wifidog源码分析 - 客户端检测线程

来源：互联网发布：淘宝8.8 编辑：程序博客网时间：2024/06/06 02:13

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

代码片段1.1

 1 void 2 thread_client_timeout_check(const void *arg) 3 { 4     pthread_cond_t        cond = PTHREAD_COND_INITIALIZER; 5     pthread_mutex_t        cond_mutex = PTHREAD_MUTEX_INITIALIZER; 6     struct    timespec    timeout; 7      8     while (1) { 9         /* 设置超时时间 */10         timeout.tv_sec = time(NULL) + config_get_config()->checkinterval;11         timeout.tv_nsec = 0;12 13         /* 使用pthread_cond_timedwait必须先上锁 */14         pthread_mutex_lock(&cond_mutex);15         16         /* 等待超时 */17         pthread_cond_timedwait(&cond, &cond_mutex, &timeout);18 19         /* 解锁 */20         pthread_mutex_unlock(&cond_mutex);21     22         debug(LOG_DEBUG, "Running fw_counter()");23     24         /* 执行核心代码 */  25         fw_sync_with_authserver();26     }27 }

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

  1 void  2 fw_sync_with_authserver(void)  3 {  4     t_authresponse  authresponse;  5     char            *token, *ip, *mac;  6     t_client        *p1, *p2;  7     unsigned long long        incoming, outgoing;  8     s_config *config = config_get_config();  9  10     /* 根据iptables流量更新最近更新时间，具体代码见 代码片段1.3 */ 11     if (-1 == iptables_fw_counters_update()) { 12         debug(LOG_ERR, "Could not get counters from firewall!"); 13         return; 14     } 15  16     LOCK_CLIENT_LIST(); 17  18     /* 遍历客户端列表 */ 19     for (p1 = p2 = client_get_first_client(); NULL != p1; p1 = p2) { 20         p2 = p1->next; 21  22         ip = safe_strdup(p1->ip); 23         token = safe_strdup(p1->token); 24         mac = safe_strdup(p1->mac); 25         outgoing = p1->counters.outgoing; 26         incoming = p1->counters.incoming; 27  28         UNLOCK_CLIENT_LIST(); 29         /* ping一下此客户端，不清楚作用 */ 30         icmp_ping(ip); 31         /* 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 */ 32         if (config->auth_servers != NULL) { 33             auth_server_request(&authresponse, REQUEST_TYPE_COUNTERS, ip, mac, token, incoming, outgoing); 34         } 35         LOCK_CLIENT_LIST(); 36  37         /* 从客户端列表获取IP,MAC对应客户端 */ 38         if (!(p1 = client_list_find(ip, mac))) { 39             debug(LOG_ERR, "Node %s was freed while being re-validated!", ip); 40         } else { 41             time_t    current_time=time(NULL); 42             debug(LOG_INFO, "Checking client %s for timeout:  Last updated %ld (%ld seconds ago), timeout delay %ld seconds, current time %ld, ", 43                         p1->ip, p1->counters.last_updated, current_time-p1->counters.last_updated, config->checkinterval * config->clienttimeout, current_time); 44             /* 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 */ 45             if (p1->counters.last_updated + 46                 (config->checkinterval * config->clienttimeout) 47                 <= current_time) { 48                 debug(LOG_INFO, "%s - Inactive for more than %ld seconds, removing client and denying in firewall", 49                         p1->ip, config->checkinterval * config->clienttimeout); 50                 /* 修改iptables禁止此客户端访问外网 */ 51                 fw_deny(p1->ip, p1->mac, p1->fw_connection_state); 52                 /* 从客户端列表中删除此客户端 */ 53                 client_list_delete(p1); 54  55                 /* 通知认证服务器此客户端下线 */ 56                 if (config->auth_servers != NULL) { 57                     UNLOCK_CLIENT_LIST(); 58                     auth_server_request(&authresponse, REQUEST_TYPE_LOGOUT, ip, mac, token, 0, 0); 59                     LOCK_CLIENT_LIST(); 60                 } 61             } else { 62                 /* 未超时处理 */ 63                 if (config->auth_servers != NULL) { 64                     /* 判断认证服务器返回信息 */ 65                     switch (authresponse.authcode) { 66                         /* 认证服务器禁止其访问网络(下线或遭拒绝) */ 67                         case AUTH_DENIED: 68                             debug(LOG_NOTICE, "%s - Denied. Removing client and firewall rules", p1->ip); 69                             fw_deny(p1->ip, p1->mac, p1->fw_connection_state); 70                             client_list_delete(p1); 71                             break; 72  73                         case AUTH_VALIDATION_FAILED: 74                             debug(LOG_NOTICE, "%s - Validation timeout, now denied. Removing client and firewall rules", p1->ip); 75                             fw_deny(p1->ip, p1->mac, p1->fw_connection_state); 76                             client_list_delete(p1); 77                             break; 78  79                         /* 认证服务器允许其访问网络(在线) */ 80                         case AUTH_ALLOWED: 81                             if (p1->fw_connection_state != FW_MARK_KNOWN) { 82                                 debug(LOG_INFO, "%s - Access has changed to allowed, refreshing firewall and clearing counters", p1->ip); 83                                 if (p1->fw_connection_state != FW_MARK_PROBATION) { 84                                     p1->counters.incoming = p1->counters.outgoing = 0; 85                                 } 86                                 else { 87                             88                                     debug(LOG_INFO, "%s - Skipped clearing counters after all, the user was previously in validation", p1->ip); 89                                 } 90                                 p1->fw_connection_state = FW_MARK_KNOWN; 91                                 fw_allow(p1->ip, p1->mac, p1->fw_connection_state); 92                             } 93                             break; 94  95                         case AUTH_VALIDATION: 96                             debug(LOG_INFO, "%s - User in validation period", p1->ip); 97                             break; 98  99                             case AUTH_ERROR:100                                     debug(LOG_WARNING, "Error communicating with auth server - leaving %s as-is for now", p1->ip);101                                     break;102 103                         default:104                             debug(LOG_ERR, "I do not know about authentication code %d", authresponse.authcode);105                             break;106                     }107                 }108             }109         }110 111         free(token);112         free(ip);113         free(mac);114     }115     UNLOCK_CLIENT_LIST();116 }

