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Use an arena to allocate stdin records in the FastCGI module
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Using a lwan_array() as an arena like the way it was being used is
dangerous as it may realloc() and the pointer may move!
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@lpereira
lpereira committed Aug 17, 2024
1 parent b3c4dc9 commit 33f31e4
Showing 1 changed file with 69 additions and 67 deletions.
136 changes: 69 additions & 67 deletions src/lib/lwan-mod-fastcgi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@

#include "int-to-str.h"
#include "realpathat.h"
#include "lwan-arena.h"
#include "lwan-cache.h"
#include "lwan-io-wrappers.h"
#include "lwan-mod-fastcgi.h"
Expand Down Expand Up @@ -573,59 +574,69 @@ try_initiating_chunked_response(struct lwan_request *request)
}

DEFINE_ARRAY_TYPE_INLINEFIRST(iovec_array, struct iovec)
DEFINE_ARRAY_TYPE_INLINEFIRST(record_array, struct record)

static bool build_stdin_records(struct lwan_request *request,
struct iovec_array *iovec_array,
struct record_array *record_array,
int fcgi_fd,
const struct lwan_value *body_data)
{
if (!body_data)
return true;

size_t to_send = body_data->len;
char *buffer = body_data->value;
struct iovec *iovec;

while (to_send) {
struct record *record;
struct iovec *iovec;
size_t block_size = LWAN_MIN(0xffffull, to_send);
if (body_data) {
struct arena *arena = coro_arena_new(request->conn->coro);
size_t to_send = body_data->len;
char *buffer = body_data->value;

record = record_array_append(record_array);
if (UNLIKELY(!record))
return false;
*record = (struct record){
.version = 1,
.type = FASTCGI_TYPE_STDIN,
.id = htons(1),
.len_content = htons((uint16_t)block_size),
};

iovec = iovec_array_append(iovec_array);
if (UNLIKELY(!iovec))
return false;
*iovec = (struct iovec){.iov_base = record, .iov_len = sizeof(*record)};
while (to_send) {
struct record *record;
size_t block_size = LWAN_MIN(0xffffull, to_send);

iovec = iovec_array_append(iovec_array);
if (UNLIKELY(!iovec))
return false;
*iovec = (struct iovec){.iov_base = buffer, .iov_len = block_size};
record = arena_alloc(arena, sizeof(*record));
if (UNLIKELY(!record))
return false;
*record = (struct record){
.version = 1,
.type = FASTCGI_TYPE_STDIN,
.id = htons(1),
.len_content = htons((uint16_t)block_size),
};

iovec = iovec_array_append(iovec_array);
if (UNLIKELY(!iovec))
return false;
*iovec =
(struct iovec){.iov_base = record, .iov_len = sizeof(*record)};

if (iovec_array_len(iovec_array) == LWAN_ARRAY_INCREMENT) {
if (lwan_writev_fd(request, fcgi_fd,
iovec_array_get_array(iovec_array),
(int)iovec_array_len(iovec_array)) < 0) {
iovec = iovec_array_append(iovec_array);
if (UNLIKELY(!iovec))
return false;
*iovec = (struct iovec){.iov_base = buffer, .iov_len = block_size};

if (iovec_array_len(iovec_array) == LWAN_ARRAY_INCREMENT) {
if (lwan_writev_fd(request, fcgi_fd,
iovec_array_get_array(iovec_array),
(int)iovec_array_len(iovec_array)) < 0) {
return false;
}
iovec_array_reset(iovec_array);
arena_destroy(arena);
}
iovec_array_reset(iovec_array);
record_array_reset(record_array);
}

to_send -= block_size;
buffer += block_size;
to_send -= block_size;
buffer += block_size;
}
}

iovec = iovec_array_append(iovec_array);
if (UNLIKELY(!iovec))
return HTTP_INTERNAL_ERROR;
*iovec = (struct iovec){
.iov_base = &(struct record){.version = 1,
.type = FASTCGI_TYPE_STDIN,
.id = htons(1)},
.iov_len = sizeof(struct record),
};

return true;
}

Expand Down Expand Up @@ -655,12 +666,10 @@ static enum lwan_http_status send_request(struct private_data *pd,
}

struct iovec_array iovec_array;
struct record_array record_array;
struct iovec *iovec;

/* These arrays should never go beyond the inlinefirst threshold, so they
/* This arrays should never go beyond the inlinefirst threshold, so it
* shouldn't leak -- thus requiring no defer to reset them. */
record_array_init(&record_array);
iovec_array_init(&iovec_array);

iovec = iovec_array_append(&iovec_array);
Expand All @@ -669,27 +678,31 @@ static enum lwan_http_status send_request(struct private_data *pd,
*iovec = (struct iovec){
.iov_base =
&(struct request_header){
.begin_request = {.version = 1,
.type = FASTCGI_TYPE_BEGIN_REQUEST,
.id = htons(1),
.len_content = htons((uint16_t)sizeof(
struct begin_request_body))},
.begin_request =
{
.version = 1,
.type = FASTCGI_TYPE_BEGIN_REQUEST,
.id = htons(1),
.len_content =
htons((uint16_t)sizeof(struct begin_request_body)),
},
.begin_request_body = {.role = htons(FASTCGI_ROLE_RESPONDER)},
.begin_params = {.version = 1,
.type = FASTCGI_TYPE_PARAMS,
.id = htons(1),
.len_content =
htons((uint16_t)lwan_strbuf_get_length(
response->buffer))}},
.begin_params =
{
.version = 1,
.type = FASTCGI_TYPE_PARAMS,
.id = htons(1),
.len_content = htons(
(uint16_t)lwan_strbuf_get_length(response->buffer)),
},
},
.iov_len = sizeof(struct request_header),
};

iovec = iovec_array_append(&iovec_array);
if (UNLIKELY(!iovec))
return HTTP_INTERNAL_ERROR;
*iovec =
(struct iovec){.iov_base = lwan_strbuf_get_buffer(response->buffer),
.iov_len = lwan_strbuf_get_length(response->buffer)};
*iovec = lwan_strbuf_to_iovec(response->buffer);

iovec = iovec_array_append(&iovec_array);
if (UNLIKELY(!iovec))
Expand All @@ -701,27 +714,16 @@ static enum lwan_http_status send_request(struct private_data *pd,
.iov_len = sizeof(struct record),
};

if (!build_stdin_records(request, &iovec_array, &record_array, fcgi_fd,
if (!build_stdin_records(request, &iovec_array, fcgi_fd,
lwan_request_get_request_body(request))) {
return HTTP_INTERNAL_ERROR;
}

iovec = iovec_array_append(&iovec_array);
if (UNLIKELY(!iovec))
return HTTP_INTERNAL_ERROR;
*iovec = (struct iovec){
.iov_base = &(struct record){.version = 1,
.type = FASTCGI_TYPE_STDIN,
.id = htons(1)},
.iov_len = sizeof(struct record),
};

if (lwan_writev_fd(request, fcgi_fd, iovec_array_get_array(&iovec_array),
(int)iovec_array_len(&iovec_array)) < 0) {
return HTTP_INTERNAL_ERROR;
}
iovec_array_reset(&iovec_array);
record_array_reset(&record_array);

lwan_strbuf_reset(response->buffer);

Expand Down

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