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20 hours ago •
vislee
vislee
nginx的过滤模块
概述
过滤模块大量的被用于结束请求前向客户端发送resp被调用。 也有被用到保存请求body。
例如：
-
static模块的回调函数ngx_http_static_handler调用ngx_http_send_header发送响应的header，调用ngx_http_output_filter发送响应的body。
-
rewrite模块的return指令调用的ngx_http_send_response函数，最终也调用ngx_http_send_header和ngx_http_output_filter。
-
处理request body的函数调用的ngx_http_top_request_body_filter。
发送响应的这两个函数的定义，最终调用的是ngx_http_top_header_filter 和 ngx_http_top_body_filter。如下函数定义。 保存请求包调用的是ngx_http_top_request_body_filter。
typedef ngx_int_t (*ngx_http_output_header_filter_pt)(ngx_http_request_t *r);
typedef ngx_int_t (*ngx_http_output_body_filter_pt)
(ngx_http_request_t *r, ngx_chain_t *chain);
typedef ngx_int_t (*ngx_http_request_body_filter_pt)
(ngx_http_request_t *r, ngx_chain_t *chain);
ngx_http_output_header_filter_pt ngx_http_top_header_filter;
ngx_http_output_body_filter_pt ngx_http_top_body_filter;
ngx_int_t
ngx_http_send_header(ngx_http_request_t *r)
{
if (r->post_action) {
return NGX_OK;
}
if (r->header_sent) {
ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
"header already sent");
return NGX_ERROR;
}
if (r->err_status) {
r->headers_out.status = r->err_status;
r->headers_out.status_line.len = 0;
}
return ngx_http_top_header_filter(r);
}
ngx_int_t
ngx_http_output_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
ngx_int_t rc;
ngx_connection_t *c;
c = r->connection;
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
"http output filter \"%V?%V\"", &r->uri, &r->args);
rc = ngx_http_top_body_filter(r, in);
if (rc == NGX_ERROR) {
/* NGX_ERROR may be returned by any filter */
c->error = 1;
}
return rc;
}
响应过滤模块
响应包过滤模块通过一个静态的变量串联成一个链表，http响应数据从过滤模块开始执行到最后一个模块，过滤模块的先后顺序也是有影响的。例如有以下响应包过滤模块，第三方过滤模块会被添加到分割线的位置。 ngx_http_write_filter_module ngx_http_header_filter_module ngx_http_chunked_filter_module ngx_http_range_header_filter_module ngx_http_gzip_filter_module ngx_http_postpone_filter_module ngx_http_headers_filter_module // 添加resp header etag expire等 =-=-======================= ngx_http_copy_filter_module ngx_http_range_body_filter_module // 和断点续传相关的 ngx_http_not_modified_filter_module // 和http缓存相关的
过滤模块会被添加到header_filter和body_filter两个虚拟的链表上，这个顺序也是添加链表的顺序，每个模块被添加到链表的表头。因此这个顺序也是执行的相反顺序。具体参考《ngx中http模块的执行顺序》这篇文章。
过滤模块和普通的http模块一样，也是通过ctx的postconfiguration函数来添加到框架中的。 在ngx_http_block函数中遍历模块列表调用的。因此首先过滤模块的ngx_http_write_filter_module模块的ctx的postconfiguration函数指针指向的函数ngx_http_write_filter_init会被调用，接着调用ngx_http_header_filter_module模块的，调用ngx_http_range_header_filter_module模块的，最后调用ngx_http_not_modified_filter_module这个模块的。
过滤模块的postconfiguration函数：
// ngx_http_write_filter_module.c
static ngx_int_t
ngx_http_write_filter_init(ngx_conf_t *cf)
{
ngx_http_top_body_filter = ngx_http_write_filter;
return NGX_OK;
}
// ngx_http_header_filter_module.c
static ngx_int_t
ngx_http_header_filter_init(ngx_conf_t *cf)
{
ngx_http_top_header_filter = ngx_http_header_filter;
return NGX_OK;
}
// ngx_http_chunked_filter_module.c
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_chunked_filter_init(ngx_conf_t *cf)
{
ngx_http_next_header_filter = ngx_http_top_header_filter;
ngx_http_top_header_filter = ngx_http_chunked_header_filter;
ngx_http_next_body_filter = ngx_http_top_body_filter;
ngx_http_top_body_filter = ngx_http_chunked_body_filter;
return NGX_OK;
}
......