代码片段1.3

 1 int 2 iptables_fw_counters_update(void) 3 { 4     FILE *output; 5     char *script, 6          ip[16], 7          rc; 8     unsigned long long int counter; 9     t_client *p1;10     struct in_addr tempaddr;11 12     /* 通过iptables获取其出口流量 */13     safe_asprintf(&script, "%s %s", "iptables", "-v -n -x -t mangle -L " TABLE_WIFIDOG_OUTGOING);14     iptables_insert_gateway_id(&script);15     output = popen(script, "r");16     free(script);17     if (!output) {18         debug(LOG_ERR, "popen(): %s", strerror(errno));19         return -1;20     }21 22     /* iptables返回信息处理 */23     while (('\n' != fgetc(output)) && !feof(output))24         ;25     while (('\n' != fgetc(output)) && !feof(output))26         ;27     while (output && !(feof(output))) {28         rc = fscanf(output, "%*s %llu %*s %*s %*s %*s %*s %15[0-9.] %*s %*s %*s %*s %*s %*s", &counter, ip);29         //rc = fscanf(output, "%*s %llu %*s %*s %*s %*s %*s %15[0-9.] %*s %*s %*s %*s %*s 0x%*u", &counter, ip);30         if (2 == rc && EOF != rc) {31             if (!inet_aton(ip, &tempaddr)) {32                 debug(LOG_WARNING, "I was supposed to read an IP address but instead got [%s] - ignoring it", ip);33                 continue;34             }35             debug(LOG_DEBUG, "Read outgoing traffic for %s: Bytes=%llu", ip, counter);36             LOCK_CLIENT_LIST();37             /* 通过ip获取客户端信息结构 */38             if ((p1 = client_list_find_by_ip(ip))) {39                 /* (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 */40                 if ((p1->counters.outgoing - p1->counters.outgoing_history) < counter) {41                     /* 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) */42                     p1->counters.outgoing = p1->counters.outgoing_history + counter;43                     /* 更新最近更新时间为当前时间 */44                     p1->counters.last_updated = time(NULL);45                     debug(LOG_DEBUG, "%s - Updated counter.outgoing to %llu bytes.  Updated last_updated to %d", ip, counter, p1->counters.last_updated);46                 }47             } else {48                 debug(LOG_ERR, "Could not find %s in client list", ip);49             }50             UNLOCK_CLIENT_LIST();51         }52     }53     pclose(output);54 55     /* 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 */56     safe_asprintf(&script, "%s %s", "iptables", "-v -n -x -t mangle -L " TABLE_WIFIDOG_INCOMING);57     iptables_insert_gateway_id(&script);58     output = popen(script, "r");59     free(script);60     if (!output) {61         debug(LOG_ERR, "popen(): %s", strerror(errno));62         return -1;63     }64 65  66     while (('\n' != fgetc(output)) && !feof(output))67         ;68     while (('\n' != fgetc(output)) && !feof(output))69         ;70     while (output && !(feof(output))) {71         rc = fscanf(output, "%*s %llu %*s %*s %*s %*s %*s %*s %15[0-9.]", &counter, ip);72         if (2 == rc && EOF != rc) {73  74             if (!inet_aton(ip, &tempaddr)) {75                 debug(LOG_WARNING, "I was supposed to read an IP address but instead got [%s] - ignoring it", ip);76                 continue;77             }78             debug(LOG_DEBUG, "Read incoming traffic for %s: Bytes=%llu", ip, counter);79             LOCK_CLIENT_LIST();80             if ((p1 = client_list_find_by_ip(ip))) {81                 if ((p1->counters.incoming - p1->counters.incoming_history) < counter) {82                     p1->counters.incoming = p1->counters.incoming_history + counter;83                     debug(LOG_DEBUG, "%s - Updated counter.incoming to %llu bytes", ip, counter);84                 }85             } else {86                 debug(LOG_ERR, "Could not find %s in client list", ip);87             }88             UNLOCK_CLIENT_LIST();89         }90     }91     pclose(output);92 93     return 1;94 }

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