nginx模块开发(三)upstream模块

使用nginx-1.13.4版本

三个文件ngx_http_mytest_module.c ,nginx.conf,config

 
./configure --prefix=/usr/local/nginx --add-module=/opt/nginx/code/chapter5/upstream --with-debug
make
make install 

注意两个细节《nginx模块开发》中到错误：

u->resolved->port = htons((in_port_t)80);

这样要加上，指定后端到端口

static ngx_str_t backendQueryLine =
        ngx_string("GET /index.html?q=%V HTTP/1.1\r\nHost: www.baidu.com\r\nConnection: close\r\n\r\n");

这是upstream后转发的地址
index.html是一个能访问到的地址用来测试


为了测试，
http://192.168.140.11:8080/test?q=haha


[img]http://dl2.iteye.com/upload/attachment/0126/7330/de15d59c-0eeb-3505-a62d-b7e5c6508b9d.png[/img]
看是否能提到这个自定义服务器


三个文件如下：
ngx_http_mytest_module.c
[code="java"]
# cat ngx_http_mytest_module.c
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


typedef struct
{
ngx_http_status_t status;
ngx_str_t backendServer;
} ngx_http_mytest_ctx_t;

typedef struct
{
ngx_http_upstream_conf_t upstream;
} ngx_http_mytest_conf_t;


static char *
ngx_http_mytest(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);

static ngx_int_t ngx_http_mytest_handler(ngx_http_request_t *r);
static void* ngx_http_mytest_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_mytest_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child);

static ngx_int_t
mytest_upstream_process_header(ngx_http_request_t *r);
static ngx_int_t
mytest_process_status_line(ngx_http_request_t *r);


static ngx_str_t ngx_http_proxy_hide_headers[] =
{
ngx_string("Date"),
ngx_string("Server"),
ngx_string("X-Pad"),
ngx_string("X-Accel-Expires"),
ngx_string("X-Accel-Redirect"),
ngx_string("X-Accel-Limit-Rate"),
ngx_string("X-Accel-Buffering"),
ngx_string("X-Accel-Charset"),
ngx_null_string
};


static ngx_command_t ngx_http_mytest_commands[] =
{

{
ngx_string("mytest"),
NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_HTTP_LMT_CONF | NGX_CONF_NOARGS,
ngx_http_mytest,
NGX_HTTP_LOC_CONF_OFFSET,
0,
NULL
},

ngx_null_command
};

static ngx_http_module_t ngx_http_mytest_module_ctx =
{
NULL, /* preconfiguration */
NULL, /* postconfiguration */

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

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

ngx_http_mytest_create_loc_conf, /* create location configuration */
ngx_http_mytest_merge_loc_conf /* merge location configuration */
};

ngx_module_t ngx_http_mytest_module =
{
NGX_MODULE_V1,
&ngx_http_mytest_module_ctx, /* module context */
ngx_http_mytest_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 void* ngx_http_mytest_create_loc_conf(ngx_conf_t *cf)
{
ngx_http_mytest_conf_t *mycf;

mycf = (ngx_http_mytest_conf_t *)ngx_pcalloc(cf->pool, sizeof(ngx_http_mytest_conf_t));
if (mycf == NULL)
{
return NULL;
}

//以下简单的硬编码ngx_http_upstream_conf_t结构中的各成员，例如
//超时时间都设为1分钟。这也是http反向代理模块的默认值
mycf->upstream.connect_timeout = 60000;
mycf->upstream.send_timeout = 60000;
mycf->upstream.read_timeout = 60000;
mycf->upstream.store_access = 0600;
//实际上buffering已经决定了将以固定大小的内存作为缓冲区来转发上游的
//响应包体，这块固定缓冲区的大小就是buffer_size。如果buffering为1
//就会使用更多的内存缓存来不及发往下游的响应，例如最多使用bufs.num个
//缓冲区、每个缓冲区大小为bufs.size，另外还会使用临时文件，临时文件的
//最大长度为max_temp_file_size
mycf->upstream.buffering = 0;
mycf->upstream.bufs.num = 8;
mycf->upstream.bufs.size = ngx_pagesize;
mycf->upstream.buffer_size = ngx_pagesize;
mycf->upstream.busy_buffers_size = 2 * ngx_pagesize;
mycf->upstream.temp_file_write_size = 2 * ngx_pagesize;
mycf->upstream.max_temp_file_size = 1024 * 1024 * 1024;

