Changeset 2725 in MondoRescue for branches/2.2.9/mindi-busybox/networking/udhcp/arpping.c

Timestamp:

Feb 25, 2011, 9:26:54 PM (13 years ago)

Author:

Bruno Cornec

Message:

• Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3

File:

• branches/2.2.9/mindi-busybox/networking/udhcp/arpping.c (modified) (5 diffs)

branches/2.2.9/mindi-busybox/networking/udhcp/arpping.c

@@ -1 +1 @@
 /* vi: set sw=4 ts=4: */
 /*
- * arpping.c
- *
  * Mostly stolen from: dhcpcd - DHCP client daemon
  * by Yoichi Hariguchi <yoichi@fore.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
-
 #include <netinet/if_ether.h>
 #include <net/if_arp.h>
@@ -12 +11 @@
 #include "common.h"
 #include "dhcpd.h"
-
 
 struct arpMsg {
@@ -31 +29 @@
     uint8_t  tInaddr[4];    /* 26 target's IP address */
     uint8_t  pad[18];       /* 2a pad for min. ethernet payload (60 bytes) */
-} ATTRIBUTE_PACKED;
+} PACKED;
 
+enum {
+    ARP_MSG_SIZE = 0x2a
+};
 
 /* Returns 1 if no reply received */
-
-int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface)
+int FAST_FUNC arpping(uint32_t test_nip,
+        const uint8_t *safe_mac,
+        uint32_t from_ip,
+        uint8_t *from_mac,
+        const char *interface)
 {
-    int timeout = 2;
-    int s;                  /* socket */
+    int timeout_ms;
+    struct pollfd pfd[1];
+#define s (pfd[0].fd)           /* socket */
     int rv = 1;             /* "no reply received" yet */
     struct sockaddr addr;   /* for interface name */
     struct arpMsg arp;
-    fd_set fdset;
-    struct timeval tm;
-    unsigned prevTime;
 
     s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
@@ -54 +56 @@
 
     if (setsockopt_broadcast(s) == -1) {
-        bb_perror_msg("cannot setsocketopt on raw socket");
+        bb_perror_msg("can't enable bcast on raw socket");
         goto ret;
     }
@@ -70 +72 @@
     memcpy(arp.sHaddr, from_mac, 6);                /* source hardware address */
     memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */
-    /* tHaddr */                                    /* target hardware address */
-    memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */
+    /* tHaddr is zero-filled */                     /* target hardware address */
+    memcpy(arp.tInaddr, &test_nip, sizeof(test_nip));/* target IP address */
 
     memset(&addr, 0, sizeof(addr));
     safe_strncpy(addr.sa_data, interface, sizeof(addr.sa_data));
-    if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
+    if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0) {
+        // TODO: error message? caller didn't expect us to fail,
+        // just returning 1 "no reply received" misleads it.
         goto ret;
+    }
 
     /* wait for arp reply, and check it */
+    timeout_ms = 2000;
     do {
+        typedef uint32_t aliased_uint32_t FIX_ALIASING;
         int r;
-        prevTime = monotonic_sec();
-        FD_ZERO(&fdset);
-        FD_SET(s, &fdset);
-        tm.tv_sec = timeout;
-        tm.tv_usec = 0;
-        r = select(s + 1, &fdset, NULL, NULL, &tm);
-        if (r < 0) {
-            bb_perror_msg("error on ARPING request");
-            if (errno != EINTR)
+        unsigned prevTime = monotonic_ms();
+
+        pfd[0].events = POLLIN;
+        r = safe_poll(pfd, 1, timeout_ms);
+        if (r < 0)
+            break;
+        if (r) {
+            r = safe_read(s, &arp, sizeof(arp));
+            if (r < 0)
                 break;
-        } else if (r) {
-            if (recv(s, &arp, sizeof(arp), 0) < 0)
-                break;
-            if (arp.operation == htons(ARPOP_REPLY)
-             && memcmp(arp.tHaddr, from_mac, 6) == 0
-             && *((uint32_t *) arp.sInaddr) == test_ip
+
+            //log3("sHaddr %02x:%02x:%02x:%02x:%02x:%02x",
+            //  arp.sHaddr[0], arp.sHaddr[1], arp.sHaddr[2],
+            //  arp.sHaddr[3], arp.sHaddr[4], arp.sHaddr[5]);
+
+            if (r >= ARP_MSG_SIZE
+             && arp.operation == htons(ARPOP_REPLY)
+             /* don't check it: Linux doesn't return proper tHaddr (fixed in 2.6.24?) */
+             /* && memcmp(arp.tHaddr, from_mac, 6) == 0 */
+             && *(aliased_uint32_t*)arp.sInaddr == test_nip
             ) {
-                rv = 0;
+                /* if ARP source MAC matches safe_mac
+                 * (which is client's MAC), then it's not a conflict
+                 * (client simply already has this IP and replies to ARPs!)
+                 */
+                if (!safe_mac || memcmp(safe_mac, arp.sHaddr, 6) != 0)
+                    rv = 0;
+                //else log2("sHaddr == safe_mac");
                 break;
             }
         }
-        timeout -= monotonic_sec() - prevTime;
-    } while (timeout > 0);
+        timeout_ms -= (unsigned)monotonic_ms() - prevTime;
+    } while (timeout_ms > 0);
 
  ret:
     close(s);
-    DEBUG("%srp reply received for this address", rv ? "No a" : "A");
+    log1("%srp reply received for this address", rv ? "No a" : "A");
     return rv;
 }