// ngx_http_not_modified_filter_module.c
static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
static ngx_int_t
ngx_http_not_modified_filter_init(ngx_conf_t *cf)
{
ngx_http_next_header_filter = ngx_http_top_header_filter;
ngx_http_top_header_filter = ngx_http_not_modified_header_filter;
return NGX_OK;
}
上面概述说了，发送响应头会调用ngx_http_top_header_filter，而ngx_http_top_header_filter最终指向的是ngx_http_not_modified_header_filter回调函数。函数实现如下，且该函数结束会调用ngx_http_next_header_filter，而ngx_http_next_header_filter变量是静态变量只在本文件有效，它指向的是倒数第二个模块的filter回调。 而每个filter回调结束都会调用一个属于本文件的ngx_http_next_header_filter指针指向的函数，最后调用到第一个被添加到header_filter这个链上的模块的回调函数ngx_http_header_filter。
static ngx_int_t
ngx_http_not_modified_header_filter(ngx_http_request_t *r)
{
if (r->headers_out.status != NGX_HTTP_OK
|| r != r->main
|| r->disable_not_modified)
{
return ngx_http_next_header_filter(r);
}
if (r->headers_in.if_unmodified_since
&& !ngx_http_test_if_unmodified(r))
{
return ngx_http_filter_finalize_request(r, NULL,
NGX_HTTP_PRECONDITION_FAILED);
}
if (r->headers_in.if_match
&& !ngx_http_test_if_match(r, r->headers_in.if_match, 0))
{
return ngx_http_filter_finalize_request(r, NULL,
NGX_HTTP_PRECONDITION_FAILED);
}
if (r->headers_in.if_modified_since || r->headers_in.if_none_match) {
if (r->headers_in.if_modified_since
&& ngx_http_test_if_modified(r))
{
return ngx_http_next_header_filter(r);
}
if (r->headers_in.if_none_match
&& !ngx_http_test_if_match(r, r->headers_in.if_none_match, 1))
{
return ngx_http_next_header_filter(r);
}
/* not modified */
r->headers_out.status = NGX_HTTP_NOT_MODIFIED;
r->headers_out.status_line.len = 0;
r->headers_out.content_type.len = 0;
ngx_http_clear_content_length(r);
ngx_http_clear_accept_ranges(r);
if (r->headers_out.content_encoding) {
r->headers_out.content_encoding->hash = 0;
r->headers_out.content_encoding = NULL;
}
return ngx_http_next_header_filter(r);
}
return ngx_http_next_header_filter(r);
}
// 真正把相应发给客户端的函数
static ngx_int_t
ngx_http_header_filter(ngx_http_request_t *r)
{
u_char *p;
size_t len;
ngx_str_t host, *status_line;
ngx_buf_t *b;
ngx_uint_t status, i, port;
ngx_chain_t out;
ngx_list_part_t *part;
ngx_table_elt_t *header;
ngx_connection_t *c;
ngx_http_core_loc_conf_t *clcf;
ngx_http_core_srv_conf_t *cscf;
u_char addr[NGX_SOCKADDR_STRLEN];
// 响应头是否已发送
if (r->header_sent) {
return NGX_OK;
}
r->header_sent = 1;
// 是否是子请求
if (r != r->main) {
return NGX_OK;
}
if (r->http_version < NGX_HTTP_VERSION_10) {
return NGX_OK;
}
if (r->method == NGX_HTTP_HEAD) {
r->header_only = 1;
}
if (r->headers_out.last_modified_time != -1) {
if (r->headers_out.status != NGX_HTTP_OK
&& r->headers_out.status != NGX_HTTP_PARTIAL_CONTENT
&& r->headers_out.status != NGX_HTTP_NOT_MODIFIED)
{
r->headers_out.last_modified_time = -1;
r->headers_out.last_modified = NULL;
}
}
len = sizeof("HTTP/1.x ") - 1 + sizeof(CRLF) - 1
/* the end of the header */
+ sizeof(CRLF) - 1;
/* status line */
if (r->headers_out.status_line.len) {
len += r->headers_out.status_line.len;
status_line = &r->headers_out.status_line;
