flow-tools  

Re: [Flow-tools] flow-tools on FreeBSD/amd64

Mark R.
Tue, 07 Oct 2008 12:04:12 -0700


Paul,
Upon further investigation, it appears as if there is an alignment issue in 'struct msgip' inside of 'struct ftnet'. I've looked at some other code, and there appear to be a handful of useful CMSG_* macros to help deal with this. RFC 2292 details them.
The attached patch works cleanly on my system and fixes the issue at hand. Hopefully it doesn't break other platforms. It's there for anybody who is interested. 

Thanks,
Mark

On Tue, 7 Oct 2008, Mark R. wrote:



Paul,

This is where I'm picking up the garbage data:

        ftnet.loc_addr.sin_addr.s_addr = ftnet.msgip.ip.s_addr
The kernel is GENERIC plus IPFW. Nothing terribly oddball. I'm wondering if this is a variable type issue somewhere. Running a 32bit build on amd64 and the same box doesn't exhibit this issue.
If you care to look into this, I can provide access to the box in question. If not, I'll might eventually figure it out.
I'm not at the point of caring about a memory leak. When I get there, I can run it through valgrind. 

Thanks,
Mark

On Tue, 7 Oct 2008, Paul P Komkoff Jr wrote:


Replying to Mark R.:

Are there any known issues with flow-tools on 64-bit platforms?  I'm
trying to run 0.68 on FreeBSD 7.0/amd64 and running into some odd
behavior with flow-capture and flow-fanout.


There is at least one known memory leak that only happens on 64-bit
FreeBSD, that I still haven't fixed (mainly because it requires to set up
FreeBSD somewhere).

This one that you telling here is new. And it's serious, I wonder why
nobody else seeing it. Maybe your kernel is broken?
Or maybe it's ipv4-over-ipv6 issue?
I don't have access to freebsd system to verify how recvmsg works
there, sorry.

--
Paul P 'Stingray' Komkoff Jr // http://stingr.net/key <- my pgp key
This message represents the official view of the voices in my head


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--- lib/ftlib.h-orig    2008-03-09 13:09:01.000000000 +0000
+++ lib/ftlib.h 2008-10-07 17:41:11.000000000 +0000
@@ -459,11 +459,16 @@
   int fd;                         /* fd receiving flows on */
   struct mymsghdr msg;            /* recvmsg data */
   struct {
-    struct cmsghdr hdr;
 #ifdef IP_RECVDSTADDR
+#ifdef CMSG_DATA
+    char cbuf[CMSG_SPACE(sizeof(struct sockaddr_storage))];
+#else
+    struct cmsghdr hdr;
     struct in_addr ip;
+#endif /* CMSG_DATA */
 #else
 #ifdef IP_PKTINFO
+    struct cmsghdr hdr;
     struct in_pktinfo pktinfo;
 #endif /* else */
 #endif /* IP RECVDSTADDR */
--- src/flow-fanout.c-orig      2008-01-27 20:48:55.000000000 +0000
+++ src/flow-fanout.c   2008-10-07 17:42:33.000000000 +0000
@@ -124,6 +124,11 @@
   int i, n, detach, one, ret, offset, hdr_len;
   int npeers, tx_delay;
   int stat_interval, stat_next, src_ip_spoof;
+#ifdef IP_RECVDSTADDR
+#ifdef CMSG_DATA
+  struct cmsghdr *cmsg;
+#endif
+#endif
 
   time_startup = time((time_t)0L);
 
@@ -625,12 +630,24 @@
 
 #ifdef IP_RECVDSTADDR
       /* got destination IP back? */
+#ifdef CMSG_DATA
+      for (cmsg = CMSG_FIRSTHDR(&ftnet.msg); cmsg != NULL;
+          cmsg = CMSG_NXTHDR(&ftnet.msg, cmsg)) {
+              if (cmsg->cmsg_level == IPPROTO_IP &&
+                  cmsg->cmsg_type == IP_RECVDSTADDR) {
+                      memcpy(&ftnet.loc_addr.sin_addr.s_addr,
+                          CMSG_DATA(cmsg), sizeof(struct in_addr));
+                      break;
+              }
+      }
+#else      
       if ((ftnet.msgip.hdr.cmsg_level == IPPROTO_IP) &&
           (ftnet.msgip.hdr.cmsg_type == IP_RECVDSTADDR)) {
           ftnet.loc_addr.sin_addr.s_addr = ftnet.msgip.ip.s_addr;
       } else {
         ftnet.loc_addr.sin_addr.s_addr = 0;
       }
+#endif /* CMSG_DATA */
 #else
 #ifdef IP_PKTINFO
       if ((ftnet.msgip.hdr.cmsg_level == IPPROTO_IP) &&
--- src/flow-receive.c-orig     2008-01-27 20:48:55.000000000 +0000
+++ src/flow-receive.c  2008-10-07 17:42:35.000000000 +0000
@@ -93,6 +93,11 @@
   char fmt_src_ip[32], fmt_dst_ip[32], fmt_dst_port[32];
   char xl_rec[FT_IO_MAXREC], *out_rec;
   int stat_interval, stat_next;
+#ifdef IP_RECVDSTADDR
+#ifdef CMSG_DATA
+  struct cmsghdr *cmsg;
+#endif
+#endif
 
