Parser in response mode does not reset on finish

[bryanp]

I noticed some unexpected behavior when parsing responses. If the response does not include a content-length header, calling llhttp_finish does not seem to reset the parser. Here's an example:

#include <stdio.h>
#include <string.h>
#include "llhttp.h"

int handle_on_headers_complete(llhttp_t *parser) {
  printf("  headers complete\n");

  return 0;
}

int handle_on_message_begin(llhttp_t *parser) {
  printf("  message begin\n");

  return 0;
}

int handle_on_message_complete(llhttp_t *parser) {
  printf("  message complete\n");

  return 0;
}

int main (void) {
  llhttp_t parser;
  llhttp_settings_t settings;

  llhttp_settings_init(&settings);

  settings.on_headers_complete = handle_on_headers_complete;
  settings.on_message_begin = handle_on_message_begin;
  settings.on_message_complete = handle_on_message_complete;

  llhttp_init(&parser, HTTP_RESPONSE, &settings);

  const char* data = "HTTP/1.1 200 OK\r\n\r\n";
  int data_len = strlen(data);
  enum llhttp_errno err;
  int i = 0;

  while (i < 3) {
    printf("parsing\n");

    err = llhttp_execute(&parser, data, data_len);

    if (err == HPE_OK) {
      // all good
    } else {
      fprintf(stderr, "  ! %s %s\n", llhttp_errno_name(err), parser.reason);
    }

    llhttp_finish(&parser);

    i++;
  }
}

Output:

parsing
  message begin
  headers complete
  message complete
parsing
  message complete
parsing
  message complete

I'd expect to see this:

parsing
  message begin
  headers complete
  message complete
parsing
  message begin
  headers complete
  message complete
parsing
  message begin
  headers complete
  message complete

[pallas]

I think this is expected, but willing to be shown otherwise. Without a content-length, the parser has no way to know the length of the response. The point of llhttp_finish is not to reset the parser, it's to figure out the final state of the current parse, possibly based on a call to on_message_complete. Once you are done with the parser, to reuse it you need to call llhttp_reset to put it back in its initial state, preserving any flags, callbacks, & cookies you've set on it.

[bryanp]

Ah, the issue is with my implementation. Thank you for pointing me in the right direction, I already have things fixed.