From 80d9312e368825bd55bf8d5959684cccfe51f75a Mon Sep 17 00:00:00 2001
From: Tobias Waldekranz <tobias@waldekranz.com>
Date: Tue, 25 Apr 2023 14:58:53 +0200
Subject: [PATCH] confd: Infer type when configuring physical interfaces

---
 src/confd/src/Makefile.am       |  4 ++--
 src/confd/src/helpers.c         | 22 +++++++++++++++++
 src/confd/src/helpers.h         |  2 ++
 src/confd/src/ietf-interfaces.c | 42 ++++++++++++++++++++++++++++++++-
 4 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/src/confd/src/Makefile.am b/src/confd/src/Makefile.am
index 8928215a..b7444543 100644
--- a/src/confd/src/Makefile.am
+++ b/src/confd/src/Makefile.am
@@ -4,8 +4,8 @@ AM_CPPFLAGS             = -D_DEFAULT_SOURCE -D_XOPEN_SOURCE -D_GNU_SOURCE -DYANG
 plugindir               = $(srpdplugindir)
 plugin_LTLIBRARIES      = confd-plugin.la
 
-confd_plugin_la_CFLAGS  = $(augeas_CFLAGS) $(libite_CFLAGS) $(sysrepo_CFLAGS) $(CFLAGS)
-confd_plugin_la_LIBADD  = $(augeas_LIBS)   $(libite_LIBS)   $(sysrepo_LIBS)
+confd_plugin_la_CFLAGS  = $(augeas_CFLAGS) $(jansson_CFLAGS) $(libite_CFLAGS) $(sysrepo_CFLAGS) $(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
diff --git a/src/confd/src/helpers.c b/src/confd/src/helpers.c
index d61488b1..72eefeea 100644
--- a/src/confd/src/helpers.c
+++ b/src/confd/src/helpers.c
@@ -1,8 +1,30 @@
 /* SPDX-License-Identifier: BSD-3-Clause */
 
+#include <errno.h>
 #include <stdarg.h>
 #include "core.h"
 
+FILE *popenf(const char *type, const char *cmdf, ...)
+{
+	va_list ap;
+	char *cmd;
+	FILE *fp;
+	int len;
+
+	va_start(ap, cmdf);
+	len = vasprintf(&cmd, cmdf, ap);
+	va_end(ap);
+
+	if (len < 0) {
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	fp = popen(cmd, type);
+	free(cmd);
+	return fp;
+}
+
 static FILE *open_file(const char *mode, const char *fmt, va_list ap)
 {
 	va_list apc;
diff --git a/src/confd/src/helpers.h b/src/confd/src/helpers.h
index 87ea93c6..ac91c193 100644
--- a/src/confd/src/helpers.h
+++ b/src/confd/src/helpers.h
@@ -3,6 +3,8 @@
 #ifndef CONFD_HELPERS_H_
 #define CONFD_HELPERS_H_
 
+FILE *popenf(const char *type, const char *cmdf, ...);
+
 int writedf(int value, const char *fmt, ...);
 int writesf(const char *str, const char *fmt, ...);
 
diff --git a/src/confd/src/ietf-interfaces.c b/src/confd/src/ietf-interfaces.c
index 1cb72899..48e414ad 100644
--- a/src/confd/src/ietf-interfaces.c
+++ b/src/confd/src/ietf-interfaces.c
@@ -1,6 +1,9 @@
 /* SPDX-License-Identifier: BSD-3-Clause */
 
 #include <fnmatch.h>
+#include <stdbool.h>
+
+#include <jansson.h>
 
 #include <net/if.h>
 
@@ -172,6 +175,41 @@ static void ifinit(sr_session_ctx_t *session)
 		ERROR("failed: %s", sr_strerror(rc));
 }
 
+static bool iface_is_phys(const char *ifname)
+{
+	bool is_phys = false;
+	json_error_t jerr;
+	const char *attr;
+	json_t *link;
+	FILE *proc;
+
+	proc = popenf("re", "ip -d -j link show dev %s", ifname);
+	if (!proc)
+		goto out;
+
+	link = json_loadf(proc, 0, &jerr);
+	pclose(proc);
+
+	if (!link)
+		goto out;
+
+	if (json_unpack(link, "[{s:s}]", "link_type", &attr))
+		goto out_free;
+
+	if (strcmp(attr, "ether"))
+		goto out_free;
+
+	if (!json_unpack(link, "[{s: { s:s }}]", "linkinfo", "info_kind", &attr))
+		goto out_free;
+
+	is_phys = true;
+
+out_free:
+	json_decref(link);
+out:
+	return is_phys;
+}
+
 static int ifchange_cand_infer_type(sr_session_ctx_t *session, const char *xpath)
 {
 	sr_val_t inferred = { .type = SR_STRING_T };
@@ -188,7 +226,9 @@ static int ifchange_cand_infer_type(sr_session_ctx_t *session, const char *xpath
 	if (!ifname)
 		return SR_ERR_INTERNAL;
 
-	if (!fnmatch("br+([0-9])", ifname, FNM_EXTMATCH))
+	if (iface_is_phys(ifname))
+		inferred.data.string_val = "iana-if-type:ethernetCsmacd";
+	else if (!fnmatch("br+([0-9])", ifname, FNM_EXTMATCH))
 		inferred.data.string_val = "iana-if-type:bridge";
 	else if (!fnmatch("lag+([0-9])", ifname, FNM_EXTMATCH))
 		inferred.data.string_val = "iana-if-type:ieee8023adLag";