pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmo-sigtran/+/41502?usp=email )

Change subject: ss7_xua_srv: Refactor xua_accept_cb() ......................................................................

ss7_xua_srv: Refactor xua_accept_cb()

Move all "readonly" (no state change) checks at the start of the function. This simplifies the later code paths in the function, also allowing for more early return checks. This in turn allows simplifying different destruction code paths of asp and its osmo_stream.

As a result, we can now call existing ss7_asp_disconnect_stream() API to close the stream when needed, and also make sure we set asp->xua_server=NULL and remove asp from oxs->siblings when the conn disconnects, otherwise it could create unexpected states if the config of the asp changes transport role client<->server or it gets assigned due to a different oxs due to change in config too.

The new logic also fixes some corner-case scenarios, like (dis)allwoing newly created dynamic ASPs for already existing previous conn after the feature configuration has changed.

Change-Id: I191f97e8545ce2f9899e3cd3cc3a7eed854daf1e --- M src/ss7_asp.c M src/ss7_xua_srv.c 2 files changed, 58 insertions(+), 56 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/libosmo-sigtran refs/changes/02/41502/1

diff --git a/src/ss7_asp.c b/src/ss7_asp.c index 5325de9..377d9e4 100644 --- a/src/ss7_asp.c +++ b/src/ss7_asp.c @@ -756,8 +756,6 @@ osmo_stream_cli_destroy(asp->client); if (asp->fi) osmo_fsm_inst_term(asp->fi, OSMO_FSM_TERM_REQUEST, NULL); - if (asp->xua_server) - llist_del(&asp->siblings);

/* unlink from all ASs we are part of */ llist_for_each_entry(as, &asp->inst->as_list, list) @@ -1360,6 +1358,10 @@ xua_asp_send_xlm_prim_simple(asp, OSMO_XLM_PRIM_M_SCTP_RELEASE, PRIM_OP_INDICATION);

asp->server = NULL; + if (asp->xua_server) { + llist_del(&asp->siblings); + asp->xua_server = NULL; + }

/* if we were dynamically allocated at accept_cb() time, let's * self-destruct now. A new connection will re-create the ASP. */ diff --git a/src/ss7_xua_srv.c b/src/ss7_xua_srv.c index 7e55777..85906b7 100644 --- a/src/ss7_xua_srv.c +++ b/src/ss7_xua_srv.c @@ -76,6 +76,7 @@

asp = ss7_asp_find_by_socket_addr(fd, oxs->cfg.trans_proto); if (asp) { + LOGP(DLSS7, LOGL_INFO, "%s: matched connection to ASP %s\n", sock_name, asp->cfg.name); if (!asp->cfg.is_server) { LOGPASP(asp, DLSS7, LOGL_NOTICE, "Reject incoming new connection from %s for ASP configured as 'transport-role client'\n", @@ -92,6 +93,26 @@ talloc_free(sock_name); return 0; } + /* we need to check if we already have a socket associated, and close it. Otherwise it might + * happen that both the listen-fd for this accept() and the old socket are marked 'readable' + * during the same scheduling interval, and we're processing them in the "wrong" order, i.e. + * we first see the accept of the new fd before we see the close on the old fd */ + if (asp->server) { + LOGPASP(asp, DLSS7, LOGL_FATAL, "accept of new connection from %s before old was closed " + "-> close old one\n", sock_name); + ss7_asp_disconnect_stream(asp); + /* Dynamic ASPs (transport-role=server) may be destroyed as a consequence, re-fetch the ASP: */ + asp = ss7_asp_find_by_socket_addr(fd, oxs->cfg.trans_proto); + } + } + + if (!asp && !oxs->cfg.accept_dyn_reg) { + LOGP(DLSS7, LOGL_NOTICE, "%s: %s connection without matching " + "ASP definition and no dynamic registration enabled, terminating\n", + sock_name, proto_name); + close(fd); + talloc_free(sock_name); + return -1; }

srv = osmo_stream_srv_create2(oxs, link, fd, NULL); @@ -127,71 +148,50 @@ } osmo_stream_srv_set_closed_cb(srv, ss7_asp_xua_srv_conn_closed_cb);