//upstream模块要求hide_headers成员必须要初始化（upstream在解析
//完上游服务器返回的包头时，会调用
//ngx_http_upstream_process_headers方法按照hide_headers成员将
//本应转发给下游的一些http头部隐藏），这里将它赋为
//NGX_CONF_UNSET_PTR ，是为了在merge合并配置项方法中使用
//upstream模块提供的ngx_http_upstream_hide_headers_hash
//方法初始化hide_headers 成员
mycf->upstream.hide_headers = NGX_CONF_UNSET_PTR;
mycf->upstream.pass_headers = NGX_CONF_UNSET_PTR;

return mycf;
}


static char *ngx_http_mytest_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
ngx_http_mytest_conf_t *prev = (ngx_http_mytest_conf_t *)parent;
ngx_http_mytest_conf_t *conf = (ngx_http_mytest_conf_t *)child;

ngx_hash_init_t hash;
hash.max_size = 100;
hash.bucket_size = 1024;
hash.name = "proxy_headers_hash";
if (ngx_http_upstream_hide_headers_hash(cf, &conf->upstream,
&prev->upstream, ngx_http_proxy_hide_headers, &hash)
!= NGX_OK)
{
return NGX_CONF_ERROR;
}

return NGX_CONF_OK;
}


static ngx_int_t
mytest_upstream_create_request(ngx_http_request_t *r)
{
//发往google上游服务器的请求很简单，就是模仿正常的搜索请求，
//以/search?q=…的URL来发起搜索请求。backendQueryLine中的%V等转化
//格式的用法，请参见4.4节中的表4-7
static ngx_str_t backendQueryLine =
ngx_string("GET /index.html?q=%V HTTP/1.1\r\nHost: www.baidu.com\r\nConnection: close\r\n\r\n");
ngx_int_t queryLineLen = backendQueryLine.len + r->args.len - 2;
//必须由内存池中申请内存，这有两点好处：在网络情况不佳的情况下，向上游
//服务器发送请求时，可能需要epoll多次调度send发送才能完成，
//这时必须保证这段内存不会被释放；请求结束时，这段内存会被自动释放，
//降低内存泄漏的可能
ngx_buf_t* b = ngx_create_temp_buf(r->pool, queryLineLen);
if (b == NULL)
return NGX_ERROR;
//last要指向请求的末尾
b->last = b->pos + queryLineLen;

//作用相当于snprintf，只是它支持4.4节中的表4-7列出的所有转换格式
ngx_snprintf(b->pos, queryLineLen ,
(char*)backendQueryLine.data, &r->args);
// r->upstream->request_bufs是一个ngx_chain_t结构，它包含着要
//发送给上游服务器的请求
r->upstream->request_bufs = ngx_alloc_chain_link(r->pool);//haohao
if (r->upstream->request_bufs == NULL)
return NGX_ERROR;

// request_bufs这里只包含1个ngx_buf_t缓冲区
r->upstream->request_bufs->buf = b;
r->upstream->request_bufs->next = NULL;

r->upstream->request_sent = 0;
r->upstream->header_sent = 0;
// header_hash不可以为0
r->header_hash = 1;
return NGX_OK;
}

static ngx_int_t
mytest_process_status_line(ngx_http_request_t *r)
{
size_t len;
ngx_int_t rc;
ngx_http_upstream_t *u;

//上下文中才会保存多次解析http响应行的状态，首先取出请求的上下文
ngx_http_mytest_ctx_t* ctx = ngx_http_get_module_ctx(r, ngx_http_mytest_module);
if (ctx == NULL)
{
return NGX_ERROR;
}

u = r->upstream;

//http框架提供的ngx_http_parse_status_line方法可以解析http
//响应行，它的输入就是收到的字符流和上下文中的ngx_http_status_t结构
rc = ngx_http_parse_status_line(r, &u->buffer, &ctx->status);
//返回NGX_AGAIN表示还没有解析出完整的http响应行，需要接收更多的
//字符流再来解析
if (rc == NGX_AGAIN)
{
return rc;
}
//返回NGX_ERROR则没有接收到合法的http响应行
if (rc == NGX_ERROR)
{
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"upstream sent no valid HTTP/1.0 header haoning eiyouwei");

r->http_version = NGX_HTTP_VERSION_9;
u->state->status = NGX_HTTP_OK;

return NGX_OK;
}

//以下表示解析到完整的http响应行，这时会做一些简单的赋值操作，将解析出
//的信息设置到r->upstream->headers_in结构体中，upstream解析完所
//有的包头时，就会把headers_in中的成员设置到将要向下游发送的
//r->headers_out结构体中，也就是说，现在我们向headers_in中设置的
//信息，最终都会发往下游客户端。为什么不是直接设置r->headers_out而要
//这样多此一举呢？这是因为upstream希望能够按照
//ngx_http_upstream_conf_t配置结构体中的hide_headers等成员对
//发往下游的响应头部做统一处理
if (u->state)
{
u->state->status = ctx->status.code;
}

u->headers_in.status_n = ctx->status.code;

len = ctx->status.end - ctx->status.start;
u->headers_in.status_line.len = len;

u->headers_in.status_line.data = ngx_pnalloc(r->pool, len);
if (u->headers_in.status_line.data == NULL)
{
return NGX_ERROR;
}

ngx_memcpy(u->headers_in.status_line.data, ctx->status.start, len);

