lib: add %*pHX + %*pHS hexdump in printfrr

(I'll get to `zlog_hexdump()` in a separate pass.)

Signed-off-by: David Lamparter <equinox@diac24.net>

doc/developer/logging.rst

@@ -91,6 +91,8 @@ Extensions
 +-----------+--------------------------+----------------------------------------------+
 | ``%pFX``  | ``struct bgp_dest *``    | ``fe80::1234/64`` (available in BGP only)    |
 +-----------+--------------------------+----------------------------------------------+
+| ``%.*pHX``| ``int len, void *ptr``   | ``12 34 56 78`` (hexdump)                    |
++-----------+--------------------------+----------------------------------------------+
 
 Printf features like field lengths can be used normally with these extensions,
 e.g. ``%-15pI4`` works correctly.

lib/printfrr.h

@@ -227,7 +227,11 @@ void printfrr_ext_reg(const struct printfrr_ext *);
 	}                                                                      \
 	/* end */
 
-/* fbuf helper functions */
+/* fbuf helper functions - note all 3 of these return the length that would
+ * be written regardless of how much space was available in the buffer, as
+ * needed for implementing printfrr extensions.  (They also accept NULL buf
+ * for that.)
+ */
 
 static inline ssize_t bputs(struct fbuf *buf, const char *str)
 {
@@ -251,6 +255,17 @@ static inline ssize_t bputch(struct fbuf *buf, char ch)
 	return 1;
 }
 
+static inline ssize_t bputhex(struct fbuf *buf, uint8_t val)
+{
+	static const char hexch[] = "0123456789abcdef";
+
+	if (buf && buf->pos < buf->buf + buf->len)
+		*buf->pos++ = hexch[(val >> 4) & 0xf];
+	if (buf && buf->pos < buf->buf + buf->len)
+		*buf->pos++ = hexch[val & 0xf];
+	return 2;
+}
+
 /* %pVA extension, equivalent to Linux kernel %pV */
 
 struct va_format {
@@ -261,6 +276,13 @@ struct va_format {
 #ifdef _FRR_ATTRIBUTE_PRINTFRR
 #pragma FRR printfrr_ext "%pFB" (struct fbuf *)
 #pragma FRR printfrr_ext "%pVA" (struct va_format *)
+
+#pragma FRR printfrr_ext "%pHX" (signed char *)
+#pragma FRR printfrr_ext "%pHX" (unsigned char *)
+#pragma FRR printfrr_ext "%pHX" (void *)
+#pragma FRR printfrr_ext "%pHS" (signed char *)
+#pragma FRR printfrr_ext "%pHS" (unsigned char *)
+#pragma FRR printfrr_ext "%pHS" (void *)
 #endif
 
 /* when using non-ISO-C compatible extension specifiers... */

lib/strformat.c

@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2019  David Lamparter, for NetDEF, Inc.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <string.h>
+
+#include "printfrr.h"
+
+printfrr_ext_autoreg_p("HX", printfrr_hexdump)
+static ssize_t printfrr_hexdump(struct fbuf *buf, struct printfrr_eargs *ea,
+				const void *ptr)
+{
+	ssize_t ret = 0;
+	ssize_t input_len = printfrr_ext_len(ea);
+	char sep = ' ';
+	const uint8_t *pos, *end;
+
+	if (ea->fmt[0] == 'c') {
+		ea->fmt++;
+		sep = ':';
+	} else if (ea->fmt[0] == 'n') {
+		ea->fmt++;
+		sep = '\0';
+	}
+
+	if (input_len < 0)
+		return 0;
+
+	for (pos = ptr, end = pos + input_len; pos < end; pos++) {
+		if (sep && pos != ptr)
+			ret += bputch(buf, sep);
+		ret += bputhex(buf, *pos);
+	}
+
+	return ret;
+}
+
+/* string analog for hexdumps / the "this." in ("74 68 69 73 0a  |this.|") */
+
+printfrr_ext_autoreg_p("HS", printfrr_hexdstr)
+static ssize_t printfrr_hexdstr(struct fbuf *buf, struct printfrr_eargs *ea,
+				const void *ptr)
+{
+	ssize_t ret = 0;
+	ssize_t input_len = printfrr_ext_len(ea);
+	const uint8_t *pos, *end;
+
+	if (input_len < 0)
+		return 0;
+
+	for (pos = ptr, end = pos + input_len; pos < end; pos++) {
+		if (*pos >= 0x20 && *pos < 0x7f)
+			ret += bputch(buf, *pos);
+		else
+			ret += bputch(buf, '.');
+	}
+
+	return ret;
+}

lib/subdir.am

@@ -90,6 +90,7 @@ lib_libfrr_la_SOURCES = \
 	lib/spf_backoff.c \
 	lib/srcdest_table.c \
 	lib/stream.c \
+	lib/strformat.c \
 	lib/strlcat.c \
 	lib/strlcpy.c \
 	lib/systemd.c \

tests/lib/test_printfrr.c

@@ -216,5 +216,15 @@ int main(int argc, char **argv)
 	sg.src.s_addr = INADDR_ANY;
 	printchk("(*,224.1.2.3)", "%pSG4", &sg);
 
+	uint8_t randhex[] = { 0x12, 0x34, 0x00, 0xca, 0xfe, 0x00, 0xaa, 0x55 };
+
+	printchk("12 34 00 ca fe 00 aa 55", "%.8pHX", randhex);
+	printchk("12 34 00 ca fe 00 aa 55", "%.*pHX",
+		 (int)sizeof(randhex), randhex);
+	printchk("12 34 00 ca", "%.4pHX", randhex);
+
+	printchk("12:34:00:ca:fe:00:aa:55", "%.8pHXc", randhex);
+	printchk("123400cafe00aa55", "%.8pHXn", randhex);
+
 	return !!errors;
 }