<p>laforge <strong>submitted</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/libosmo-sccp/+/22789">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Jenkins Builder: Verified
pespin: Looks good to me, but someone else must approve
laforge: Looks good to me, approved
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">sccp: Add minimalistic SCMG implementation<br><br>SCMG (SCCP Management) is a special sub-system that normally resides<br>at SSN=1. In Osmocom we so far ignored its existence. However,<br>in terms of interop with other implementation, we should implement<br>at least some basic features.<br><br>The only procedure implemented in this initial commit is the response<br>to an incoming SST (Subsystem Test) message. If we don't respond to<br>this message, a remote SCCP entity could assume the SSN is dead on<br>our side, rendering communication impossible.<br><br>Change-Id: I04b162476f7652ef0540b5ea7299e9447efd1d09<br>---<br>M include/osmocom/sigtran/Makefile.am<br>A include/osmocom/sigtran/protocol/sccp_scmg.h<br>M src/sccp_internal.h<br>M src/sccp_scmg.c<br>M src/sccp_user.c<br>5 files changed, 166 insertions(+), 1 deletion(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmocom/sigtran/Makefile.am b/include/osmocom/sigtran/Makefile.am</span><br><span>index 0aa90cb..d9cc20c 100644</span><br><span>--- a/include/osmocom/sigtran/Makefile.am</span><br><span>+++ b/include/osmocom/sigtran/Makefile.am</span><br><span>@@ -3,5 +3,6 @@</span><br><span> </span><br><span> sigtrandir = $(includedir)/osmocom/sigtran</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">-sigtran_prot_HEADERS = protocol/sua.h protocol/m3ua.h protocol/mtp.h</span><br><span style="color: hsl(120, 100%, 40%);">+sigtran_prot_HEADERS = protocol/sua.h protocol/m3ua.h protocol/mtp.h \</span><br><span style="color: hsl(120, 100%, 40%);">+ protocol/sccp_scmg.h</span><br><span> sigtran_protdir = $(includedir)/osmocom/sigtran/protocol</span><br><span>diff --git a/include/osmocom/sigtran/protocol/sccp_scmg.h b/include/osmocom/sigtran/protocol/sccp_scmg.h</span><br><span>new file mode 100644</span><br><span>index 0000000..5d97828</span><br><span>--- /dev/null</span><br><span>+++ b/include/osmocom/sigtran/protocol/sccp_scmg.h</span><br><span>@@ -0,0 +1,25 @@</span><br><span style="color: hsl(120, 100%, 40%);">+#pragma once</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/* SCCP Management as per Section 5.3 of ITU-T Q.713 */</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+enum sccp_scmg_msg_type {</span><br><span style="color: hsl(120, 100%, 40%);">+ SCCP_SCMG_MSGT_SSA = 0x01, /* Subsystem Allowed */</span><br><span style="color: hsl(120, 100%, 40%);">+ SCCP_SCMG_MSGT_SSP = 0x02, /* Subsystem Prohibited */</span><br><span style="color: hsl(120, 100%, 40%);">+ SCCP_SCMG_MSGT_SST = 0x03, /* Subsystem Status Test */</span><br><span style="color: hsl(120, 100%, 40%);">+ SCCP_SCMG_MSGT_SOR = 0x04, /* Subsystem Out-of-service Request */</span><br><span style="color: hsl(120, 100%, 40%);">+ SCCP_SCMG_MSGT_SOG = 0x05, /* Subsystem Out-of-service Grant */</span><br><span style="color: hsl(120, 100%, 40%);">+ SCCP_SCMG_MSGT_SSC = 0x06, /* Subsystem Congested */</span><br><span style="color: hsl(120, 100%, 40%);">+};</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+struct sccp_scmg_msg {</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t msg_type; /* enum sccp_scmg_msg_type */</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t affected_ssn;</span><br><span style="color: hsl(120, 100%, 40%);">+ uint16_t affected_pc;</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t smi;</span><br><span style="color: hsl(120, 100%, 40%);">+ /* one octet, only in case of SSC */</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t ssc_congestion_lvl[0];</span><br><span style="color: hsl(120, 100%, 40%);">+} __attribute__ ((packed));</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+extern const struct value_string sccp_scmg_msgt_names[];</span><br><span style="color: hsl(120, 100%, 40%);">+static inline const char *sccp_scmg_msgt_name(enum sccp_scmg_msg_type msgt)</span><br><span style="color: hsl(120, 100%, 