//下一步将开始解析http头部，设置process_header回调方法为
//mytest_upstream_process_header，
//之后再收到的新字符流将由mytest_upstream_process_header解析
u->process_header = mytest_upstream_process_header;

//如果本次收到的字符流除了http响应行外，还有多余的字符，
//将由mytest_upstream_process_header方法解析
return mytest_upstream_process_header(r);
}


static ngx_int_t
mytest_upstream_process_header(ngx_http_request_t *r)
{
ngx_int_t rc;
ngx_table_elt_t *h;
ngx_http_upstream_header_t *hh;
ngx_http_upstream_main_conf_t *umcf;

//这里将upstream模块配置项ngx_http_upstream_main_conf_t取了
//出来，目的只有1个，对将要转发给下游客户端的http响应头部作统一
//处理。该结构体中存储了需要做统一处理的http头部名称和回调方法
umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);

//循环的解析所有的http头部
for ( ;; )
{
// http框架提供了基础性的ngx_http_parse_header_line
//方法，它用于解析http头部
rc = ngx_http_parse_header_line(r, &r->upstream->buffer, 1);
//返回NGX_OK表示解析出一行http头部
if (rc == NGX_OK)
{
//向headers_in.headers这个ngx_list_t链表中添加http头部
h = ngx_list_push(&r->upstream->headers_in.headers);
if (h == NULL)
{
return NGX_ERROR;
}
//以下开始构造刚刚添加到headers链表中的http头部
h->hash = r->header_hash;

h->key.len = r->header_name_end - r->header_name_start;
h->value.len = r->header_end - r->header_start;
//必须由内存池中分配存放http头部的内存
h->key.data = ngx_pnalloc(r->pool,
h->key.len + 1 + h->value.len + 1 + h->key.len);
if (h->key.data == NULL)
{
return NGX_ERROR;
}

h->value.data = h->key.data + h->key.len + 1;
h->lowcase_key = h->key.data + h->key.len + 1 + h->value.len + 1;

ngx_memcpy(h->key.data, r->header_name_start, h->key.len);
h->key.data[h->key.len] = '\0';
ngx_memcpy(h->value.data, r->header_start, h->value.len);
h->value.data[h->value.len] = '\0';

if (h->key.len == r->lowcase_index)
{
ngx_memcpy(h->lowcase_key, r->lowcase_header, h->key.len);
}
else
{
ngx_strlow(h->lowcase_key, h->key.data, h->key.len);
}

//upstream模块会对一些http头部做特殊处理
hh = ngx_hash_find(&umcf->headers_in_hash, h->hash,
h->lowcase_key, h->key.len);

if (hh && hh->handler(r, h, hh->offset) != NGX_OK)
{
return NGX_ERROR;
}

continue;
}

//返回NGX_HTTP_PARSE_HEADER_DONE表示响应中所有的http头部都解析
//完毕，接下来再接收到的都将是http包体
if (rc == NGX_HTTP_PARSE_HEADER_DONE)
{
//如果之前解析http头部时没有发现server和date头部，以下会
//根据http协议添加这两个头部
if (r->upstream->headers_in.server == NULL)
{
h = ngx_list_push(&r->upstream->headers_in.headers);
if (h == NULL)
{
return NGX_ERROR;
}

h->hash = ngx_hash(ngx_hash(ngx_hash(ngx_hash(
ngx_hash('s', 'e'), 'r'), 'v'), 'e'), 'r');

ngx_str_set(&h->key, "Server");
ngx_str_null(&h->value);
h->lowcase_key = (u_char *) "server";
}

if (r->upstream->headers_in.date == NULL)
{
h = ngx_list_push(&r->upstream->headers_in.headers);
if (h == NULL)
{
return NGX_ERROR;
}

h->hash = ngx_hash(ngx_hash(ngx_hash('d', 'a'), 't'), 'e');

ngx_str_set(&h->key, "Date");
ngx_str_null(&h->value);
h->lowcase_key = (u_char *) "date";
}

return NGX_OK;
}

//如果返回NGX_AGAIN则表示状态机还没有解析到完整的http头部，
//要求upstream模块继续接收新的字符流再交由process_header
//回调方法解析
if (rc == NGX_AGAIN)
{
return NGX_AGAIN;
}

