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ngx_http_upstream.c
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// annotated by chrono since 2016
//
// * ngx_http_upstream_create
// * ngx_http_upstream_init
// * ngx_http_upstream_init_request
// * ngx_http_upstream_send_request
// * ngx_http_upstream_process_header
// * ngx_http_upstream_finalize_request
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
#if (NGX_HTTP_CACHE)
static ngx_int_t ngx_http_upstream_cache(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_cache_get(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_http_file_cache_t **cache);
static ngx_int_t ngx_http_upstream_cache_send(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_cache_background_update(
ngx_http_request_t *r, ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_cache_check_range(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_cache_status(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_cache_last_modified(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_cache_etag(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
#endif
// 启动upstream框架，开始与上游服务器异步交互
static void ngx_http_upstream_init_request(ngx_http_request_t *r);
static void ngx_http_upstream_resolve_handler(ngx_resolver_ctx_t *ctx);
static void ngx_http_upstream_rd_check_broken_connection(ngx_http_request_t *r);
static void ngx_http_upstream_wr_check_broken_connection(ngx_http_request_t *r);
static void ngx_http_upstream_check_broken_connection(ngx_http_request_t *r,
ngx_event_t *ev);
// 尝试连接后端服务器
static void ngx_http_upstream_connect(ngx_http_request_t *r,
ngx_http_upstream_t *u);
// 如果已经发送了请求
// 需要重新初始化，调用reinit_request
// 如果有下游请求体数据也要重新初始化
static ngx_int_t ngx_http_upstream_reinit(ngx_http_request_t *r,
ngx_http_upstream_t *u);
// 向后端发送请求
static void ngx_http_upstream_send_request(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_uint_t do_write);
// 后端服务器连接成功，发送数据
static ngx_int_t ngx_http_upstream_send_request_body(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_uint_t do_write);
static void ngx_http_upstream_send_request_handler(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_read_request_handler(ngx_http_request_t *r);
static void ngx_http_upstream_process_header(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_test_next(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_intercept_errors(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_test_connect(ngx_connection_t *c);
// upstream机制处理头信息
// 拷贝信息到主请求的header结构体里
static ngx_int_t ngx_http_upstream_process_headers(ngx_http_request_t *r,
ngx_http_upstream_t *u);
//static void ngx_http_upstream_process_body_in_memory(ngx_http_request_t *r,
static ngx_int_t ngx_http_upstream_process_trailers(ngx_http_request_t *r,
ngx_http_upstream_t *u);
// 发送数据给下游，之前已经正确处理了上游的响应头
static void ngx_http_upstream_send_response(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_upgrade(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_upgraded_read_downstream(ngx_http_request_t *r);
static void ngx_http_upstream_upgraded_write_downstream(ngx_http_request_t *r);
static void ngx_http_upstream_upgraded_read_upstream(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_upgraded_write_upstream(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_process_upgraded(ngx_http_request_t *r,
ngx_uint_t from_upstream, ngx_uint_t do_write);
static void
ngx_http_upstream_process_non_buffered_downstream(ngx_http_request_t *r);
static void
ngx_http_upstream_process_non_buffered_upstream(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void
ngx_http_upstream_process_non_buffered_request(ngx_http_request_t *r,
ngx_uint_t do_write);
// 下面两个函数在1.19.1改为非static
// 什么也不做，空函数
//static ngx_int_t ngx_http_upstream_non_buffered_filter_init(void *data);
// 简单地把buffer里收到的数据依次挂到out_bufs链表的末尾
// 这意味着upstream框架设置的buffer必须足够大，能够容纳上游的所有数据
//static ngx_int_t ngx_http_upstream_non_buffered_filter(void *data,
// ssize_t bytes);
#if (NGX_THREADS)
static ngx_int_t ngx_http_upstream_thread_handler(ngx_thread_task_t *task,
ngx_file_t *file);
static void ngx_http_upstream_thread_event_handler(ngx_event_t *ev);
#endif
static ngx_int_t ngx_http_upstream_output_filter(void *data,
