LibC: Implement {get,free}ifaddrs

userspace/libraries/LibC/ifaddrs.cpp

@@ -1,15 +1,148 @@
+#include <dirent.h>
+#include <fcntl.h>
 #include <ifaddrs.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
 
-#include <BAN/Assert.h>
+static int selector(const dirent* dirent)
+{
+	if (strcmp(dirent->d_name, "lo") == 0)
+		return 1;
+	if (strncmp(dirent->d_name, "eth", 3) == 0)
+		return 1;
+	return 0;
+}
+
+static int comparator(const dirent** d1, const dirent** d2)
+{
+	if (strcmp((*d1)->d_name, "lo"))
+		return -1;
+	if (strcmp((*d2)->d_name, "lo"))
+		return +1;
+	return alphasort(d1, d2);
+}
+
+static void free_ifaddrs(ifaddrs* ifa)
+{
+	if (ifa->ifa_name)
+		free(ifa->ifa_name);
+	if (ifa->ifa_addr)
+		free(ifa->ifa_addr);
+	if (ifa->ifa_netmask)
+		free(ifa->ifa_netmask);
+	if (ifa->ifa_ifu.ifu_broadaddr)
+		free(ifa->ifa_ifu.ifu_broadaddr);
+	if (ifa->ifa_data)
+		free(ifa->ifa_data);
+	free(ifa);
+}
+
+static sockaddr* dup_sockaddr(const sockaddr* saddr)
+{
+	size_t size;
+	switch (saddr->sa_family)
+	{
+		case AF_INET:
+			size = sizeof(sockaddr_in);
+			break;
+		case AF_INET6:
+			size = sizeof(sockaddr_in6);
+			break;
+		default:
+			return nullptr;
+	}
+
+	sockaddr* result = static_cast<sockaddr*>(malloc(size));
+	if (result == nullptr)
+		return nullptr;
+	memcpy(result, saddr, size);
+	return result;
+}
+
+static ifaddrs* open_ifaddrs(const char* path)
+{
+	int fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return nullptr;
+
+	ifaddrs* ifa = static_cast<ifaddrs*>(calloc(1, sizeof(ifaddrs)));
+	if (ifa == nullptr)
+		goto open_ifaddrs_error;
+
+	ifreq ifreq;
+
+	if (ioctl(fd, SIOCGIFNAME, &ifreq) == -1)
+		goto open_ifaddrs_error;
+	ifa->ifa_name = strdup(ifreq.ifr_name);
+	if (ifa->ifa_name == nullptr)
+		goto open_ifaddrs_error;
+
+	if (ioctl(fd, SIOCGIFFLAGS, &ifreq) == -1)
+		goto open_ifaddrs_error;
+	ifa->ifa_flags = ifreq.ifr_flags;
+
+	if (ioctl(fd, SIOCGIFADDR, &ifreq) == -1)
+		goto open_ifaddrs_error;
+	ifa->ifa_addr = dup_sockaddr(&ifreq.ifr_addr);
+	if (ifa->ifa_addr == nullptr)
+		goto open_ifaddrs_error;
+
+	if (ioctl(fd, SIOCGIFNETMASK, &ifreq) == -1)
+		goto open_ifaddrs_error;
+	ifa->ifa_netmask = dup_sockaddr(&ifreq.ifr_netmask);
+	if (ifa->ifa_netmask == nullptr)
+		goto open_ifaddrs_error;
+
+	// TODO: broadcast/point-to-point
+
+	close(fd);
+	return ifa;
+
+open_ifaddrs_error:
+	if (ifa != nullptr)
+		free_ifaddrs(ifa);
+	close(fd);
+	return nullptr;
+}
 
 int getifaddrs(struct ifaddrs** ifap)
 {
-	(void)ifap;
-	ASSERT_NOT_REACHED();
+	dirent** namelist;
+
+	const int count = scandir("/dev", &namelist, selector, comparator);
+	if (count == -1)
+		return -1;
+
+	*ifap = nullptr;
+
+	for (int i = 0; i < count; i++)
+	{
+		char path[5 + sizeof(namelist[i]->d_name)];
+		sprintf(path, "/dev/%s", namelist[i]->d_name);
+
+		ifaddrs* ifa = open_ifaddrs(path);
+		if (ifa == nullptr)
+			continue;
+		*ifap = ifa;
+		ifap = &ifa->ifa_next;
+	}
+
+	for (int i = 0; i < count; i++)
+		free(namelist[i]);
+	free(namelist);
+
+	return 0;
 }
 
-void freeifaddrs(struct ifaddrs*  ifa)
+void freeifaddrs(struct ifaddrs* ifa)
 {
-	(void)ifa;
-	ASSERT_NOT_REACHED();
+	while (ifa)
+	{
+		auto* next = ifa->ifa_next;
+		free_ifaddrs(ifa);
+		ifa = next;
+	}
 }