| 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 | #define UNIX_PATH_MAX 108 |
| 8 | |
| 9 | //#define SOCKETDIR "/var/run/ust/socks" |
| 10 | #define SOCKETDIR "/tmp/socks" |
| 11 | #define SOCKETDIRLEN sizeof(SOCKETDIR) |
| 12 | #define USTSIGNAL SIGIO |
| 13 | |
| 14 | #define DBG(fmt, args...) fprintf(stderr, fmt "\n", ## args) |
| 15 | #define WARN(fmt, args...) fprintf(stderr, "usertrace: WARNING: " fmt "\n", ## args) |
| 16 | #define ERR(fmt, args...) fprintf(stderr, "usertrace: ERROR: " fmt "\n", ## args) |
| 17 | #define PERROR(call) perror("usertrace: ERROR: " call) |
| 18 | |
| 19 | struct tracecmd { /* no padding */ |
| 20 | uint32_t size; |
| 21 | uint16_t command; |
| 22 | }; |
| 23 | |
| 24 | |
| 25 | pid_t mypid; |
| 26 | char mysocketfile[UNIX_PATH_MAX] = ""; |
| 27 | |
| 28 | void do_command(struct tracecmd *cmd) |
| 29 | { |
| 30 | } |
| 31 | |
| 32 | void receive_commands() |
| 33 | { |
| 34 | } |
| 35 | |
| 36 | /* The signal handler itself. */ |
| 37 | |
| 38 | void sighandler(int sig) |
| 39 | { |
| 40 | DBG("sighandler"); |
| 41 | receive_commands(); |
| 42 | } |
| 43 | |
| 44 | /* Called by the app signal handler to chain it to us. */ |
| 45 | |
| 46 | void chain_signal() |
| 47 | { |
| 48 | sighandler(USTSIGNAL); |
| 49 | } |
| 50 | |
| 51 | int init_socket() |
| 52 | { |
| 53 | int result; |
| 54 | int fd; |
| 55 | char pidstr[6]; |
| 56 | int pidlen; |
| 57 | |
| 58 | struct sockaddr_un addr; |
| 59 | |
| 60 | result = fd = socket(PF_UNIX, SOCK_SEQPACKET, 0); |
| 61 | if(result == -1) { |
| 62 | PERROR("socket"); |
| 63 | return -1; |
| 64 | } |
| 65 | |
| 66 | addr.sun_family = AF_UNIX; |
| 67 | |
| 68 | result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s/%d", SOCKETDIR, mypid); |
| 69 | if(result >= UNIX_PATH_MAX) { |
| 70 | ERR("string overflow allocating socket name"); |
| 71 | goto close_sock; |
| 72 | } |
| 73 | //DBG("opening socket at %s", addr.sun_path); |
| 74 | |
| 75 | result = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); |
| 76 | if(result == -1) { |
| 77 | PERROR("bind"); |
| 78 | goto close_sock; |
| 79 | } |
| 80 | |
| 81 | strcpy(mysocketfile, addr.sun_path); |
| 82 | |
| 83 | close_sock: |
| 84 | close(fd); |
| 85 | |
| 86 | return -1; |
| 87 | } |
| 88 | |
| 89 | void destroy_socket() |
| 90 | { |
| 91 | int result; |
| 92 | |
| 93 | if(mysocketfile[0] == '\0') |
| 94 | return; |
| 95 | |
| 96 | result = unlink(mysocketfile); |
| 97 | if(result == -1) { |
| 98 | PERROR("unlink"); |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | int init_signal_handler(void) |
| 103 | { |
| 104 | /* Attempt to handler SIGIO. If the main program wants to |
| 105 | * handle it, fine, it'll override us. They it'll have to |
| 106 | * use the chaining function. |
| 107 | */ |
| 108 | |
| 109 | int result; |
| 110 | struct sigaction act; |
| 111 | |
| 112 | result = sigemptyset(&act.sa_mask); |
| 113 | if(result == -1) { |
| 114 | PERROR("sigemptyset"); |
| 115 | return -1; |
| 116 | } |
| 117 | |
| 118 | act.sa_handler = sighandler; |
| 119 | act.sa_flags = SA_RESTART; |
| 120 | |
| 121 | /* Only defer ourselves. Also, try to restart interrupted |
| 122 | * syscalls to disturb the traced program as little as possible. |
| 123 | */ |
| 124 | result = sigaction(SIGIO, &act, NULL); |
| 125 | if(result == -1) { |
| 126 | PERROR("sigaction"); |
| 127 | return -1; |
| 128 | } |
| 129 | |
| 130 | return 0; |
| 131 | } |
| 132 | |
| 133 | void __attribute__((constructor)) init() |
| 134 | { |
| 135 | int result; |
| 136 | |
| 137 | mypid = getpid(); |
| 138 | |
| 139 | /* if using instead seperate thread, then should create thread */ |
| 140 | result = init_signal_handler(); |
| 141 | result = init_socket(); |
| 142 | |
| 143 | return; |
| 144 | |
| 145 | /* should decrementally destroy stuff if error */ |
| 146 | |
| 147 | } |
| 148 | |
| 149 | /* This is only called if we terminate normally, not with an unhandled signal, |
| 150 | * so we cannot rely on it. */ |
| 151 | |
| 152 | void __attribute__((destructor)) fini() |
| 153 | { |
| 154 | destroy_socket(); |
| 155 | } |