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ngx_stream_proxy_module.c
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// annotated by chrono since 2016
//
// * ngx_stream_proxy_pass
// * ngx_stream_proxy_handler
// * ngx_stream_proxy_connect_handler
// * ngx_stream_proxy_init_upstream
// * ngx_stream_proxy_process
/*
* Copyright (C) Roman Arutyunyan
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_stream.h>
// 定义各种连接上游服务器的参数
// 例如超时、缓冲区大小
typedef struct {
ngx_addr_t *addr;
ngx_stream_complex_value_t *value;
#if (NGX_HAVE_TRANSPARENT_PROXY)
ngx_uint_t transparent; /* unsigned transparent:1; */
#endif
} ngx_stream_upstream_local_t;
// proxy_pass的各种配置参数，比较容易理解
typedef struct {
ngx_msec_t connect_timeout;
ngx_msec_t timeout;
ngx_msec_t next_upstream_timeout;
size_t buffer_size;
ngx_stream_complex_value_t *upload_rate;
ngx_stream_complex_value_t *download_rate;
ngx_uint_t requests;
ngx_uint_t responses;
ngx_uint_t next_upstream_tries;
ngx_flag_t next_upstream;
ngx_flag_t proxy_protocol;
ngx_flag_t half_close;
ngx_stream_upstream_local_t *local;
ngx_flag_t socket_keepalive;
#if (NGX_STREAM_SSL)
ngx_flag_t ssl_enable;
ngx_flag_t ssl_session_reuse;
ngx_uint_t ssl_protocols;
ngx_str_t ssl_ciphers;
ngx_stream_complex_value_t *ssl_name;
ngx_flag_t ssl_server_name;
ngx_flag_t ssl_verify;
ngx_uint_t ssl_verify_depth;
ngx_str_t ssl_trusted_certificate;
ngx_str_t ssl_crl;
ngx_stream_complex_value_t *ssl_certificate;
ngx_stream_complex_value_t *ssl_certificate_key;
ngx_array_t *ssl_passwords;
ngx_array_t *ssl_conf_commands;
ngx_ssl_t *ssl;
#endif
// 将要转发的上游服务器集群
// 定义为一个upstream{}
ngx_stream_upstream_srv_conf_t *upstream;
// proxy_pass支持复杂变量
ngx_stream_complex_value_t *upstream_value;
} ngx_stream_proxy_srv_conf_t;
// ngx_stream_init_connection->ngx_stream_init_session之后调用，处理请求
// 即content handler
//
// 创建连接上游的结构体
// 里面有如何获取负载均衡server、上下游buf等
// 负载均衡算法初始化
// 准备开始连接，设置开始时间，秒数，没有毫秒
// 最后启动连接
static void ngx_stream_proxy_handler(ngx_stream_session_t *s);
static ngx_int_t ngx_stream_proxy_eval(ngx_stream_session_t *s,
ngx_stream_proxy_srv_conf_t *pscf);
static ngx_int_t ngx_stream_proxy_set_local(ngx_stream_session_t *s,
ngx_stream_upstream_t *u, ngx_stream_upstream_local_t *local);
// 连接上游
// 使用ngx_peer_connection_t连接上游服务器
// 连接失败，需要尝试下一个上游server
// 连接成功要调用init初始化上游
static void ngx_stream_proxy_connect(ngx_stream_session_t *s);
// 分配供上游读取数据的缓冲区
// 进入此函数，肯定已经成功连接了上游服务器
// 修改上游读写事件，不再测试连接，改为ngx_stream_proxy_upstream_handler
// 实际是ngx_stream_proxy_process_connection(ev, !ev->write);
static void ngx_stream_proxy_init_upstream(ngx_stream_session_t *s);
static void ngx_stream_proxy_resolve_handler(ngx_resolver_ctx_t *ctx);
// 连接成功之后的事件处理函数
// 实际是ngx_stream_proxy_process_connection(ev, !ev->write);
static void ngx_stream_proxy_upstream_handler(ngx_event_t *ev);
// 处理下游的handler
// ev->write==true，即向下游写数据
static void ngx_stream_proxy_downstream_handler(ngx_event_t *ev);
// 处理上下游的数据收发
// from_upstream参数标记是否是上游，使用的是ev->write
// 可读是上游，可写是下游
static void ngx_stream_proxy_process_connection(ngx_event_t *ev,
ngx_uint_t from_upstream);
