| 1 | #include <stdio.h> |
| 2 | #include <stdint.h> |
| 3 | #include <signal.h> |
| 4 | #include <sys/types.h> |
| 5 | #include <sys/socket.h> |
| 6 | #include <sys/un.h> |
| 7 | #include <sched.h> |
| 8 | #define UNIX_PATH_MAX 108 |
| 9 | |
| 10 | //#define SOCKETDIR "/var/run/ust/socks" |
| 11 | #define SOCKETDIR "/tmp/socks" |
| 12 | #define SOCKETDIRLEN sizeof(SOCKETDIR) |
| 13 | #define USTSIGNAL SIGIO |
| 14 | |
| 15 | #define DBG(fmt, args...) fprintf(stderr, fmt "\n", ## args) |
| 16 | #define WARN(fmt, args...) fprintf(stderr, "usertrace: WARNING: " fmt "\n", ## args) |
| 17 | #define ERR(fmt, args...) fprintf(stderr, "usertrace: ERROR: " fmt "\n", ## args) |
| 18 | #define PERROR(call) perror("usertrace: ERROR: " call) |
| 19 | |
| 20 | #define MAX_MSG_SIZE (100) |
| 21 | #define MSG_NOTIF 1 |
| 22 | #define MSG_REGISTER_NOTIF 2 |
| 23 | |
| 24 | struct tracecmd { /* no padding */ |
| 25 | uint32_t size; |
| 26 | uint16_t command; |
| 27 | }; |
| 28 | |
| 29 | //struct listener_arg { |
| 30 | // int pipe_fd; |
| 31 | //}; |
| 32 | |
| 33 | struct trctl_msg { |
| 34 | /* size: the size of all the fields except size itself */ |
| 35 | uint32_t size; |
| 36 | uint16_t type; |
| 37 | /* Only the necessary part of the payload is transferred. It |
| 38 | * may even be none of it. |
| 39 | */ |
| 40 | char payload[94]; |
| 41 | }; |
| 42 | |
| 43 | pid_t mypid; |
| 44 | char mysocketfile[UNIX_PATH_MAX] = ""; |
| 45 | int pfd = -1; |
| 46 | |
| 47 | void do_command(struct tracecmd *cmd) |
| 48 | { |
| 49 | } |
| 50 | |
| 51 | void receive_commands() |
| 52 | { |
| 53 | } |
| 54 | |
| 55 | int fd_notif = -1; |
| 56 | void notif_cb(void) |
| 57 | { |
| 58 | int result; |
| 59 | struct trctl_msg msg; |
| 60 | |
| 61 | /* FIXME: fd_notif should probably be protected by a spinlock */ |
| 62 | |
| 63 | if(fd_notif == -1) |
| 64 | return; |
| 65 | |
| 66 | msg.type = MSG_NOTIF; |
| 67 | msg.size = sizeof(msg.type); |
| 68 | |
| 69 | /* FIXME: don't block here */ |
| 70 | result = write(fd_notif, &msg, msg.size+sizeof(msg.size)); |
| 71 | if(result == -1) { |
| 72 | PERROR("write"); |
| 73 | return; |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | int listener_main(void *p) |
| 78 | { |
| 79 | int result; |
| 80 | |
| 81 | /* Allowing only 1 connection for now. */ |
| 82 | result = listen(pfd, 1); |
| 83 | if(result == -1) { |
| 84 | PERROR("listen"); |
| 85 | return 1; |
| 86 | } |
| 87 | |
| 88 | for(;;) { |
| 89 | |
| 90 | uint32_t size; |
| 91 | int fd; |
| 92 | struct sockaddr_un addr; |
| 93 | socklen_t addrlen = sizeof(addr); |
| 94 | |
| 95 | result = fd = accept(pfd, (struct sockaddr *)&addr, &addrlen); |
| 96 | if(result == -1) { |
| 97 | PERROR("accept"); |
| 98 | continue; |
| 99 | } |
| 100 | |
| 101 | for(;;) { |
| 102 | struct trctl_msg msg; |
| 103 | unsigned char dontclose=0; |
| 104 | |
| 105 | result = read(fd, &msg.size, sizeof(msg.size)); |
| 106 | if(result == -1) { |
| 107 | PERROR("read"); |
| 108 | continue; |
| 109 | } |
| 110 | |
| 111 | if(size > MAX_MSG_SIZE) { |
| 112 | ERR("trctl message too big"); |
| 113 | break; |
| 114 | } |
| 115 | |
| 116 | result = read(fd, &msg.type, sizeof(msg.type)); |
| 117 | if(result == -1) { |
| 118 | PERROR("read"); |
| 119 | continue; |
| 120 | } |
| 121 | |
| 122 | switch(msg.type) { |
| 123 | case MSG_REGISTER_NOTIF: |
| 124 | /* TODO: put it in notif mode */ |
| 125 | goto next_conn; |
| 126 | }; |
| 127 | } |
| 128 | next_conn:; |
| 129 | } |
| 130 | } |
| 131 | |
| 132 | void create_listener(void) |
| 133 | { |
| 134 | int result; |
| 135 | static char listener_stack[16384]; |
| 136 | |
| 137 | result = clone(listener_main, listener_stack+sizeof(listener_stack)-1, CLONE_FS | CLONE_FILES | CLONE_VM, NULL); |
