Nginx HTTP filter module development-PHP Tutorial-php.cn

Nginx filter module

Development steps of HTTP filter module

Determine the source code file name;
Create a config script and add the directory when configure is executed;
Define the filter module and instantiate a module of type ngx_module_t Structure;
Process configuration items of interest by setting the ngx_command_t array in the ngx_module_t structure;
Implement the initialization function. The initialization method is to insert the ngx_http_output_header_filter_t and ngx_http_output_body_filter_t functions into the head of the filter module list;
Implement ngx_http_output_header_ filter_pt and ngx_http_output_body_filter_pt functions;
After compilation and installation, modify the filter module option in the nginx.conf configuration file to enable it or not.

Configuration script

<code>ngx_add

HTTP_FILTER_MODULES=<span>"<span>$HTTP_FILTER_MODULES</span> ngx_http_myfilter_module"</span>
NGX_ADD>"<span>$NGX_ADDON_SRCS</span><span>$ngx_addon_dir</span>/ngx_http_myfilter_module.c"</code>

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Module content

<code><span>#include <../src/core/ngx_config.h></span><span>#include <../src/core/ngx_core.h></span><span>#include <../src/http/ngx_http.h></span><span>//Declare</span><span>static</span> ngx_int_t ngx_http_myfilter_header_filter(ngx_http_request_t *);
<span>static</span> ngx_int_t ngx_http_myfilter_body_filter(ngx_http_request_t*,ngx_chain_t*);
<span>static</span> ngx_http_output_header_filter_pt ngx_http_next_header_filter;
<span>static</span> ngx_http_output_body_filter_pt ngx_http_next_body_filter;


<span>//On/Off</span><span>typedef</span><span>struct</span> {
    ngx_flag_t enable;
}ngx_http_myfilter_conf_t;

<span>static</span><span>void</span> *ngx_http_myfilter_create_conf(ngx_conf_t *cf){
    ngx_http_myfilter_conf_t *mycf;

    <span>//Allocate memory</span>
    mycf = (ngx_http_myfilter_conf_t*)ngx_pcalloc(cf->pool,<span>sizeof</span>(ngx_http_myfilter_conf_t));
    <span>if</span>(mycf == <span>NULL</span>)
        <span>return</span><span>NULL</span>;

    mycf->enable = NGX_CONF_UNSET;

    <span>return</span> mycf;
}

<span>static</span><span>char</span> *
ngx_http_myfilter_merge_conf(ngx_conf_t *cf,<span>void</span> *parent,<span>void</span> *child){
    ngx_http_myfilter_conf_t *prev = (ngx_http_myfilter_conf_t*)parent;
    ngx_http_myfilter_conf_t *conf = (ngx_http_myfilter_conf_t*)child;
    ngx_conf_merge_value(conf->enable,prev->enable,<span>0</span>);
    <span>return</span> NGX_CONF_OK;
}

<span>/* ------------------------------------------- */</span><span>//State for prefix</span><span>typedef</span><span>struct</span> {
    <span>/* add_prefix = 
     * 0    the filter module is off
     * 1    can add prefix
     * 2    has been added prefix already
     */</span>
    ngx_int_t add_prefix;
} ngx_http_myfilter_ctx_t;

<span>//Analyse configure</span><span>static</span> ngx_command_t
ngx_http_myfilter_commands[]={
    {ngx_string(<span>"add_prefix"</span>),
        NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LMT_CONF|NGX_CONF_FLAG,
        ngx_conf_set_flag_slot,
        NGX_HTTP_LOC_CONF_OFFSET,
        offsetof(ngx_http_myfilter_conf_t,enable),
        <span>NULL</span>},
    ngx_null_command
};

<span>static</span> ngx_int_t
ngx_http_myfilter_init(ngx_conf_t *cf){
    <span>//Insert before the first node</span>
    ngx_http_next_header_filter = ngx_http_top_header_filter;
    ngx_http_top_header_filter = ngx_http_myfilter_header_filter;

    ngx_http_next_body_filter = ngx_http_top_body_filter;
    ngx_http_top_body_filter = ngx_http_myfilter_body_filter;

    <span>return</span> NGX_OK;
}

<span>/* ------------------------------------------- */</span><span>//Parse</span><span>static</span> ngx_http_module_t
ngx_http_myfilter_module_ctx = {
    <span>NULL</span>,
    ngx_http_myfilter_init,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    ngx_http_myfilter_create_conf,
    ngx_http_myfilter_merge_conf
};

