Hodlinvoice fail

[niftynei]

Make a python plugin, have it spin in htlc_accepted.

Call plugin stop.

Crashes!

To reproduce:

source contrib/startup_regtest.sh
start_ln
fund_nodes
l2-cli plugin start $(pwd)/hodl.py  # see below for hodl.py code
l2-cli invoice 134 1 go_bang
l2-cli hodlinvoice <payment_hash>
l1-cli pay <bolt11>
l2-cli plugin stop hodl.py

(cln-meta-project-py3.10) zircon:lightning (master)☇ l2-cli plugin stop $(pwd)/hodl.py                                                                                                 
Already in transaction from lightningd/jsonrpc.c:1087                                                                                                                                  
lightningd: FATAL SIGNAL 6 (version v23.08rc2-12-g5531c9d-modded)                                                                                                                      
0x55700ba86e78 send_backtrace                                                                                                                                                          
        common/daemon.c:33                                                                 
0x55700ba87063 crashdump                           
        common/daemon.c:75                         
0x7fe86364251f ???                                 
        ./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0                                                                                    
0x7fe863696a7c __pthread_kill_implementation                                                                                       
        ./nptl/pthread_kill.c:44                                 
0x7fe863696a7c __pthread_kill_internal                           
        ./nptl/pthread_kill.c:78                                 
0x7fe863696a7c __GI___pthread_kill                                          
        ./nptl/pthread_kill.c:89                                            
0x7fe863642475 __GI_raise                                                   
        ../sysdeps/posix/raise.c:26                                         
0x7fe8636287f2 __GI_abort                                                                  
        ./stdlib/abort.c:79                                                                
0x55700ba10c36 fatal_vfmt                                                                  
        lightningd/log.c:1025                                                              
0x55700ba59737 db_error                                                                    
        wallet/db.c:1051                                                                   
0x55700baf6874 db_fatal                                                                    
        db/utils.c:327                                                                     
0x55700baa9487 db_begin_transaction_                                                       
        db/exec.c:127                                                                      
0x55700ba48cd3 plugin_hook_callback                                                        
        lightningd/plugin_hook.c:212                                                       
0x55700ba489ce plugin_hook_killed                                                          
        lightningd/plugin_hook.c:137                                                       
0x55700bc31edc notify                                                                      
        ccan/ccan/tal/tal.c:246                                                            
0x55700bc324bd del_tree                                                                    
        ccan/ccan/tal/tal.c:437                                                            
0x55700bc3250f del_tree                                                                    
        ccan/ccan/tal/tal.c:447                                                            
0x55700bc32863 tal_free                                                                    
        ccan/ccan/tal/tal.c:521                                                            
0x55700ba418b6 plugin_kill                                                                 
        lightningd/plugin.c:385                                                            
0x55700ba47a7c plugin_stop                                                                 
        lightningd/plugin_control.c:120                                                    
0x55700ba47d14 plugin_dynamic_stop                                                         
        lightningd/plugin_control.c:175                                                    
0x55700ba47f69 json_plugin_control                                                         
        lightningd/plugin_control.c:233                                                    
0x55700ba07eeb command_exec                                                                
        lightningd/jsonrpc.c:658                                                           
0x55700ba08507 rpc_command_hook_final                                                      
        lightningd/jsonrpc.c:786                                                           
0x55700ba490d3 plugin_hook_call_                                                           
        lightningd/plugin_hook.c:285                                                       
0x55700ba0890a plugin_hook_call_rpc_command                                                
        lightningd/jsonrpc.c:874                                                           
0x55700ba08ec7 parse_request                                                               
        lightningd/jsonrpc.c:984                                                           
0x55700ba093a0 read_json                                                                   
        lightningd/jsonrpc.c:1090                                                          
0x55700bc1f5c0 next_plan                                                                   
        ccan/ccan/io/io.c:59                                                               
0x55700bc201f5 do_plan                                                                     
        ccan/ccan/io/io.c:407                                                              
0x55700bc20237 io_ready                                                                    
        ccan/ccan/io/io.c:417                                                              
0x55700bc225d3 io_loop                                                                     
        ccan/ccan/io/poll.c:453                                                            
0x55700ba06055 io_loop_with_timers                                                         
        lightningd/io_loop_with_timers.c:22                                                
0x55700ba0d0bb main                                                                        
        lightningd/lightningd.c:1332                                                       
0x7fe863629d8f __libc_start_call_main                                                      
        ../sysdeps/nptl/libc_start_call_main.h:58
0x7fe863629e3f __libc_start_main_impl                                                      
        ../csu/libc-start.c:392                                                            
0x55700b9d4d64 ???                                                                         
        ???:0                                                                              
0xffffffffffffffff ???                                                                     
        ???:0                    

[niftynei]

plugin codes

#!/usr/bin/env python3
from pyln.client import Plugin

import asyncio
import time


plugin = Plugin()

wait_for = []


@plugin.hook('htlc_accepted')
def on_htlc_accepted(onion, htlc, plugin, **kwargs):
    if htlc['payment_hash'] in wait_for:
        print("hodling {}".format(htlc['payment_hash']))

    while htlc['payment_hash'] in wait_for:
        time.sleep(2)

    return {'result': 'continue'}


@plugin.method("hodlinvoice")
def hodlinvoice(payment_hash):
    if payment_hash not in wait_for:
        wait_for.append(payment_hash)
    return {'payment_hash': payment_hash,
            'hodled': True }


@plugin.method("unhodlinvoice")
def unhodlinvoice(payment_hash):
    if payment_hash in wait_for:
        wait_for.remove(payment_hash)
        return {'payment_hash': payment_hash,
                'unhodled': True }

    return {'payment_hash': payment_hash,
            'unhodled': False }

plugin.run()

[rustyrussell]

Yeah, we don't handle plugins dying in the middle of hooks very well. I'll keep it, but defer to next release...