Patch from Lars Ellenberg

git-svn-id: svn://svn.debian.org/pkg-net-snmp/trunk@50 db575a87-f10d-0410-9662-f1d5ac62e4ba

2 files changed, 221 insertions, 0 deletions

diff --git a/debian/patches/24_pktinfo.README b/debian/patches/24_pktinfo.README
new file mode 100644
index 0000000..373187a
--- /dev/null
+++ b/debian/patches/24_pktinfo.README
@@ -0,0 +1,9 @@
+ send udp replies from the ip alias they have been received
+ if you have a box with some virtual/cluster/alias ips,
+ currently a udp request received on the alias ip will be
+ answered using the primary ip.
+ this patch uses the linux IP_PKTINFO socket option to
+ be able to send back replies with the same source ip
+ the corresponding request has been received on.
+
+ -- Lars Ellenberg
diff --git a/debian/patches/24_pktinfo.patch b/debian/patches/24_pktinfo.patch
new file mode 100644
index 0000000..a73d39f
--- /dev/null
+++ b/debian/patches/24_pktinfo.patch
@@ -0,0 +1,212 @@
+--- net-snmp-5.2.2.orig/snmplib/snmpUDPDomain.c	2005-09-16 12:30:41.000000000 +0200
++++ net-snmp-5.2.2/snmplib/snmpUDPDomain.c	2006-06-06 23:28:31.822443722 +0200
+@@ -97,7 +97,7 @@
+ }
+ 
+ 
+-
++#ifndef IP_PKTINFO
+ /*
+  * You can write something into opaque that will subsequently get passed back 
+  * to your send function if you like.  For instance, you might want to
+@@ -178,6 +178,151 @@
+     return rc;
+ }
+ 
++#else
++/* we have IP_PKTINFO */
++/*
++ * we try to remember the ip we received a request on,
++ * so we can use it again to send back the answer.
++ */
++
++struct _netsnmp_udp_info {
++	struct sockaddr_in remote;
++	struct cmsghdr     cmsg;
++	struct in_pktinfo  pktinfo;
++} __attribute((packed));
++
++static int
++netsnmp_udp_recv(netsnmp_transport *t, void *buf, int size,
++		 void **opaque, int *olength)
++{
++    int             rc = -1;
++    struct _netsnmp_udp_info *info;
++
++    if (t != NULL && t->sock >= 0) {
++	struct msghdr msg;
++	u_char hdrbuf[128]; /* FIXME how much do we need? */
++	struct iovec iov;
++	struct cmsghdr *cmsg;
++
++        info = malloc(sizeof(*info));
++        if (info == NULL) {
++	    /* XXX BUG ALERT
++	     * why do you (re)initialize something that may need to be freed?
++	     *
++            *opaque = NULL;
++            *olength = 0;
++	     */
++            return -1;
++        } else {
++            memset(info, 0, sizeof(*info));
++	    *opaque = info;
++	    *olength = sizeof(*info);
++        }
++
++	iov.iov_base=buf;
++	iov.iov_len=size;
++
++	msg.msg_name=(caddr_t)&info->remote;
++	msg.msg_namelen=(uint)sizeof(info->remote);
++	msg.msg_iov=&iov;
++	msg.msg_iovlen=1;
++	msg.msg_control=hdrbuf;
++	msg.msg_controllen=sizeof(hdrbuf);
++	msg.msg_flags=0;
++	while (rc < 0) {
++	    rc = recvmsg(t->sock, &msg, 0);
++	    if (rc < 0 && errno != EINTR) {
++		break;
++	    }
++	}
++
++        if (rc >= 0) {
++	    char *str, *str_local = "???";
++	    int pktinfo_found = 0;
++            str = netsnmp_udp_fmtaddr(NULL, &info->remote, sizeof(info->remote));
++	    if (msg.msg_controllen>0) {
++		for (cmsg=CMSG_FIRSTHDR(&msg);cmsg;cmsg=CMSG_NXTHDR(&msg,cmsg)) {
++		    if (cmsg->cmsg_type==IP_PKTINFO) {
++			/* maybe it was easier to just copy msg_control opaque,
++			 * and later supply it unaltered to sendmsg...
++			 * but I'd rather be explicit.
++			 */
++			info->pktinfo = *(struct in_pktinfo*)CMSG_DATA(cmsg);
++			/* XXX static buffer; if you add more inet_ntoa, or move this line up,
++			 * you'd need an other pair of strdup/free */
++			str_local = inet_ntoa(info->pktinfo.ipi_addr);
++			pktinfo_found = 1;
++		    }
++		}
++	    }