// 第一次连接上游不成功后的handler
// 当上游连接再次有读写事件发生时测试连接
// 测试连接是否成功，失败就再试下一个上游
// 最后还是要调用init初始化上游
static void ngx_stream_proxy_connect_handler(ngx_event_t *ev);
// 测试连接是否成功，失败就再试下一个上游
static ngx_int_t ngx_stream_proxy_test_connect(ngx_connection_t *c);
// 核心处理函数，处理两个连接的数据收发
// 可以处理上下游的数据收发
// 参数标记是否是上游、是否写数据
static void ngx_stream_proxy_process(ngx_stream_session_t *s,
ngx_uint_t from_upstream, ngx_uint_t do_write);
// 1.15.7
static ngx_int_t ngx_stream_proxy_test_finalize(ngx_stream_session_t *s,
ngx_uint_t from_upstream);
// 连接失败，尝试下一个上游server
static void ngx_stream_proxy_next_upstream(ngx_stream_session_t *s);
// 关闭上下游的连接
static void ngx_stream_proxy_finalize(ngx_stream_session_t *s, ngx_uint_t rc);
static u_char *ngx_stream_proxy_log_error(ngx_log_t *log, u_char *buf,
size_t len);
// 配置结构体相关函数，比较简单
static void *ngx_stream_proxy_create_srv_conf(ngx_conf_t *cf);
static char *ngx_stream_proxy_merge_srv_conf(ngx_conf_t *cf, void *parent,
void *child);
// 解析proxy_pass指令，设置处理handler，在init建立连接之后会调用
// 获取一个upstream{}块的配置信息
static char *ngx_stream_proxy_pass(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static char *ngx_stream_proxy_bind(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
#if (NGX_STREAM_SSL)
static ngx_int_t ngx_stream_proxy_send_proxy_protocol(ngx_stream_session_t *s);
static char *ngx_stream_proxy_ssl_password_file(ngx_conf_t *cf,
ngx_command_t *cmd, void *conf);
static char *ngx_stream_proxy_ssl_conf_command_check(ngx_conf_t *cf, void *post,
void *data);
static void ngx_stream_proxy_ssl_init_connection(ngx_stream_session_t *s);
static void ngx_stream_proxy_ssl_handshake(ngx_connection_t *pc);
static void ngx_stream_proxy_ssl_save_session(ngx_connection_t *c);
static ngx_int_t ngx_stream_proxy_ssl_name(ngx_stream_session_t *s);
static ngx_int_t ngx_stream_proxy_ssl_certificate(ngx_stream_session_t *s);
static ngx_int_t ngx_stream_proxy_merge_ssl(ngx_conf_t *cf,
ngx_stream_proxy_srv_conf_t *conf, ngx_stream_proxy_srv_conf_t *prev);
static ngx_int_t ngx_stream_proxy_set_ssl(ngx_conf_t *cf,
ngx_stream_proxy_srv_conf_t *pscf);
static ngx_conf_bitmask_t ngx_stream_proxy_ssl_protocols[] = {
{ ngx_string("SSLv2"), NGX_SSL_SSLv2 },
{ ngx_string("SSLv3"), NGX_SSL_SSLv3 },
{ ngx_string("TLSv1"), NGX_SSL_TLSv1 },
{ ngx_string("TLSv1.1"), NGX_SSL_TLSv1_1 },
{ ngx_string("TLSv1.2"), NGX_SSL_TLSv1_2 },
{ ngx_string("TLSv1.3"), NGX_SSL_TLSv1_3 },
{ ngx_null_string, 0 }
};
static ngx_conf_post_t ngx_stream_proxy_ssl_conf_command_post =
{ ngx_stream_proxy_ssl_conf_command_check };
#endif
static ngx_conf_deprecated_t ngx_conf_deprecated_proxy_downstream_buffer = {
ngx_conf_deprecated, "proxy_downstream_buffer", "proxy_buffer_size"
};
static ngx_conf_deprecated_t ngx_conf_deprecated_proxy_upstream_buffer = {
ngx_conf_deprecated, "proxy_upstream_buffer", "proxy_buffer_size"
};
// proxy模块定义的各种指令
static ngx_command_t ngx_stream_proxy_commands[] = {
// 关键指令， 设置处理handler，在init建立连接之后会调用
{ ngx_string("proxy_pass"),
NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_proxy_pass,
NGX_STREAM_SRV_CONF_OFFSET,
0,
