text: #include "first.h"
  
  #include "base.h"
  #include "plugin.h"
  #include "log.h"
  #include "stat_cache.h"
  
  #include <stdlib.h>
  #include <string.h>
  
  /**
   *
   * #
   * # define a pattern for the host url finding
   * # %% => % sign
   * # %0 => domain name + tld
   * # %1 => tld
   * # %2 => domain name without tld
   * # %3 => subdomain 1 name
   * # %4 => subdomain 2 name
   * # %_ => fqdn (without port info)
   * #
   * evhost.path-pattern = "/home/ckruse/dev/www/%3/htdocs/"
   *
   */
  
  typedef struct {
      /* pieces for path creation */
      const buffer *path_pieces;
  } plugin_config;
  
  typedef struct {
      PLUGIN_DATA;
      plugin_config defaults;
      plugin_config conf;
  
      buffer tmp_buf;
      array split_vals;
  } plugin_data;
  
  INIT_FUNC(mod_evhost_init) {
      return calloc(1, sizeof(plugin_data));
  }
  
  static void mod_evhost_free_path_pieces(const buffer *path_pieces) {
      buffer *b;
      *(const buffer **)&b = path_pieces;
      for (; path_pieces->ptr; ++path_pieces) free(path_pieces->ptr);
      free(b);
  }
  
  FREE_FUNC(mod_evhost_free) {
      plugin_data * const p = p_d;
      free(p->tmp_buf.ptr);
      array_free_data(&p->split_vals);
      if (NULL == p->cvlist) return;
      /* (init i to 0 if global context; to 1 to skip empty global context) */
      for (int i = !p->cvlist[0].v.u2[1], used = p->nconfig; i < used; ++i) {
          config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
          for (; -1 != cpv->k_id; ++cpv) {
              if (cpv->vtype != T_CONFIG_LOCAL || NULL == cpv->v.v) continue;
              switch (cpv->k_id) {
                case 0: /* evhost.path-pattern */
                  mod_evhost_free_path_pieces(cpv->v.v);
                  break;
                default:
                  break;
              }
          }
      }
  }
  
  __attribute_cold__
  static buffer * mod_evhost_parse_pattern_err(buffer *bptr) {
      for (; bptr->ptr; ++bptr) free(bptr->ptr);
      return NULL;
  }
  
  static buffer * mod_evhost_parse_pattern(const char *ptr) {
  	uint32_t used = 0;
  	const uint32_t sz = 127;/* (sz+1 must match bptr[] num elts below) */
  	const char *pos;
  	buffer bptr[128]; /* (128 elements takes 2k on stack in 64-bit) */
  	memset(bptr, 0, sizeof(bptr));
  
  	for(pos=ptr;*ptr;ptr++) {
  		if(*ptr == '%') {
  			size_t len;
  			if (used >= sz-1) /* (should not happen) */
  				return mod_evhost_parse_pattern_err(bptr);
  
  			/* "%%" "%_" "%x" "%{x.y}" where x and y are *single digit* 0 - 9 */
  			if (ptr[1] == '%' || ptr[1] == '_' || light_isdigit(ptr[1])) {
  				len = 2;
  			} else if (ptr[1] == '{') {
  				if (!light_isdigit(ptr[2]))
  					return mod_evhost_parse_pattern_err(bptr);
  				if (ptr[3] == '.') {
  					if (!light_isdigit(ptr[4]))
  						return mod_evhost_parse_pattern_err(bptr);
  					if (ptr[5] != '}')
  						return mod_evhost_parse_pattern_err(bptr);
  					len = 6;
  				} else if (ptr[3] == '}') {
  					len = 4;
  				} else {
  					return mod_evhost_parse_pattern_err(bptr);
  				}
  			} else {
  				return mod_evhost_parse_pattern_err(bptr);
  			}
  
  			buffer_copy_string_len(bptr+used, pos, ptr-pos);
  			pos = ptr + len;
  
  			buffer_copy_string_len(bptr+used+1, ptr, len);
  			ptr += len - 1; /*(ptr++ in for() loop)*/
  
  			used += 2;
  		}
  	}
  
  	if(*pos != '\0') {
  		if (used >= sz) /* (should not happen) */
  			return mod_evhost_parse_pattern_err(bptr);
  		buffer_copy_string_len(bptr+used, pos, ptr-pos);
  		++used;
  	}
  
  	buffer * const path_pieces =
  	  malloc(sizeof(bptr) + ((used+1) * sizeof(buffer)));
  	force_assert(path_pieces);
  	return memcpy(path_pieces, bptr, (used+1) * sizeof(buffer));
  }
  