ngx_chain_t *chain);
static void ngx_http_upstream_process_downstream(ngx_http_request_t *r);
static void ngx_http_upstream_process_upstream(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_process_request(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_store(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_dummy_handler(ngx_http_request_t *r,
ngx_http_upstream_t *u);
static void ngx_http_upstream_next(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_uint_t ft_type);
static void ngx_http_upstream_cleanup(void *data);
// 结束请求，这时会调用finalize_request回调函数
// 让upstream模块有机会做一些自己的收尾工作
// 最后调用ngx_http_finalize_request
static void ngx_http_upstream_finalize_request(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_int_t rc);
static ngx_int_t ngx_http_upstream_process_header_line(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_content_length(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_last_modified(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_set_cookie(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t
ngx_http_upstream_process_cache_control(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_ignore_header_line(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_expires(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_accel_expires(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_limit_rate(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_buffering(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_charset(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_connection(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t
ngx_http_upstream_process_transfer_encoding(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_vary(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_header_line(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t
ngx_http_upstream_copy_multi_header_lines(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_content_type(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_last_modified(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_rewrite_location(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_rewrite_refresh(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_rewrite_set_cookie(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_allow_ranges(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
#if (NGX_HTTP_GZIP)
static ngx_int_t ngx_http_upstream_copy_content_encoding(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
#endif
static ngx_int_t ngx_http_upstream_add_variables(ngx_conf_t *cf);
static ngx_int_t ngx_http_upstream_addr_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_status_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_response_time_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_response_length_variable(
ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_header_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_trailer_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_cookie_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
static char *ngx_http_upstream(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy);
static char *ngx_http_upstream_server(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static ngx_int_t ngx_http_upstream_set_local(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_http_upstream_local_t *local);
static void *ngx_http_upstream_create_main_conf(ngx_conf_t *cf);
// upstream框架会调用peer.init_upstream
// 初始化每个上游服务器列表所使用的load-balance模块
static char *ngx_http_upstream_init_main_conf(ngx_conf_t *cf, void *conf);
#if (NGX_HTTP_SSL)
static void ngx_http_upstream_ssl_init_connection(ngx_http_request_t *,
ngx_http_upstream_t *u, ngx_connection_t *c);
static void ngx_http_upstream_ssl_handshake_handler(ngx_connection_t *c);
static void ngx_http_upstream_ssl_handshake(ngx_http_request_t *,
ngx_http_upstream_t *u, ngx_connection_t *c);
static void ngx_http_upstream_ssl_save_session(ngx_connection_t *c);
static ngx_int_t ngx_http_upstream_ssl_name(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_connection_t *c);
static ngx_int_t ngx_http_upstream_ssl_certificate(ngx_http_request_t *r,
ngx_http_upstream_t *u, ngx_connection_t *c);
