src/confd: initial support for DHCPv4 yang model

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/confd/src/Makefile.am

@@ -8,4 +8,5 @@ confd_plugin_la_CFLAGS  = $(augeas_CFLAGS) $(jansson_CFLAGS) $(libite_CFLAGS) $(
 confd_plugin_la_LIBADD  = $(augeas_LIBS)   $(jansson_LIBS)   $(libite_LIBS)   $(sysrepo_LIBS)
 confd_plugin_la_LDFLAGS = -module -avoid-version -shared
 confd_plugin_la_SOURCES = core.c core.h helpers.c helpers.h srx_module.c srx_module.h srx_val.c srx_val.h \
-			  ietf-system.c ietf-interfaces.c systemv.c systemv.h lyx.c lyx.h dagger.c dagger.h
+			  ietf-system.c ietf-interfaces.c systemv.c systemv.h lyx.c lyx.h dagger.c dagger.h \
+			  infix-dhcp.c

src/confd/src/core.c

@@ -102,6 +102,9 @@ int sr_plugin_init_cb(sr_session_ctx_t *session, void **priv)
 	if (rc)
 		goto err;
 	rc = ietf_system_init(&confd);
+	if (rc)
+		goto err;
+	rc = infix_dhcp_init(&confd);
 	if (rc)
 		goto err;
 

src/confd/src/core.h

@@ -137,4 +137,7 @@ int ietf_interfaces_init(struct confd *confd);
 /* ietf-system.c */
 int ietf_system_init(struct confd *confd);
 
+/* infix-dhcp.c */
+int infix_dhcp_init(struct confd *confd);
+
 #endif	/* CONFD_CORE_H_ */

src/confd/src/infix-dhcp.c

@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#include <assert.h>
+#include <ctype.h>
+#include <pwd.h>
+#include <sys/utsname.h>
+#include <sys/sysinfo.h>
+#include <sys/types.h>
+
+#include "core.h"
+#include "lyx.h"
+#include "srx_module.h"
+#include "srx_val.h"
+
+static const struct srx_module_requirement infix_dhcp_reqs[] = {
+	{ .dir = YANG_PATH_, .name = "infix-dhcp-client", .rev = "2023-05-22" },
+	{ NULL }
+};
+
+static int is_enabled(struct lyd_node *parent, const char *name)
+{
+	const char *attr;
+
+	attr = lydx_get_cattr(parent, name);
+	if (!attr || !strcmp(attr, "true"))
+		return 1;
+
+	return 0;
+}
+
+static int client_change(sr_session_ctx_t *session, uint32_t sub_id, const char *module,
+	const char *xpath, sr_event_t event, unsigned request_id, void *_confd)
+{
+	struct lyd_node *global, *diff, *cifs, *difs, *cif, *dif;
+	sr_error_t err = 0;
+	sr_data_t *cfg;
+	int ena = 0;
+
+	switch (event) {
+	case SR_EV_DONE:
+		break;
+	case SR_EV_CHANGE:
+	case SR_EV_ABORT:
+	default:
+		return SR_ERR_OK;
+	}
+
+	ERROR("Got DHCP client change");
+	err = sr_get_data(session, "/dhcp-client//.", 0, 0, 0, &cfg);
+	if (err)
+		goto err_abandon;
+
+	err = srx_get_diff(session, (struct lyd_node **)&diff);
+	if (err)
+		goto err_release_data;
+
+	global = lydx_get_descendant(cfg->tree, "dhcp-client", NULL);
+	ena = is_enabled(global, "enabled");
+
+	cifs = lydx_get_descendant(cfg->tree, "dhcp-client", "client-if", NULL);
+	difs = lydx_get_descendant(diff, "dhcp-client", "client-if", NULL);
+
+	LYX_LIST_FOR_EACH(difs, dif, "client-if") {
+		/* find the modified one, delete or recreate only that */
+		LYX_LIST_FOR_EACH(cifs, cif, "client-if") {
+			const char *ifname = lydx_get_cattr(dif, "if-name");
+			FILE *fp;
+
+			if (strcmp(ifname, lydx_get_cattr(cif, "if-name")))
+				continue;
+
+			if (!ena || !is_enabled(cif, "enabled")) {
+				systemf("initctl delete dhcp-%s", ifname);
+				continue;
+			}
+
+			fp = fopenf("w", "/etc/finit.d/available/dhcp-%s.conf", ifname);
+			if (!fp) {
+				ERROR("failed creating DHCP client service for %s: %s",
+				      ifname, strerror(errno));
+				continue;
+			}
+
+			fprintf(fp, "service name:dhcp :%s udhcpc -f -S -i %s -- DHCP client @%s",
+				ifname, ifname, ifname);
+			fclose(fp);
+			systemf("initctl enable dhcp-%s", ifname);
+		}
+	}
+
+	lyd_free_tree(diff);
+err_release_data:
+	sr_release_data(cfg);
+err_abandon:
+
+	return err;
+}
+
+
+int infix_dhcp_init(struct confd *confd)
+{
+	int rc;
+
+	rc = srx_require_modules(confd->conn, infix_dhcp_reqs);
+	if (rc)
+		goto fail;
+
+	ERROR("Loaded DHCP model");
+	REGISTER_CHANGE(confd->session, "infix-dhcp-client", "/infix-dhcp-client:dhcp-client",
+			0, client_change, confd, &confd->sub);
+	ERROR("Registered DHCP change callback");
+	return SR_ERR_OK;
+fail:
+	ERROR("init failed: %s", sr_strerror(rc));
+	return rc;
+}

src/confd/yang/infix-dhcp-client@2023-05-22.yang

@@ -0,0 +1,56 @@
+module infix-dhcp-client {
+  yang-version 1.1;
+  namespace "urn:ietf:params:xml:ns:yang:infix-dhcp-client";
+  prefix dhc4-clnt;
+
+  import ietf-interfaces {
+    prefix "if";
+  }
+
+  contact      "kernelkit@googlegroups.com";
+  description  "This module implements an IPv4 DHCP client";
+
+  revision 2023-05-22 {
+    description   "Initial revision.";
+    reference     "rfc2131 rfc7950";
+  }
+
+  /*
+   * Data Nodes
+   */
+
+  container dhcp-client {
+    description
+      "DHCPv4 client configuration";
+    leaf enabled {
+      type boolean;
+      default "true";
+      description
+        "Globally enables the DHCP client function.";
+    }
+    list client-if {
+      key "if-name";
+      description
+        "The list of interfaces for which the client will
+         be requesting DHCPv4 configuration.";
+      leaf if-name {
+        type if:interface-ref;
+        mandatory true;
+        description
+          "Reference to the interface entry that the requested
+           configuration is relevant to.";
+      }
+      leaf enabled {
+        type boolean;
+        default "true";
+        description
+          "Enables the DHCP client function for this interface.";
+      }
+      leaf client-id {
+	type string;
+	description
+	  "DHCP client identifier";
+      }
+    }
+  }
+}