Check if ip address is valid for given interface

ethsock.c

@@ -28,6 +28,7 @@
 
 struct ethsock
 {
+	const char *intf;
 	pcap_t *pcap;
 #ifndef NMRPFLASH_WINDOWS
 	int fd;
@@ -276,7 +277,8 @@ struct ethsock *ethsock_create(const char *intf, uint16_t protocol)
 
 	buf[0] = '\0';
 
-	sock->pcap = pcap_open_live(intf, BUFSIZ, 1, 1, buf);
+	sock->intf = intf;
+	sock->pcap = pcap_open_live(sock->intf, BUFSIZ, 1, 1, buf);
 	if (!sock->pcap) {
 		fprintf(stderr, "%s.\n", buf);
 		goto cleanup_malloc;
@@ -541,3 +543,35 @@ int ethsock_list_all(void)
 
 	return 0;
 }
+
+int ethsock_is_same_subnet(struct ethsock *sock, struct in_addr *ipaddr,
+		struct in_addr *ipmask)
+{
+	pcap_if_t *devs, *dev;
+	pcap_addr_t *addr;
+	uint32_t ip, mask, net;
+
+	if (x_pcap_findalldevs(&devs) != 0) {
+		return -1;
+	}
+
+	net = ipaddr->s_addr & ipmask->s_addr;
+
+	for (dev = devs; dev; dev = dev->next) {
+		if (strcmp(sock->intf, dev->name)) {
+			continue;
+		}
+
+		for (addr = dev->addresses; addr; addr = addr->next) {
+			if (addr->addr->sa_family == AF_INET) {
+				ip = ((struct sockaddr_in*)addr->addr)->sin_addr.s_addr;
+				mask = ((struct sockaddr_in*)addr->netmask)->sin_addr.s_addr;
+				if ((ip & mask) == net) {
+					return 1;
+				}
+			}
+		}
+	}
+
+	return 0;
+}

nmrp.c

@@ -287,7 +287,7 @@ int nmrp_do(struct nmrpd_args *args)
 	char *filename;
 	struct in_addr ipaddr, ipmask;
 	time_t beg;
-	int i, err, ulreqs, expect;
+	int i, status, ulreqs, expect;
 	struct ethsock *sock;
 	void (*sigh_orig)(int);
 
@@ -324,13 +324,22 @@ int nmrp_do(struct nmrpd_args *args)
 		}
 	}
 
-	err = 1;
+	status = 1;
 
 	sock = ethsock_create(args->intf, ETH_P_NMRP);
 	if (!sock) {
 		return 1;
 	}
 
+	status = ethsock_is_same_subnet(sock, &ipaddr, &ipmask);
+	if (status <= 0) {
+		if (!status) {
+			fprintf(stderr, "Address %s/%s invalid for interface %s.\n",
+					args->ipaddr, args->ipmask, args->intf);
+		}
+		return 1;
+	}
+
 	gsock = sock;
 	sigh_orig = signal(SIGINT, sigh);
 
@@ -375,10 +384,10 @@ int nmrp_do(struct nmrpd_args *args)
 			goto out;
 		}
 
-		err = pkt_recv(sock, &rx);
+		status = pkt_recv(sock, &rx);
-		if (err == 0 && memcmp(rx.eh.ether_dhost, src, 6) == 0) {
+		if (status == 0 && memcmp(rx.eh.ether_dhost, src, 6) == 0) {
 			break;
-		} else if (err == 1) {
+		} else if (status == 1) {
 			printf("ERR\n");
 			goto out;
 		} else {
@@ -406,13 +415,13 @@ int nmrp_do(struct nmrpd_args *args)
 		tx.msg.num_opts = 0;
 		tx.msg.len = 0;
 
-		err = 1;
+		status = 1;
 
 		switch (rx.msg.code) {
 			case NMRP_C_ADVERTISE:
 				printf("Received NMRP advertisement from %s.\n",
 						mac_to_str(rx.eh.ether_shost));
-				err = 1;
+				status = 1;
 				goto out;
 			case NMRP_C_CONF_REQ:
 				tx.msg.code = NMRP_C_CONF_ACK;
@@ -471,20 +480,20 @@ int nmrp_do(struct nmrpd_args *args)
 					printf("Received upload request with empty filename.");
 				}
 
-				err = 0;
+				status = 0;
 
 				if (args->tftpcmd) {
 					printf("Executing '%s' ... ", args->tftpcmd);
 					fflush(stdout);
-					err = system(args->tftpcmd);
+					status = system(args->tftpcmd);
-					if (!err) {
+					if (!status) {
 						printf("OK\n");
 					} else {
 						printf("ERR\n");
 					}
 				}
 
-				if (!err && args->file_local) {
+				if (!status && args->file_local) {
 					if (verbosity) {
 						printf("Using remote filename '%s'.\n",
 								args->file_remote);
@@ -496,14 +505,14 @@ int nmrp_do(struct nmrpd_args *args)
 						printf("Uploading %s ... ", args->file_local);
 					}
 					fflush(stdout);
-					err = tftp_put(args);
+					status = tftp_put(args);
 				}
 
-				if (!err) {
+				if (!status) {
 					printf("OK\nWaiting for remote to respond.\n");
 					ethsock_set_timeout(sock, args->ul_timeout);
 					expect = NMRP_C_CLOSE_REQ;
-				} else if (err == -2) {
+				} else if (status == -2) {
 					expect = NMRP_C_TFTP_UL_REQ;
 				} else {
 					goto out;
@@ -517,7 +526,7 @@ int nmrp_do(struct nmrpd_args *args)
 				tx.msg.code = NMRP_C_CLOSE_ACK;
 				break;
 			case NMRP_C_CLOSE_ACK:
-				err = 0;
+				status = 0;
 				goto out;
 			default:
 				fprintf(stderr, "Unknown message code 0x%02x!\n",
@@ -540,9 +549,9 @@ int nmrp_do(struct nmrpd_args *args)
 			break;
 		}
 
-		err = pkt_recv(sock, &rx);
+		status = pkt_recv(sock, &rx);
-		if (err) {
+		if (status) {
-			if (err == 2) {
+			if (status == 2) {
 				fprintf(stderr, "Timeout while waiting for 0x%02x.\n", expect);
 			}
 			goto out;
@@ -552,7 +561,7 @@ int nmrp_do(struct nmrpd_args *args)
 
 	} while (1);
 
-	err = 0;
+	status = 0;
 
 	printf("Reboot your device now.\n");
 
@@ -560,5 +569,5 @@ out:
 	signal(SIGINT, sigh_orig);
 	gsock = NULL;
 	ethsock_close(sock);
-	return err;
+	return status;
 }

nmrpd.h

@@ -97,5 +97,6 @@ ssize_t ethsock_recv(struct ethsock *sock, void *buf, size_t len);
 int ethsock_set_timeout(struct ethsock *sock, unsigned msec);
 uint8_t *ethsock_get_hwaddr(struct ethsock *sock);
 int ethsock_list_all(void);
+int ethsock_is_same_subnet(struct ethsock *sock, struct in_addr* ip, struct in_addr *mask);
 
 #endif