details: https://hg.nginx.org/nginx/rev/575480d3fd01
branches:
changeset: 7525:575480d3fd01
user: Maxim Dounin <mdounin@mdounin.ru>
date: Fri Jul 12 13:56:21 2019 +0300
description:
Perl: propagate errors.

When an error happens, the ctx->error bit is now set, and croak()
is called to terminate further processing. The ctx->error bit is
checked in ngx_http_perl_call_handler() to cancel further processing,
and is also checked in various output functions - to make sure these won't
be called if croak() was handled by an eval{} in perl code.

In particular, this ensures that output chain won't be called after
errors, as filters might not expect this to happen. This fixes some
segmentation faults under low memory conditions. Also this stops
request processing after filter finalization or request body reading
errors.

For cases where an HTTP error status can be additionally returned (for
example, 416 (Requested Range Not Satisfiable) from the range filter),
the ctx->status field is also added.

diffstat:

src/http/modules/perl/nginx.xs | 72 +++++++++++++++++++++++++--
src/http/modules/perl/ngx_http_perl_module.c | 20 +++++++
src/http/modules/perl/ngx_http_perl_module.h | 5 +-
3 files changed, 90 insertions(+), 7 deletions(-)

diffs (239 lines):

diff --git a/src/http/modules/perl/nginx.xs b/src/http/modules/perl/nginx.xs
--- a/src/http/modules/perl/nginx.xs
+++ b/src/http/modules/perl/nginx.xs
@@ -125,9 +125,14 @@ send_http_header(r, ...)
ngx_http_request_t *r;
ngx_http_perl_ctx_t *ctx;
SV *sv;
+ ngx_int_t rc;

ngx_http_perl_set_request(r, ctx);

+ if (ctx->error) {
+ croak("send_http_header(): called after error");
+ }
+
if (r->headers_out.status == 0) {
r->headers_out.status = NGX_HTTP_OK;
}
@@ -151,7 +156,13 @@ send_http_header(r, ...)

r->disable_not_modified = 1;

- (void) ngx_http_send_header(r);
+ rc = ngx_http_send_header(r);
+
+ if (rc == NGX_ERROR || rc > NGX_OK) {
+ ctx->error = 1;
+ ctx->status = rc;
+ croak("ngx_http_send_header() failed");
+ }


void
@@ -381,6 +392,7 @@ has_request_body(r, next)
dXSTARG;
ngx_http_request_t *r;
ngx_http_perl_ctx_t *ctx;
+ ngx_int_t rc;

ngx_http_perl_set_request(r, ctx);

@@ -398,7 +410,14 @@ has_request_body(r, next)
r->request_body_file_log_level = 0;
}

- ngx_http_read_client_request_body(r, ngx_http_perl_handle_request);
+ rc = ngx_http_read_client_request_body(r, ngx_http_perl_handle_request);
+
+ if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
+ ctx->error = 1;
+ ctx->status = rc;
+ ctx->next = NULL;
+ croak("ngx_http_read_client_request_body() failed");
+ }

sv_upgrade(TARG, SVt_IV);
sv_setiv(TARG, 1);
@@ -494,10 +513,17 @@ discard_request_body(r)

ngx_http_request_t *r;
ngx_http_perl_ctx_t *ctx;
+ ngx_int_t rc;

ngx_http_perl_set_request(r, ctx);

- ngx_http_discard_request_body(r);
+ rc = ngx_http_discard_request_body(r);
+
+ if (rc != NGX_OK) {
+ ctx->error = 1;
+ ctx->status = rc;
+ croak("ngx_http_discard_request_body() failed");
+ }


void
@@ -512,6 +538,10 @@ header_out(r, key, value)

ngx_http_perl_set_request(r, ctx);

+ if (ctx->error) {
+ croak("header_out(): called after error");
+ }
+
key = ST(1);
value = ST(2);

@@ -588,10 +618,15 @@ print(r, ...)
u_char *p;
size_t size;
STRLEN len;
+ ngx_int_t rc;
ngx_buf_t *b;

ngx_http_perl_set_request(r, ctx);

+ if (ctx->error) {
+ croak("print(): called after error");
+ }
+
if (items == 2) {

