Wifidog是一个linux下开源的认证网关软件，它主要用于配合认证服务器实现无线路由器的认证放行功能。
wifidog是一个后台的服务程序，可以通过wdctrl命令对wifidog主程序进行控制。
本文解释wifidog在启动阶段所做的初始化主要工作（代码片段1.1）
- 初始化配置（先将配置结构体初始化为默认值，在读取配置文件修改配置结构体）
- 初始化已连接客户端列表（如果是通过wdctrl重启wifidog，将会读取之前wifidog的已连接客户端列表 代码片段1.2 代码片段1.3）
- 如无特殊情况，分离进程，建立守护进程 （代码片段1.1）
- 添加多个http请求回调函数（包括404错误回调函数） （见之后章节）
- 摧毁删除现有的iptables路由表规则 （见之后章节）
- 建立新的iptables路由表规则 （见之后章节）
- 启动多个功能线程 （见之后章节）
- 循环等待客户端连接 （见之后章节）
代码片段1.1
1 int main(int argc, char **argv) {
2
3 s_config *config = config_get_config(); //就是返回全局变量config结构体的地址
4 config_init(); //初始化全局变量config结构体为默认值
5
6 parse_commandline(argc, argv); //根据传入参数执行操作（如果参数有-x则会设置restart_orig_pid为已运行的wifidog的pid）
7
8 /* Initialize the config */
9 config_read(config->configfile); //根据配置文件设置全局变量config结构体
10 config_validate(); //判断GatewayInterface和AuthServer是否为空，空则无效退出程序。
11
12 /* Initializes the linked list of connected clients */
13 client_list_init(); //将已连接客户端链表置空。
14
15 /* Init the signals to catch chld/quit/etc */
16 init_signals(); //初始化一些信号
17
18 if (restart_orig_pid) { //用于restart，如果有已运行的wifidog，先会kill它
19 /*
20 * We were restarted and our parent is waiting for us to talk to it over the socket
21 */
22 get_clients_from_parent(); //从已运行的wifidog中获取客户端列表，详见 代码片段1.2
23
24 /*
25 * At this point the parent will start destroying itself and the firewall. Let it finish it‘s job before we continue
26 */
27
28 while (kill(restart_orig_pid, 0) != -1) { //kill已运行的wifidog
29 debug(LOG_INFO, "Waiting for parent PID %d to die before continuing loading", restart_orig_pid);
30 sleep(1);
31 }
32
33 debug(LOG_INFO, "Parent PID %d seems to be dead. Continuing loading.");
34 }
35
36 if (config->daemon) { //创建为守护进程，config->daemon默认值为-1
37
38 debug(LOG_INFO, "Forking into background");
39
40 switch(safe_fork()) {
41 case 0: /* child */
42 setsid(); //创建新会话，脱离此终端，实现守护进程
43 append_x_restartargv();
44 main_loop(); //进入主循环（核心代码在此）。
45 break;
46
47 default: /* parent */
48 exit(0);
49 break;
50 }
51 }
52 else {
53 append_x_restartargv();
54 main_loop();
55 }
56
57 return(0); /* never reached */
58 }
代码片段1.2（获取已启动的wifidog的客户端列表）：
此段代表描述了新启动的wifidog如何从已启动的wifidog程序中获取已连接的客户端列表。发送端见 代码片段1.3
1 void get_clients_from_parent(void) {
2 int sock;
3 struct sockaddr_un sa_un;
4 s_config * config = NULL;
5 char linebuffer[MAX_BUF];
6 int len = 0;
7 char *running1 = NULL;
8 char *running2 = NULL;
9 char *token1 = NULL;
10 char *token2 = NULL;
11 char onechar;
12 char *command = NULL;
13 char *key = NULL;
14 char *value = NULL;
15 t_client * client = NULL;
16 t_client * lastclient = NULL;
17
18 config = config_get_config();
19
20 debug(LOG_INFO, "Connecting to parent to download clients");
21
22 /* 连接socket */
23 sock = socket(AF_UNIX, SOCK_STREAM, 0);
24 memset(&sa_un, 0, sizeof(sa_un));
25 sa_un.sun_family = AF_UNIX;
26 strncpy(sa_un.sun_path, config->internal_sock, (sizeof(sa_un.sun_path) - 1)); //config->internal_sock的值为"/tmp/wifidog.sock"