#if (NGX_SUPPRESS_WARN)
status = 0;
#endif
} else {
status = r->headers_out.status;
if (status >= NGX_HTTP_OK
&& status < NGX_HTTP_LAST_2XX)
{
/* 2XX */
if (status == NGX_HTTP_NO_CONTENT) {
r->header_only = 1;
ngx_str_null(&r->headers_out.content_type);
r->headers_out.last_modified_time = -1;
r->headers_out.last_modified = NULL;
r->headers_out.content_length = NULL;
r->headers_out.content_length_n = -1;
}
status -= NGX_HTTP_OK;
status_line = &ngx_http_status_lines[status];
len += ngx_http_status_lines[status].len;
} else if (status >= NGX_HTTP_MOVED_PERMANENTLY
&& status < NGX_HTTP_LAST_3XX)
{
/* 3XX */
if (status == NGX_HTTP_NOT_MODIFIED) {
r->header_only = 1;
}
status = status - NGX_HTTP_MOVED_PERMANENTLY + NGX_HTTP_OFF_3XX;
status_line = &ngx_http_status_lines[status];
len += ngx_http_status_lines[status].len;
} else if (status >= NGX_HTTP_BAD_REQUEST
&& status < NGX_HTTP_LAST_4XX)
{
/* 4XX */
status = status - NGX_HTTP_BAD_REQUEST
+ NGX_HTTP_OFF_4XX;
status_line = &ngx_http_status_lines[status];
len += ngx_http_status_lines[status].len;
} else if (status >= NGX_HTTP_INTERNAL_SERVER_ERROR
&& status < NGX_HTTP_LAST_5XX)
{
/* 5XX */
status = status - NGX_HTTP_INTERNAL_SERVER_ERROR
+ NGX_HTTP_OFF_5XX;
status_line = &ngx_http_status_lines[status];
len += ngx_http_status_lines[status].len;
} else {
len += NGX_INT_T_LEN + 1 /* SP */;
status_line = NULL;
}
if (status_line && status_line->len == 0) {
status = r->headers_out.status;
len += NGX_INT_T_LEN + 1 /* SP */;
status_line = NULL;
}
}
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
if (r->headers_out.server == NULL) {
if (clcf->server_tokens == NGX_HTTP_SERVER_TOKENS_ON) {
len += sizeof(ngx_http_server_full_string) - 1;
} else if (clcf->server_tokens == NGX_HTTP_SERVER_TOKENS_BUILD) {
len += sizeof(ngx_http_server_build_string) - 1;
} else {
len += sizeof(ngx_http_server_string) - 1;
}
}
if (r->headers_out.date == NULL) {
len += sizeof("Date: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
}
if (r->headers_out.content_type.len) {
len += sizeof("Content-Type: ") - 1
+ r->headers_out.content_type.len + 2;
if (r->headers_out.content_type_len == r->headers_out.content_type.len
&& r->headers_out.charset.len)
{
len += sizeof("; charset=") - 1 + r->headers_out.charset.len;
}
}
if (r->headers_out.content_length == NULL
&& r->headers_out.content_length_n >= 0)
{
len += sizeof("Content-Length: ") - 1 + NGX_OFF_T_LEN + 2;
}
if (r->headers_out.last_modified == NULL
&& r->headers_out.last_modified_time != -1)
{
len += sizeof("Last-Modified: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
}
c = r->connection;
if (r->headers_out.location
&& r->headers_out.location->value.len
&& r->headers_out.location->value.data[0] == '/'
&& clcf->absolute_redirect)
{
r->headers_out.location->hash = 0;
if (clcf->server_name_in_redirect) {
cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);
host = cscf->server_name;
} else if (r->headers_in.server.len) {
host = r->headers_in.server;
} else {
host.len = NGX_SOCKADDR_STRLEN;