#endif
// 解析常用的上游响应头字段
// 使用函数ngx_http_upstream_process_header_line设置到headers_in里
static ngx_http_upstream_header_t ngx_http_upstream_headers_in[] = {
{ ngx_string("Status"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, status),
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("Content-Type"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, content_type),
ngx_http_upstream_copy_content_type, 0, 1 },
{ ngx_string("Content-Length"),
ngx_http_upstream_process_content_length, 0,
ngx_http_upstream_ignore_header_line, 0, 0 },
{ ngx_string("Date"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, date),
ngx_http_upstream_copy_header_line,
offsetof(ngx_http_headers_out_t, date), 0 },
{ ngx_string("Last-Modified"),
ngx_http_upstream_process_last_modified, 0,
ngx_http_upstream_copy_last_modified, 0, 0 },
{ ngx_string("ETag"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, etag),
ngx_http_upstream_copy_header_line,
offsetof(ngx_http_headers_out_t, etag), 0 },
{ ngx_string("Server"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, server),
ngx_http_upstream_copy_header_line,
offsetof(ngx_http_headers_out_t, server), 0 },
{ ngx_string("WWW-Authenticate"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, www_authenticate),
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("Location"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, location),
ngx_http_upstream_rewrite_location, 0, 0 },
{ ngx_string("Refresh"),
ngx_http_upstream_ignore_header_line, 0,
ngx_http_upstream_rewrite_refresh, 0, 0 },
{ ngx_string("Set-Cookie"),
ngx_http_upstream_process_set_cookie,
offsetof(ngx_http_upstream_headers_in_t, cookies),
ngx_http_upstream_rewrite_set_cookie, 0, 1 },
{ ngx_string("Content-Disposition"),
ngx_http_upstream_ignore_header_line, 0,
ngx_http_upstream_copy_header_line, 0, 1 },
{ ngx_string("Cache-Control"),
ngx_http_upstream_process_cache_control, 0,
ngx_http_upstream_copy_multi_header_lines,
offsetof(ngx_http_headers_out_t, cache_control), 1 },
{ ngx_string("Expires"),
ngx_http_upstream_process_expires, 0,
ngx_http_upstream_copy_header_line,
offsetof(ngx_http_headers_out_t, expires), 1 },
{ ngx_string("Accept-Ranges"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, accept_ranges),
ngx_http_upstream_copy_allow_ranges,
offsetof(ngx_http_headers_out_t, accept_ranges), 1 },
{ ngx_string("Content-Range"),
ngx_http_upstream_ignore_header_line, 0,
ngx_http_upstream_copy_header_line,
offsetof(ngx_http_headers_out_t, content_range), 0 },
{ ngx_string("Connection"),
ngx_http_upstream_process_connection, 0,
ngx_http_upstream_ignore_header_line, 0, 0 },
{ ngx_string("Keep-Alive"),
ngx_http_upstream_ignore_header_line, 0,
ngx_http_upstream_ignore_header_line, 0, 0 },
{ ngx_string("Vary"),
ngx_http_upstream_process_vary, 0,
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("Link"),
ngx_http_upstream_ignore_header_line, 0,
ngx_http_upstream_copy_multi_header_lines,
offsetof(ngx_http_headers_out_t, link), 0 },
{ ngx_string("X-Accel-Expires"),
ngx_http_upstream_process_accel_expires, 0,
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("X-Accel-Redirect"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, x_accel_redirect),
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("X-Accel-Limit-Rate"),
ngx_http_upstream_process_limit_rate, 0,
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("X-Accel-Buffering"),
ngx_http_upstream_process_buffering, 0,
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("X-Accel-Charset"),
ngx_http_upstream_process_charset, 0,
ngx_http_upstream_copy_header_line, 0, 0 },
{ ngx_string("Transfer-Encoding"),
ngx_http_upstream_process_transfer_encoding, 0,
ngx_http_upstream_ignore_header_line, 0, 0 },
#if (NGX_HTTP_GZIP)
{ ngx_string("Content-Encoding"),
ngx_http_upstream_process_header_line,
offsetof(ngx_http_upstream_headers_in_t, content_encoding),
ngx_http_upstream_copy_content_encoding, 0, 0 },
#endif
{ ngx_null_string, NULL, 0, NULL, 0, 0 }
};
static ngx_command_t ngx_http_upstream_commands[] = {
{ ngx_string("upstream"),
NGX_HTTP_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE1,
ngx_http_upstream,
0,
0,
NULL },
{ ngx_string("server"),
NGX_HTTP_UPS_CONF|NGX_CONF_1MORE,
ngx_http_upstream_server,
NGX_HTTP_SRV_CONF_OFFSET,
0,
NULL },
ngx_null_command
};
static ngx_http_module_t ngx_http_upstream_module_ctx = {
ngx_http_upstream_add_variables, /* preconfiguration */
NULL, /* postconfiguration */
ngx_http_upstream_create_main_conf, /* create main configuration */
ngx_http_upstream_init_main_conf, /* init main configuration */
NULL, /* create server configuration */
NULL, /* merge server configuration */
NULL, /* create location configuration */
NULL /* merge location configuration */
};
ngx_module_t ngx_http_upstream_module = {
NGX_MODULE_V1,
&ngx_http_upstream_module_ctx, /* module context */
ngx_http_upstream_commands, /* 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_variable_t ngx_http_upstream_vars[] = {
{ ngx_string("upstream_addr"), NULL,
ngx_http_upstream_addr_variable, 0,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_status"), NULL,
ngx_http_upstream_status_variable, 0,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_connect_time"), NULL,
ngx_http_upstream_response_time_variable, 2,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_header_time"), NULL,
ngx_http_upstream_response_time_variable, 1,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_response_time"), NULL,
ngx_http_upstream_response_time_variable, 0,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_response_length"), NULL,
ngx_http_upstream_response_length_variable, 0,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_bytes_received"), NULL,
ngx_http_upstream_response_length_variable, 1,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_bytes_sent"), NULL,
ngx_http_upstream_response_length_variable, 2,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
#if (NGX_HTTP_CACHE)
{ ngx_string("upstream_cache_status"), NULL,
ngx_http_upstream_cache_status, 0,
NGX_HTTP_VAR_NOCACHEABLE, 0 },
{ ngx_string("upstream_cache_last_modified"), NULL,
ngx_http_upstream_cache_last_modified, 0,
NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_NOHASH, 0 },
{ ngx_string("upstream_cache_etag"), NULL,
ngx_http_upstream_cache_etag, 0,
NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_NOHASH, 0 },
#endif
{ ngx_string("upstream_http_"), NULL, ngx_http_upstream_header_variable,
0, NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_PREFIX, 0 },
{ ngx_string("upstream_trailer_"), NULL, ngx_http_upstream_trailer_variable,
0, NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_PREFIX, 0 },
{ ngx_string("upstream_cookie_"), NULL, ngx_http_upstream_cookie_variable,
0, NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_PREFIX, 0 },
ngx_http_null_variable
};
static ngx_http_upstream_next_t ngx_http_upstream_next_errors[] = {
{ 500, NGX_HTTP_UPSTREAM_FT_HTTP_500 },
{ 502, NGX_HTTP_UPSTREAM_FT_HTTP_502 },
{ 503, NGX_HTTP_UPSTREAM_FT_HTTP_503 },
{ 504, NGX_HTTP_UPSTREAM_FT_HTTP_504 },
{ 403, NGX_HTTP_UPSTREAM_FT_HTTP_403 },
{ 404, NGX_HTTP_UPSTREAM_FT_HTTP_404 },
{ 429, NGX_HTTP_UPSTREAM_FT_HTTP_429 },
{ 0, 0 }
};
ngx_conf_bitmask_t ngx_http_upstream_cache_method_mask[] = {
{ ngx_string("GET"), NGX_HTTP_GET },
{ ngx_string("HEAD"), NGX_HTTP_HEAD },
{ ngx_string("POST"), NGX_HTTP_POST },
{ ngx_null_string, 0 }
};
ngx_conf_bitmask_t ngx_http_upstream_ignore_headers_masks[] = {
{ ngx_string("X-Accel-Redirect"), NGX_HTTP_UPSTREAM_IGN_XA_REDIRECT },
{ ngx_string("X-Accel-Expires"), NGX_HTTP_UPSTREAM_IGN_XA_EXPIRES },
{ ngx_string("X-Accel-Limit-Rate"), NGX_HTTP_UPSTREAM_IGN_XA_LIMIT_RATE },
{ ngx_string("X-Accel-Buffering"), NGX_HTTP_UPSTREAM_IGN_XA_BUFFERING },
{ ngx_string("X-Accel-Charset"), NGX_HTTP_UPSTREAM_IGN_XA_CHARSET },
{ ngx_string("Expires"), NGX_HTTP_UPSTREAM_IGN_EXPIRES },
{ ngx_string("Cache-Control"), NGX_HTTP_UPSTREAM_IGN_CACHE_CONTROL },
{ ngx_string("Set-Cookie"), NGX_HTTP_UPSTREAM_IGN_SET_COOKIE },
{ ngx_string("Vary"), NGX_HTTP_UPSTREAM_IGN_VARY },
{ ngx_null_string, 0 }
};
// Nginx HTTP框架接收到下游的连接就会调用ngx_http_create_request()
// 创建ngx_http_request_t结构体
// 这时成员upstream默认是空指针，表示不使用upstream框架。
ngx_int_t
ngx_http_upstream_create(ngx_http_request_t *r)
{
ngx_http_upstream_t *u;
// 获取当前请求里的upstream结构
u = r->upstream;
// 如果已经存在，表示之前调用过，就要清理
if (u && u->cleanup) {
r->main->count++;
ngx_http_upstream_cleanup(r);
}
// 此时upstream应该是一个空指针
// 创建upstream结构体
u = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_t));
if (u == NULL) {
return NGX_ERROR;
}
// 赋值给请求对象
r->upstream = u;
u->peer.log = r->connection->log;
u->peer.log_error = NGX_ERROR_ERR;
#if (NGX_HTTP_CACHE)
r->cache = NULL;
#endif
// 默认上游的数据是unset
u->headers_in.content_length_n = -1;
u->headers_in.last_modified_time = -1;
return NGX_OK;
}
// 启动upstream框架，开始与上游服务器异步交互
void
ngx_http_upstream_init(ngx_http_request_t *r)
{
ngx_connection_t *c;
// 获取连接
c = r->connection;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
"http init upstream, client timer: %d", c->read->timer_set);
#if (NGX_HTTP_V2)
if (r->stream) {
ngx_http_upstream_init_request(r);
return;
}
#endif
// 如果连接设置了超时，那么就要删除定时器
// 保证连接后端时不会被超时结束
if (c->read->timer_set) {
ngx_del_timer(c->read);
}
// clear event也就是et模式
// 注册写事件
if (ngx_event_flags & NGX_USE_CLEAR_EVENT) {
if (!c->write->active) {
if (ngx_add_event(c->write, NGX_WRITE_EVENT, NGX_CLEAR_EVENT)
== NGX_ERROR)
{
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
}
}
// 真正的启动操作在这里
ngx_http_upstream_init_request(r);
}
// 启动upstream框架，开始与上游服务器异步交互
// 调用模块的create_request,创建要发送给后端的请求数据
static void
ngx_http_upstream_init_request(ngx_http_request_t *r)
{
ngx_str_t *host;
ngx_uint_t i;
ngx_resolver_ctx_t *ctx, temp;
ngx_http_cleanup_t *cln;
ngx_http_upstream_t *u;
ngx_http_core_loc_conf_t *clcf;
ngx_http_upstream_srv_conf_t *uscf, **uscfp;
ngx_http_upstream_main_conf_t *umcf;
if (r->aio) {
return;
}
// 获取当前请求里的upstream结构
u = r->upstream;
#if (NGX_HTTP_CACHE)
if (u->conf->cache) {
ngx_int_t rc;
rc = ngx_http_upstream_cache(r, u);
if (rc == NGX_BUSY) {
r->write_event_handler = ngx_http_upstream_init_request;
return;
}
r->write_event_handler = ngx_http_request_empty_handler;
if (rc == NGX_ERROR) {
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
if (rc == NGX_OK) {
rc = ngx_http_upstream_cache_send(r, u);
if (rc == NGX_DONE) {
return;
}
if (rc == NGX_HTTP_UPSTREAM_INVALID_HEADER) {
rc = NGX_DECLINED;
r->cached = 0;
u->buffer.start = NULL;
u->cache_status = NGX_HTTP_CACHE_MISS;
u->request_sent = 1;
}
}
if (rc != NGX_DECLINED) {
ngx_http_finalize_request(r, rc);
return;
}
}
#endif
u->store = u->conf->store;
// 检查客户端断连
if (!u->store && !r->post_action && !u->conf->ignore_client_abort) {
if (r->connection->read->ready) {
ngx_post_event(r->connection->read, &ngx_posted_events);
} else {
if (ngx_handle_read_event(r->connection->read, 0) != NGX_OK) {
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
}
r->read_event_handler = ngx_http_upstream_rd_check_broken_connection;
r->write_event_handler = ngx_http_upstream_wr_check_broken_connection;
}
// 检查下游请求里的请求体数据
if (r->request_body) {
// 如果有就赋值给upstream结构体
u->request_bufs = r->request_body->bufs;
}
// 调用模块的create_request
// 创建要发送给后端的请求数据
if (u->create_request(r) != NGX_OK) {
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
if (ngx_http_upstream_set_local(r, u, u->conf->local) != NGX_OK) {
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
// 是否要求上游keep alive
if (u->conf->socket_keepalive) {
u->peer.so_keepalive = 1;
}
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
u->output.alignment = clcf->directio_alignment;
u->output.pool = r->pool;
u->output.bufs.num = 1;
u->output.bufs.size = clcf->client_body_buffer_size;
if (u->output.output_filter == NULL) {
u->output.output_filter = ngx_chain_writer;
u->output.filter_ctx = &u->writer;
}
u->writer.pool = r->pool;
// 上游的连接状态，可能连接多个，所以是数组
if (r->upstream_states == NULL) {
r->upstream_states = ngx_array_create(r->pool, 1,
sizeof(ngx_http_upstream_state_t));
if (r->upstream_states == NULL) {
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
} else {
u->state = ngx_array_push(r->upstream_states);
if (u->state == NULL) {
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));
}
// 添加请求的清理机制
cln = ngx_http_cleanup_add(r, 0);
if (cln == NULL) {
ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
// 设置清理handler
cln->handler = ngx_http_upstream_cleanup;
cln->data = r;
u->cleanup = &cln->handler;
// 没有手工指定上游地址
// 使用upsteam{}配置，负载均衡
if (u->resolved == NULL) {
uscf = u->conf->upstream;
} else {
#if (NGX_HTTP_SSL)
u->ssl_name = u->resolved->host;
#endif
host = &u->resolved->host;
umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);
uscfp = umcf->upstreams.elts;
for (i = 0; i < umcf->upstreams.nelts; i++) {
uscf = uscfp[i];
if (uscf->host.len == host->len
&& ((uscf->port == 0 && u->resolved->no_port)
|| uscf->port == u->resolved->port)
&& ngx_strncasecmp(uscf->host.data, host->data, host->len) == 0)
{
goto found;
}
}
if (u->resolved->sockaddr) {
if (u->resolved->port == 0
&& u->resolved->sockaddr->sa_family != AF_UNIX)
{
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"no port in upstream \"%V\"", host);
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
if (ngx_http_upstream_create_round_robin_peer(r, u->resolved)
!= NGX_OK)
{
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
ngx_http_upstream_connect(r, u);
return;
}
if (u->resolved->port == 0) {
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"no port in upstream \"%V\"", host);
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
temp.name = *host;
ctx = ngx_resolve_start(clcf->resolver, &temp);
if (ctx == NULL) {
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
if (ctx == NGX_NO_RESOLVER) {
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"no resolver defined to resolve %V", host);
ngx_http_upstream_finalize_request(r, u, NGX_HTTP_BAD_GATEWAY);
return;
}
ctx->name = *host;
ctx->handler = ngx_http_upstream_resolve_handler;
ctx->data = r;
ctx->timeout = clcf->resolver_timeout;
u->resolved->ctx = ctx;
if (ngx_resolve_name(ctx) != NGX_OK) {
u->resolved->ctx = NULL;
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
return;
}
found:
if (uscf == NULL) {
ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
"no upstream configuration");
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
// 设置upstream服务器配置
u->upstream = uscf;
#if (NGX_HTTP_SSL)
u->ssl_name = uscf->host;
#endif
// 调用peer.init，loadbalance模块负载均衡选择后端服务器
if (uscf->peer.init(r, uscf) != NGX_OK) {
ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_INTERNAL_SERVER_ERROR);
return;
}
// 开始连接上游的时间
u->peer.start_time = ngx_current_msec;
if (u->conf->next_upstream_tries
&& u->peer.tries > u->conf->next_upstream_tries)
{
u->peer.tries = u->conf->next_upstream_tries;
}
// 尝试连接后端服务器
ngx_http_upstream_connect(r, u);
}
#if (NGX_HTTP_CACHE)
static ngx_int_t
ngx_http_upstream_cache(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
ngx_int_t rc;
ngx_http_cache_t *c;
ngx_http_file_cache_t *cache;
c = r->cache;
if (c == NULL) {
if (!(r->method & u->conf->cache_methods)) {
return NGX_DECLINED;
}
rc = ngx_http_upstream_cache_get(r, u, &cache);
if (rc != NGX_OK) {
return rc;
}
if (r->method == NGX_HTTP_HEAD && u->conf->cache_convert_head) {
u->method = ngx_http_core_get_method;
}
if (ngx_http_file_cache_new(r) != NGX_OK) {
return NGX_ERROR;
}
if (u->create_key(r) != NGX_OK) {
return NGX_ERROR;
}
/* TODO: add keys */
ngx_http_file_cache_create_key(r);
if (r->cache->header_start + 256 > u->conf->buffer_size) {
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"%V_buffer_size %uz is not enough for cache key, "
"it should be increased to at least %uz",
&u->conf->module, u->conf->buffer_size,
ngx_align(r->cache->header_start + 256, 1024));
r->cache = NULL;
return NGX_DECLINED;
}
u->cacheable = 1;
c = r->cache;
c->body_start = u->conf->buffer_size;
c->min_uses = u->conf->cache_min_uses;
c->file_cache = cache;
switch (ngx_http_test_predicates(r, u->conf->cache_bypass)) {
case NGX_ERROR:
return NGX_ERROR;
case NGX_DECLINED:
u->cache_status = NGX_HTTP_CACHE_BYPASS;
return NGX_DECLINED;
default: /* NGX_OK */
break;
}
c->lock = u->conf->cache_lock;
c->lock_timeout = u->conf->cache_lock_timeout;
c->lock_age = u->conf->cache_lock_age;
u->cache_status = NGX_HTTP_CACHE_MISS;
}
rc = ngx_http_file_cache_open(r);
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
"http upstream cache: %i", rc);
switch (rc) {
case NGX_HTTP_CACHE_STALE:
if (((u->conf->cache_use_stale & NGX_HTTP_UPSTREAM_FT_UPDATING)
|| c->stale_updating) && !r->background
&& u->conf->cache_background_update)
{
if (ngx_http_upstream_cache_background_update(r, u) == NGX_OK) {
r->cache->background = 1;
u->cache_status = rc;
rc = NGX_OK;
} else {