++            DEBUGMSGTL(("netsnmp_udp",
++			"recvfrom fd %d got %d bytes (on %s from %s)\n",
++			t->sock, rc, str_local, str));
++            free(str);
++        } else {
++            DEBUGMSGTL(("netsnmp_udp", "recvfrom fd %d err %d (\"%s\")\n",
++                        t->sock, errno, strerror(errno)));
++        }
++    }
++    return rc;
++}
++
++
++
++static int
++netsnmp_udp_send(netsnmp_transport *t, void *buf, int size,
++		 void **opaque, int *olength)
++{
++    int rc = -1;
++    struct sockaddr_in *to = NULL;
++    struct _netsnmp_udp_info *info = NULL;
++
++    if (opaque != NULL && *opaque != NULL &&
++        *olength == sizeof(struct _netsnmp_udp_info)) {
++        info = (struct _netsnmp_udp_info *) (*opaque);
++	to = &info->remote;
++    } else if (t != NULL && t->data != NULL &&
++               t->data_length == sizeof(struct sockaddr_in)) {
++        to = (struct sockaddr_in *) (t->data);
++    }
++    if (to != NULL && t != NULL && t->sock >= 0) {
++        char *str = netsnmp_udp_fmtaddr(NULL, (void *) to,
++					sizeof(struct sockaddr_in));
++	char *str_local = "DEFAULT";
++	struct msghdr msg;
++	struct iovec iov;
++
++	iov.iov_base=buf;
++	iov.iov_len=size;
++
++	msg.msg_name=(caddr_t)to;
++	msg.msg_namelen=(uint)sizeof(*to);
++	msg.msg_iov=&iov;
++	msg.msg_iovlen=1;
++	msg.msg_control = NULL;
++	msg.msg_controllen = 0;
++	msg.msg_flags=0;
++	if (info) {
++	    info->cmsg.cmsg_len = sizeof(info->cmsg) + sizeof(info->pktinfo);
++	    info->cmsg.cmsg_level = SOL_IP;
++	    info->cmsg.cmsg_type = IP_PKTINFO;
++	    msg.msg_control = &info->cmsg;
++	    msg.msg_controllen = info->cmsg.cmsg_len;
++	    str_local = inet_ntoa(info->pktinfo.ipi_addr);
++	}
++        DEBUGMSGTL(("netsnmp_udp", "send %d bytes from %p with src ip %s to %s on fd %d\n",
++                    size, buf, str_local, str, t->sock));
++        free(str);
++	while (rc < 0) {
++	    rc = sendmsg(t->sock, &msg, 0);
++	    if (rc < 0 && errno != EINTR) {
++		break;
++	    }
++	}
++    }
++    return rc;
++}
++#endif
+ 
+ 
+ static int
+@@ -625,6 +770,17 @@
+     }
+ #endif                          /*SO_REUSEADDR */
+ #endif
++#ifdef  IP_PKTINFO
++    /*
++     * if we have multiple ip aliases, send back on the ip we received with.
++     */
++    {
++        int             one = 1;
++        DEBUGMSGTL(("socket:option", "setting socket option IP_PKTINFO\n"));
++        setsockopt(fd, SOL_IP, IP_PKTINFO, (void *) &one,
++                   sizeof(one));
++    }
++#endif                          /*IP_PKTINFO */
+ 
+     /*
+      * Try to set the send and receive buffers to a reasonably large value, so
+@@ -991,7 +1147,7 @@
+                        char **contextName)
+ {
+     com2SecEntry   *c;
+-    struct sockaddr_in *from = (struct sockaddr_in *) opaque;
++    struct sockaddr_in *from = NULL;
+     char           *ztcommunity = NULL;
+ 
+     if (secName != NULL) {
+@@ -1008,13 +1164,19 @@
+         return 0;
+     }
+ 
++#ifdef IP_PKTINFO
++    if (opaque && olength == sizeof(struct _netsnmp_udp_info))
++	from = &((struct _netsnmp_udp_info *)opaque)->remote;
++#else
++    if (opaque && olength == sizeof(struct sockaddr_in))
++	from = (struct sockaddr_in *) opaque;
++#endif
+     /*
+      * If there is no IPv4 source address, then there can be no valid security
+      * name.  
+      */
+ 
+-    if (opaque == NULL || olength != sizeof(struct sockaddr_in) ||
+-        from->sin_family != AF_INET) {
++    if (from == NULL || from->sin_family != AF_INET) {
+         DEBUGMSGTL(("netsnmp_udp_getSecName",
+ 		    "no IPv4 source address in PDU?\n"));
+         return 1;