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dtrace: add missing translator
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Add missing translator for node_dtrace_http_*_request_t types.

Fixes nodejs#2667.
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@bnoordhuis
Dave Pacheco authored and bnoordhuis committed Feb 3, 2012
1 parent 74a2528 commit 9fb088e
Showing 1 changed file with 189 additions and 33 deletions.
222 changes: 189 additions & 33 deletions src/node.d
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Original file line number Diff line number Diff line change
Expand Up @@ -64,96 +64,252 @@ translator node_connection_t <node_dtrace_connection_t *nc> {
&((node_dtrace_connection64_t *)nc)->buffered, sizeof (int32_t));
};

/*
* 32-bit and 64-bit structures received from node for HTTP client request
* probe.
*/
typedef struct {
uint32_t url;
uint32_t method;
} node_dtrace_http_client_request_t;

typedef struct {
uint64_t url;
uint64_t method;
} node_dtrace_http_client_request64_t;

/*
* The following structures are never used directly, but must exist to bind the
* types specified in the provider to the translators defined here.
* Ultimately, they always get cast to a more specific type inside the
* translator. To add to the confusion, the DTrace compiler does not allow
* declaring two translators with the same destination type if the source types
* are structures with the same size (because libctf says they're compatible,
* so dtrace considers them equivalent). Since we must define translators from
* node_dtrace_http_client_request_t (above), node_dtrace_http_request_t, and
* node_dtrace_http_server_request_t (both below), each of these three structs
* must be declared with a different size.
*/
typedef struct {
uint32_t version;
uint64_t dummy1;
} node_dtrace_http_request_t;

typedef struct {
uint32_t version;
uint64_t dummy2;
uint64_t dummy3;
} node_dtrace_http_server_request_t;

/*
* Actual 32-bit and 64-bit, v0 and v1 structures received from node for the
* HTTP server request probe.
*/
typedef struct {
uint32_t url;
uint32_t method;
} node_dtrace_http_request_v0_t;
} node_dtrace_http_server_request_v0_t;

typedef struct {
uint32_t version;
uint32_t url;
uint32_t method;
uint32_t forwardedFor;
} node_dtrace_http_request_v1_t;
} node_dtrace_http_server_request_v1_t;

typedef struct {
uint64_t url;
uint64_t method;
} node_dtrace_http_request64_v0_t;
} node_dtrace_http_server_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;
} node_dtrace_http_server_request64_v1_t;

/*
* In the end, both client and server request probes from both old and new
* binaries translate their arguments to node_http_request_t, which is what the
* user's D script ultimately sees.
*/
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.
* The following translators are particularly filthy for reasons of backwards
* compatibility. Stable versions of node prior to 0.6 used a single
* http_request struct with fields for "url" and "method" for both client and
* server probes. 0.6 added a "forwardedFor" field intended for the server
* probe only, and the http_request struct passed by the application was split
* first into client_http_request and server_http_request and the latter was
* again split for v0 (the old struct) and v1.
*
* To distinguish the binary representations of the two versions of these
* structs, the new version prepends a "version" member (where the old one has
* a "url" pointer). 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 D library files since we cannot
* rely on cpp being present at runtime.
*
* In retrospect, the versioning bit might have been unnecessary since the type
* of the object passed in should allow DTrace to select which translator to
* use. However, DTrace does sometimes use translators whose source types
* don't quite match, and since we know this versioning logic works, we just
* leave it alone. Each of the translators below is functionally identical
* (except that the client -> client translator doesn't bother translating
* forwardedFor) and should actually work with any version of any of the client
* or server structs transmitted by the application up to this point.
*/
translator node_http_request_t <node_dtrace_http_request_t *nd> {
url = (*(uint32_t *)copyin((uintptr_t)&nd->version, sizeof (uint32_t))) >= 4096 ?

/*
* Translate from node_dtrace_http_server_request_t (received from node 0.6 and
* later versions) to node_http_request_t.
*/
translator node_http_request_t <node_dtrace_http_server_request_t *nd> {
url = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v0_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v0_t *)nd)->url,
sizeof (uint64_t)))) :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v1_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v1_t *)nd)->url,
sizeof (uint64_t))));

method = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v0_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v0_t *)nd)->method,
sizeof (uint64_t)))) :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v0_t *)nd)->url,
&((node_dtrace_http_server_request_v1_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v0_t *)nd)->url,
&((node_dtrace_http_server_request64_v1_t *)nd)->method,
sizeof (uint64_t))));

forwardedFor = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ? "" :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v1_t *)nd)->forwardedFor,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v1_t *)nd)->
forwardedFor, sizeof (uint64_t))));
};

/*
* Translate from node_dtrace_http_client_request_t (received from node 0.6 and
* later versions) to node_http_request_t.
*/
translator node_http_request_t <node_dtrace_http_client_request_t *nd> {
url = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v0_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_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,
&((node_dtrace_http_server_request_v1_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v1_t *)nd)->url,
&((node_dtrace_http_server_request64_v1_t *)nd)->url,
sizeof (uint64_t))));

method = (*(uint32_t *)copyin((uintptr_t)&nd->version, sizeof (uint32_t))) >= 4096 ?
method = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v0_t *)nd)->method,
&((node_dtrace_http_server_request_v0_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v0_t *)nd)->method,
&((node_dtrace_http_server_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,
&((node_dtrace_http_server_request_v1_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v1_t *)nd)->method,
&((node_dtrace_http_server_request64_v1_t *)nd)->method,
sizeof (uint64_t))));

forwardedFor = (*(uint32_t *)
copyin((uintptr_t)&nd->version, sizeof (uint32_t))) >= 4096 ? "" :

forwardedFor = "";
};

/*
* Translate from node_dtrace_http_request_t (received from versions of node
* prior to 0.6) to node_http_request_t. This is used for both the server and
* client probes since these versions of node didn't distinguish between the
* types used in these probes.
*/
translator node_http_request_t <node_dtrace_http_request_t *nd> {
url = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_request_v1_t *)nd)->forwardedFor,
&((node_dtrace_http_server_request_v0_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_request64_v1_t *)nd)->forwardedFor,
&((node_dtrace_http_server_request64_v0_t *)nd)->url,
sizeof (uint64_t)))) :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v1_t *)nd)->url,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v1_t *)nd)->url,
sizeof (uint64_t))));

method = (*(uint32_t *)copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ?
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v0_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v0_t *)nd)->method,
sizeof (uint64_t)))) :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v1_t *)nd)->method,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v1_t *)nd)->method,
sizeof (uint64_t))));

forwardedFor = (*(uint32_t *) copyin((uintptr_t)(uint32_t *)nd,
sizeof (uint32_t))) >= 4096 ? "" :
(curpsinfo->pr_dmodel == PR_MODEL_ILP32 ?
copyinstr(*(uint32_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request_v1_t *)nd)->forwardedFor,
sizeof (uint32_t))) :
copyinstr(*(uint64_t *)copyin((uintptr_t)
&((node_dtrace_http_server_request64_v1_t *)nd)->
forwardedFor, sizeof (uint64_t))));
};

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