/*
@@ -671,7 +706,12 @@ print(r, ...)

out:

- (void) ngx_http_perl_output(r, ctx, b);
+ rc = ngx_http_perl_output(r, ctx, b);
+
+ if (rc == NGX_ERROR) {
+ ctx->error = 1;
+ croak("ngx_http_perl_output() failed");
+ }


void
@@ -683,6 +723,7 @@ sendfile(r, filename, offset = -1, bytes
char *filename;
off_t offset;
size_t bytes;
+ ngx_int_t rc;
ngx_str_t path;
ngx_buf_t *b;
ngx_open_file_info_t of;
@@ -690,6 +731,10 @@ sendfile(r, filename, offset = -1, bytes

ngx_http_perl_set_request(r, ctx);

+ if (ctx->error) {
+ croak("sendfile(): called after error");
+ }
+
filename = SvPV_nolen(ST(1));

if (filename == NULL) {
@@ -762,7 +807,12 @@ sendfile(r, filename, offset = -1, bytes
b->file->log = r->connection->log;
b->file->directio = of.is_directio;

- (void) ngx_http_perl_output(r, ctx, b);
+ rc = ngx_http_perl_output(r, ctx, b);
+
+ if (rc == NGX_ERROR) {
+ ctx->error = 1;
+ croak("ngx_http_perl_output() failed");
+ }


void
@@ -771,10 +821,15 @@ flush(r)

ngx_http_request_t *r;
ngx_http_perl_ctx_t *ctx;
+ ngx_int_t rc;
ngx_buf_t *b;

ngx_http_perl_set_request(r, ctx);

+ if (ctx->error) {
+ croak("flush(): called after error");
+ }
+
b = ngx_calloc_buf(r->pool);
if (b == NULL) {
XSRETURN_EMPTY;
@@ -784,7 +839,12 @@ flush(r)

ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "$r->flush");

- (void) ngx_http_perl_output(r, ctx, b);
+ rc = ngx_http_perl_output(r, ctx, b);
+
+ if (rc == NGX_ERROR) {
+ ctx->error = 1;
+ croak("ngx_http_perl_output() failed");
+ }

XSRETURN_EMPTY;

diff --git a/src/http/modules/perl/ngx_http_perl_module.c b/src/http/modules/perl/ngx_http_perl_module.c
--- a/src/http/modules/perl/ngx_http_perl_module.c
+++ b/src/http/modules/perl/ngx_http_perl_module.c
@@ -246,6 +246,11 @@ ngx_http_perl_handle_request(ngx_http_re
ctx->filename.data = NULL;
ctx->redirect_uri.len = 0;

+ if (rc == NGX_ERROR) {
+ ngx_http_finalize_request(r, rc);
+ return;
+ }
+
if (ctx->done || ctx->next) {
ngx_http_finalize_request(r, NGX_DONE);
return;
@@ -690,6 +695,9 @@ ngx_http_perl_call_handler(pTHX_ ngx_htt

status = 0;

+ ctx->error = 0;
+ ctx->status = NGX_OK;
+
ENTER;
SAVETMPS;

@@ -739,6 +747,18 @@ ngx_http_perl_call_handler(pTHX_ ngx_htt
FREETMPS;
LEAVE;

+ if (ctx->error) {
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
+ "call_sv: error, %d", ctx->status);
+
+ if (ctx->status != NGX_OK) {
+ return ctx->status;
+ }
+
+ return NGX_ERROR;
+ }
+
/* check $@ */

if (SvTRUE(ERRSV)) {
diff --git a/src/http/modules/perl/ngx_http_perl_module.h b/src/http/modules/perl/ngx_http_perl_module.h
--- a/src/http/modules/perl/ngx_http_perl_module.h
+++ b/src/http/modules/perl/ngx_http_perl_module.h
@@ -29,7 +29,10 @@ typedef struct {

SV *next;

- ngx_uint_t done; /* unsigned done:1; */
+ ngx_int_t status;
+
+ unsigned done:1;
+ unsigned error:1;

ngx_array_t *variables; /* array of ngx_http_perl_var_t */

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