From 5ee78e28addfaa4f18723bb04dcc58664c59a930 Mon Sep 17 00:00:00 2001
From: Joachim Wiberg <troglobit@gmail.com>
Date: Sun, 26 Jan 2025 04:40:15 +0100
Subject: [PATCH] confd: add support for setting fqdn hostnames

The hostname leaf in ietf-system.yang defines it as an fqdn.  This patch
adds support for splitting the host and domain parts to set them in
Linux according to hosts(5).

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
 src/confd/src/core.h             |  2 +-
 src/confd/src/ietf-system.c      | 54 ++++++++++++++++++++++----------
 src/confd/src/infix-containers.c |  2 +-
 src/confd/yang/infix-system.yang |  2 +-
 4 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/src/confd/src/core.h b/src/confd/src/core.h
index fa3fd170..4dc8c19b 100644
--- a/src/confd/src/core.h
+++ b/src/confd/src/core.h
@@ -208,7 +208,7 @@ int ietf_syslog_init(struct confd *confd);
 
 /* ietf-system.c */
 int ietf_system_init (struct confd *confd);
-int hostnamefmt      (struct confd *confd, const char *fmt, char *buf, size_t len);
+int hostnamefmt      (struct confd *confd, const char *fmt, char *hostnm, size_t hostlen, char *domain, size_t domlen);
 
 /* infix-containers.c */
 #ifdef CONTAINERS
diff --git a/src/confd/src/ietf-system.c b/src/confd/src/ietf-system.c
index 564635cc..62cf9c5d 100644
--- a/src/confd/src/ietf-system.c
+++ b/src/confd/src/ietf-system.c
@@ -1614,37 +1614,48 @@ static char *get_mac(struct confd *confd, char *mac, size_t len)
  * NOTE: to be forward compatible, any unknown % combination will be silently consumed.
  *       E.g., "example-%z" will become "example-"
  */
-int hostnamefmt(struct confd *confd, const char *fmt, char *buf, size_t len)
+int hostnamefmt(struct confd *confd, const char *fmt, char *hostnm, size_t hostlen,
+		char *domain, size_t domlen)
 {
 	char mac[10];
+	char *ptr;
 	size_t i;
 
 	if (!fmt || !*fmt)
 		return -1;
 
-	memset(buf, 0, len);
+	memset(hostnm, 0, hostlen);
+	if (domain)
+		memset(domain, 0, domlen);
+
+	ptr = strchr(fmt, '.');
+	if (ptr) {
+		*ptr++ = 0;
+		if (domain)
+			strlcpy(domain, ptr, domlen);
+	}
 
 	for (i = 0; i < strlen(fmt); i++) {
 		if (fmt[i] == '%') {
 			switch (fmt[++i]) {
 			case 'i':
-				strlcat(buf, id, len);
+				strlcat(hostnm, id, hostlen);
 				break;
 			case 'h':
-				strlcat(buf, nm, len);
+				strlcat(hostnm, nm, hostlen);
 				break;
 			case 'm':
-				strlcat(buf, get_mac(confd, mac, sizeof(mac)), len);
+				strlcat(hostnm, get_mac(confd, mac, sizeof(mac)), hostlen);
 				break;
 			case '%':
-				strlcat(buf, "%", len);
+				strlcat(hostnm, "%", hostlen);
 				break;
 			default:
 				break; /* Unknown, skip */
 			}
 		} else {
 			char ch[2] = { fmt[i], 0 };
-			strlcat(buf, ch, len);
+			strlcat(hostnm, ch, hostlen);
 		}
 	}
 
@@ -1656,8 +1667,8 @@ static int change_hostname(sr_session_ctx_t *session, uint32_t sub_id, const cha
 {
 	struct confd *confd = (struct confd *)priv;
 	const char *hostip = "127.0.1.1";
-	char  hostnm[65], buf[256];
-	char *fmt;
+	char  hostnm[65], domain[65];
+	char buf[256], *fmt;
 	FILE *nfp, *fp;
 	int err, fd;
 
@@ -1665,11 +1676,13 @@ static int change_hostname(sr_session_ctx_t *session, uint32_t sub_id, const cha
 		return SR_ERR_OK;
 
 	fmt = srx_get_str(session, "%s", xpath);
-	if (!fmt) {
-	fallback:
-		strlcpy(hostnm, nm, sizeof(hostnm));
-	} else if (hostnamefmt(confd, fmt, hostnm, sizeof(hostnm)))
-		goto fallback;
+	if (!fmt)
+		fmt = strdup(nm);
+
+	if (hostnamefmt(confd, fmt, hostnm, sizeof(hostnm), domain, sizeof(domain))) {
+		err = SR_ERR_SYS;
+		goto err;
+	}
 
 	err = sethostname(hostnm, strlen(hostnm));
 	if (err) {
@@ -1678,6 +1691,11 @@ static int change_hostname(sr_session_ctx_t *session, uint32_t sub_id, const cha
 		goto err;
 	}
 
+	if (domain[0] && setdomainname(domain, strlen(domain))) {
+		ERROR("failed setting domain name");
+		/* Not cause for failing this function */
+	}
+
 	fp = fopen(_PATH_HOSTNAME, "w");
 	if (!fp) {
 		err = SR_ERR_INTERNAL;
@@ -1706,8 +1724,12 @@ static int change_hostname(sr_session_ctx_t *session, uint32_t sub_id, const cha
 	}
 
 	while (fgets(buf, sizeof(buf), fp)) {
-		if (!strncmp(buf, hostip, strlen(hostip)))
-			snprintf(buf, sizeof(buf), "%s\t%s\n", hostip, hostnm);
+		if (!strncmp(buf, hostip, strlen(hostip))) {
+			if (domain[0])
+				snprintf(buf, sizeof(buf), "%s\t%s.%s %s\n", hostip, hostnm, domain, hostnm);
+			else
+				snprintf(buf, sizeof(buf), "%s\t%s\n", hostip, hostnm);
+		}
 		fputs(buf, nfp);
 	}
 
diff --git a/src/confd/src/infix-containers.c b/src/confd/src/infix-containers.c
index 0724690c..9d26bc8a 100644
--- a/src/confd/src/infix-containers.c
+++ b/src/confd/src/infix-containers.c
@@ -67,7 +67,7 @@ static int add(const char *name, struct lyd_node *cif)
 	if ((string = lydx_get_cattr(cif, "hostname"))) {
 		char buf[65];
 
-		if (hostnamefmt(&confd, string, buf, sizeof(buf)))
+		if (hostnamefmt(&confd, string, buf, sizeof(buf), NULL, 0))
 			ERRNO("%s: failed setting custom hostname", name);
 		else
 			fprintf(fp, " --hostname %s", buf);
diff --git a/src/confd/yang/infix-system.yang b/src/confd/yang/infix-system.yang
index 393f4052..372606a9 100644
--- a/src/confd/yang/infix-system.yang
+++ b/src/confd/yang/infix-system.yang
@@ -237,7 +237,7 @@ module infix-system {
         + '|%[him]'
         + ')'
         + '([a-zA-Z0-9\-_\.]|%[him])*';
-      length "1..64";
+      length "1..128";
     }
     description "Linux have the same restrictions as IETF, only shorter.
                  Format specifiers are for, default hostname, ID, and the