40%);">+{ return get_value_string(sccp_scmg_msgt_names, msgt); }</span><br><span>diff --git a/src/sccp_internal.h b/src/sccp_internal.h</span><br><span>index 6ad7ee3..6bd2af9 100644</span><br><span>--- a/src/sccp_internal.h</span><br><span>+++ b/src/sccp_internal.h</span><br><span>@@ -139,3 +139,4 @@</span><br><span> /* SCCP Management (SCMG) */</span><br><span> void sccp_scmg_rx_mtp_pause(struct osmo_sccp_instance *inst, uint32_t dpc);</span><br><span> void sccp_scmg_rx_mtp_resume(struct osmo_sccp_instance *inst, uint32_t dpc);</span><br><span style="color: hsl(120, 100%, 40%);">+int sccp_scmg_init(struct osmo_sccp_instance *inst);</span><br><span>diff --git a/src/sccp_scmg.c b/src/sccp_scmg.c</span><br><span>index 4a8ccf6..0e3905d 100644</span><br><span>--- a/src/sccp_scmg.c</span><br><span>+++ b/src/sccp_scmg.c</span><br><span>@@ -30,6 +30,7 @@</span><br><span> </span><br><span> #include <osmocom/sigtran/sccp_sap.h></span><br><span> #include <osmocom/sigtran/protocol/sua.h></span><br><span style="color: hsl(120, 100%, 40%);">+#include <osmocom/sigtran/protocol/sccp_scmg.h></span><br><span> #include <osmocom/sccp/sccp_types.h></span><br><span> </span><br><span> #include "xua_internal.h"</span><br><span>@@ -81,3 +82,133 @@</span><br><span> /* 8) local broadcast of "user-in-service"</span><br><span> * [this would require us to track SSNs at each PC, which we don't] */</span><br><span> }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+const struct value_string sccp_scmg_msgt_names[] = {</span><br><span style="color: hsl(120, 100%, 40%);">+ { SCCP_SCMG_MSGT_SSA, "SSA (Subsystem Allowed)" },</span><br><span style="color: hsl(120, 100%, 40%);">+ { SCCP_SCMG_MSGT_SSP, "SSP (Subsystem Prohibited)" },</span><br><span style="color: hsl(120, 100%, 40%);">+ { SCCP_SCMG_MSGT_SST, "SST (Subsystem Status Test)" },</span><br><span style="color: hsl(120, 100%, 40%);">+ { SCCP_SCMG_MSGT_SOR, "SOR (Subsystem Out-of-service Request)" },</span><br><span style="color: hsl(120, 100%, 40%);">+ { SCCP_SCMG_MSGT_SOG, "SOG (Subsystem Out-of-service Grant)" },</span><br><span style="color: hsl(120, 100%, 40%);">+ { SCCP_SCMG_MSGT_SSC, "SSC (Subsystem Congested)" },</span><br><span style="color: hsl(120, 100%, 40%);">+ { 0, NULL }</span><br><span style="color: hsl(120, 100%, 40%);">+};</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+static int sccp_scmg_tx(struct osmo_sccp_user *scu, const struct osmo_sccp_addr *calling_addr,</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct osmo_sccp_addr *called_addr,</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t msg_type, uint8_t ssn, uint16_t pc, uint8_t smi, uint8_t *ssc_cong_lvl)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct msgb *msg = sccp_msgb_alloc(__func__);</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_scu_prim *prim;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_scu_unitdata_param *param;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct sccp_scmg_msg *scmg;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* fill primitive header */</span><br><span style="color: hsl(120, 100%, 40%);">+ prim = (struct osmo_scu_prim *) msgb_put(msg, sizeof(*prim));</span><br><span style="color: hsl(120, 100%, 40%);">+ param = &prim->u.unitdata;</span><br><span style="color: hsl(120, 100%, 40%);">+ memcpy(¶m->calling_addr, calling_addr, sizeof(*calling_addr));</span><br><span style="color: hsl(120, 100%, 40%);">+ memcpy(¶m->called_addr, called_addr, sizeof(*called_addr));</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_prim_init(&prim->oph, SCCP_SAP_USER, OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_REQUEST, msg);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Fill the actual SCMG message */</span><br><span style="color: hsl(120, 100%, 40%);">+ msg->l2h = msgb_put(msg, sizeof(*scmg));</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg = (struct sccp_scmg_msg *) msg->l2h;</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg->msg_type = msg_type;</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg->affected_ssn = ssn;</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg->affected_pc = pc;</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg->smi = smi;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* add congestion level in case of SSC message */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (msg_type == SCCP_SCMG_MSGT_SSC) {</span><br><span style="color: hsl(120, 100%, 40%);">+ msgb_put(msg, 1);</span><br><span style="color: hsl(120, 100%, 40%);">+ OSMO_ASSERT(ssc_cong_lvl);</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg->ssc_congestion_lvl[1] = *ssc_cong_lvl;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ return osmo_sccp_user_sap_down(scu, &prim->oph);</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/* Subsystem Test received */</span><br><span style="color: hsl(120, 100%, 40%);">+static int scmg_rx_sst(struct osmo_sccp_user *scu, const struct osmo_sccp_addr *calling_addr,</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct osmo_sccp_addr *called_addr, const struct sccp_scmg_msg *sst)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Q.714 5.3.4.3 Actions at the receiving side (of SST) */</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* check "ignore subsystem status test" and bail out */</span><br><span style="color: hsl(120, 100%, 40%);">+ /* check if SSN in question is available. If yes, return SSA. If not, ignore */</span><br><span style="color: hsl(120, 100%, 40%);">+ scu = sccp_user_find(scu->inst, sst->affected_ssn, sst->affected_pc);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!scu)</span><br><span style="color: hsl(120, 100%, 40%);">+ return 0;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* is subsystem available? */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (0 /* !subsys_available(scu) */)</span><br><span style="color: hsl(120, 100%, 40%);">+ return 0;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ return sccp_scmg_tx(scu, called_addr, calling_addr, SCCP_SCMG_MSGT_SSA,</span><br><span style="color: hsl(120, 100%, 40%);">+ sst->affected_ssn, sst->affected_pc, 0, NULL);</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+static int scmg_rx(struct osmo_sccp_user *scu, const struct osmo_sccp_addr *calling_addr,</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct osmo_sccp_addr *called_addr, const struct sccp_scmg_msg *scmg)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ switch (scmg->msg_type) {</span><br><span style="color: hsl(120, 100%, 40%);">+ case SCCP_SCMG_MSGT_SST:</span><br><span style="color: hsl(120, 100%, 40%);">+ return scmg_rx_sst(scu, calling_addr, called_addr, scmg);</span><br><span style="color: hsl(120, 100%, 40%);">+ case SCCP_SCMG_MSGT_SSP:</span><br><span style="color: hsl(120, 100%, 40%);">+ case SCCP_SCMG_MSGT_SSA:</span><br><span style="color: hsl(120, 100%, 40%);">+ case SCCP_SCMG_MSGT_SOR:</span><br><span style="color: hsl(120, 100%, 40%);">+ case SCCP_SCMG_MSGT_SOG:</span><br><span style="color: hsl(120, 100%, 40%);">+ case SCCP_SCMG_MSGT_SSC:</span><br><span style="color: hsl(120, 100%, 40%);">+ default:</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGP(DLSCCP, LOGL_NOTICE, "Rx unsupported SCCP SCMG %s, ignoring",</span><br><span style="color: hsl(120, 100%, 40%);">+ sccp_scmg_msgt_name(scmg->msg_type));</span><br><span style="color: hsl(120, 100%, 40%);">+ break;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ return 0;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/* main entry point for SCCP user primitives from SCRC/SCOC */</span><br><span style="color: hsl(120, 100%, 40%);">+static int scmg_prim_cb(struct osmo_prim_hdr *oph, void *_scu)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_sccp_user *scu = _scu;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_scu_prim *prim = (struct osmo_scu_prim *) oph;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_scu_unitdata_param *param;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct sccp_scmg_msg *scmg;</span><br><span style="color: hsl(120, 100%, 40%);">+ int rc = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ switch (OSMO_PRIM_HDR(oph)) {</span><br><span style="color: hsl(120, 100%, 40%);">+ case OSMO_PRIM(OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_INDICATION):</span><br><span