host.data = addr;
if (ngx_connection_local_sockaddr(c, &host, 0) != NGX_OK) {
return NGX_ERROR;
}
}
port = ngx_inet_get_port(c->local_sockaddr);
len += sizeof("Location: https://") - 1
+ host.len
+ r->headers_out.location->value.len + 2;
if (clcf->port_in_redirect) {
#if (NGX_HTTP_SSL)
if (c->ssl)
port = (port == 443) ? 0 : port;
else
#endif
port = (port == 80) ? 0 : port;
} else {
port = 0;
}
if (port) {
len += sizeof(":65535") - 1;
}
} else {
ngx_str_null(&host);
port = 0;
}
if (r->chunked) {
len += sizeof("Transfer-Encoding: chunked" CRLF) - 1;
}
if (r->headers_out.status == NGX_HTTP_SWITCHING_PROTOCOLS) {
len += sizeof("Connection: upgrade" CRLF) - 1;
} else if (r->keepalive) {
len += sizeof("Connection: keep-alive" CRLF) - 1;
/*
* MSIE and Opera ignore the "Keep-Alive: timeout=<N>" header.
* MSIE keeps the connection alive for about 60-65 seconds.
* Opera keeps the connection alive very long.
* Mozilla keeps the connection alive for N plus about 1-10 seconds.
* Konqueror keeps the connection alive for about N seconds.
*/
if (clcf->keepalive_header) {
len += sizeof("Keep-Alive: timeout=") - 1 + NGX_TIME_T_LEN + 2;
}
} else {
len += sizeof("Connection: close" CRLF) - 1;
}
#if (NGX_HTTP_GZIP)
if (r->gzip_vary) {
if (clcf->gzip_vary) {
len += sizeof("Vary: Accept-Encoding" CRLF) - 1;
} else {
r->gzip_vary = 0;
}
}
#endif
part = &r->headers_out.headers.part;
header = part->elts;
for (i = 0; /* void */; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
header = part->elts;
i = 0;
}
if (header[i].hash == 0) {
continue;
}
len += header[i].key.len + sizeof(": ") - 1 + header[i].value.len
+ sizeof(CRLF) - 1;
}
b = ngx_create_temp_buf(r->pool, len);
if (b == NULL) {
return NGX_ERROR;
}
/* "HTTP/1.x " */
b->last = ngx_cpymem(b->last, "HTTP/1.1 ", sizeof("HTTP/1.x ") - 1);
/* status line */
if (status_line) {
b->last = ngx_copy(b->last, status_line->data, status_line->len);
} else {
b->last = ngx_sprintf(b->last, "%03ui ", status);
}
*b->last++ = CR; *b->last++ = LF;
if (r->headers_out.server == NULL) {
if (clcf->server_tokens == NGX_HTTP_SERVER_TOKENS_ON) {
p = ngx_http_server_full_string;
len = sizeof(ngx_http_server_full_string) - 1;
} else if (clcf->server_tokens == NGX_HTTP_SERVER_TOKENS_BUILD) {
p = ngx_http_server_build_string;
len = sizeof(ngx_http_server_build_string) - 1;
} else {
p = ngx_http_server_string;
len = sizeof(ngx_http_server_string) - 1;
}
b->last = ngx_cpymem(b->last, p, len);
}
if (r->headers_out.date == NULL) {
b->last = ngx_cpymem(b->last, "Date: ", sizeof("Date: ") - 1);
b->last = ngx_cpymem(b->last, ngx_cached_http_time.data,
ngx_cached_http_time.len);
*b->last++ = CR; *b->last++ = LF;
}
if (r->headers_out.content_type.len) {
b->last = ngx_cpymem(b->last, "Content-Type: ",
sizeof("Content-Type: ") - 1);
p = b->last;
b->last = ngx_copy(b->last, r->headers_out.content_type.data,
r->headers_out.content_type.len);
if (r->headers_out.content_type_len == r->headers_out.content_type.len
&& r->headers_out.charset.len)
{
