   * Non-blocking version of h2_fifo_peek.
   */
  apr_status_t h2_fifo_try_peek(h2_fifo *fifo, h2_fifo_peek_fn *fn, void *ctx);
  
  /**
   * Remove the elem from the queue, will remove multiple appearances.
   * @param elem  the element to remove
   * @return APR_SUCCESS iff > 0 elems were removed, APR_EAGAIN otherwise.
   */
  apr_status_t h2_fifo_remove(h2_fifo *fifo, void *elem);
  
  /*******************************************************************************
   * iFIFO queue (int elements)
   ******************************************************************************/
  
  /**
   * A thread-safe FIFO queue with some extra bells and whistles, if you
   * do not need anything special, better use 'apr_queue'.
   */
  typedef struct h2_ififo h2_ififo;
  
  /**
   * Create a FIFO queue that can hold up to capacity int. ints can
   * appear several times.
   */
  apr_status_t h2_ififo_create(h2_ififo **pfifo, apr_pool_t *pool, int capacity);
  
  /**
   * Create a FIFO set that can hold up to capacity integers. Ints only
   * appear once. Pushing an int already present does not change the
   * queue and is successful.
   */
  apr_status_t h2_ififo_set_create(h2_ififo **pfifo, apr_pool_t *pool, int capacity);
  
  apr_status_t h2_ififo_term(h2_ififo *fifo);
  
  int h2_ififo_count(h2_ififo *fifo);
  
  /**
   * Push an int into the queue. Blocks if there is no capacity left.
   * 
   * @param fifo the FIFO queue
   * @param id  the int to push
   * @return APR_SUCCESS on push, APR_EAGAIN on try_push on a full queue,
   *         APR_EEXIST when in set mode and elem already there.
   */
  apr_status_t h2_ififo_push(h2_ififo *fifo, int id);
  apr_status_t h2_ififo_try_push(h2_ififo *fifo, int id);
  
  apr_status_t h2_ififo_pull(h2_ififo *fifo, int *pi);
  apr_status_t h2_ififo_try_pull(h2_ififo *fifo, int *pi);
  
  typedef h2_fifo_op_t h2_ififo_peek_fn(int head, void *ctx);
  
  /**
   * Call given function on the head of the queue, once it exists, and
   * perform the returned operation on it. The queue will hold its lock during
   * this time, so no other operations on the queue are possible.
   * @param fifo the queue to peek at
   * @param fn   the function to call on the head, once available
   * @param ctx  context to pass in call to function
   */
  apr_status_t h2_ififo_peek(h2_ififo *fifo, h2_ififo_peek_fn *fn, void *ctx);
  
  /**
   * Non-blocking version of h2_fifo_peek.
   */
  apr_status_t h2_ififo_try_peek(h2_ififo *fifo, h2_ififo_peek_fn *fn, void *ctx);
  
  /**
   * Remove the integer from the queue, will remove multiple appearances.
   * @param id  the integer to remove
   * @return APR_SUCCESS iff > 0 ints were removed, APR_EAGAIN otherwise.
   */
  apr_status_t h2_ififo_remove(h2_ififo *fifo, int id);
  
  /*******************************************************************************
   * common helpers
   ******************************************************************************/
  /* h2_log2(n) iff n is a power of 2 */
  unsigned char h2_log2(int n);
  
  /**
   * Count the bytes that all key/value pairs in a table have
   * in length (exlucding terminating 0s), plus additional extra per pair.
   *
   * @param t the table to inspect
   * @param pair_extra the extra amount to add per pair
   * @return the number of bytes all key/value pairs have
   */
  apr_size_t h2_util_table_bytes(apr_table_t *t, apr_size_t pair_extra);
  
  /** Match a header value against a string constance, case insensitive */
  #define H2_HD_MATCH_LIT(l, name, nlen)  \
      ((nlen == sizeof(l) - 1) && !apr_strnatcasecmp(l, name))
  
  /*******************************************************************************
   * HTTP/2 header helpers
   ******************************************************************************/
  int h2_req_ignore_header(const char *name, size_t len);
  int h2_req_ignore_trailer(const char *name, size_t len);
  int h2_res_ignore_trailer(const char *name, size_t len);
  