style="color: hsl(120, 100%, 40%);">+ param = &prim->u.unitdata;</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg = msgb_l2(oph->msg);</span><br><span style="color: hsl(120, 100%, 40%);">+ /* ensure minimum length based on message type */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (msgb_l2len(oph->msg) < sizeof(*scmg)) {</span><br><span style="color: hsl(120, 100%, 40%);">+ rc = -1;</span><br><span style="color: hsl(120, 100%, 40%);">+ break;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ if (scmg->msg_type == SCCP_SCMG_MSGT_SSC && msgb_l2len(oph->msg) < sizeof(*scmg)+1) {</span><br><span style="color: hsl(120, 100%, 40%);">+ rc = -1;</span><br><span style="color: hsl(120, 100%, 40%);">+ break;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ /* interestingly, PC is specified to be encoded in little endian ?!? */</span><br><span style="color: hsl(120, 100%, 40%);">+ scmg->affected_pc = osmo_load16le(&scmg->affected_pc);</span><br><span style="color: hsl(120, 100%, 40%);">+ rc = scmg_rx(scu, ¶m->calling_addr, ¶m->called_addr, scmg);</span><br><span style="color: hsl(120, 100%, 40%);">+ break;</span><br><span style="color: hsl(120, 100%, 40%);">+ default:</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGP(DLSCCP, LOGL_ERROR, "unsupported SCCP user primitive %s\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_scu_prim_name(oph));</span><br><span style="color: hsl(120, 100%, 40%);">+ break;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ msgb_free(oph->msg);</span><br><span style="color: hsl(120, 100%, 40%);">+ return rc;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/* register SCMG as SCCP user for SSN=1 */</span><br><span style="color: hsl(120, 100%, 40%);">+int sccp_scmg_init(struct osmo_sccp_instance *inst)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_sccp_user *scu;</span><br><span style="color: hsl(120, 100%, 40%);">+ scu = osmo_sccp_user_bind(inst, "SCCP Maangement", scmg_prim_cb, SCCP_SSN_MANAGEMENT);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!scu)</span><br><span style="color: hsl(120, 100%, 40%);">+ return -1;</span><br><span style="color: hsl(120, 100%, 40%);">+ return 0;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span>diff --git a/src/sccp_user.c b/src/sccp_user.c</span><br><span>index 880cab1..d8e78f0 100644</span><br><span>--- a/src/sccp_user.c</span><br><span>+++ b/src/sccp_user.c</span><br><span>@@ -220,6 +220,7 @@</span><br><span> osmo_sccp_instance_create(struct osmo_ss7_instance *ss7, void *priv)</span><br><span> {</span><br><span> struct osmo_sccp_instance *inst;</span><br><span style="color: hsl(120, 100%, 40%);">+ int rc;</span><br><span> </span><br><span> inst = talloc_zero(ss7, struct osmo_sccp_instance);</span><br><span> if (!inst)</span><br><span>@@ -235,6 +236,12 @@</span><br><span> inst->ss7_user.prim_cb = mtp_user_prim_cb;</span><br><span> inst->ss7_user.priv = inst;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ rc = sccp_scmg_init(inst);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (rc < 0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ talloc_free(inst);</span><br><span style="color: hsl(120, 100%, 40%);">+ return NULL;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> osmo_ss7_user_register(ss7, MTP_SI_SCCP, &inst->ss7_user);</span><br><span> </span><br><span> llist_add_tail(&inst->list, &sccp_instances);</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/libosmo-sccp/+/22789">change 22789</a>. To unsubscribe, or for help writing mail filters, visit <a href="https://gerrit.osmocom.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.osmocom.org/c/libosmo-sccp/+/22789"/><meta itemprop="name" content="View Change"/></div></div>
<div style="display:none"> Gerrit-Project: libosmo-sccp </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: I04b162476f7652ef0540b5ea7299e9447efd1d09 </div>
<div style="display:none"> Gerrit-Change-Number: 22789 </div>
<div style="display:none"> Gerrit-PatchSet: 3 </div>
<div style="display:none"> Gerrit-Owner: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-Reviewer: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>