b->last = ngx_cpymem(b->last, "; charset=",
sizeof("; charset=") - 1);
b->last = ngx_copy(b->last, r->headers_out.charset.data,
r->headers_out.charset.len);
/* update r->headers_out.content_type for possible logging */
r->headers_out.content_type.len = b->last - p;
r->headers_out.content_type.data = p;
}
*b->last++ = CR; *b->last++ = LF;
}
if (r->headers_out.content_length == NULL
&& r->headers_out.content_length_n >= 0)
{
b->last = ngx_sprintf(b->last, "Content-Length: %O" CRLF,
r->headers_out.content_length_n);
}
if (r->headers_out.last_modified == NULL
&& r->headers_out.last_modified_time != -1)
{
b->last = ngx_cpymem(b->last, "Last-Modified: ",
sizeof("Last-Modified: ") - 1);
b->last = ngx_http_time(b->last, r->headers_out.last_modified_time);
*b->last++ = CR; *b->last++ = LF;
}
if (host.data) {
p = b->last + sizeof("Location: ") - 1;
b->last = ngx_cpymem(b->last, "Location: http",
sizeof("Location: http") - 1);
#if (NGX_HTTP_SSL)
if (c->ssl) {
*b->last++ ='s';
}
#endif
*b->last++ = ':'; *b->last++ = '/'; *b->last++ = '/';
b->last = ngx_copy(b->last, host.data, host.len);
if (port) {
b->last = ngx_sprintf(b->last, ":%ui", port);
}
b->last = ngx_copy(b->last, r->headers_out.location->value.data,
r->headers_out.location->value.len);
/* update r->headers_out.location->value for possible logging */
r->headers_out.location->value.len = b->last - p;
r->headers_out.location->value.data = p;
ngx_str_set(&r->headers_out.location->key, "Location");
*b->last++ = CR; *b->last++ = LF;
}
if (r->chunked) {
b->last = ngx_cpymem(b->last, "Transfer-Encoding: chunked" CRLF,
sizeof("Transfer-Encoding: chunked" CRLF) - 1);
}
if (r->headers_out.status == NGX_HTTP_SWITCHING_PROTOCOLS) {
b->last = ngx_cpymem(b->last, "Connection: upgrade" CRLF,
sizeof("Connection: upgrade" CRLF) - 1);
} else if (r->keepalive) {
b->last = ngx_cpymem(b->last, "Connection: keep-alive" CRLF,
sizeof("Connection: keep-alive" CRLF) - 1);
if (clcf->keepalive_header) {
b->last = ngx_sprintf(b->last, "Keep-Alive: timeout=%T" CRLF,
clcf->keepalive_header);
}
} else {
b->last = ngx_cpymem(b->last, "Connection: close" CRLF,
sizeof("Connection: close" CRLF) - 1);
}
#if (NGX_HTTP_GZIP)
if (r->gzip_vary) {
b->last = ngx_cpymem(b->last, "Vary: Accept-Encoding" CRLF,
sizeof("Vary: Accept-Encoding" CRLF) - 1);
}
#endif
part = &r->headers_out.headers.part;
header = part->elts;
for (i = 0; /* void */; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
header = part->elts;
i = 0;
}
if (header[i].hash == 0) {
continue;
}
b->last = ngx_copy(b->last, header[i].key.data, header[i].key.len);
*b->last++ = ':'; *b->last++ = ' ';
b->last = ngx_copy(b->last, header[i].value.data, header[i].value.len);
*b->last++ = CR; *b->last++ = LF;
}
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
"%*s", (size_t) (b->last - b->pos), b->pos);
/* the end of HTTP header */
*b->last++ = CR; *b->last++ = LF;
r->header_size = b->last - b->pos;
if (r->header_only) {
b->last_buf = 1;
}
out.buf = b;
out.next = NULL;
return ngx_http_write_filter(r, &out);
}
