net: socketutils: Add utils to manipulate network address strings

Two utils to manipulate addresses in format "addr[:port]". I.e.,
network address (domain name or numeric), optionally followed by
port number:

* net_addr_str_find_port(), to return pointer to port number
substring (or NULL if not present).
* net_getaddrinfo_addr_str(), which is effectively getaddrinfo()
wrapper taking a "addr[:port]" string as a parameter.

The header file is named socketutils.h to emphasize that these
utility functions are implemented on top of BSD Sockets API
(and other POSIX/ANSI C functions), and thus portable to other
POSIX systems (e.g., Linux), so can be used in apps testing
POSIX compatibility. More utility functions (beyond address
manipulation) can be added later.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>

include/net/socketutils.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2019 Linaro Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @brief Find port in addr:port string.
+ *
+ * @param addr_str String of addr[:port] format
+ *
+ * @return Pointer to "port" part, or NULL is none.
+ */
+const char *net_addr_str_find_port(const char *addr_str);
+
+/**
+ * @brief Call getaddrinfo() on addr:port string
+ *
+ * Convenience function to split addr[:port] string into address vs port
+ * components (or use default port number), and call getaddrinfo() on the
+ * result.
+ *
+ * @param addr_str String of addr[:port] format
+ * @param def_port Default port number to use if addr_str doesn't contain it
+ * @param hints getaddrinfo() hints
+ * @param res Result of getaddrinfo() (freeaddrinfo() should be called on it
+ *            as usual.
+ *
+ * @return Result of getaddrinfo() call.
+ */
+int net_getaddrinfo_addr_str(const char *addr_str, const char *def_port,
+			     const struct addrinfo *hints,
+			     struct addrinfo **res);

subsys/net/lib/CMakeLists.txt

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 
+add_subdirectory(utils)
 add_subdirectory_if_kconfig(coap)
 add_subdirectory_if_kconfig(lwm2m)
 add_subdirectory_if_kconfig(socks)

subsys/net/lib/utils/CMakeLists.txt

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_sources(
+  addr_utils.c
+)

subsys/net/lib/utils/addr_utils.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2019 Linaro Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <net/socket.h>
+
+/* These utility functions are intended to be on top of POSIX API, and don't
+ * make sense if it's not available.
+ */
+#ifdef CONFIG_NET_SOCKETS_POSIX_NAMES
+
+const char *net_addr_str_find_port(const char *addr_str)
+{
+	const char *p = strrchr(addr_str, ':');
+
+	if (p == NULL) {
+		return NULL;
+	}
+
+	/* If it's not IPv6 numeric notation, we guaranteedly got a port */
+	if (*addr_str != '[') {
+		return p + 1;
+	}
+
+	/* IPv6 numeric address, and ':' preceeded by ']' */
+	if (p[-1] == ']') {
+		return p + 1;
+	}
+
+	/* Otherwise, just raw IPv6 address, ':' is component separator */
+	return NULL;
+}
+
+int net_getaddrinfo_addr_str(const char *addr_str, const char *def_port,
+			     const struct addrinfo *hints,
+			     struct addrinfo **res)
+{
+	const char *port;
+	char host[NI_MAXHOST];
+
+	if (addr_str == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	port  = net_addr_str_find_port(addr_str);
+
+	if (port == NULL) {
+		port = def_port;
+	} else {
+		int host_len = port - addr_str - 1;
+
+		if (host_len > sizeof(host) - 1) {
+			errno = EINVAL;
+			return -1;
+		}
+		strncpy(host, addr_str, host_len + 1);
+		host[host_len] = '\0';
+		addr_str = host;
+	}
+
+	return getaddrinfo(addr_str, port, hints, res);
+}
+
+#endif