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 }
时间： 2024-11-09 05:03:34