27
28 /* 连接已启动的wifidog */
29 if (connect(sock, (struct sockaddr *)&sa_un, strlen(sa_un.sun_path) + sizeof(sa_un.sun_family))) {
30 debug(LOG_ERR, "Failed to connect to parent (%s) - client list not downloaded", strerror(errno));
31 return;
32 }
33
34 debug(LOG_INFO, "Connected to parent. Downloading clients");
35
36 LOCK_CLIENT_LIST();
37
38 command = NULL;
39 memset(linebuffer, 0, sizeof(linebuffer));
40 len = 0;
41 client = NULL;
42 /* 接收数据，逐个字符接收 */
43 /* 数据包格式为 CLIENT|ip=%s|mac=%s|token=%s|fw_connection_state=%u|fd=%d|counters_incoming=%llu|counters_outgoing=%llu|counters_last_updated=%lu\n */
44 while (read(sock, &onechar, 1) == 1) {
45 if (onechar == ‘\n‘) {
46 /* 如果接收到末尾（‘\n‘），则转为‘\0‘ */
47 onechar = ‘\0‘;
48 }
49 linebuffer[len++] = onechar;
50
51 if (!onechar) {
52 /* 以下将数据转化为t_client结构体添加到客户端列表 */
53 debug(LOG_DEBUG, "Received from parent: [%s]", linebuffer);
54 running1 = linebuffer;
55 while ((token1 = strsep(&running1, "|")) != NULL) {
56 if (!command) {
57 /* The first token is the command */
58 command = token1;
59 }
60 else {
61 /* Token1 has something like "foo=bar" */
62 running2 = token1;
63 key = value = NULL;
64 while ((token2 = strsep(&running2, "=")) != NULL) {
65 if (!key) {
66 key = token2;
67 }
68 else if (!value) {
69 value = token2;
70 }
71 }
72 }
73
74 if (strcmp(command, "CLIENT") == 0) {
75 /* This line has info about a client in the client list */
76 if (!client) {
77 /* Create a new client struct */
78 client = safe_malloc(sizeof(t_client));
79 memset(client, 0, sizeof(t_client));
80 }
81 }
82
83 if (key && value) {
84 if (strcmp(command, "CLIENT") == 0) {
85 /* Assign the key into the appropriate slot in the connection structure */
86 if (strcmp(key, "ip") == 0) {
87 client->ip = safe_strdup(value);
88 }
89 else if (strcmp(key, "mac") == 0) {
90 client->mac = safe_strdup(value);
91 }
92 else if (strcmp(key, "token") == 0) {
93 client->token = safe_strdup(value);
94 }
95 else if (strcmp(key, "fw_connection_state") == 0) {
96 client->fw_connection_state = atoi(value);
97 }
98 else if (strcmp(key, "fd") == 0) {
99 client->fd = atoi(value);
100 }
101 else if (strcmp(key, "counters_incoming") == 0) {
102 client->counters.incoming_history = atoll(value);
103 client->counters.incoming = client->counters.incoming_history;
104 }
105 else if (strcmp(key, "counters_outgoing") == 0) {
106 client->counters.outgoing_history = atoll(value);
107 client->counters.outgoing = client->counters.outgoing_history;
108 }
109 else if (strcmp(key, "counters_last_updated") == 0) {
110 client->counters.last_updated = atol(value);
111 }
112 else {
113 debug(LOG_NOTICE, "I don‘t know how to inherit key [%s] value [%s] from parent", key, value);
114 }
115 }
116 }
117 }
118
119 /* End of parsing this command */
120 if (client) {
