module.c

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

typedef struct {
  ngx_str_t abusers_filename;
} ngx_http_repsheet_loc_conf_t;

static char *ngx_http_repsheet(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static void *ngx_http_repsheet_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_repsheet_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child);
static ngx_int_t ngx_http_repsheet_init(ngx_conf_t *cf);
int is_abuser(ngx_str_t *ip_addr);

static ngx_command_t ngx_http_repsheet_commands[] = {
  { ngx_string("process_repsheet"),
    NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
    ngx_http_repsheet,
    NGX_HTTP_LOC_CONF_OFFSET,
    0,
    NULL },

  ngx_null_command
};

static ngx_http_module_t ngx_http_repsheet_module_ctx = {
  NULL,                              /* preconfiguration */
  ngx_http_repsheet_init,            /* postconfiguration */

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

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

  ngx_http_repsheet_create_loc_conf, /* create location configuration */
  ngx_http_repsheet_merge_loc_conf   /* merge location configuration */
};

ngx_module_t ngx_http_repsheet_module = {
  NGX_MODULE_V1,
  &ngx_http_repsheet_module_ctx, /* module context */
  ngx_http_repsheet_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 char *
ngx_http_repsheet(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) {
  ngx_http_repsheet_loc_conf_t *rlcf = conf;
  ngx_str_t *value;

  value = cf->args->elts;
  rlcf->abusers_filename = value[1];

  return NGX_CONF_OK;
}

static void *
ngx_http_repsheet_create_loc_conf(ngx_conf_t *cf) {
  ngx_http_repsheet_loc_conf_t *conf;

  conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_repsheet_loc_conf_t));
  if (conf == NULL) {
    return NULL;
  }

  return conf;
}

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

  if (conf->abusers_filename.len == 0) {
    conf->abusers_filename = prev->abusers_filename;
  }

  return NGX_CONF_OK;
}

static ngx_int_t
ngx_http_repsheet_handler(ngx_http_request_t *r) {
  ngx_table_elt_t *h;
  ngx_http_repsheet_loc_conf_t *rlcf;

  rlcf = ngx_http_get_module_loc_conf(r, ngx_http_repsheet_module);

  if (rlcf->abusers_filename.len == 0) {
    ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "Handler got no filename");
  }

  if (is_abuser(&r->connection->addr_text)) {
    h = ngx_list_push(&r->headers_out.headers);
    if (h == NULL) {
      return NGX_ERROR;
    }

    h->hash = 1;
    h->key.len = sizeof ("X-Repsheet") - 1;
    h->key.data = (u_char *) "X-Repsheet";
    h->value.len = sizeof("true") - 1;
    h->value.data = (u_char *) "true";
  }

  return NGX_DECLINED;
}

static ngx_int_t
ngx_http_repsheet_init(ngx_conf_t *cf)
{
  ngx_http_handler_pt *h;
  ngx_http_core_main_conf_t *cmcf;

  cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);

  h = ngx_array_push(&cmcf->phases[NGX_HTTP_POST_READ_PHASE].handlers);
  if (h == NULL) {
    return NGX_ERROR;
  }

  *h = ngx_http_repsheet_handler;

  return NGX_OK;
}

int is_abuser(ngx_str_t *ip_addr) {
  const char filename[] = "/Users/abedra/Desktop/abusers.txt";
  FILE *fp = fopen(filename, "r");
  if (fp != NULL) {
    char addr[16], svc[256];
    char c;
    int a_pos = 0, s_pos = 0;

    while ((c = getc(fp)) != EOF) {
      bzero(&addr, sizeof(addr));
      bzero(&svc, sizeof(svc));
      a_pos = 0;
      s_pos = 0;

      addr[a_pos++] = c;
      while ((addr[a_pos++] = getc(fp)) != ':');
      addr[a_pos-1] = '\0';

      while ((svc[s_pos++] = getc(fp)) != '\n');
      svc[s_pos-1] = '\0';

      if (ngx_strcmp((u_char *)addr, ip_addr->data) == 0) {
        fclose(fp);
        return 1;
      }
    }
    fclose(fp);
    return 0;
  } else {
    perror(filename);
  }
  fclose(fp);
  return 0;
}