Nginx C Module.

config

addon_name=ngx_http_echo_module
HTTP_MODULES="$HTTP_MODULES ngx_http_echo_module"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_echo_module.c"

ngx_http_echo_module

/*
 *Nginx Http Echo Module
 *
 */

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


typedef struct {
    ngx_str_t ed;
} ngx_http_echo_loc_conf_t;

static char *ngx_http_echo(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static void *ngx_http_echo_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_echo_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child);

static ngx_command_t ngx_http_echo_commands[] = {
    { ngx_string("echo"),
      NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_http_echo,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_echo_loc_conf_t,ed),
      NULL 
      },
      ngx_null_command

};


static ngx_http_module_t ngx_http_echo_module_ctx = {
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    ngx_http_echo_create_loc_conf,
    ngx_http_echo_merge_loc_conf,
};


ngx_module_t  ngx_http_echo_module = {
    NGX_MODULE_V1,
    &ngx_http_echo_module_ctx,
    ngx_http_echo_commands,
    NGX_HTTP_MODULE,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NGX_MODULE_V1_PADDING
};


static ngx_int_t
ngx_http_echo_handler(ngx_http_request_t *r) {
    ngx_int_t rc;
    ngx_buf_t *b;
    ngx_chain_t out;
    ngx_http_echo_loc_conf_t *elcf;
    elcf = ngx_http_get_module_loc_conf(r, ngx_http_echo_module);
    if (!(r->method &(NGX_HTTP_HEAD|NGX_HTTP_GET))) {
        return NGX_HTTP_NOT_ALLOWED;    
    }

    //ngx_str_t content_type = ngx_string("text/html");
    //r->headers_out.content_type = content_type;
    r->headers_out.content_type.len = sizeof("text/html") -1;
    r->headers_out.content_type.data = (u_char *) "text/html";
    r->headers_out.status = NGX_HTTP_OK;
    r->headers_out.content_length_n = elcf->ed.len;
    
    if (r->method == NGX_HTTP_HEAD) {
        rc = ngx_http_send_header(r);
        if (rc != NGX_OK) {
            return rc;
        }
    }

    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));

    if (b == NULL) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "Failed to allocate response buffer.");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    out.buf = b;
    out.next = NULL;
    b->pos = elcf->ed.data;
    b->last = elcf->ed.data + (elcf->ed.len);
    b->memory = 1;
    b->last_buf = 1;
    rc = ngx_http_send_header(r);
    if (rc != NGX_OK) {
        return rc;    
    }

    return ngx_http_output_filter(r,&out);

}



static char *
ngx_http_echo(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) {
    ngx_http_core_loc_conf_t *clcf;
    clcf = ngx_http_conf_get_module_loc_conf(cf,ngx_http_core_module);
    clcf->handler = ngx_http_echo_handler;
    ngx_conf_set_str_slot(cf,cmd,conf);
    return NGX_CONF_OK;
}

static void *
ngx_http_echo_create_loc_conf(ngx_conf_t *cf) {
  ngx_http_echo_loc_conf_t *conf;
  conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_echo_loc_conf_t));
  if (conf == NULL) {
      return NGX_CONF_ERROR;
  }
  conf->ed.len = 0;
  conf->ed.data = NULL;
  return conf;
}


static char *
ngx_http_echo_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) {
    ngx_http_echo_loc_conf_t *prev = parent;
    ngx_http_echo_loc_conf_t *conf = child;
    ngx_conf_merge_str_value(conf->ed, prev->ed, "");
    return NGX_CONF_OK;
    
}