diff options
Diffstat (limited to 'listening.c')
| -rw-r--r-- | listening.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/listening.c b/listening.c new file mode 100644 index 0000000..bb4d241 --- /dev/null +++ b/listening.c @@ -0,0 +1,208 @@ +/* + * listening - check if a TCP server is listening + * + * To the extent possible under law, Leah Neukirchen <leah@vuxu.org> + * has waived all copyright and related or neighboring rights to this work. + * http://creativecommons.org/publicdomain/zero/1.0/ + */ + +#include <sys/socket.h> + +#include <arpa/inet.h> +#include <errno.h> +#include <netinet/in.h> +#include <netinet/tcp.h> +#include <poll.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include <unistd.h> + +uint64_t wait_timeout = 0; // nanoseconds +uint64_t connect_timeout = 200; // milliseconds + +struct timespec now; +struct timespec deadline; +struct timespec delay; + +int +scanfix(char *s, uint64_t *result, int scale) +{ + uint64_t r = 0; + char *d = 0; + + if (!*s) + return -EINVAL; + + while (*s) { + if ((unsigned)(*s)-'0' < 10) { + if (r <= UINT64_MAX/10 && 10*r <= UINT64_MAX-((*s)-'0')) + r = r*10 + ((*s)-'0'); + else + return -ERANGE; + } else if (*s == '.') { + if (d) + return -EINVAL; + d = s + 1; + } else { + return -EINVAL; + } + + s++; + } + + if (!d) + d = s; + + int o = scale - (int)(s-d); + for (; o > 0; o--) { + if (r > UINT64_MAX/10) + return -ERANGE; + r *= 10; + } + for (; o < 0; o++) { + if (r % 10 != 0) + return -ERANGE; + r /= 10; + } + + *result = r; + + return 0; +} + +int +syn_scan(const char *host, int port) +{ + printf("test %s:%d\n", host, port); + + struct sockaddr_in addr; + memset(&addr, 0, sizeof (struct sockaddr_in)); + addr.sin_family = AF_INET; + addr.sin_port = htons(port); + // XXX use GAI + inet_aton(host, &addr.sin_addr); + + int sock = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0); + struct linger l = {1, 0}; + setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&l, sizeof (struct linger)); + int zero = 0; + setsockopt(sock, IPPROTO_TCP, TCP_QUICKACK, (void *)&zero, sizeof zero); + int r; + errno = 0; + r = connect(sock, (struct sockaddr *)&addr, sizeof (struct sockaddr_in)); + if (r > 0 || errno != EINPROGRESS) { + fprintf(stderr, "connect failed: %m\n"); + close(sock); + return 99; + } + + struct pollfd fds[1]; + fds[0] = (struct pollfd){ sock, POLLIN | POLLOUT | POLLERR, 0 }; + r = poll(fds, 1, connect_timeout); + if (r == 0) { + printf("timeout"); + return 2; + } else if (r != 1) { + printf("??? poll = %d %m\n", r); + close(sock); + return 99; + } + + if (fds[0].revents & POLLERR) { + int error = 0; + socklen_t errlen = sizeof error; + getsockopt(sock, SOL_SOCKET, SO_ERROR, (void *)&error, &errlen); + printf("SO_ERROR = %d %s\n", error, strerror(error)); + close(sock); + return 1; + } else if (fds[0].revents & POLLOUT) { + printf("socket is up\n"); + close(sock); + return 0; + } + + return 99; // unreachable +} + +int +main(int argc, char *argv[]) +{ + int c, err; + + while ((c = getopt(argc, argv, "+t:w:")) != -1) { + switch (c) { + case 't': + if ((err = scanfix(optarg, &connect_timeout, 3)) < 0) { + fprintf(stderr, "failed to parse number '%s': %s\n", + optarg, strerror(-err)); + goto usage; + } + break; + case 'w': + if ((err = scanfix(optarg, &wait_timeout, 9)) < 0) { + fprintf(stderr, "failed to parse number '%s': %s\n", + optarg, strerror(-err)); + goto usage; + } + break; + default: + usage: + fprintf(stderr, + "Usage: %s [-w WAIT_TIMEOUT] [-t CONNECT_TIMEOUT] [HOST:]PORT\n", + argv[0]); + exit(99); + } + } + + if (optind != argc - 1) + goto usage; + + int port; + const char *host = argv[argc-1]; + char *colon = strchr(host, ':'); + if (colon) { + *colon = 0; + port = atoi(colon+1); + } else { + port = atoi(host); + host = "127.0.0.1"; + } + + if (wait_timeout == 0) + return syn_scan(host, port); + + /* else we are waiting for the port to come up: */ + + clock_gettime(CLOCK_MONOTONIC, &now); + deadline.tv_sec = now.tv_sec; + deadline.tv_nsec = now.tv_nsec + wait_timeout; + if (deadline.tv_nsec >= 1000000000L) { + deadline.tv_sec += deadline.tv_nsec / 1000000000L; + deadline.tv_nsec = deadline.tv_nsec % 1000000000L; + } + delay.tv_sec = 0; + delay.tv_nsec = connect_timeout * 100000L; + if (delay.tv_nsec >= 1000000000L) { + delay.tv_sec += delay.tv_nsec / 1000000000L; + delay.tv_nsec = delay.tv_nsec % 1000000000L; + } + + while (now.tv_sec < deadline.tv_sec || + (now.tv_sec == deadline.tv_sec && now.tv_nsec <= deadline.tv_nsec)) { + switch (syn_scan(host, port)) { + case 0: + return 0; + case 99: + return 99; + case 1: + nanosleep(&delay, 0); // avoid busy wait + } + + clock_gettime(CLOCK_MONOTONIC, &now); + } + + return 2; +} |