121 /* Add this client to the client list */
122 if (!firstclient) {
123 firstclient = client;
124 lastclient = firstclient;
125 }
126 else {
127 lastclient->next = client;
128 lastclient = client;
129 }
130 }
131
132 /* Clean up */
133 command = NULL;
134 memset(linebuffer, 0, sizeof(linebuffer));
135 len = 0;
136 client = NULL;
137 }
138 }
139
140 UNLOCK_CLIENT_LIST();
141 debug(LOG_INFO, "Client list downloaded successfully from parent");
142
143 close(sock);
144 }
代码片段1.3（已启动的wifidog发送客户端列表到新启动的wifidog）：
1 //thread_wdctl_handler(void *arg)函数是wifidog创建的控制线程，主要用于与wdctrl进行socket通信，根据wdctrl命令执行不同的操作。这里我们着重讲解的是wdctrl发送restart后wifidog的执行逻辑。
2 static void *
3 thread_wdctl_handler(void *arg)
4 {
5 int fd,
6 done,
7 i;
8 char request[MAX_BUF];
9 ssize_t read_bytes,
10 len;
11
12 debug(LOG_DEBUG, "Entering thread_wdctl_handler....");
13
14 fd = (int)arg;
15
16 debug(LOG_DEBUG, "Read bytes and stuff from %d", fd);
17
18 /* 初始化变量 */
19 read_bytes = 0;
20 done = 0;
21 memset(request, 0, sizeof(request));
22
23 /* 读取命令 */
24 while (!done && read_bytes < (sizeof(request) - 1)) {
25 len = read(fd, request + read_bytes,
26 sizeof(request) - read_bytes); //读取wdctrl发送的命令
27
28 /* 判断命令正确性 */
29 for (i = read_bytes; i < (read_bytes + len); i++) {
30 if (request[i] == ‘\r‘ || request[i] == ‘\n‘) {
31 request[i] = ‘\0‘;
32 done = 1;
33 }
34 }
35
36 /* Increment position */
37 read_bytes += len;
38 }
39
40 //判断命令
41 if (strncmp(request, "status", 6) == 0) {
42 wdctl_status(fd);
43 } else if (strncmp(request, "stop", 4) == 0) {
44 wdctl_stop(fd);
45 } else if (strncmp(request, "reset", 5) == 0) {
46 wdctl_reset(fd, (request + 6));
47 } else if (strncmp(request, "restart", 7) == 0) {
48 wdctl_restart(fd); //执行wdctl_restart(int afd)函数
49 }
50
51 if (!done) {
52 debug(LOG_ERR, "Invalid wdctl request.");
53 //关闭套接字
54 shutdown(fd, 2);
55 close(fd);
56 pthread_exit(NULL);
57 }
58
59 debug(LOG_DEBUG, "Request received: [%s]", request);
60
61 //关闭套接字
62 shutdown(fd, 2);
63 close(fd);
64 debug(LOG_DEBUG, "Exiting thread_wdctl_handler....");
65
66 return NULL;
67 }
68
69
70 //wdctl_restart(int afd)函数详解
71 static void
72 wdctl_restart(int afd)
73 {
74 int sock,
75 fd;
76 char *sock_name;
77 struct sockaddr_un sa_un;
78 s_config * conf = NULL;
79 t_client * client = NULL;
80 char * tempstring = NULL;
81 pid_t pid;
82 ssize_t written;
83 socklen_t len;
84
85 conf = config_get_config();
86
87 debug(LOG_NOTICE, "Will restart myself");
88
89 /*
90 * 准备内部连接socket
91 */
92 memset(&sa_un, 0, sizeof(sa_un));
93 sock_name = conf->internal_sock; //conf->internal_sock值为"/tmp/wifidog.sock"
94 debug(LOG_DEBUG, "Socket name: %s", sock_name);
95
96 if (strlen(sock_name) > (sizeof(sa_un.sun_path) - 1)) {
97
98 debug(LOG_ERR, "INTERNAL socket name too long");
99 return;
100 }
101
102 debug(LOG_DEBUG, "Creating socket");
103 sock = socket(PF_UNIX, SOCK_STREAM, 0); //建立内部socket套接字
