ngx_http_sub_filter_module.c

nginx 反向代理0.7.1版本 用于实现反向代理

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


typedef struct {
    ngx_str_t      match;
    ngx_str_t      sub;

    ngx_array_t   *types;     /* array of ngx_str_t */

    ngx_array_t   *sub_lengths;
    ngx_array_t   *sub_values;

    ngx_flag_t     once;
} ngx_http_sub_loc_conf_t;


typedef enum {
    sub_start_state = 0,
    sub_match_state,
} ngx_http_sub_state_e;


typedef struct {
    ngx_str_t      match;

    ngx_uint_t     once;   /* unsigned  once:1 */

    ngx_buf_t     *buf;

    u_char        *pos;
    u_char        *copy_start;
    u_char        *copy_end;

    ngx_chain_t   *in;
    ngx_chain_t   *out;
    ngx_chain_t  **last_out;
    ngx_chain_t   *busy;
    ngx_chain_t   *free;

    ngx_str_t      sub;

    ngx_uint_t     state;
    size_t         saved;
    size_t         looked;
} ngx_http_sub_ctx_t;


static ngx_int_t ngx_http_sub_output(ngx_http_request_t *r,
    ngx_http_sub_ctx_t *ctx);
static ngx_int_t ngx_http_sub_parse(ngx_http_request_t *r,
    ngx_http_sub_ctx_t *ctx);

static char * ngx_http_sub_filter(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_sub_types(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static void *ngx_http_sub_create_conf(ngx_conf_t *cf);
static char *ngx_http_sub_merge_conf(ngx_conf_t *cf,
    void *parent, void *child);
static ngx_int_t ngx_http_sub_filter_init(ngx_conf_t *cf);


static ngx_command_t  ngx_http_sub_filter_commands[] = {

    { ngx_string("sub_filter"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE2,
      ngx_http_sub_filter,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("sub_filter_types"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
      ngx_http_sub_types,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("sub_filter_once"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_sub_loc_conf_t, once),
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_sub_filter_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_sub_filter_init,              /* postconfiguration */

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

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

    ngx_http_sub_create_conf,              /* create location configuration */
    ngx_http_sub_merge_conf                /* merge location configuration */
};


ngx_module_t  ngx_http_sub_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_sub_filter_module_ctx,       /* module context */
    ngx_http_sub_filter_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_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_sub_header_filter(ngx_http_request_t *r)
{
    ngx_str_t                *type;
    ngx_uint_t                i;
    ngx_http_sub_ctx_t        *ctx;
    ngx_http_sub_loc_conf_t  *slcf;

    slcf = ngx_http_get_module_loc_conf(r, ngx_http_sub_filter_module);

    if (slcf->match.len == 0
        || r->headers_out.content_type.len == 0
        || r->headers_out.content_length_n == 0)
    {
        return ngx_http_next_header_filter(r);
    }

    type = slcf->types->elts;
    for (i = 0; i < slcf->types->nelts; i++) {
        if (r->headers_out.content_type.len >= type[i].len
            && ngx_strncasecmp(r->headers_out.content_type.data,
                               type[i].data, type[i].len) == 0)
        {
            goto found;
        }
    }

    return ngx_http_next_header_filter(r);

found:

    ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_sub_ctx_t));
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    ngx_http_set_ctx(r, ctx, ngx_http_sub_filter_module);

    ctx->match = slcf->match;
    ctx->last_out = &ctx->out;
    ctx->sub = slcf->sub;

    r->filter_need_in_memory = 1;

    if (r == r->main) {
        ngx_http_clear_content_length(r);
        ngx_http_clear_last_modified(r);
    }

    return ngx_http_next_header_filter(r);
}


static ngx_int_t
ngx_http_sub_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    ngx_int_t                  rc;
    ngx_buf_t                 *b;
    ngx_chain_t               *cl;
    ngx_http_sub_ctx_t        *ctx;
    ngx_http_sub_loc_conf_t   *slcf;

    ctx = ngx_http_get_module_ctx(r, ngx_http_sub_filter_module);

    if (ctx == NULL) {
        return ngx_http_next_body_filter(r, in);
    }

    if ((in == NULL
         && ctx->buf == NULL
         && ctx->in == NULL
         && ctx->busy == NULL))
    {
        return ngx_http_next_body_filter(r, in);
    }

    if (ctx->once && (ctx->buf == NULL || ctx->in == NULL)) {

        if (ctx->busy) {
            if (ngx_http_sub_output(r, ctx) == NGX_ERROR) {
                return NGX_ERROR;
            }
        }