  static void mod_evhost_merge_config_cpv(plugin_config * const pconf, const config_plugin_value_t * const cpv) {
      switch (cpv->k_id) { /* index into static config_plugin_keys_t cpk[] */
        case 0: /* evhost.path-pattern */
          if (cpv->vtype == T_CONFIG_LOCAL)
              pconf->path_pieces = cpv->v.v;
          break;
        default:/* should not happen */
          return;
      }
  }
  
  static void mod_evhost_merge_config(plugin_config * const pconf, const config_plugin_value_t *cpv) {
      do {
          mod_evhost_merge_config_cpv(pconf, cpv);
      } while ((++cpv)->k_id != -1);
  }
  
  static void mod_evhost_patch_config(request_st * const r, plugin_data * const p) {
      p->conf = p->defaults; /* copy small struct instead of memcpy() */
      /*memcpy(&p->conf, &p->defaults, sizeof(plugin_config));*/
      for (int i = 1, used = p->nconfig; i < used; ++i) {
          if (config_check_cond(r, (uint32_t)p->cvlist[i].k_id))
              mod_evhost_merge_config(&p->conf, p->cvlist + p->cvlist[i].v.u2[0]);
      }
  }
  
  SETDEFAULTS_FUNC(mod_evhost_set_defaults) {
      static const config_plugin_keys_t cpk[] = {
        { CONST_STR_LEN("evhost.path-pattern"),
          T_CONFIG_STRING,
          T_CONFIG_SCOPE_CONNECTION }
       ,{ NULL, 0,
          T_CONFIG_UNSET,
          T_CONFIG_SCOPE_UNSET }
      };
  
      plugin_data * const p = p_d;
      if (!config_plugin_values_init(srv, p, cpk, "mod_evhost"))
          return HANDLER_ERROR;
  
      /* process and validate config directives
       * (init i to 0 if global context; to 1 to skip empty global context) */
      for (int i = !p->cvlist[0].v.u2[1]; i < p->nconfig; ++i) {
          config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
          for (; -1 != cpv->k_id; ++cpv) {
              switch (cpv->k_id) {
                case 0: /* evhost.path-pattern */
                  if (!buffer_string_is_empty(cpv->v.b)) {
                      const char * const ptr = cpv->v.b->ptr;
                      cpv->v.v = mod_evhost_parse_pattern(ptr);
                      if (NULL == cpv->v.v) {
                          log_error(srv->errh, __FILE__, __LINE__,
                            "invalid evhost.path-pattern: %s", ptr);
                          return HANDLER_ERROR;
                      }
                      cpv->vtype = T_CONFIG_LOCAL;
                  }
                  break;
                default:/* should not happen */
                  break;
              }
          }
      }
  
      /* initialize p->defaults from global config context */
      if (p->nconfig > 0 && p->cvlist->v.u2[1]) {
          const config_plugin_value_t *cpv = p->cvlist + p->cvlist->v.u2[0];
          if (-1 != cpv->k_id)
              mod_evhost_merge_config(&p->defaults, cpv);
      }
  
      return HANDLER_GO_ON;
  }
  
  /**
   * assign the different parts of the domain to array-indezes (sub2.sub1.domain.tld)
   * - %0 - domain.tld
   * - %1 - tld
   * - %2 - domain
   * - %3 - sub1
   * - ...
   */
  
  static void mod_evhost_parse_host(buffer *key, array *host, buffer *authority) {
  	char *ptr = authority->ptr + buffer_string_length(authority);
  	char *colon = ptr; /* needed to filter out the colon (if exists) */
  	int first = 1;
  	int i;
  
  	/*if (ptr == authority->ptr) return;*//*(no authority checked earlier)*/
  
  	if (*authority->ptr == '[') { /* authority is IPv6 literal address */
                  colon = ptr;
                  if (ptr[-1] != ']') {
  			do { --ptr; } while (ptr > authority->ptr && ptr[-1] != ']');
  			if (*ptr != ':') return; /*(should not happen for valid authority)*/
  			colon = ptr;
  		}
  		ptr = authority->ptr;
  		array_set_key_value(host,CONST_STR_LEN("%0"),ptr,colon-ptr);
  		return;
  	}
  
  	/* first, find the domain + tld */
  	for(; ptr > authority->ptr; --ptr) {
  		if(*ptr == '.') {
  			if(first) first = 0;
  			else      break;
  		} else if(*ptr == ':') {
  			colon = ptr;
  			first = 1;
  		}
  	}
  
  	/* if we stopped at a dot, skip the dot */
  	if (*ptr == '.') ptr++;
  	array_set_key_value(host, CONST_STR_LEN("%0"), ptr, colon-ptr);
  