NULL },
{ ngx_string("proxy_bind"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE12,
ngx_stream_proxy_bind,
NGX_STREAM_SRV_CONF_OFFSET,
0,
NULL },
{ ngx_string("proxy_socket_keepalive"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, socket_keepalive),
NULL },
{ ngx_string("proxy_connect_timeout"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, connect_timeout),
NULL },
{ ngx_string("proxy_timeout"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, timeout),
NULL },
{ ngx_string("proxy_buffer_size"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_size_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, buffer_size),
NULL },
{ ngx_string("proxy_downstream_buffer"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_size_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, buffer_size),
&ngx_conf_deprecated_proxy_downstream_buffer },
{ ngx_string("proxy_upstream_buffer"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_size_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, buffer_size),
&ngx_conf_deprecated_proxy_upstream_buffer },
{ ngx_string("proxy_upload_rate"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_set_complex_value_size_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, upload_rate),
NULL },
{ ngx_string("proxy_download_rate"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_set_complex_value_size_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, download_rate),
NULL },
{ ngx_string("proxy_requests"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, requests),
NULL },
{ ngx_string("proxy_responses"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, responses),
NULL },
{ ngx_string("proxy_next_upstream"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, next_upstream),
NULL },
{ ngx_string("proxy_next_upstream_tries"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, next_upstream_tries),
NULL },
{ ngx_string("proxy_next_upstream_timeout"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, next_upstream_timeout),
NULL },
{ ngx_string("proxy_protocol"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, proxy_protocol),
NULL },
{ ngx_string("proxy_half_close"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, half_close),
NULL },
#if (NGX_STREAM_SSL)
{ ngx_string("proxy_ssl"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_enable),
NULL },
{ ngx_string("proxy_ssl_session_reuse"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_session_reuse),
NULL },
{ ngx_string("proxy_ssl_protocols"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_1MORE,
ngx_conf_set_bitmask_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_protocols),
&ngx_stream_proxy_ssl_protocols },
{ ngx_string("proxy_ssl_ciphers"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_str_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_ciphers),
NULL },
{ ngx_string("proxy_ssl_name"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_set_complex_value_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_name),
NULL },
{ ngx_string("proxy_ssl_server_name"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_server_name),
NULL },
{ ngx_string("proxy_ssl_verify"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_verify),
NULL },
{ ngx_string("proxy_ssl_verify_depth"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_verify_depth),
NULL },
{ ngx_string("proxy_ssl_trusted_certificate"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_str_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_trusted_certificate),
NULL },
{ ngx_string("proxy_ssl_crl"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_conf_set_str_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_crl),
NULL },
{ ngx_string("proxy_ssl_certificate"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_set_complex_value_zero_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_certificate),
NULL },
{ ngx_string("proxy_ssl_certificate_key"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_set_complex_value_zero_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_certificate_key),
NULL },
{ ngx_string("proxy_ssl_password_file"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
ngx_stream_proxy_ssl_password_file,
NGX_STREAM_SRV_CONF_OFFSET,
0,
NULL },
{ ngx_string("proxy_ssl_conf_command"),
NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE2,
ngx_conf_set_keyval_slot,
NGX_STREAM_SRV_CONF_OFFSET,
offsetof(ngx_stream_proxy_srv_conf_t, ssl_conf_commands),
&ngx_stream_proxy_ssl_conf_command_post },
#endif
ngx_null_command
};
// 没有main配置，都在server{}里
static ngx_stream_module_t ngx_stream_proxy_module_ctx = {
NULL, /* preconfiguration */
NULL, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
ngx_stream_proxy_create_srv_conf, /* create server configuration */
ngx_stream_proxy_merge_srv_conf /* merge server configuration */
};
// 模块功能集成定义
ngx_module_t ngx_stream_proxy_module = {
NGX_MODULE_V1,
&ngx_stream_proxy_module_ctx, /* module context */
ngx_stream_proxy_commands, /* module directives */
NGX_STREAM_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
};
// ngx_stream_init_connection->ngx_stream_init_session之后调用，处理请求
// 创建连接上游的结构体
// 里面有如何获取负载均衡server、上下游buf等
// 负载均衡算法初始化
// 准备开始连接，设置开始时间，秒数，没有毫秒
// 使用内存池分配接收数据的缓冲区
// 最后启动连接
static void
ngx_stream_proxy_handler(ngx_stream_session_t *s)
{
u_char *p;
ngx_str_t *host;
ngx_uint_t i;
ngx_connection_t *c;
ngx_resolver_ctx_t *ctx, temp;
ngx_stream_upstream_t *u;
ngx_stream_core_srv_conf_t *cscf;
ngx_stream_proxy_srv_conf_t *pscf;
ngx_stream_upstream_srv_conf_t *uscf, **uscfp;
ngx_stream_upstream_main_conf_t *umcf;
// 获取连接对象
c = s->connection;
pscf = ngx_stream_get_module_srv_conf(s, ngx_stream_proxy_module);
ngx_log_debug0(NGX_LOG_DEBUG_STREAM, c->log, 0,
"proxy connection handler");
// 创建连接上游的结构体
// 里面有如何获取负载均衡server、上下游buf等
u = ngx_pcalloc(c->pool, sizeof(ngx_stream_upstream_t));
if (u == NULL) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
// 关联到会话对象
s->upstream = u;
s->log_handler = ngx_stream_proxy_log_error;
// 1.15新增
u->requests = 1;
u->peer.log = c->log;
u->peer.log_error = NGX_ERROR_ERR;
if (ngx_stream_proxy_set_local(s, u, pscf->local) != NGX_OK) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
if (pscf->socket_keepalive) {
u->peer.so_keepalive = 1;
}
// 连接的类型，tcp or udp
u->peer.type = c->type;
// 开始连接后端的时间
// 准备开始连接，设置开始时间，秒数，没有毫秒
u->start_sec = ngx_time();
// 连接的读写事件都设置为ngx_stream_proxy_downstream_handler
// 注意这个连接是客户端发起的连接，即下游
// 当客户端连接可读或可写时就会调用ngx_stream_proxy_downstream_handler
c->write->handler = ngx_stream_proxy_downstream_handler;
c->read->handler = ngx_stream_proxy_downstream_handler;
// 使用数组，可能会连接多个上游服务器
s->upstream_states = ngx_array_create(c->pool, 1,
sizeof(ngx_stream_upstream_state_t));
if (s->upstream_states == NULL) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
// 1.15给udp/tcp都创建一个缓冲区，用来接收数据
p = ngx_pnalloc(c->pool, pscf->buffer_size);
if (p == NULL) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
// 注意是给下游使用的缓冲区
u->downstream_buf.start = p;
u->downstream_buf.end = p + pscf->buffer_size;
u->downstream_buf.pos = p;
u->downstream_buf.last = p;
// 连接可读，表示客户端有数据发过来
// 加入到&ngx_posted_events
// 稍后由ngx_stream_proxy_downstream_handler来处理
if (c->read->ready) {
ngx_post_event(c->read, &ngx_posted_events);
}
// udp不需要，始终用一个固定大小的数组接收数据
// proxy_pass支持复杂变量
// 如果使用了"proxy_pass $xxx"，那么就要解析复杂变量
if (pscf->upstream_value) {
if (ngx_stream_proxy_eval(s, pscf) != NGX_OK) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
}
// 检查proxy_pass的目标地址
if (u->resolved == NULL) {
uscf = pscf->upstream;
} else {
#if (NGX_STREAM_SSL)
u->ssl_name = u->resolved->host;
#endif
host = &u->resolved->host;
// 获取上游的配置结构体
// 在ngx_stream_proxy_pass里设置的
//uscf = pscf->upstream;
umcf = ngx_stream_get_module_main_conf(s, ngx_stream_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, c->log, 0,
"no port in upstream \"%V\"", host);
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
if (ngx_stream_upstream_create_round_robin_peer(s, u->resolved)
!= NGX_OK)
{
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
ngx_stream_proxy_connect(s);
return;
}
if (u->resolved->port == 0) {
ngx_log_error(NGX_LOG_ERR, c->log, 0,
"no port in upstream \"%V\"", host);
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
temp.name = *host;
cscf = ngx_stream_get_module_srv_conf(s, ngx_stream_core_module);
ctx = ngx_resolve_start(cscf->resolver, &temp);
if (ctx == NULL) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
if (ctx == NGX_NO_RESOLVER) {
ngx_log_error(NGX_LOG_ERR, c->log, 0,
"no resolver defined to resolve %V", host);
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
ctx->name = *host;
ctx->handler = ngx_stream_proxy_resolve_handler;
ctx->data = s;
ctx->timeout = cscf->resolver_timeout;
u->resolved->ctx = ctx;
if (ngx_resolve_name(ctx) != NGX_OK) {
u->resolved->ctx = NULL;
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
return;
}
found:
if (uscf == NULL) {
ngx_log_error(NGX_LOG_ALERT, c->log, 0, "no upstream configuration");
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
u->upstream = uscf;
#if (NGX_STREAM_SSL)
u->ssl_name = uscf->host;
#endif
// 负载均衡算法初始化
if (uscf->peer.init(s, uscf) != NGX_OK) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
