/* Provenance: curl/curl Curl_build_unencoding_stack (fixed).
 * repo: curl/curl
 * commit: 3a09fbb7f264c67c438d01a30669ce325aa508e2
 * parent: 6ecdf5136b52af747e7bda08db9a748256b1cd09
 * commit_url: https://github.com/curl/curl/commit/3a09fbb7f264c67c438d01a30669ce325aa508e2
 * cve: CVE-2022-32206
 * license: curl
 * function: Curl_build_unencoding_stack
 * relpath: lib/content_encoding.c
 * provenance: human
 * mechanism: other
 */

CURLcode Curl_build_unencoding_stack(struct Curl_easy *data,
                                     const char *enclist, int maybechunked)
{
  struct SingleRequest *k = &data->req;
  int counter = 0;

  do {
    const char *name;
    size_t namelen;

    /* Parse a single encoding name. */
    while(ISSPACE(*enclist) || *enclist == ',')
      enclist++;

    name = enclist;

    for(namelen = 0; *enclist && *enclist != ','; enclist++)
      if(!ISSPACE(*enclist))
        namelen = enclist - name + 1;

    /* Special case: chunked encoding is handled at the reader level. */
    if(maybechunked && namelen == 7 && strncasecompare(name, "chunked", 7)) {
      k->chunk = TRUE;             /* chunks coming our way. */
      Curl_httpchunk_init(data);   /* init our chunky engine. */
    }
    else if(namelen) {
      const struct content_encoding *encoding = find_encoding(name, namelen);
      struct contenc_writer *writer;

      if(!k->writer_stack) {
        k->writer_stack = new_unencoding_writer(data, &client_encoding, NULL);

        if(!k->writer_stack)
          return CURLE_OUT_OF_MEMORY;
      }

      if(!encoding)
        encoding = &error_encoding;  /* Defer error at stack use. */

      if(++counter >= MAX_ENCODE_STACK) {
        failf(data, "Reject response due to %u content encodings",
              counter);
        return CURLE_BAD_CONTENT_ENCODING;
      }
      /* Stack the unencoding stage. */
      writer = new_unencoding_writer(data, encoding, k->writer_stack);
      if(!writer)
        return CURLE_OUT_OF_MEMORY;
      k->writer_stack = writer;
    }
  } while(*enclist);

  return CURLE_OK;
}