<span>/* ------------------------------------------- */</span><span>//Module information</span>
ngx_module_t ngx_http_myfilter_module = {
    NGX_MODULE_V1,
    &ngx_http_myfilter_module_ctx,
    ngx_http_myfilter_commands,
    NGX_HTTP_MODULE,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    <span>NULL</span>,
    NGX_MODULE_V1_PADDING
};

<span>/* ------------------------------------------- */</span><span>static</span> ngx_str_t filter_prefix = ngx_string(<span>"[my filter module]"</span>);

<span>//Filter to process the header</span><span>static</span> ngx_int_t
ngx_http_myfilter_header_filter(ngx_http_request_t *r){
    ngx_http_myfilter_ctx_t *ctx;
    ngx_http_myfilter_conf_t *conf;

    <span>if</span>(r->headers_out<span>.status</span> != NGX_HTTP_OK){
        <span>return</span> ngx_http_next_header_filter(r);
    }

    <span>//Get context</span>
    ctx = ngx_http_get_module_ctx(r,ngx_http_myfilter_module);
    <span>if</span>(ctx){
        <span>return</span> ngx_http_next_header_filter(r);
    }

    <span>//Get configure by ngx_http_myfilter_conf_t</span>
    conf = ngx_http_get_module_loc_conf(r,ngx_http_myfilter_module);

    <span>if</span>(conf->enable == <span>0</span>){<span>//add_prefix off</span><span>return</span> ngx_http_next_header_filter(r);
    }

    <span>//Create ngx_http_myfilter_ctx_t</span>
    ctx = ngx_pcalloc(r->pool,<span>sizeof</span>(ngx_http_myfilter_ctx_t));
    <span>if</span>(ctx == <span>NULL</span>){
        <span>return</span> NGX_ERROR;
    }

    <span>//add_prefix = 0 express do not add prefix</span>
    ctx->add_prefix = <span>0</span>;

    <span>//Set context</span>
    ngx_http_set_ctx(r,ctx,ngx_http_myfilter_module);

    <span>//myfilter module only figure out Content-Type="text/plain"</span><span>if</span>(r->headers_out<span>.content_type</span><span>.len</span>>=<span>sizeof</span>(<span>"text/plain"</span>) - <span>1</span> &&
            ngx_strncasecmp(r->headers_out<span>.content_type</span><span>.data</span>,(u_char*)<span>"text/plain"</span>,<span>sizeof</span>(<span>"text/plain"</span>)-<span>1</span>)==<span>0</span>){
        <span>//Set add_prefix</span>
        ctx->add_prefix = <span>1</span>;
        <span>if</span>(r->headers_out<span>.content_length_n</span>><span>0</span>)
            r->headers_out<span>.content_length_n</span> += filter_prefix<span>.len</span>;
    }
        <span>return</span> ngx_http_next_header_filter(r);
}

<span>//Filter to process the body</span><span>static</span> ngx_int_t
ngx_http_myfilter_body_filter(ngx_http_request_t *r,ngx_chain_t *in){
    ngx_http_myfilter_ctx_t *ctx;
    ctx = ngx_http_get_module_ctx(r,ngx_http_myfilter_module);
    <span>//If cannot get context or the add_prefix is 0/2,do not process</span><span>if</span>(ctx == <span>NULL</span> || ctx->add_prefix !=<span>1</span>)
        <span>return</span> ngx_http_next_body_filter(r,in);

    <span>//To make sure never add prefix again</span>
    ctx->add_prefix = <span>2</span>;

    <span>//Get prefix string</span>
    ngx_buf_t *b = ngx_create_temp_buf(r->pool,filter_prefix<span>.len</span>);
    b->start = b->pos = filter_prefix<span>.data</span>;
    b->last = b->pos + filter_prefix<span>.len</span>;

    <span>//Get and set ngx_chain_t list at the bginning</span>
    ngx_chain_t *cl = ngx_alloc_chain_link(r->pool);
    cl->buf = b;
    cl->next = in;

    <span>return</span> ngx_http_next_body_filter(r,cl);
}</code>

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Configuration file nginx.conf

Add
in http{} add_prefix on;
Turn on the filtering module

Compile

<code>./configure --<span>add</span>-<span>module</span>=模块路径/
make
make install</code>

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The HTTP filtering module is also an HTTP module, so the writing of the HTTP module is roughly the same.

The above has introduced the development of Nginx HTTP filtering module, including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.