  	/* if the : is not the start of the authority, go on parsing the hostname */
  
  	if (colon != authority->ptr) {
  		for(ptr = colon - 1, i = 1; ptr > authority->ptr; --ptr) {
  			if(*ptr == '.') {
  				if (ptr != colon - 1) {
  					/* is something between the dots */
  					buffer_copy_string_len(key, CONST_STR_LEN("%"));
  					buffer_append_int(key, i++);
  					array_set_key_value(host, CONST_BUF_LEN(key), ptr+1, colon-ptr-1);
  				}
  				colon = ptr;
  			}
  		}
  
  		/* if the . is not the first character of the hostname */
  		if (colon != ptr) {
  			buffer_copy_string_len(key, CONST_STR_LEN("%"));
  			buffer_append_int(key, i /* ++ */);
  			array_set_key_value(host, CONST_BUF_LEN(key), ptr, colon-ptr);
  		}
  	}
  }
  
  static void mod_evhost_build_doc_root_path(buffer *b, array *parsed_host, buffer *authority, const buffer *path_pieces) {
  	array_reset_data_strings(parsed_host);
  	mod_evhost_parse_host(b, parsed_host, authority);
  	buffer_clear(b);
  
  	for (const char *ptr; (ptr = path_pieces->ptr); ++path_pieces) {
  		if (*ptr == '%') {
  			const data_string *ds;
  
  			if (*(ptr+1) == '%') {
  				/* %% */
  				buffer_append_string_len(b, CONST_STR_LEN("%"));
  			} else if (*(ptr+1) == '_' ) {
  				/* %_ == full hostname */
  				char *colon = strchr(authority->ptr, ':');
  
  				if(colon == NULL) {
  					buffer_append_string_buffer(b, authority); /* adds fqdn */
  				} else {
  					/* strip the port out of the authority-part of the URI scheme */
  					buffer_append_string_len(b, authority->ptr, colon - authority->ptr); /* adds fqdn */
  				}
  			} else if (ptr[1] == '{' ) {
  				char s[3] = "% ";
  				s[1] = ptr[2]; /*(assumes single digit before '.', and, optionally, '.' and single digit after '.')*/
  				if (NULL != (ds = (data_string *)array_get_element_klen(parsed_host, s, 2))) {
  					if (ptr[3] != '.' || ptr[4] == '0') {
  						buffer_append_string_buffer(b, &ds->value);
  					} else {
  						if ((size_t)(ptr[4]-'0') <= buffer_string_length(&ds->value)) {
  							buffer_append_string_len(b, ds->value.ptr+(ptr[4]-'0')-1, 1);
  						}
  					}
  				} else {
  					/* unhandled %-sequence */
  				}
  			} else if (NULL != (ds = (data_string *)array_get_element_klen(parsed_host, CONST_BUF_LEN(path_pieces)))) {
  				buffer_append_string_buffer(b, &ds->value);
  			} else {
  				/* unhandled %-sequence */
  			}
  		} else {
  			buffer_append_string_buffer(b, path_pieces);
  		}
  	}
  
  	buffer_append_slash(b);
  }
  
  static handler_t mod_evhost_uri_handler(request_st * const r, void *p_d) {
  	plugin_data *p = p_d;
  	stat_cache_entry *sce = NULL;
  
  	/* not authority set */
  	if (buffer_string_is_empty(&r->uri.authority)) return HANDLER_GO_ON;
  
  	mod_evhost_patch_config(r, p);
  
  	/* missing even default(global) conf */
  	if (NULL == p->conf.path_pieces) return HANDLER_GO_ON;
  
  	buffer * const b = &p->tmp_buf;
  	mod_evhost_build_doc_root_path(b, &p->split_vals, &r->uri.authority, p->conf.path_pieces);
  
  	sce = stat_cache_get_entry(b);
  	if (NULL == sce) {
  		log_perror(r->conf.errh, __FILE__, __LINE__, "%s", b->ptr);
  	} else if(!S_ISDIR(sce->st.st_mode)) {
  		log_error(r->conf.errh, __FILE__, __LINE__, "not a directory: %s", b->ptr);
  	} else {
  		buffer_copy_buffer(&r->physical.doc_root, b);
  	}
  
  	return HANDLER_GO_ON;
  }
  
  int mod_evhost_plugin_init(plugin *p);
  int mod_evhost_plugin_init(plugin *p) {
  	p->version     = LIGHTTPD_VERSION_ID;
  	p->name        = "evhost";
  	p->init                    = mod_evhost_init;
  	p->set_defaults            = mod_evhost_set_defaults;
  	p->handle_docroot          = mod_evhost_uri_handler;
  	p->cleanup                 = mod_evhost_free;
  
  	return 0;
  }
  