네트워크 인터페이스의 IP 주소와 넷마스크를 얻는 함수

김태훈
1 parent 6cb3e01888
Showing 2 changed files with 125 additions and 0 deletions Show diff stats
c/inet.c
c/inet.h
@@ -0,0 +1,110 @@
+#include <netdb.h>
+#include <string.h>
+#include <ifaddrs.h>
+
+#include "inet.h"
+
+static struct sockaddr *find_address_of(char *name, struct ifaddrs *from)
+{
+    struct ifaddrs *ifa;
+    int n;
+    for (ifa = from, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
+        if (strcmp(ifa->ifa_name, name)) {
+            continue;
+        }
+
+        if (ifa->ifa_addr == NULL) {
+            continue;
+        }
+
+        int family = ifa->ifa_addr->sa_family;
+        if (family == AF_INET || family == AF_INET6) {
+            return ifa->ifa_addr;
+        }
+    }
+
+    return NULL;
+}
+
+static struct sockaddr *find_netmask_of(char *name, struct ifaddrs *from)
+{
+    struct ifaddrs *ifa;
+    int n;
+    for (ifa = from, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
+        if (strcmp(ifa->ifa_name, name)) {
+            continue;
+        }
+
+        if (ifa->ifa_netmask == NULL) {
+            continue;
+        }
+
+        int family = ifa->ifa_netmask->sa_family;
+        if (family == AF_INET || family == AF_INET6) {
+            return ifa->ifa_netmask;
+        }
+    }
+
+    return NULL;
+}
+
+static int address_to_string(struct sockaddr *addr, char *buffer, int size)
+{
+    return getnameinfo(addr,
+        (addr->sa_family == AF_INET)
+            ? sizeof(struct sockaddr_in)
+            : sizeof(struct sockaddr_in6),
+        buffer, size,
+        NULL, 0,
+        NI_NUMERICHOST);
+}
+
+int get_ip_addr(char *p_ip, int sz_ip)
+{
+    struct ifaddrs *ifaddr;
+    if (getifaddrs(&ifaddr) == -1) {
+        return -1;
+    }
+
+    struct sockaddr *address = find_address_of(IFNAME, ifaddr);
+    if (address == NULL) {
+        goto ERROR;
+    }
+
+    int ret = address_to_string(address, p_ip, sz_ip);
+    if (ret != 0) {
+        goto ERROR;
+    }
+
+    freeifaddrs(ifaddr);
+    return 0;
+
+ERROR:
+    freeifaddrs(ifaddr);
+    return -1;
+}
+
+int get_netmask(char *p_netmask, int sz_netmask)
+{
+    struct ifaddrs *ifaddr;
+    if (getifaddrs(&ifaddr) == -1) {
+        return -1;
+    }
+
+    struct sockaddr *netmask = find_netmask_of(IFNAME, ifaddr);
+    if (netmask == NULL) {
+        goto ERROR;
+    }
+
+    int ret = address_to_string(netmask, p_netmask, sz_netmask);
+    if (ret != 0) {
+        goto ERROR;
+    }
+
+    freeifaddrs(ifaddr);
+    return 0;
+
+ERROR:
+    freeifaddrs(ifaddr);
+    return -1;
+}
@@ -0,0 +1,15 @@
+#ifndef INET_H
+#define INET_H
+
+// 인터페이스 이름
+#define IFNAME "eth0"
+
+// p_ip:    ip를 받는 버퍼
+// sz_ip:   버퍼 크기
+int get_ip_addr(char *p_ip, int sz_ip);
+
+// p_netmask:   넷마스크를 받는 버퍼
+// sz_netmask:  버퍼 크기
+int get_netmask(char *p_netmask, int sz_netmask);
+
+#endif /* INET_H */
