Привет.

Написал простой фильтр для nginx.
nginx фронтенд(localhost:8000). apache бэкенд(localhost:80).

Код фильтра.
[code]
#include "pg.h"

#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>

static ngx_int_t ngx_http_pg_filter_init(ngx_conf_t *cf);
static ngx_int_t ngx_http_pg_header_filter(ngx_http_request_t *r);
static ngx_int_t ngx_http_pg_body_filter(ngx_http_request_t *r, ngx_chain_t *in);

static ngx_http_module_t ngx_http_pg_module_ctx = {
NULL, /* preconfiguration */
ngx_http_pg_filter_init, /* postconfiguration */

NULL, /* create main configuration */
NULL, /* init main configuration */

NULL, /* create server configuration */
NULL, /* merge server configuration */

NULL, /* create location configuration */
NULL /* merge location configuration */
};

ngx_module_t ngx_http_pg_module = {
NGX_MODULE_V1,
&ngx_http_pg_module_ctx, /* module context */
NULL, /* module directives */
NGX_HTTP_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};

static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
static ngx_http_output_body_filter_pt ngx_http_next_body_filter;

static ngx_int_t ngx_http_pg_header_filter(ngx_http_request_t *r)
{

return ngx_http_next_header_filter(r);
}

static ngx_int_t ngx_http_pg_body_filter(ngx_http_request_t *r, ngx_chain_t *in) {

if(in == NULL || r->header_only)
return ngx_http_next_body_filter(r, in);
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,"buf_size:%d", ngx_buf_size(in->buf));
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,"status:%d", r->headers_out.status);
return ngx_http_next_body_filter(r, in);
}

static ngx_int_t ngx_http_pg_filter_init(ngx_conf_t *cf) {
ngx_http_next_header_filter = ngx_http_top_header_filter;
ngx_http_top_header_filter = ngx_http_pg_header_filter;

ngx_http_next_body_filter = ngx_http_top_body_filter;
ngx_http_top_body_filter = ngx_http_pg_body_filter;

return NGX_OK;
}
[/code]

Файл nginx.conf
[code]
daemon off;

worker_processes 1;

events {
worker_connections 1024;
}

http {
include mime.types;
default_type application/octet-stream;

keepalive_timeout 0;

server {

listen 8000;
server_name localhost;

location / {
proxy_pass http://localhost:80;
}
}
}
[/code]

В браузере шлю запрос http://localhost:8000/1.html.

1.html выглядит так:
[code]
HELLO
[/code]

Получаю в error.log
[code]
#нормальный ответ
2010/06/01 14:54:15 [error] 11576#0: *1 buf_size:5 while sending to client, client: 127.0.0.1, server: localhost, request: "GET /1.html HTTP/1.1", upstream: "http://127.0.0.1:80/1.html", host: "localhost:8000"
2010/06/01 14:54:15 [error] 11576#0: *1 status:200 while sending to client, client: 127.0.0.1, server: localhost, request: "GET /1.html HTTP/1.1", upstream: "http://127.0.0.1:80/1.html", host: "localhost:8000"

#повторный ответ с пустым буфером
2010/06/01 14:54:15 [error] 11576#0: *1 [b]buf_size:0[/b] while sending to client, client: 127.0.0.1, server: localhost, request: "GET /1.html HTTP/1.1", upstream: "http://127.0.0.1:80/1.html", host: "localhost:8000"
2010/06/01 14:54:15 [error] 11576#0: *1 status:200 while sending to client, client: 127.0.0.1, server: localhost, request: "GET /1.html HTTP/1.1", upstream: "http://127.0.0.1:80/1.html", host: "localhost:8000"


#нормальный ответ
2010/06/01 14:54:15 [error] 11576#0: *3 buf_size:283 while sending to client, client: 127.0.0.1, server: localhost, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:80/favicon.ico", host: "localhost:8000"
2010/06/01 14:54:15 [error] 11576#0: *3 status:404 while sending to client, client: 127.0.0.1, server: localhost, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:80/favicon.ico", host: "localhost:8000"

#повторный ответ с пустым буфером
2010/06/01 14:54:15 [error] 11576#0: *3 [b]buf_size:0[/b] while sending to client, client: 127.0.0.1, server: localhost, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:80/favicon.ico", host: "localhost:8000"
2010/06/01 14:54:15 [error] 11576#0: *3 status:404 while sending to client, client: 127.0.0.1, server: localhost, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:80/favicon.ico", host: "localhost:8000"
[/code]

Откуда берется повторный ответ с пустым буфером?