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DTrace probes: support X-Forwarded-For

INTRO-385
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davepacheco authored and ry committed Jun 4, 2011
1 parent b6a742d commit e142fe2be6ef3e5cd27b89d59175a3937b9fdb31
Showing with 136 additions and 18 deletions.
  1. +78 −12 src/node.d
  2. +18 −2 src/node_dtrace.cc
  3. +33 −1 src/node_dtrace.h
  4. +7 −3 src/node_provider.d
@@ -64,30 +64,96 @@ translator node_connection_t <node_dtrace_connection_t *nc> {
&((node_dtrace_connection64_t *)nc)->buffered, sizeof (int32_t));
};

typedef struct {
uint32_t version;
} node_dtrace_http_request_t;

typedef struct {
uint32_t url;
uint32_t method;
} node_dtrace_http_request_t;
} node_dtrace_http_request_v0_t;

typedef struct {
uint32_t version;
uint32_t url;
uint32_t method;
uint32_t forwardedFor;
} node_dtrace_http_request_v1_t;

typedef struct {
uint64_t url;
uint64_t method;
} node_dtrace_http_request64_t;
} node_dtrace_http_request64_v0_t;

typedef struct {
uint32_t version;
uint32_t pad;
uint64_t url;
uint64_t method;
uint64_t forwardedFor;
} node_dtrace_http_request64_v1_t;

typedef struct {
string url;
string method;
string forwardedFor;
} node_http_request_t;

/*
* This translator is even filthier than usual owing to our attempts to
* maintain backwards compatibility. Previous versions of node used an
* http_request struct that had fields for "url" and "method". The current
* version also provides a "forwardedFor" field. To distinguish the binary
* representations of these structs, the new version also prepends a "version"
* member (where the old one has a "url" pointer). So each field that we're
* translating below first switches on the value of this "version" field: if
* it's larger than 4096, we know we must be looking at the "url" pointer of
* the older structure version. Otherwise, we must be looking at the new
* version. Besides this, we have the usual switch based on the userland
* process data model. This would all be simpler with macros, but those aren't
* available in delivered D library files since that would make DTrace
* dependent on cpp, which isn't always available.
*/
translator node_http_request_t <node_dtrace_http_request_t *nd> {
url = curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr((uintptr_t)*(uint32_t *)copyin((uintptr_t)&nd->url,
sizeof (int32_t))) :
copyinstr((uintptr_t)*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_t *)nd)->url, sizeof (int64_t)));
method = curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr((uintptr_t)*(uint32_t *)copyin((uintptr_t)&nd->method,
sizeof (int32_t))) :
copyinstr((uintptr_t)*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_t *)nd)->method, sizeof (int64_t)));
url = (*(uint32_t *)copyin((uintptr_t)&nd->version, sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v0_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v0_t *)nd)->url,
sizeof (uint64_t)))) :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v1_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v1_t *)nd)->url,
sizeof (uint64_t))));

method = (*(uint32_t *)copyin((uintptr_t)&nd->version, sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v0_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v0_t *)nd)->method,
sizeof (uint64_t)))) :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v1_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v1_t *)nd)->method,
sizeof (uint64_t))));

forwardedFor = (*(uint32_t *)
copyin((uintptr_t)&nd->version, sizeof (uint32_t))) >= 4096 ? "" :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v1_t *)nd)->forwardedFor,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v1_t *)nd)->forwardedFor,
sizeof (uint64_t))));
};
@@ -20,6 +20,7 @@
// USE OR OTHER DEALINGS IN THE SOFTWARE.

