posix: net: add kconfig option and inet_addr()

Add a Kconfig option for POSIX_NETWORKING and implement
inet_addr().

Signed-off-by: Chris Friedt <chrisfriedt@gmail.com>

Author: cfriedt

include/zephyr/posix/arpa/inet.h

@@ -32,6 +32,9 @@ static inline int inet_pton(sa_family_t family, const char *src, void *dst)
 
 #endif /* CONFIG_NET_SOCKETS_POSIX_NAMES */
 
+in_addr_t inet_addr(const char *cp);
+char *inet_ntoa(struct in_addr in);
+
 #ifdef __cplusplus
 }
 #endif

lib/posix/options/CMakeLists.txt

@@ -44,6 +44,7 @@ zephyr_library_sources_ifdef(CONFIG_POSIX_CONFSTR confstr.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_ENV env.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_FS fs.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MQUEUE mqueue.c)
+zephyr_library_sources_ifdef(CONFIG_POSIX_NETWORKING net.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_PUTMSG stropts.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_SIGNAL signal.c ${STRSIGNAL_TABLE_H})
 zephyr_library_sources_ifdef(CONFIG_POSIX_SYSCONF_IMPL_FULL sysconf.c)

lib/posix/options/Kconfig

@@ -37,6 +37,7 @@ rsource "Kconfig.getopt"
 rsource "Kconfig.key"
 rsource "Kconfig.mqueue"
 rsource "Kconfig.mutex"
+rsource "Kconfig.net"
 rsource "Kconfig.pthread"
 rsource "Kconfig.rwlock"
 rsource "Kconfig.sched"

lib/posix/options/Kconfig.net

@@ -0,0 +1,11 @@
+# Copyright (c) 2024, Friedt Professional Engineering Services, Inc
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config POSIX_NETWORKING
+	bool "POSIX Networking API"
+	default y if POSIX_API
+	depends on NETWORKING
+	help
+	  Enable this option to support the POSIX networking API. This includes
+	  support for BSD Sockets.

lib/posix/options/net.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2024, Friedt Professional Engineering Services, Inc
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <ctype.h>
+
+#include <zephyr/posix/arpa/inet.h>
+#include <zephyr/posix/netinet/in.h>
+
+in_addr_t inet_addr(const char *cp)
+{
+	int val = 0;
+	int len = 0;
+	int dots = 0;
+	int digits = 0;
+
+	/* error checking */
+	if (cp == NULL) {
+		return -1;
+	}
+
+	for (int i = 0, subdigits = 0; i <= INET_ADDRSTRLEN; ++i, ++len) {
+		if (subdigits > 3) {
+			return -1;
+		}
+		if (cp[i] == '\0') {
+			break;
+		} else if (cp[i] == '.') {
+			if (subdigits == 0) {
+				return -1;
+			}
+			++dots;
+			subdigits = 0;
+			continue;
+		} else if (isdigit((int)cp[i])) {
+			++digits;
+			++subdigits;
+			continue;
+		} else if (isspace((int)cp[i])) {
+			break;
+		}
+
+		return -1;
+	}
+
+	if (dots != 3 || digits < 4) {
+		return -1;
+	}
+
+	/* conversion */
+	for (int i = 0, tmp = 0; i < len; ++i, ++cp) {
+		if (*cp != '.') {
+			tmp *= 10;
+			tmp += *cp - '0';
+		}
+
+		if (*cp == '.' || i == len - 1) {
+			val <<= 8;
+			val |= tmp;
+			tmp = 0;
+		}
+	}
+
+	return htonl(val);
+}