   time_startup = time((time_t)0L);
 
@@ -488,12 +493,24 @@
 
 #ifdef IP_RECVDSTADDR
       /* got destination IP back? */
+#ifdef CMSG_DATA
+      for (cmsg = CMSG_FIRSTHDR(&ftnet.msg); cmsg != NULL;
+          cmsg = CMSG_NXTHDR(&ftnet.msg, cmsg)) {
+              if (cmsg->cmsg_level == IPPROTO_IP &&
+                  cmsg->cmsg_type == IP_RECVDSTADDR) {
+                      memcpy(&ftnet.loc_addr.sin_addr.s_addr,
+                          CMSG_DATA(cmsg), sizeof(struct in_addr));
+                      break;
+              }
+      }
+#else      
       if ((ftnet.msgip.hdr.cmsg_level == IPPROTO_IP) &&
           (ftnet.msgip.hdr.cmsg_type == IP_RECVDSTADDR)) {
           ftnet.loc_addr.sin_addr.s_addr = ftnet.msgip.ip.s_addr;
       } else {
         ftnet.loc_addr.sin_addr.s_addr = 0;
       }
+#endif /* CMSG_DATA */
 #else
 #ifdef IP_PKTINFO
       if ((ftnet.msgip.hdr.cmsg_level == IPPROTO_IP) &&
--- src/flow-capture.c-orig     2008-01-27 20:48:55.000000000 +0000
+++ src/flow-capture.c  2008-10-07 17:42:30.000000000 +0000
@@ -170,6 +170,11 @@
   int stat_interval, stat_next, child_status;
   int v_flag;
   int preserve_umask;
+#ifdef IP_RECVDSTADDR
+#ifdef CMSG_DATA
+  struct cmsghdr *cmsg;
+#endif
+#endif
 
   time_startup = time((time_t)0L);
 
@@ -621,7 +626,12 @@
   ftnet.msg.msg_name = &ftnet.rem_addr;
   ftnet.msg.msg_namelen = sizeof ftnet.rem_addr;
   ftnet.msg.msg_control = &ftnet.msgip;
+  
+#ifdef CMSG_DATA
+  ftnet.msg.msg_controllen = CMSG_LEN(sizeof(struct sockaddr_storage));
+#else
   ftnet.msg.msg_controllen = sizeof ftnet.msgip;
+#endif
 
   while (1) {
 
@@ -853,12 +863,24 @@
 
 #ifdef IP_RECVDSTADDR
       /* got destination IP back? */
+#ifdef CMSG_DATA
+      for (cmsg = CMSG_FIRSTHDR(&ftnet.msg); cmsg != NULL;
+          cmsg = CMSG_NXTHDR(&ftnet.msg, cmsg)) {
+              if (cmsg->cmsg_level == IPPROTO_IP &&
+                  cmsg->cmsg_type == IP_RECVDSTADDR) {
+                      memcpy(&ftnet.loc_addr.sin_addr.s_addr,
+                          CMSG_DATA(cmsg), sizeof(struct in_addr));
+                      break;
+              }
+      }
+#else      
       if ((ftnet.msgip.hdr.cmsg_level == IPPROTO_IP) &&
           (ftnet.msgip.hdr.cmsg_type == IP_RECVDSTADDR)) {
           ftnet.loc_addr.sin_addr.s_addr = ftnet.msgip.ip.s_addr;
       } else {
         ftnet.loc_addr.sin_addr.s_addr = 0;
       }
+#endif /* CMSG_DATA */
 #else
 #ifdef IP_PKTINFO
       if ((ftnet.msgip.hdr.cmsg_level == IPPROTO_IP) &&

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