- if (asp) { - LOGP(DLSS7, LOGL_INFO, "%s: matched connection to ASP %s\n", - sock_name, asp->cfg.name); - /* we need to check if we already have a socket associated, and close it. Otherwise it might - * happen that both the listen-fd for this accept() and the old socket are marked 'readable' - * during the same scheduling interval, and we're processing them in the "wrong" order, i.e. - * we first see the accept of the new fd before we see the close on the old fd */ - if (asp->server) { - LOGPASP(asp, DLSS7, LOGL_FATAL, "accept of new connection from %s before old was closed " - "-> close old one\n", sock_name); - osmo_stream_srv_set_data(asp->server, NULL); - osmo_stream_srv_destroy(asp->server); - asp->server = NULL; - } - } else { - if (!oxs->cfg.accept_dyn_reg) { - LOGP(DLSS7, LOGL_NOTICE, "%s: %s connection without matching " - "ASP definition and no dynamic registration enabled, terminating\n", - sock_name, proto_name); - } else { - char namebuf[32]; - static uint32_t dyn_asp_num = 0; - snprintf(namebuf, sizeof(namebuf), "asp-dyn-%u", dyn_asp_num++); - asp = osmo_ss7_asp_find_or_create2(oxs->inst, namebuf, 0, 0, - oxs->cfg.trans_proto, - oxs->cfg.proto); - if (asp) { - char hostbuf[INET6_ADDRSTRLEN]; - const char *hostbuf_ptr = &hostbuf[0]; - char portbuf[16]; - - osmo_sock_get_ip_and_port(fd, hostbuf, sizeof(hostbuf), portbuf, sizeof(portbuf), false); - LOGP(DLSS7, LOGL_INFO, "%s: created dynamic ASP %s\n", - sock_name, asp->cfg.name); - asp->cfg.is_server = true; - asp->cfg.role = OSMO_SS7_ASP_ROLE_SG; - asp->cfg.local.port = oxs->cfg.local.port; - asp->cfg.remote.port = atoi(portbuf); - asp->dyn_allocated = true; - asp->server = srv; - ss7_asp_peer_set_hosts(&asp->cfg.local, asp, - (const char * const*)oxs->cfg.local.host, - oxs->cfg.local.host_cnt); - ss7_asp_peer_set_hosts(&asp->cfg.remote, asp, - &hostbuf_ptr, 1); - if ((rc = xua_asp_fsm_start(asp, asp->cfg.role, LOGL_DEBUG)) < 0) { - talloc_free(sock_name); - osmo_ss7_asp_destroy(asp); - return rc; - } - OSMO_ASSERT(asp->fi); - } - } + if (!asp) { + /* Dynamic registration: */ + char namebuf[32]; + char hostbuf[INET6_ADDRSTRLEN]; + const char *hostbuf_ptr = &hostbuf[0]; + char portbuf[16]; + static uint32_t dyn_asp_num = 0; + snprintf(namebuf, sizeof(namebuf), "asp-dyn-%u", dyn_asp_num++); + asp = osmo_ss7_asp_find_or_create2(oxs->inst, namebuf, 0, 0, + oxs->cfg.trans_proto, + oxs->cfg.proto); if (!asp) { osmo_stream_srv_destroy(srv); talloc_free(sock_name); return -1; } - llist_add_tail(&asp->siblings, &oxs->asp_list); + + osmo_sock_get_ip_and_port(fd, hostbuf, sizeof(hostbuf), portbuf, sizeof(portbuf), false); + LOGP(DLSS7, LOGL_INFO, "%s: created dynamic ASP %s\n", sock_name, asp->cfg.name); + asp->cfg.is_server = true; + asp->cfg.role = OSMO_SS7_ASP_ROLE_SG; + asp->cfg.local.port = oxs->cfg.local.port; + asp->cfg.remote.port = atoi(portbuf); + asp->dyn_allocated = true; + asp->server = srv; + ss7_asp_peer_set_hosts(&asp->cfg.local, asp, + (const char * const*)oxs->cfg.local.host, + oxs->cfg.local.host_cnt); + ss7_asp_peer_set_hosts(&asp->cfg.remote, asp, + &hostbuf_ptr, 1); + if ((rc = xua_asp_fsm_start(asp, asp->cfg.role, LOGL_DEBUG)) < 0) { + talloc_free(sock_name); + osmo_ss7_asp_destroy(asp); + return rc; + } + OSMO_ASSERT(asp->fi); } + OSMO_ASSERT(asp);

/* update the ASP reference back to the server over which the * connection came in */ asp->server = srv; asp->xua_server = oxs; + llist_add_tail(&asp->siblings, &oxs->asp_list);

/* update the ASP socket name */ talloc_free(asp->sock_name);