add osmo_sockaddr_to_str_c(), osmo_sockaddr_to_str_buf2()

To easily log and print a sockaddr using OTC_SELECT, add
osmo_sockaddr_to_str_c().

Implement osmo_sockaddr_to_str_buf2() using osmo_strbuf, so that we can
return the chars_needed which osmo_sockaddr_to_str_c() uses.

From previous osmo_sockaddr_to_str_buf(), call
osmo_sockaddr_to_str_buf2() and return NULL if the buf_len was
insufficient, to mimick previous behavior. This makes it more
consistently returning NULL for insufficient buf_len, as shown in the
tweak that is needed in socket_test.c. Before osmo_sockaddr_to_str_buf()
would return a truncated port number, now it's all or NULL.

I will use osmo_sockaddr_to_str_c() in the new osmo-upf implementation.

Related: SYS#5599
Change-Id: I12771bf8a021e6785217b1faad03c09ec1cfef0e

1 files changed, 44 insertions, 28 deletions

diff --git a/src/socket.c b/src/socket.c
index 449c8258..0ffa11d4 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -1776,52 +1776,68 @@ const char *osmo_sockaddr_to_str(const struct osmo_sockaddr *sockaddr)
 	return osmo_sockaddr_to_str_buf(buf, sizeof(buf), sockaddr);
 }
 
-/*! string-format a given osmo_sockaddr address into a user-supplied buffer
+/*! string-format a given osmo_sockaddr address into a user-supplied buffer.
+ * Same as osmo_sockaddr_to_str_buf() but returns a would-be length in snprintf() style.
  *  \param[in] buf user-supplied output buffer
  *  \param[in] buf_len size of the user-supplied output buffer in bytes
  *  \param[in] sockaddr the osmo_sockaddr to print
- *  \return pointer to the string on success; NULL on error
+ *  \return number of characters that would be written if the buffer is large enough, like snprintf().
  */
-char *osmo_sockaddr_to_str_buf(char *buf, size_t buf_len,
-			    const struct osmo_sockaddr *sockaddr)
+int osmo_sockaddr_to_str_buf2(char *buf, size_t buf_len, const struct osmo_sockaddr *sockaddr)
 {
+	struct osmo_strbuf sb = { .buf = buf, .len = buf_len };
 	uint16_t port = 0;
-	size_t written;
-	if (buf_len < 5)
-		return NULL;
 
-	if (!sockaddr)
-		return NULL;
+	if (!sockaddr) {
+		OSMO_STRBUF_PRINTF(sb, "NULL");
+		return sb.chars_needed;
+	}
 
 	switch (sockaddr->u.sa.sa_family) {
 	case AF_INET:
-		written = osmo_sockaddr_to_str_and_uint(buf, buf_len, &port, &sockaddr->u.sa);
-		if (written + 1 >= buf_len && port)
-			return NULL;
+		OSMO_STRBUF_APPEND(sb, osmo_sockaddr_to_str_and_uint, &port, &sockaddr->u.sa);
 		if (port)
-			snprintf(buf + written, buf_len - written, ":%u", port);
+			OSMO_STRBUF_PRINTF(sb, ":%u", port);
 		break;
 	case AF_INET6:
-		buf[0] = '[';
-		written = osmo_sockaddr_to_str_and_uint(buf + 1, buf_len - 1, &port, &sockaddr->u.sa);
-		if (written + 2 >= buf_len)
-			return NULL;
-
-		if (written + 3 >= buf_len && port)
-			return NULL;
-
+		OSMO_STRBUF_PRINTF(sb, "[");
+		OSMO_STRBUF_APPEND(sb, osmo_sockaddr_to_str_and_uint, &port, &sockaddr->u.sa);
+		OSMO_STRBUF_PRINTF(sb, "]");
 		if (port)
-			snprintf(buf + 1 + written, buf_len - written - 1, "]:%u", port);
-		else {
-			buf[written + 1] = ']';
-			buf[written + 2] = 0;
-		}
+			OSMO_STRBUF_PRINTF(sb, ":%u", port);
 		break;
 	default:
-		snprintf(buf, buf_len, "unsupported family %d", sockaddr->u.sa.sa_family);
-		return buf;
+		OSMO_STRBUF_PRINTF(sb, "unsupported family %d", sockaddr->u.sa.sa_family);
+		break;
 	}
 
+	return sb.chars_needed;
+}
+
+/*! string-format a given osmo_sockaddr address into a talloc allocated buffer.
+ * Like osmo_sockaddr_to_str_buf2() but returns a talloc allocated string.
+ *  \param[in] ctx  talloc context to allocate from, e.g. OTC_SELECT.
+ *  \param[in] sockaddr  the osmo_sockaddr to print.
+ *  \return human readable string.
+ */
+char *osmo_sockaddr_to_str_c(void *ctx, const struct osmo_sockaddr *sockaddr)
+{
+	OSMO_NAME_C_IMPL(ctx, 64, "ERROR", osmo_sockaddr_to_str_buf2, sockaddr)
+}
+
+/*! string-format a given osmo_sockaddr address into a user-supplied buffer.
+ * Like osmo_sockaddr_to_str_buf2() but returns buf, or NULL if too short.
+ *  \param[in] buf user-supplied output buffer
+ *  \param[in] buf_len size of the user-supplied output buffer in bytes
+ *  \param[in] sockaddr the osmo_sockaddr to print
+ *  \return pointer to the string on success; NULL on error
+ */
+char *osmo_sockaddr_to_str_buf(char *buf, size_t buf_len,
+			    const struct osmo_sockaddr *sockaddr)
+{
+	int chars_needed = osmo_sockaddr_to_str_buf2(buf, buf_len, sockaddr);
+	if (chars_needed >= buf_len)
+		return NULL;
 	return buf;
 }