libcli/http: Optimise reading for content-length

Instead of reading byte-by-byte we know the content length we
want to read so lets use it.

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15611

diff --git a/libcli/http/http.c b/libcli/http/http.c
index 96c573af137fd5d9e60fb26b1ff4efb4a4bff318..0cc8525e6aa587ddd4054483684060d1a8c2eab3 100644 (file)
--- a/libcli/http/http.c
+++ b/libcli/http/http.c
@@ -527,20 +527,59 @@ static int http_read_response_next_vector(struct tstream_context *stream,
                                *_count = 1;
                        }
                        break;
-               case HTTP_MORE_DATA_EXPECTED:
-                       /* TODO Optimize, allocating byte by byte */
-                       state->buffer.data = talloc_realloc(state, state->buffer.data,
-                                                           uint8_t, state->buffer.length + 1);
+               case HTTP_MORE_DATA_EXPECTED: {
+                       size_t toread = 1;
+                       size_t total;
+                       if (state->parser_state == HTTP_READING_BODY) {
+                               struct http_request *resp = state->response;
+                               toread = resp->remaining_content_length -
+                                        state->buffer.length;
+                       }
+
+                       total = toread + state->buffer.length;
+
+                       if (total < state->buffer.length)  {
+                               DBG_ERR("adding %zu to buf len %zu "
+                                       "will overflow\n",
+                                       toread,
+                                       state->buffer.length);
+                                       return -1;
+                       }
+
+                       /*
+                        * test if content-length message exceeds the
+                        * specified max_content_length
+                        * Note: This check wont be hit at the moment
+                        *       due to an existing check in parse_headers
+                        *       which will skip the body. Check is here
+                        *       for completeness and to cater for future
+                        *       code changes.
+                        */
+                       if (state->parser_state == HTTP_READING_BODY) {
+                               if (total > state->max_content_length)  {
+                                       DBG_ERR("content size %zu exceeds "
+                                               "max content len %zu\n",
+                                               total,
+                                               state->max_content_length);
+                                       return -1;
+                               }
+                       }
+
+                       state->buffer.data =
+                               talloc_realloc(state, state->buffer.data,
+                                              uint8_t,
+                                              state->buffer.length + toread);
                        if (!state->buffer.data) {
                                return -1;
                        }
-                       state->buffer.length++;
+                       state->buffer.length += toread;
                        vector[0].iov_base = (void *)(state->buffer.data +
-                                                     state->buffer.length - 1);
-                       vector[0].iov_len = 1;
+                                            state->buffer.length - toread);
+                       vector[0].iov_len = toread;
                        *_vector = vector;
                        *_count = 1;
                        break;
+               }
                case HTTP_DATA_CORRUPTED:
                case HTTP_REQUEST_CANCELED:
                case HTTP_DATA_TOO_LONG: