* Build udhcpc binary from source.

[grml-terminalserver.git] / udhcp / arpping.c

diff --git a/udhcp/arpping.c b/udhcp/arpping.c
new file mode 100644 (file)
index 0000000..6662d0b
--- /dev/null
+++ b/udhcp/arpping.c
@@ -0,0 +1,108 @@
+/*
+ * arpping.c
+ *
+ * Mostly stolen from: dhcpcd - DHCP client daemon
+ * by Yoichi Hariguchi <yoichi@fore.com>
+ */
+
+#include <sys/time.h>
+#include <time.h>
+#include <sys/socket.h>
+#include <netinet/if_ether.h>
+#include <net/if_arp.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "dhcpd.h"
+#include "arpping.h"
+#include "common.h"
+
+/* args:       yiaddr - what IP to ping
+ *             ip - our ip
+ *             mac - our arp address
+ *             interface - interface to use
+ * retn:       1 addr free
+ *             0 addr used
+ *             -1 error
+ */
+
+/* FIXME: match response against chaddr */
+int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *mac, char *interface)
+{
+
+       int     timeout = 2;
+       int     optval = 1;
+       int     s;                      /* socket */
+       int     rv = 1;                 /* return value */
+       struct sockaddr addr;           /* for interface name */
+       struct arpMsg   arp;
+       fd_set          fdset;
+       struct timeval  tm;
+       time_t          prevTime;
+
+
+       if ((s = socket (PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) == -1) {
+#ifdef IN_BUSYBOX
+               LOG(LOG_ERR, bb_msg_can_not_create_raw_socket);
+#else
+               LOG(LOG_ERR, "Could not open raw socket");
+#endif
+               return -1;
+       }
+
+       if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) == -1) {
+               LOG(LOG_ERR, "Could not setsocketopt on raw socket");
+               close(s);
+               return -1;
+       }
+
+       /* send arp request */
+       memset(&arp, 0, sizeof(arp));
+       memcpy(arp.h_dest, MAC_BCAST_ADDR, 6);          /* MAC DA */
+       memcpy(arp.h_source, mac, 6);                   /* MAC SA */
+       arp.h_proto = htons(ETH_P_ARP);                 /* protocol type (Ethernet) */
+       arp.htype = htons(ARPHRD_ETHER);                /* hardware type */
+       arp.ptype = htons(ETH_P_IP);                    /* protocol type (ARP message) */
+       arp.hlen = 6;                                   /* hardware address length */
+       arp.plen = 4;                                   /* protocol address length */
+       arp.operation = htons(ARPOP_REQUEST);           /* ARP op code */
+       memcpy(arp.sInaddr, &ip, sizeof(ip));           /* source IP address */
+       memcpy(arp.sHaddr, mac, 6);                     /* source hardware address */
+       memcpy(arp.tInaddr, &yiaddr, sizeof(yiaddr));   /* target IP address */
+
+       memset(&addr, 0, sizeof(addr));
+       //closes http://bugs.debian.org/283582
+       //strcpy(addr.sa_data, interface);
+       strncpy(addr.sa_data, interface, sizeof(addr.sa_data)-1);
+       if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
+               rv = 0;
+
+       /* wait arp reply, and check it */
+       tm.tv_usec = 0;
+       prevTime = uptime();
+       while (timeout > 0) {
+               FD_ZERO(&fdset);
+               FD_SET(s, &fdset);
+               tm.tv_sec = timeout;
+               if (select(s + 1, &fdset, (fd_set *) NULL, (fd_set *) NULL, &tm) < 0) {
+                       DEBUG(LOG_ERR, "Error on ARPING request: %m");
+                       if (errno != EINTR) rv = 0;
+               } else if (FD_ISSET(s, &fdset)) {
+                       if (recv(s, &arp, sizeof(arp), 0) < 0 ) rv = 0;
+                       if (arp.operation == htons(ARPOP_REPLY) &&
+                           bcmp(arp.tHaddr, mac, 6) == 0 &&
+                           *((uint32_t *) arp.sInaddr) == yiaddr) {
+                               DEBUG(LOG_INFO, "Valid arp reply receved for this address");
+                               rv = 0;
+                               break;
+                       }
+               }
+               timeout -= uptime() - prevTime;
+               prevTime = uptime();
+       }
+       close(s);
+       DEBUG(LOG_INFO, "%salid arp replies for this address", rv ? "No v" : "V");      
+       return rv;
+}