// 准备开始连接，设置开始时间，毫秒
u->peer.start_time = ngx_current_msec;
// 设置负载均衡的重试次数
if (pscf->next_upstream_tries
&& u->peer.tries > pscf->next_upstream_tries)
{
u->peer.tries = pscf->next_upstream_tries;
}
//u->proxy_protocol = pscf->proxy_protocol;
// 最后启动连接
// 使用ngx_peer_connection_t连接上游服务器
// 连接失败，需要尝试下一个上游server
// 连接成功要调用init初始化上游
ngx_stream_proxy_connect(s);
}
// proxy_pass支持复杂变量
// 如果使用了"proxy_pass $xxx"，那么就要解析复杂变量
static ngx_int_t
ngx_stream_proxy_eval(ngx_stream_session_t *s,
ngx_stream_proxy_srv_conf_t *pscf)
{
ngx_str_t host;
ngx_url_t url;
ngx_stream_upstream_t *u;
if (ngx_stream_complex_value(s, pscf->upstream_value, &host) != NGX_OK) {
return NGX_ERROR;
}
ngx_memzero(&url, sizeof(ngx_url_t));
url.url = host;
url.no_resolve = 1;
if (ngx_parse_url(s->connection->pool, &url) != NGX_OK) {
if (url.err) {
ngx_log_error(NGX_LOG_ERR, s->connection->log, 0,
"%s in upstream \"%V\"", url.err, &url.url);
}
return NGX_ERROR;
}
u = s->upstream;
u->resolved = ngx_pcalloc(s->connection->pool,
sizeof(ngx_stream_upstream_resolved_t));
if (u->resolved == NULL) {
return NGX_ERROR;
}
if (url.addrs) {
u->resolved->sockaddr = url.addrs[0].sockaddr;
u->resolved->socklen = url.addrs[0].socklen;
u->resolved->name = url.addrs[0].name;
u->resolved->naddrs = 1;
}
u->resolved->host = url.host;
u->resolved->port = url.port;
u->resolved->no_port = url.no_port;
return NGX_OK;
}
static ngx_int_t
ngx_stream_proxy_set_local(ngx_stream_session_t *s, ngx_stream_upstream_t *u,
ngx_stream_upstream_local_t *local)
{
ngx_int_t rc;
ngx_str_t val;
ngx_addr_t *addr;
if (local == NULL) {
u->peer.local = NULL;
return NGX_OK;
}
#if (NGX_HAVE_TRANSPARENT_PROXY)
u->peer.transparent = local->transparent;
#endif
if (local->value == NULL) {
u->peer.local = local->addr;
return NGX_OK;
}
if (ngx_stream_complex_value(s, local->value, &val) != NGX_OK) {
return NGX_ERROR;
}
if (val.len == 0) {
return NGX_OK;
}
addr = ngx_palloc(s->connection->pool, sizeof(ngx_addr_t));
if (addr == NULL) {
return NGX_ERROR;
}
rc = ngx_parse_addr_port(s->connection->pool, addr, val.data, val.len);
if (rc == NGX_ERROR) {
return NGX_ERROR;
}
if (rc != NGX_OK) {
ngx_log_error(NGX_LOG_ERR, s->connection->log, 0,
"invalid local address \"%V\"", &val);
return NGX_OK;
}
addr->name = val;
u->peer.local = addr;
return NGX_OK;
}
// 连接上游
// 使用ngx_peer_connection_t连接上游服务器
// 连接失败，需要尝试下一个上游server
// 连接成功要调用init初始化上游
static void
ngx_stream_proxy_connect(ngx_stream_session_t *s)
{
ngx_int_t rc;
ngx_connection_t *c, *pc;
ngx_stream_upstream_t *u;
ngx_stream_proxy_srv_conf_t *pscf;
// 获取连接对象
c = s->connection;
c->log->action = "connecting to upstream";
pscf = ngx_stream_get_module_srv_conf(s, ngx_stream_proxy_module);
// 连接上游的结构体
// 里面有如何获取负载均衡server、上下游buf等
u = s->upstream;
u->connected = 0;
u->proxy_protocol = pscf->proxy_protocol;
// 何时会执行这个？
if (u->state) {
u->state->response_time = ngx_current_msec - u->start_time;
}
// 把一个上游的状态添加进会话的数组
u->state = ngx_array_push(s->upstream_states);
if (u->state == NULL) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