104
105 debug(LOG_DEBUG, "Got internal socket %d", sock);
106
107 /* 如果sock_name文件存在，则删除*/
108 unlink(sock_name);
109
110 debug(LOG_DEBUG, "Filling sockaddr_un");
111 strcpy(sa_un.sun_path, sock_name);
112 sa_un.sun_family = AF_UNIX;
113
114 debug(LOG_DEBUG, "Binding socket (%s) (%d)", sa_un.sun_path, strlen(sock_name));
115
116
117 if (bind(sock, (struct sockaddr *)&sa_un, strlen(sock_name) + sizeof(sa_un.sun_family))) {
118 debug(LOG_ERR, "Could not bind internal socket: %s", strerror(errno));
119 return;
120 }
121
122 if (listen(sock, 5)) {
123 debug(LOG_ERR, "Could not listen on internal socket: %s", strerror(errno));
124 return;
125 }
126
127 /*
128 * socket建立完成，创建子进程
129 */
130 debug(LOG_DEBUG, "Forking in preparation for exec()...");
131 pid = safe_fork();
132 if (pid > 0) {
133 /* 父进程 */
134
135 /* 等待子进程连接此socket :*/
136 debug(LOG_DEBUG, "Waiting for child to connect on internal socket");
137 len = sizeof(sa_un);
138 if ((fd = accept(sock, (struct sockaddr *)&sa_un, &len)) == -1){ //接受连接
139 debug(LOG_ERR, "Accept failed on internal socket: %s", strerror(errno));
140 close(sock);
141 return;
142 }
143
144 close(sock);
145
146 debug(LOG_DEBUG, "Received connection from child. Sending them all existing clients");
147
148 /*子进程已经完成连接，发送客户端列表 */
149 LOCK_CLIENT_LIST();
150 client = client_get_first_client(); //获取第一个客户端
151 while (client) {
152 /* Send this client */
153 safe_asprintf(&tempstring, "CLIENT|ip=%s|mac=%s|token=%s|fw_connection_state=%u|fd=%d|counters_incoming=%llu|counters_outgoing=%llu|counters_last_updated=%lu\n", client->ip, client->mac, client->token, client->fw_connection_state, client->fd, client->counters.incoming, client->counters.outgoing, client->counters.last_updated);
154 debug(LOG_DEBUG, "Sending to child client data: %s", tempstring);
155 len = 0;
156 while (len != strlen(tempstring)) {
157 written = write(fd, (tempstring + len), strlen(tempstring) - len); //发送给子进程
158 if (written == -1) {
159 debug(LOG_ERR, "Failed to write client data to child: %s", strerror(errno));
160 free(tempstring);
161 break;
162 }
163 else {
164 len += written;
165 }
166 }
167 free(tempstring);
168 client = client->next;
169 }
170 UNLOCK_CLIENT_LIST();
171
172 close(fd);
173
174 debug(LOG_INFO, "Sent all existing clients to child. Committing suicide!");
175
176 shutdown(afd, 2);
177 close(afd);
178
179
180 wdctl_stop(afd);
181 }
182 else {
183 /* 子进程，先关闭资源 */
184 close(wdctl_socket_server);
185 close(icmp_fd);
186 close(sock);
187 shutdown(afd, 2);
188 close(afd);
189 debug(LOG_NOTICE, "Re-executing myself (%s)", restartargv[0]);
190
191 setsid();
192 execvp(restartargv[0], restartargv); //执行外部命令，这里重新启动wifidog
193
194 debug(LOG_ERR, "I failed to re-execute myself: %s", strerror(errno));
195 debug(LOG_ERR, "Exiting without cleanup");
196 exit(1);
197 }
198 }
时间： 2024-10-01 02:56:44