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netsnmp_patch.diff
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netsnmp_patch.diff
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diff --git a/src/include/net-snmp/library/snmp_api.h b/src/include/net-snmp/library/snmp_api.h
index 6f658d5..5587715 100644
--- a/src/include/net-snmp/library/snmp_api.h
+++ b/src/include/net-snmp/library/snmp_api.h
@@ -160,6 +160,7 @@ typedef struct request_list {
#define SNMP_DETAIL_SIZE 512
+#define SNMP_FLAGS_AX_ASYNC_SELECT 0x200000 /* Indicates that myvoid has an async select. */
#define SNMP_FLAGS_UDP_BROADCAST 0x800
#define SNMP_FLAGS_RESP_CALLBACK 0x400 /* Additional callback on response */
#define SNMP_FLAGS_USER_CREATED 0x200 /* USM user has been created */
diff --git a/src/include/net-snmp/library/snmp_transport.h b/src/include/net-snmp/library/snmp_transport.h
index 4162897..f3cdb0b 100644
--- a/src/include/net-snmp/library/snmp_transport.h
+++ b/src/include/net-snmp/library/snmp_transport.h
@@ -50,6 +50,34 @@ extern "C" {
#define NETSNMP_TRANSPORT_FLAG_OPENED 0x20 /* f_open called */
#define NETSNMP_TRANSPORT_FLAG_HOSTNAME 0x80 /* for fmtaddr hook */
+/* I know this is wired shit.
+ * The root cause for this: fd_set only supports 1024 sockets.
+ * To understand why this causes trouble here is bit more backround:
+ * As you know a socket is just a number (file descriptor),
+ * so when you request a socket from the kernel you get just a number back.
+ * The problem with fd_set is, it's only a bitmap. Which means for socket
+ * number 30, the bit 30 is set. For socket number 700, bit 700 is set.
+ * .... and so on.
+ * As written above fd_set only support 1024 sockets, which means the bitmap
+ * supports only sockets till number 1024.
+ * Well, what happens now if we have a socket with number 2000.
+ * (2000 sockets is nothing abnormal for a high concurrent snmp collector).
+ * Inside snmp_api.c the following would happen: FD_SET(fdset, 2000)
+ * FD_SET is pretty stupid and just sets the bit 2000 starting from fdset.
+ * However fdset is only 1024 bits big, => FD_SET(fdset, 2000) sets bits in a
+ * memory region its not allowed to. Flipping bits in random memory regions
+ * leads to SEGFAULT.
+ *
+ * When we use gevent_snmp this fdset is NOT needed at all => the problematic
+ * calls FD_SET, FD_ISSET, FD_CLR are not required.
+ * This is what the SNMP_FLAGS_AX_IGNORE_FDSET should trigger. Its set on the
+ * session->flags and can be tested everywhere in the code.
+ *
+ * In snmplib 5.7 they invented a 'large_fdset', which leads to segfaults.
+ * So even for jessi it is needed as well.
+ */
+#define NETSNMP_TRANSPORT_FLAG_AX_IGNORE_FDSET 0x100000
+
/* The standard SNMP domains. */
NETSNMP_IMPORT oid netsnmpUDPDomain[]; /* = { 1, 3, 6, 1, 6, 1, 1 }; */
diff --git a/src/snmplib/snmp_api.c b/src/snmplib/snmp_api.c
index 1823e0c..2998e39 100644
--- a/src/snmplib/snmp_api.c
+++ b/src/snmplib/snmp_api.c
@@ -343,7 +343,7 @@ static int snmp_detail_f = 0;
int snmp_build(u_char ** pkt, size_t * pkt_len,
size_t * offset, netsnmp_session * pss,
netsnmp_pdu *pdu);
-static int snmp_parse(void *, netsnmp_session *, netsnmp_pdu *,
+int snmp_parse(void *, netsnmp_session *, netsnmp_pdu *,
u_char *, size_t);
static void snmpv3_calc_msg_flags(int, int, u_char *);
@@ -4321,7 +4321,7 @@ _snmp_parse(void *sessp,
return result;
}
-static int
+int
snmp_parse(void *sessp,
netsnmp_session * pss,
netsnmp_pdu *pdu, u_char * data, size_t length)
@@ -5508,12 +5508,14 @@ _sess_read(void *sessp, netsnmp_large_fd_set * fdset)
return 0;
}
- if (!fdset || !(NETSNMP_LARGE_FD_ISSET(transport->sock, fdset))) {
- DEBUGMSGTL(("sess_read", "not reading %d (fdset %p set %d)\n",
- transport->sock, fdset,
- fdset ? NETSNMP_LARGE_FD_ISSET(transport->sock, fdset)
- : -9));
- return 0;
+ if (!(transport->flags & NETSNMP_TRANSPORT_FLAG_AX_IGNORE_FDSET)) {
+ if (!fdset || !(NETSNMP_LARGE_FD_ISSET(transport->sock, fdset))) {
+ DEBUGMSGTL(("sess_read", "not reading %d (fdset %p set %d)\n",
+ transport->sock, fdset,
+ fdset ? NETSNMP_LARGE_FD_ISSET(transport->sock, fdset)
+ : -9));
+ return 0;
+ }
}
sp->s_snmp_errno = 0;
@@ -6048,7 +6050,10 @@ snmp_sess_select_info2_flags(void *sessp, int *numfds,
*numfds = (slp->transport->sock + 1);
}
- NETSNMP_LARGE_FD_SET(slp->transport->sock, fdset);
+ if (!(slp->transport->flags & NETSNMP_TRANSPORT_FLAG_AX_IGNORE_FDSET)) {
+ NETSNMP_LARGE_FD_SET(slp->transport->sock, fdset);
+ }
+
if (slp->internal != NULL && slp->internal->requests) {
/*
* Found another session with outstanding requests.
diff --git a/src/snmplib/snmp_client.c b/src/snmplib/snmp_client.c
index c1aa9c4..d7a6261 100644
--- a/src/snmplib/snmp_client.c
+++ b/src/snmplib/snmp_client.c
@@ -1111,6 +1111,17 @@ snmp_synch_response(netsnmp_session * ss,
return snmp_synch_response_cb(ss, pdu, response, snmp_synch_input);
}
+typedef int (*ax_select_func) (void* ctx, struct timeval* timeout);
+
+typedef struct {
+ ax_select_func func;
+ void* ctx;
+} ax_async_ctx_t;
+
+#define GET_AX_ASYNC_FUNC(ss) (((ax_async_ctx_t*)(ss->myvoid))->func)
+#define GET_AX_ASYNC_CTX(ss) (((ax_async_ctx_t*)(ss->myvoid))->ctx)
+
+
int
snmp_sess_synch_response(void *sessp,
netsnmp_pdu *pdu, netsnmp_pdu **response)
@@ -1152,7 +1163,14 @@ snmp_sess_synch_response(void *sessp,
NETSNMP_SELECT_NOALARMS);
if (block == 1)
tvp = NULL; /* block without timeout */
- count = select(numfds, &fdset, NULL, NULL, tvp);
+
+ if ((ss->myvoid != NULL) && (ss->flags & SNMP_FLAGS_AX_ASYNC_SELECT)) {
+ count = GET_AX_ASYNC_FUNC(ss)(GET_AX_ASYNC_CTX(ss), tvp);
+ }
+ else {
+ count = select(numfds, &fdset, NULL, NULL, tvp);
+ }
+
if (count > 0) {
snmp_sess_read(sessp, &fdset);
} else