ngx_memzero(u->state, sizeof(ngx_stream_upstream_state_t));
// 1.15.7
u->start_time = ngx_current_msec;
// 这两个值置为-1，表示未初始化
u->state->connect_time = (ngx_msec_t) -1;
u->state->first_byte_time = (ngx_msec_t) -1;
// 用来计算响应时间，保存当前的毫秒值
// 之后连接成功后就会两者相减
u->state->response_time = (ngx_msec_t) -1;
// 连接上游
// 使用ngx_peer_connection_t连接上游服务器
// 从upstream{}里获取一个上游server地址
// 从cycle的连接池获取一个空闲连接
// 设置连接的数据收发接口函数
// 向epoll添加连接，即同时添加读写事件
// 当与上游服务器有任何数据收发时都会触发epoll
// socket api调用连接上游服务器
// 写事件ready，即可以立即向上游发送数据
rc = ngx_event_connect_peer(&u->peer);
ngx_log_debug1(NGX_LOG_DEBUG_STREAM, c->log, 0, "proxy connect: %i", rc);
if (rc == NGX_ERROR) {
ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
return;
}
u->state->peer = u->peer.name;
// 所有上游都busy
if (rc == NGX_BUSY) {
ngx_log_error(NGX_LOG_ERR, c->log, 0, "no live upstreams");
ngx_stream_proxy_finalize(s, NGX_STREAM_BAD_GATEWAY);
return;
}
// 连接失败，需要尝试下一个上游server
if (rc == NGX_DECLINED) {
ngx_stream_proxy_next_upstream(s);
return;
}
/* rc == NGX_OK || rc == NGX_AGAIN || rc == NGX_DONE */
// 连接“成功”，again/done表示正在连接过程中
pc = u->peer.connection;
pc->data = s;
pc->log = c->log;
pc->pool = c->pool;
pc->read->log = c->log;
pc->write->log = c->log;
// 连接成功
// 分配供上游读取数据的缓冲区
// 修改上游读写事件，不再测试连接，改为ngx_stream_proxy_upstream_handler
// 实际是ngx_stream_proxy_process_connection(ev, !ev->write);
if (rc != NGX_AGAIN) {
ngx_stream_proxy_init_upstream(s);
return;
}
// again，要再次尝试连接
// 设置上游的读写事件处理函数是ngx_stream_proxy_connect_handler
// 第一次连接上游不成功后的handler
// 当上游连接再次有读写事件发生时测试连接
// 测试连接是否成功，失败就再试下一个上游
// 最后还是要调用init初始化上游
pc->read->handler = ngx_stream_proxy_connect_handler;
pc->write->handler = ngx_stream_proxy_connect_handler;
// 连接上游先写，所以设置写事件的超时时间
ngx_add_timer(pc->write, pscf->connect_timeout);
}
// 分配供上游读取数据的缓冲区
// 进入此函数，肯定已经成功连接了上游服务器
// 修改上游读写事件，不再测试连接，改为ngx_stream_proxy_upstream_handler
// 实际是ngx_stream_proxy_process_connection(ev, !ev->write);
static void
ngx_stream_proxy_init_upstream(ngx_stream_session_t *s)
{
u_char *p;
ngx_chain_t *cl;
ngx_connection_t *c, *pc;
ngx_log_handler_pt handler;
ngx_stream_upstream_t *u;
ngx_stream_core_srv_conf_t *cscf;
ngx_stream_proxy_srv_conf_t *pscf;
// u保存了上游相关的信息
u = s->upstream;
// pc是上游的连接对象
pc = u->peer.connection;
cscf = ngx_stream_get_module_srv_conf(s, ngx_stream_core_module);
if (pc->type == SOCK_STREAM
&& cscf->tcp_nodelay
&& ngx_tcp_nodelay(pc) != NGX_OK)
{
ngx_stream_proxy_next_upstream(s);
return;
}
pscf = ngx_stream_get_module_srv_conf(s, ngx_stream_proxy_module);
#if (NGX_STREAM_SSL)
if (pc->type == SOCK_STREAM && pscf->ssl_enable) {
if (u->proxy_protocol) {
if (ngx_stream_proxy_send_proxy_protocol(s) != NGX_OK) {
return;
}
u->proxy_protocol = 0;
}
if (pc->ssl == NULL) {
ngx_stream_proxy_ssl_init_connection(s);
return;
}
}
#endif
// c是到客户端即下游的连接对象
c = s->connection;
if (c->log->log_level >= NGX_LOG_INFO) {
ngx_str_t str;
u_char addr[NGX_SOCKADDR_STRLEN];
str.len = NGX_SOCKADDR_STRLEN;
str.data = addr;
if (ngx_connection_local_sockaddr(pc, &str, 1) == NGX_OK) {
handler = c->log->handler;
c->log->handler = NULL;
ngx_log_error(NGX_LOG_INFO, c->log, 0,