  /**
   * Set the push policy for the given request. Takes request headers into 
   * account, see draft https://tools.ietf.org/html/draft-ruellan-http-accept-push-policy-00
   * for details.
   * 
   * @param headers the http headers to inspect
   * @param p the pool to use
   * @param push_enabled if HTTP/2 server push is generally enabled for this request
   * @return the push policy desired
   */
  int h2_push_policy_determine(apr_table_t *headers, apr_pool_t *p, int push_enabled);
  
  /*******************************************************************************
   * base64 url encoding, different table from normal base64
   ******************************************************************************/
  /**
   * I always wanted to write my own base64url decoder...not. See 
   * https://tools.ietf.org/html/rfc4648#section-5 for description.
   */
  apr_size_t h2_util_base64url_decode(const char **decoded, 
                                      const char *encoded, 
                                      apr_pool_t *pool);
  const char *h2_util_base64url_encode(const char *data, 
                                       apr_size_t len, apr_pool_t *pool);
  
  /*******************************************************************************
   * nghttp2 helpers
   ******************************************************************************/
  
  #define H2_HD_MATCH_LIT_CS(l, name)  \
      ((strlen(name) == sizeof(l) - 1) && !apr_strnatcasecmp(l, name))
  
  #define H2_CREATE_NV_LIT_CS(nv, NAME, VALUE) nv->name = (uint8_t *)NAME;      \
                                               nv->namelen = sizeof(NAME) - 1;  \
                                               nv->value = (uint8_t *)VALUE;    \
                                               nv->valuelen = strlen(VALUE)
  
  #define H2_CREATE_NV_CS_LIT(nv, NAME, VALUE) nv->name = (uint8_t *)NAME;      \
                                               nv->namelen = strlen(NAME);      \
                                               nv->value = (uint8_t *)VALUE;    \
                                               nv->valuelen = sizeof(VALUE) - 1
  
  #define H2_CREATE_NV_CS_CS(nv, NAME, VALUE) nv->name = (uint8_t *)NAME;       \
                                              nv->namelen = strlen(NAME);       \
                                              nv->value = (uint8_t *)VALUE;     \
                                              nv->valuelen = strlen(VALUE)
  
  int h2_util_ignore_header(const char *name);
  
  struct h2_headers;
  
  typedef struct h2_ngheader {
      nghttp2_nv *nv;
      apr_size_t nvlen;
  } h2_ngheader;
  
  apr_status_t h2_res_create_ngtrailer(h2_ngheader **ph, apr_pool_t *p, 
                                       struct h2_headers *headers); 
  apr_status_t h2_res_create_ngheader(h2_ngheader **ph, apr_pool_t *p, 
                                      struct h2_headers *headers); 
  apr_status_t h2_req_create_ngheader(h2_ngheader **ph, apr_pool_t *p, 
                                      const struct h2_request *req);
  
  /**
   * Add a HTTP/2 header and return the table key if it really was added
   * and not ignored.
   */
  apr_status_t h2_req_add_header(apr_table_t *headers, apr_pool_t *pool, 
                                 const char *name, size_t nlen,
                                 const char *value, size_t vlen,
                                 size_t max_field_len, int *pwas_added);
  
  /*******************************************************************************
   * h2_request helpers
   ******************************************************************************/
  
  struct h2_request *h2_req_create(int id, apr_pool_t *pool, const char *method, 
                                   const char *scheme, const char *authority, 
                                   const char *path, apr_table_t *header,
                                   int serialize);
  
  /*******************************************************************************
   * apr brigade helpers
   ******************************************************************************/
  
  /**
   * Concatenate at most length bytes from src to dest brigade, splitting
   * buckets if necessary and reading buckets of indeterminate length.
   */
  apr_status_t h2_brigade_concat_length(apr_bucket_brigade *dest, 
                                        apr_bucket_brigade *src,
                                        apr_off_t length);
                                  
  /**
   * Copy at most length bytes from src to dest brigade, splitting
   * buckets if necessary and reading buckets of indeterminate length.
   */
  apr_status_t h2_brigade_copy_length(apr_bucket_brigade *dest, 
                                      apr_bucket_brigade *src,
                                      apr_off_t length);
                                  