//其他返回值都是非法的
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"upstream sent invalid header");

return NGX_HTTP_UPSTREAM_INVALID_HEADER;
}
}

static void
mytest_upstream_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
{
ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
"mytest_upstream_finalize_request");
}


static char *
ngx_http_mytest(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ngx_http_core_loc_conf_t *clcf;

//首先找到mytest配置项所属的配置块，clcf貌似是location块内的数据
//结构，其实不然，它可以是main、srv或者loc级别配置项，也就是说在每个
//http{}和server{}内也都有一个ngx_http_core_loc_conf_t结构体
clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);

//http框架在处理用户请求进行到NGX_HTTP_CONTENT_PHASE阶段时，如果
//请求的主机域名、URI与mytest配置项所在的配置块相匹配，就将调用我们
//实现的ngx_http_mytest_handler方法处理这个请求
clcf->handler = ngx_http_mytest_handler;

return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_mytest_handler(ngx_http_request_t *r)
{
//首先建立http上下文结构体ngx_http_mytest_ctx_t
ngx_http_mytest_ctx_t* myctx = ngx_http_get_module_ctx(r, ngx_http_mytest_module);
if (myctx == NULL)
{
myctx = ngx_palloc(r->pool, sizeof(ngx_http_mytest_ctx_t));
if (myctx == NULL)
{
return NGX_ERROR;
}
//将新建的上下文与请求关联起来
ngx_http_set_ctx(r, myctx, ngx_http_mytest_module);
}
//对每1个要使用upstream的请求，必须调用且只能调用1次
//ngx_http_upstream_create方法，它会初始化r->upstream成员
if (ngx_http_upstream_create(r) != NGX_OK)
{
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "ngx_http_upstream_create() failed");
return NGX_ERROR;
}

//得到配置结构体ngx_http_mytest_conf_t
ngx_http_mytest_conf_t *mycf = (ngx_http_mytest_conf_t *) ngx_http_get_module_loc_conf(r, ngx_http_mytest_module);
ngx_http_upstream_t *u = r->upstream;
//这里用配置文件中的结构体来赋给r->upstream->conf成员
u->conf = &mycf->upstream;
//决定转发包体时使用的缓冲区
u->buffering = mycf->upstream.buffering;

//以下代码开始初始化resolved结构体，用来保存上游服务器的地址
u->resolved = (ngx_http_upstream_resolved_t*) ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_resolved_t));
if (u->resolved == NULL)
{
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"ngx_pcalloc resolved error. %s.", strerror(errno));
return NGX_ERROR;
}

//这里的上游服务器就是www.google.com
static struct sockaddr_in backendSockAddr;
struct hostent *pHost = gethostbyname((char*) "www.baidu.com");
if (pHost == NULL)
{
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"gethostbyname fail. %s", strerror(errno));

return NGX_ERROR;
}

//访问上游服务器的80端口
backendSockAddr.sin_family = AF_INET;
backendSockAddr.sin_port = htons((in_port_t) 80);
char* pDmsIP = inet_ntoa(*(struct in_addr*) (pHost->h_addr_list[0]));
backendSockAddr.sin_addr.s_addr = inet_addr(pDmsIP);
myctx->backendServer.data = (u_char*)pDmsIP;
myctx->backendServer.len = strlen(pDmsIP);

//将地址设置到resolved成员中
u->resolved->sockaddr = (struct sockaddr *)&backendSockAddr;
u->resolved->socklen = sizeof(struct sockaddr_in);
u->resolved->naddrs = 1;
u->resolved->port = htons((in_port_t)80);

//设置三个必须实现的回调方法，也就是5.3.3节至5.3.5节中实现的3个方法
u->create_request = mytest_upstream_create_request;
u->process_header = mytest_process_status_line;
u->finalize_request = mytest_upstream_finalize_request;

//这里必须将count成员加1，理由见5.1.5节
r->main->count++;
//启动upstream
ngx_http_upstream_init(r);
//必须返回NGX_DONE
return NGX_DONE;
}


#
[/code]

nginx.conf
[code="java"]
# cat nginx.conf

#user nobody;
worker_processes 1;

error_log logs/error.log debug;

events {
worker_connections 1024;
}


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

#log_format main '$remote_addr - $remote_user [$time_local] "$request" '
# '$status $body_bytes_sent "$http_referer" '
# '"$http_user_agent" "$http_x_forwarded_for"';

#access_log logs/access.log main;

keepalive_timeout 65;

server {
listen 8080;
location /test {
mytest;
}
}
}
[/code]
config
[code="java"]
# cat config
ngx_addon_name=ngx_http_mytest_module
HTTP_MODULES="$HTTP_MODULES ngx_http_mytest_module"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_mytest_module.c"
[/code]