wifidog源码分析 - 客户端检测线程
引言当wifidog启动时，会启动一个线程(thread_client_timeout_check)维护客户端列表，具体就是wifidog必须定时检测客户端列表中的每个客户端是否在线，而wifidog是通过两种方式进行检测客户端在线情况，一种是定时通过iptables获取客户端出入总流量更新客户端时间，通过最近更新时间进行判断（有新的出入流量则更新客户端时间，之后使用最新客户端时间与当前时间判断），一种是查询认证服务器，通过认证服务器的返回信息进行判断（将客户端IP和状态请求发送给认证服务器，认证服务器会返回客户端是否在线，这种情况是用于客户端是在认证服务器上正常登出）。thread_client_timeout_check
此线程执行函数用于维护客户端列表，此线程是一个while （1）循环，每隔一个配置文件中的checkinterval时间间隔执行一次fw_sync_with_authserver函数，核心代码处于fw_sync_with_authserver函数中，我们先具体代码，voidthread_client_timeout_check(const void *arg){ pthread_cond_t cond = PTHREAD_COND_INITIALIZER; pthread_mutex_t cond_mutex = PTHREAD_MUTEX_INITIALIZER; struct timespec timeout; while (1) { /* 设置超时时间 */ timeout.tv_sec = time(NULL) + config_get_config()->checkinterval; timeout.tv_nsec = 0; /* 使用pthread_cond_timedwait必须先上锁 */ pthread_mutex_lock(&cond_mutex); /* 等待超时 */ pthread_cond_timedwait(&cond, &cond_mutex, &timeout); /* 解锁 */ pthread_mutex_unlock(&cond_mutex); debug(LOG_DEBUG, "Running fw_counter()"); /* 执行核心代码 */ fw_sync_with_authserver(); }}fw_sync_with_authserver
此函数是此线程的核心函数，维护客户端列表就在此中，其首先会遍历客户端列表，通过iptables获取每个客户端列表的出入流量，之后根据出口流量(入口流量不做判断，详见 代码片段1.3)更新客户端最近更新时间（last_updated），之后使用每个客户端最近更新时间与当前时间比较，如果超过超时间隔则判断为下线，而如果未超时，则还会从认证服务器中获取此客户端状态，确定其是否在线。具体流程如下更新客户端出入口流量，根据出口流量更新每个客户端的最近更新时间
客户端超时则从客户端列表中移除并通过iptables禁止其访问网络，并告知认证服务器此客户端下线
客户端未超时则从认证服务器获取此客户端信息，判断其是否通过认证服务器下线
代码片段1.2：voidfw_sync_with_authserver(void){ t_authresponseauthresponse; char *token, *ip, *mac; t_client *p1, *p2; unsigned long long incoming, outgoing; s_config *config = config_get_config(); /* 根据iptables流量更新最近更新时间，具体代码见 代码片段1.3 */ if (-1 == iptables_fw_counters_update()) { debug(LOG_ERR, "Could not get counters from firewall!"); return; } LOCK_CLIENT_LIST(); /* 遍历客户端列表 */ for (p1 = p2 = client_get_first_client(); NULL != p1; p1 = p2) { p2 = p1->next; ip = safe_strdup(p1->ip); token = safe_strdup(p1->token); mac = safe_strdup(p1->mac); outgoing = p1->counters.outgoing; incoming = p1->counters.incoming; UNLOCK_CLIENT_LIST(); /* ping一下此客户端，不清楚作用 */ icmp_ping(ip); /* 将客户端的出入流量上传至认证服务器，此时如果此客户端在认证服务器上下线会返回告知wifidog */ if (config->auth_servers != NULL) { auth_server_request(&authresponse, REQUEST_TYPE_COUNTERS, ip, mac, token, incoming, outgoing); } LOCK_CLIENT_LIST(); /* 从客户端列表获取IP,MAC对应客户端 */ if (!(p1 = client_list_find(ip, mac))) { debug(LOG_ERR, "Node %s was freed while being re-validated!", ip); } else { time_t current_time=time(NULL); debug(LOG_INFO, "Checking client %s for timeout:Last updated %ld (%ld seconds ago), timeout delay %ld seconds, current time %ld, ", p1->ip, p1->counters.last_updated, current_time-p1->counters.last_updated, config->checkinterval * config->clienttimeout, current_time); /* 判断是否超时，(最近更新时间 + 超时时间 <= 当前时间) 表明以超过超时时间，下线 */ if (p1->counters.last_updated + (config->checkinterval * config->clienttimeout) <= current_time) { debug(LOG_INFO, "%s - Inactive for more than %ld seconds, removing client and denying in firewall", p1->ip, config->checkinterval * config->clienttimeout); /* 修改iptables禁止此客户端访问外网 */ fw_deny(p1->ip, p1->mac, p1->fw_connection_state); /* 从客户端列表中删除此客户端 */ client_list_delete(p1); /* 通知认证服务器此客户端下线 */ if (config->auth_servers != NULL) { UNLOCK_CLIENT_LIST(); auth_server_request(&authresponse, REQUEST_TYPE_LOGOUT, ip, mac, token, 0, 0); LOCK_CLIENT_LIST(); } } else { /* 未超时处理 */ if (config->auth_servers != NULL) { /* 判断认证服务器返回信息 */ switch (authresponse.authcode) { /* 认证服务器禁止其访问网络(下线或遭拒绝) */ case AUTH_DENIED: debug(LOG_NOTICE, "%s - Denied. Removing client and firewall rules", p1->ip); fw_deny(p1->ip, p1->mac, p1->fw_connection_state); client_list_delete(p1); break; case AUTH_VALIDATION_FAILED: debug(LOG_NOTICE, "%s - Validation timeout, now denied. Removing client and firewall rules", p1->ip); fw_deny(p1->ip, p1->mac, p1->fw_connection_state); client_list_delete(p1); break; /* 认证服务器允许其访问网络(在线) */ case