lib: add `%pFXh` to print prefix w/o prefixlen

Mostly for pimd, for the time being.  May be removed again if unused.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

3 files changed, 56 insertions, 3 deletions

diff --git a/doc/developer/logging.rst b/doc/developer/logging.rst
index 4e6fc04206..7046361204 100644
--- a/doc/developer/logging.rst
+++ b/doc/developer/logging.rst
@@ -163,6 +163,10 @@ Networking data types
    - :c:union:`prefixptr` (dereference to get :c:struct:`prefix`)
    - :c:union:`prefixconstptr` (dereference to get :c:struct:`prefix`)
 
+   Options:
+
+   ``%pFXh``: (address only) :frrfmtout:`1.2.3.0` / :frrfmtout:`fe80::1234`
+
 .. frrfmt:: %pPSG4 (struct prefix_sg *)
 
    :frrfmtout:`(*,1.2.3.4)`
diff --git a/lib/prefix.c b/lib/prefix.c
index 90ab48a13b..89c5be8f38 100644
--- a/lib/prefix.c
+++ b/lib/prefix.c
@@ -1071,6 +1071,26 @@ const char *prefix2str(union prefixconstptr pu, char *str, int size)
 	return str;
 }
 
+static ssize_t prefixhost2str(struct fbuf *fbuf, union prefixconstptr pu)
+{
+	const struct prefix *p = pu.p;
+	char buf[PREFIX2STR_BUFFER];
+
+	switch (p->family) {
+	case AF_INET:
+	case AF_INET6:
+		inet_ntop(p->family, &p->u.prefix, buf, sizeof(buf));
+		return bputs(fbuf, buf);
+
+	case AF_ETHERNET:
+		prefix_mac2str(&p->u.prefix_eth, buf, sizeof(buf));
+		return bputs(fbuf, buf);
+
+	default:
+		return bprintfrr(fbuf, "{prefix.af=%dPF}", p->family);
+	}
+}
+
 void prefix_mcast_inet4_dump(const char *onfail, struct in_addr addr,
 		char *buf, int buf_size)
 {
@@ -1458,13 +1478,24 @@ printfrr_ext_autoreg_p("FX", printfrr_pfx);
 static ssize_t printfrr_pfx(struct fbuf *buf, struct printfrr_eargs *ea,
 			    const void *ptr)
 {
-	char cbuf[PREFIX_STRLEN];
+	bool host_only = false;
+
+	if (ea->fmt[0] == 'h') {
+		ea->fmt++;
+		host_only = true;
+	}
 
 	if (!ptr)
 		return bputs(buf, "(null)");
 
-	prefix2str(ptr, cbuf, sizeof(cbuf));
-	return bputs(buf, cbuf);
+	if (host_only)
+		return prefixhost2str(buf, (struct prefix *)ptr);
+	else {
+		char cbuf[PREFIX_STRLEN];
+
+		prefix2str(ptr, cbuf, sizeof(cbuf));
+		return bputs(buf, cbuf);
+	}
 }
 
 printfrr_ext_autoreg_p("PSG4", printfrr_psg);
diff --git a/tests/lib/test_printfrr.c b/tests/lib/test_printfrr.c
index 8f9d637afd..59d08ae82b 100644
--- a/tests/lib/test_printfrr.c
+++ b/tests/lib/test_printfrr.c
@@ -207,6 +207,24 @@ int main(int argc, char **argv)
 	assert(strcmp(p, "test#5") == 0);
 	XFREE(MTYPE_TMP, p);
 
+	struct prefix pfx;
+
+	str2prefix("192.168.1.23/24", &pfx);
+	printchk("192.168.1.23/24", "%pFX", &pfx);
+	printchk("192.168.1.23", "%pFXh", &pfx);
+
+	str2prefix("2001:db8::1234/64", &pfx);
+	printchk("2001:db8::1234/64", "%pFX", &pfx);
+	printchk("2001:db8::1234", "%pFXh", &pfx);
+
+	pfx.family = AF_UNIX;
+	printchk("UNK prefix", "%pFX", &pfx);
+	printchk("{prefix.af=AF_UNIX}", "%pFXh", &pfx);
+
+	str2prefix_eth("02:ca:fe:f0:0d:1e/48", (struct prefix_eth *)&pfx);
+	printchk("02:ca:fe:f0:0d:1e/48", "%pFX", &pfx);
+	printchk("02:ca:fe:f0:0d:1e", "%pFXh", &pfx);
+
 	struct prefix_sg sg;
 	sg.src.s_addr = INADDR_ANY;
 	sg.grp.s_addr = INADDR_ANY;