  /**
   * Return != 0 iff there is a FLUSH or EOS bucket in the brigade.
   * @param bb the brigade to check on
   * @return != 0 iff brigade holds FLUSH or EOS bucket (or both)
   */
  int h2_util_has_eos(apr_bucket_brigade *bb, apr_off_t len);
  
  /**
   * Check how many bytes of the desired amount are available and if the
   * end of stream is reached by that amount.
   * @param bb the brigade to check
   * @param plen the desired length and, on return, the available length
   * @param on return, if eos has been reached
   */
  apr_status_t h2_util_bb_avail(apr_bucket_brigade *bb, 
                                apr_off_t *plen, int *peos);
  
  typedef apr_status_t h2_util_pass_cb(void *ctx, 
                                       const char *data, apr_off_t len);
  
  /**
   * Read at most *plen bytes from the brigade and pass them into the
   * given callback. If cb is NULL, just return the amount of data that
   * could have been read.
   * If an EOS was/would be encountered, set *peos != 0.
   * @param bb the brigade to read from
   * @param cb the callback to invoke for the read data
   * @param ctx optional data passed to callback
   * @param plen inout, as input gives the maximum number of bytes to read,
   *    on return specifies the actual/would be number of bytes
   * @param peos != 0 iff an EOS bucket was/would be encountered.
   */
  apr_status_t h2_util_bb_readx(apr_bucket_brigade *bb, 
                                h2_util_pass_cb *cb, void *ctx, 
                                apr_off_t *plen, int *peos);
  
  /**
   * Print a bucket's meta data (type and length) to the buffer.
   * @return number of characters printed
   */
  apr_size_t h2_util_bucket_print(char *buffer, apr_size_t bmax, 
                                  apr_bucket *b, const char *sep);
                                  
  /**
   * Prints the brigade bucket types and lengths into the given buffer
   * up to bmax.
   * @return number of characters printed
   */
  apr_size_t h2_util_bb_print(char *buffer, apr_size_t bmax, 
                              const char *tag, const char *sep, 
                              apr_bucket_brigade *bb);
  /**
   * Logs the bucket brigade (which bucket types with what length)
   * to the log at the given level.
   * @param c the connection to log for
   * @param sid the stream identifier this brigade belongs to
   * @param level the log level (as in APLOG_*)
   * @param tag a short message text about the context
   * @param bb the brigade to log
   */
  #define h2_util_bb_log(c, sid, level, tag, bb) \
  do { \
      char buffer[4 * 1024]; \
      const char *line = "(null)"; \
      apr_size_t len, bmax = sizeof(buffer)/sizeof(buffer[0]); \
      len = h2_util_bb_print(buffer, bmax, (tag), "", (bb)); \
      ap_log_cerror(APLOG_MARK, level, 0, (c), "bb_dump(%ld): %s", \
          ((c)->master? (c)->master->id : (c)->id), (len? buffer : line)); \
  } while(0)
  
  
  typedef int h2_bucket_gate(apr_bucket *b);
  /**
   * Transfer buckets from one brigade to another with a limit on the 
   * maximum amount of bytes transferred. Does no setaside magic, lifetime
   * of brigades must fit. 
   * @param to   brigade to transfer buckets to
   * @param from brigades to remove buckets from
   * @param plen maximum bytes to transfer, actual bytes transferred
   * @param peos if an EOS bucket was transferred
   */
  apr_status_t h2_append_brigade(apr_bucket_brigade *to,
                                 apr_bucket_brigade *from, 
                                 apr_off_t *plen,
                                 int *peos,
                                 h2_bucket_gate *should_append);
  
  /**
   * Get an approximnation of the memory footprint of the given
   * brigade. This varies from apr_brigade_length as
   * - no buckets are ever read
   * - only buckets known to allocate memory (HEAP+POOL) are counted
   * - the bucket struct itself is counted
   */
  apr_off_t h2_brigade_mem_size(apr_bucket_brigade *bb);
  
  #endif /* defined(__mod_h2__h2_util__) */
  