#include <node_dtrace.h>
#include <strings.h>

#ifdef HAVE_DTRACE
#include "node_provider.h"
@@ -180,18 +181,33 @@ Handle<Value> DTRACE_NET_SOCKET_WRITE(const Arguments& args) {
}

Handle<Value> DTRACE_HTTP_SERVER_REQUEST(const Arguments& args) {
node_dtrace_http_request_t req;
node_dtrace_http_server_request_t req;

if (!NODE_HTTP_SERVER_REQUEST_ENABLED())
return Undefined();

HandleScope scope;

Local<Object> arg0 = Local<Object>::Cast(args[0]);
Local<Object> headers;

bzero(&req, sizeof(req));
req._un.version = 1;
SLURP_STRING(arg0, url, &req.url);
SLURP_STRING(arg0, method, &req.method);

SLURP_OBJECT(arg0, headers, &headers);

if (!(headers)->IsObject())
return (ThrowException(Exception::Error(String::New("expected "
"object for request to contain string member headers"))));

Local<Value> strfwdfor = headers->Get(String::New("x-forwarded-for"));
String::Utf8Value fwdfor(strfwdfor->ToString());

if (!strfwdfor->IsString() || (req.forwardedFor = *fwdfor) == NULL)
req.forwardedFor = "";

SLURP_CONNECTION(args[1], conn);

NODE_HTTP_SERVER_REQUEST(&req, &conn);
@@ -211,7 +227,7 @@ Handle<Value> DTRACE_HTTP_SERVER_RESPONSE(const Arguments& args) {
}

Handle<Value> DTRACE_HTTP_CLIENT_REQUEST(const Arguments& args) {
node_dtrace_http_request_t req;
node_dtrace_http_client_request_t req;
char *header;

if (!NODE_HTTP_CLIENT_REQUEST_ENABLED())
@@ -27,6 +27,14 @@

extern "C" {

/*
* The following structures are passed directly to DTrace when probes are fired.
* Translators in node.d translate these structures into the corresponding D
* structures, taking care of dealing with the user process data model (32-bit
* or 64-bit) and structure versions (see node_dtrace_http_server_request_t
* below).
*/

typedef struct {
int32_t fd;
int32_t port;
@@ -37,7 +45,31 @@ typedef struct {
typedef struct {
char *url;
char *method;
} node_dtrace_http_request_t;
} node_dtrace_http_client_request_t;

/*
* The original version of this structure contained only a url and method, just
* like the client request above. To add the new forwardedFor field, the
* structure layout was changed to begin with an integer version. The
* translator knows whether it's looking at an old- or new-version structure
* based on whether the version field's value is a reasonable pointer (i.e.
* address greater than 4K). No doubt this is filthy, but there's not much else
* we can do, and it works reliably.
*
* This version of the structure also contains padding that should be zeroed out
* by the consumer so that future versions of the translator can simply check if
* a field is present by checking it against NULL.
*/
typedef struct {
union {
uint32_t version;
uintptr_t unused; /* for compat. with old 64-bit struct */
} _un;
char *url;
char *method;
char *forwardedFor;
char *_pad[8];
} node_dtrace_http_server_request_t;

}

@@ -41,7 +41,11 @@ typedef struct {

typedef struct {
int dummy;
} node_dtrace_http_request_t;
} node_dtrace_http_server_request_t;

typedef struct {
int dummy;
} node_dtrace_http_client_request_t;

typedef struct {
int dummy;
@@ -56,12 +60,12 @@ provider node {
(node_connection_t *c, int b);
probe net__socket__write(node_dtrace_connection_t *c, int b) :
(node_connection_t *c, int b);
probe http__server__request(node_dtrace_http_request_t *h,
probe http__server__request(node_dtrace_http_server_request_t *h,
node_dtrace_connection_t *c) :
(node_http_request_t *h, node_connection_t *c);
probe http__server__response(node_dtrace_connection_t *c) :
(node_connection_t *c);
probe http__client__request(node_dtrace_http_request_t *h,
probe http__client__request(node_dtrace_http_client_request_t *h,
node_dtrace_connection_t *c) :
(node_http_request_t *h, node_connection_t *c);
probe http__client__response(node_dtrace_connection_t *c) :

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