AUTH_ALLOWED: if (p1->fw_connection_state != FW_MARK_KNOWN) { debug(LOG_INFO, "%s - Access has changed to allowed, refreshing firewall and clearing counters", p1->ip); if (p1->fw_connection_state != FW_MARK_PROBATION) { p1->counters.incoming = p1->counters.outgoing = 0; } else { debug(LOG_INFO, "%s - Skipped clearing counters after all, the user was previously in validation", p1->ip); } p1->fw_connection_state = FW_MARK_KNOWN; fw_allow(p1->ip, p1->mac, p1->fw_connection_state); } break; case AUTH_VALIDATION: debug(LOG_INFO, "%s - User in validation period", p1->ip); break; case AUTH_ERROR: debug(LOG_WARNING, "Error communicating with auth server - leaving %s as-is for now", p1->ip); break; default: debug(LOG_ERR, "I do not know about authentication code %d", authresponse.authcode); break; } } } } free(token); free(ip); free(mac); } UNLOCK_CLIENT_LIST();}代码片段1.3：intiptables_fw_counters_update(void){ FILE *output; char *script, ip, rc; unsigned long long int counter; t_client *p1; struct in_addr tempaddr; /* 通过iptables获取其出口流量 */ safe_asprintf(&script, "%s %s", "iptables", "-v -n -x -t mangle -L " TABLE_WIFIDOG_OUTGOING); iptables_insert_gateway_id(&script); output = popen(script, "r"); free(script); if (!output) { debug(LOG_ERR, "popen(): %s", strerror(errno)); return -1; } /* iptables返回信息处理 */ while (('\n' != fgetc(output)) && !feof(output)) ; while (('\n' != fgetc(output)) && !feof(output)) ; while (output && !(feof(output))) { rc = fscanf(output, "%*s %llu %*s %*s %*s %*s %*s %15 %*s %*s %*s %*s %*s %*s", &counter, ip); //rc = fscanf(output, "%*s %llu %*s %*s %*s %*s %*s %15 %*s %*s %*s %*s %*s 0x%*u", &counter, ip); if (2 == rc && EOF != rc) { if (!inet_aton(ip, &tempaddr)) { debug(LOG_WARNING, "I was supposed to read an IP address but instead got [%s] - ignoring it", ip); continue; } debug(LOG_DEBUG, "Read outgoing traffic for %s: Bytes=%llu", ip, counter); LOCK_CLIENT_LIST(); /* 通过ip获取客户端信息结构 */ if ((p1 = client_list_find_by_ip(ip))) { /* (上一次出口总流量(outgoing) + wifidog启动时的出口总流量(outgoing_history) < iptables返回的出口总流量) 表示此客户端有新的出口流量 */ if ((p1->counters.outgoing - p1->counters.outgoing_history) < counter) { /* 更新上一次出口总流量(outgoing)为wifidog启动时的出口总流量(outgoing_history) + iptables返回总流量(counter) */ p1->counters.outgoing = p1->counters.outgoing_history + counter; /* 更新最近更新时间为当前时间 */ p1->counters.last_updated = time(NULL); debug(LOG_DEBUG, "%s - Updated counter.outgoing to %llu bytes.Updated last_updated to %d", ip, counter, p1->counters.last_updated); } } else { debug(LOG_ERR, "Could not find %s in client list", ip); } UNLOCK_CLIENT_LIST(); } } pclose(output); /* 通过iptables获取其入口流量，入口流量不做更新最近更新时间参考，只用于更新后上传至认证服务器，其原理同上，后面的代码不做详细分析 */ safe_asprintf(&script, "%s %s", "iptables", "-v -n -x -t mangle -L " TABLE_WIFIDOG_INCOMING); iptables_insert_gateway_id(&script); output = popen(script, "r"); free(script); if (!output) { debug(LOG_ERR, "popen(): %s", strerror(errno)); return -1; } while (('\n' != fgetc(output)) && !feof(output)) ; while (('\n' != fgetc(output)) && !feof(output)) ; while (output && !(feof(output))) { rc = fscanf(output, "%*s %llu %*s %*s %*s %*s %*s %*s %15", &counter, ip); if (2 == rc && EOF != rc) { if (!inet_aton(ip, &tempaddr)) { debug(LOG_WARNING, "I was supposed to read an IP address but instead got [%s] - ignoring it", ip); continue; } debug(LOG_DEBUG, "Read incoming traffic for %s: Bytes=%llu", ip, counter); LOCK_CLIENT_LIST(); if ((p1 = client_list_find_by_ip(ip))) { if ((p1->counters.incoming - p1->counters.incoming_history) < counter) { p1->counters.incoming = p1->counters.incoming_history + counter; debug(LOG_DEBUG, "%s - Updated counter.incoming to %llu bytes", ip, counter); } } else { debug(LOG_ERR, "Could not find %s in client list", ip); } UNLOCK_CLIENT_LIST(); } } pclose(output); return 1;}原文转自：www.wifidog.pro
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