| 138 | if(result == -1) { |
| 139 | perror("clone"); |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | /* The signal handler itself. */ |
| 144 | |
| 145 | void sighandler(int sig) |
| 146 | { |
| 147 | DBG("sighandler"); |
| 148 | receive_commands(); |
| 149 | } |
| 150 | |
| 151 | /* Called by the app signal handler to chain it to us. */ |
| 152 | |
| 153 | void chain_signal(void) |
| 154 | { |
| 155 | sighandler(USTSIGNAL); |
| 156 | } |
| 157 | |
| 158 | static int init_socket(void) |
| 159 | { |
| 160 | int result; |
| 161 | int fd; |
| 162 | char pidstr[6]; |
| 163 | int pidlen; |
| 164 | |
| 165 | struct sockaddr_un addr; |
| 166 | |
| 167 | result = fd = socket(PF_UNIX, SOCK_SEQPACKET, 0); |
| 168 | if(result == -1) { |
| 169 | PERROR("socket"); |
| 170 | return -1; |
| 171 | } |
| 172 | |
| 173 | addr.sun_family = AF_UNIX; |
| 174 | |
| 175 | result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s/%d", SOCKETDIR, mypid); |
| 176 | if(result >= UNIX_PATH_MAX) { |
| 177 | ERR("string overflow allocating socket name"); |
| 178 | goto close_sock; |
| 179 | } |
| 180 | //DBG("opening socket at %s", addr.sun_path); |
| 181 | |
| 182 | result = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); |
| 183 | if(result == -1) { |
| 184 | PERROR("bind"); |
| 185 | goto close_sock; |
| 186 | } |
| 187 | |
| 188 | strcpy(mysocketfile, addr.sun_path); |
| 189 | |
| 190 | pfd = fd; |
| 191 | return 0; |
| 192 | |
| 193 | close_sock: |
| 194 | close(fd); |
| 195 | |
| 196 | return -1; |
| 197 | } |
| 198 | |
| 199 | static void destroy_socket(void) |
| 200 | { |
| 201 | int result; |
| 202 | |
| 203 | if(mysocketfile[0] == '\0') |
| 204 | return; |
| 205 | |
| 206 | result = unlink(mysocketfile); |
| 207 | if(result == -1) { |
| 208 | PERROR("unlink"); |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | static int init_signal_handler(void) |
| 213 | { |
| 214 | /* Attempt to handler SIGIO. If the main program wants to |
| 215 | * handle it, fine, it'll override us. They it'll have to |
| 216 | * use the chaining function. |
| 217 | */ |
| 218 | |
| 219 | int result; |
| 220 | struct sigaction act; |
| 221 | |
| 222 | result = sigemptyset(&act.sa_mask); |
| 223 | if(result == -1) { |
| 224 | PERROR("sigemptyset"); |
| 225 | return -1; |
| 226 | } |
| 227 | |
| 228 | act.sa_handler = sighandler; |
| 229 | act.sa_flags = SA_RESTART; |
| 230 | |
| 231 | /* Only defer ourselves. Also, try to restart interrupted |
| 232 | * syscalls to disturb the traced program as little as possible. |
| 233 | */ |
| 234 | result = sigaction(SIGIO, &act, NULL); |
| 235 | if(result == -1) { |
| 236 | PERROR("sigaction"); |
| 237 | return -1; |
| 238 | } |
| 239 | |
| 240 | return 0; |
| 241 | } |
| 242 | |
| 243 | static void __attribute__((constructor)) init() |
| 244 | { |
| 245 | int result; |
| 246 | |
| 247 | mypid = getpid(); |
| 248 | |
| 249 | /* Must create socket before signal handler to prevent races |
| 250 | * on pfd variable. |
| 251 | */ |
| 252 | result = init_socket(); |
| 253 | if(result == -1) { |
| 254 | ERR("init_socket error"); |
| 255 | return; |
| 256 | } |
| 257 | result = init_signal_handler(); |
| 258 | if(result == -1) { |
| 259 | ERR("init_signal_handler error"); |
| 260 | return; |
| 261 | } |
| 262 | |
| 263 | return; |
| 264 | |
| 265 | /* should decrementally destroy stuff if error */ |
| 266 | |
| 267 | } |
| 268 | |
| 269 | /* This is only called if we terminate normally, not with an unhandled signal, |
| 270 | * so we cannot rely on it. */ |
| 271 | |
| 272 | static void __attribute__((destructor)) fini() |
| 273 | { |
| 274 | destroy_socket(); |
| 275 | } |