        return ngx_http_next_body_filter(r, in);
    }

    /* add the incoming chain to the chain ctx->in */

    if (in) {
        if (ngx_chain_add_copy(r->pool, &ctx->in, in) == NGX_ERROR) {
            return NGX_ERROR;
        }
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http sub filter \"%V\"", &r->uri);

    while (ctx->in || ctx->buf) {

        if (ctx->buf == NULL ){
            ctx->buf = ctx->in->buf;
            ctx->in = ctx->in->next;
            ctx->pos = ctx->buf->pos;
        }

        if (ctx->state == sub_start_state) {
            ctx->copy_start = ctx->pos;
            ctx->copy_end = ctx->pos;
        }

        b = NULL;

        while (ctx->pos < ctx->buf->last) {

            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "saved: %d state: %d", ctx->saved, ctx->state);

            rc = ngx_http_sub_parse(r, ctx);

            ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "parse: %d, looked: %d %p-%p",
                           rc, ctx->looked, ctx->copy_start, ctx->copy_end);

            if (rc == NGX_ERROR) {
                return rc;
            }

            if (ctx->copy_start != ctx->copy_end) {

                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                               "saved: %d", ctx->saved);

                if (ctx->saved) {

                    if (ctx->free) {
                        cl = ctx->free;
                        ctx->free = ctx->free->next;
                        b = cl->buf;
                        ngx_memzero(b, sizeof(ngx_buf_t));

                    } else {
                        b = ngx_calloc_buf(r->pool);
                        if (b == NULL) {
                            return NGX_ERROR;
                        }

                        cl = ngx_alloc_chain_link(r->pool);
                        if (cl == NULL) {
                            return NGX_ERROR;
                        }

                        cl->buf = b;
                    }

                    b->memory = 1;
                    b->pos = ctx->match.data;
                    b->last = ctx->match.data + ctx->saved;

                    *ctx->last_out = cl;
                    ctx->last_out = &cl->next;

                    ctx->saved = 0;
                }

                if (ctx->free) {
                    cl = ctx->free;
                    ctx->free = ctx->free->next;
                    b = cl->buf;

                } else {
                    b = ngx_alloc_buf(r->pool);
                    if (b == NULL) {
                        return NGX_ERROR;
                    }

                    cl = ngx_alloc_chain_link(r->pool);
                    if (cl == NULL) {
                        return NGX_ERROR;
                    }

                    cl->buf = b;
                }

                ngx_memcpy(b, ctx->buf, sizeof(ngx_buf_t));

                b->pos = ctx->copy_start;
                b->last = ctx->copy_end;
                b->shadow = NULL;
                b->last_buf = 0;
                b->recycled = 0;

                if (b->in_file) {
                    b->file_last = b->file_pos + (b->last - b->start);
                    b->file_pos += b->pos - b->start;
                }

                cl->next = NULL;
                *ctx->last_out = cl;
                ctx->last_out = &cl->next;
            }

            if (ctx->state == sub_start_state) {
                ctx->copy_start = ctx->pos;
                ctx->copy_end = ctx->pos;

            } else {
                ctx->copy_start = NULL;
                ctx->copy_end = NULL;
            }

            if (rc == NGX_AGAIN) {
                continue;
            }


            /* rc == NGX_OK */

            b = ngx_calloc_buf(r->pool);
            if (b == NULL) {
                return NGX_ERROR;
            }

            cl = ngx_alloc_chain_link(r->pool);
            if (cl == NULL) {
                return NGX_ERROR;
            }

            slcf = ngx_http_get_module_loc_conf(r, ngx_http_sub_filter_module);

            if (ctx->sub.data == NULL) {

                if (ngx_http_script_run(r, &ctx->sub, slcf->sub_lengths->elts,
                                        0, slcf->sub_values->elts)
                    == NULL)
                {
                    return NGX_ERROR;
                }
            }

            if (ctx->sub.len) {
                b->memory = 1;
                b->pos = ctx->sub.data;
                b->last = ctx->sub.data + ctx->sub.len;

            } else {
                b->sync = 1;
            }

            cl->buf = b;
            cl->next = NULL;
            *ctx->last_out = cl;
            ctx->last_out = &cl->next;

            ctx->once = slcf->once;

            continue;
        }

        if (ctx->buf->last_buf || ngx_buf_in_memory(ctx->buf)) {
            if (b == NULL) {
                if (ctx->free) {
                    cl = ctx->free;
                    ctx->free = ctx->free->next;
                    b = cl->buf;
                    ngx_memzero(b, sizeof(ngx_buf_t));

                } else {
                    b = ngx_calloc_buf(r->pool);
                    if (b == NULL) {
                        return NGX_ERROR;
                    }