@@ -0,0 +1,110 @@		@@ -0,0 +1,110 @@
	1	+#include <netdb.h>
	2	+#include <string.h>
	3	+#include <ifaddrs.h>
	4	+
	5	+#include "inet.h"
	6	+
	7	+static struct sockaddr find_address_of(char name, struct ifaddrs *from)
	8	+{
	9	+ struct ifaddrs *ifa;
	10	+ int n;
	11	+ for (ifa = from, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
	12	+ if (strcmp(ifa->ifa_name, name)) {
	13	+ continue;
	14	+ }
	15	+
	16	+ if (ifa->ifa_addr == NULL) {
	17	+ continue;
	18	+ }
	19	+
	20	+ int family = ifa->ifa_addr->sa_family;
	21	+ if (family == AF_INET \|\| family == AF_INET6) {
	22	+ return ifa->ifa_addr;
	23	+ }
	24	+ }
	25	+
	26	+ return NULL;
	27	+}
	28	+
	29	+static struct sockaddr find_netmask_of(char name, struct ifaddrs *from)
	30	+{
	31	+ struct ifaddrs *ifa;
	32	+ int n;
	33	+ for (ifa = from, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
	34	+ if (strcmp(ifa->ifa_name, name)) {
	35	+ continue;
	36	+ }
	37	+
	38	+ if (ifa->ifa_netmask == NULL) {
	39	+ continue;
	40	+ }
	41	+
	42	+ int family = ifa->ifa_netmask->sa_family;
	43	+ if (family == AF_INET \|\| family == AF_INET6) {
	44	+ return ifa->ifa_netmask;
	45	+ }
	46	+ }
	47	+
	48	+ return NULL;
	49	+}
	50	+
	51	+static int address_to_string(struct sockaddr addr, char buffer, int size)
	52	+{
	53	+ return getnameinfo(addr,
	54	+ (addr->sa_family == AF_INET)
	55	+ ? sizeof(struct sockaddr_in)
	56	+ : sizeof(struct sockaddr_in6),
	57	+ buffer, size,
	58	+ NULL, 0,
	59	+ NI_NUMERICHOST);
	60	+}
	61	+
	62	+int get_ip_addr(char *p_ip, int sz_ip)
	63	+{
	64	+ struct ifaddrs *ifaddr;
	65	+ if (getifaddrs(&ifaddr) == -1) {
	66	+ return -1;
	67	+ }
	68	+
	69	+ struct sockaddr *address = find_address_of(IFNAME, ifaddr);
	70	+ if (address == NULL) {
	71	+ goto ERROR;
	72	+ }
	73	+
	74	+ int ret = address_to_string(address, p_ip, sz_ip);
	75	+ if (ret != 0) {
	76	+ goto ERROR;
	77	+ }
	78	+
	79	+ freeifaddrs(ifaddr);
	80	+ return 0;
	81	+
	82	+ERROR:
	83	+ freeifaddrs(ifaddr);
	84	+ return -1;
	85	+}
	86	+
	87	+int get_netmask(char *p_netmask, int sz_netmask)
	88	+{
	89	+ struct ifaddrs *ifaddr;
	90	+ if (getifaddrs(&ifaddr) == -1) {
	91	+ return -1;
	92	+ }
	93	+
	94	+ struct sockaddr *netmask = find_netmask_of(IFNAME, ifaddr);
	95	+ if (netmask == NULL) {
	96	+ goto ERROR;
	97	+ }
	98	+
	99	+ int ret = address_to_string(netmask, p_netmask, sz_netmask);
	100	+ if (ret != 0) {
	101	+ goto ERROR;
	102	+ }
	103	+
	104	+ freeifaddrs(ifaddr);
	105	+ return 0;
	106	+
	107	+ERROR:
	108	+ freeifaddrs(ifaddr);
	109	+ return -1;
	110	+}
@@ -0,0 +1,15 @@		@@ -0,0 +1,15 @@
	1	+#ifndef INET_H
	2	+#define INET_H
	3	+
	4	+// 인터페이스 이름
	5	+#define IFNAME "eth0"
	6	+
	7	+// p_ip: ip를 받는 버퍼
	8	+// sz_ip: 버퍼 크기
	9	+int get_ip_addr(char *p_ip, int sz_ip);
	10	+
	11	+// p_netmask: 넷마스크를 받는 버퍼
	12	+// sz_netmask: 버퍼 크기
	13	+int get_netmask(char *p_netmask, int sz_netmask);
	14	+
	15	+#endif /* INET_H */