On Thu, Jun 26, 2014 at 7:43 AM, Arne Becker <arne_bec...@genua.de> wrote:
> Hi.
>
>> Now soliciting diffs to change readwrite to a loop with two buffers
>> that poll()s in all four directions. :)
>
> Good thing you made me remember I wrote just this a while ago.
> This is my first OpenBSD diff, so tell me if I missed anything obvious.
> Tested quite extensively originally; for this diff I only checked a
> simple nc to nc "hello".
>
> Index: netcat.c
> ===================================================================
> RCS file: /mount/cvsdev/cvs/openbsd/src/usr.bin/nc/netcat.c,v
> retrieving revision 1.121
> diff -u -p -r1.121 netcat.c
> --- netcat.c 10 Jun 2014 16:35:42 -0000 1.121
> +++ netcat.c 26 Jun 2014 11:29:45 -0000
> @@ -65,6 +65,12 @@
> #define PORT_MAX_LEN 6
> #define UNIX_DG_TMP_SOCKET_SIZE 19
>
> +#define POLL_STDIN 0
> +#define POLL_NETOUT 1
> +#define POLL_NETIN 2
> +#define POLL_STDOUT 3
> +#define BUFSIZE 16384
> +
> /* Command Line Options */
> int dflag; /* detached, no stdin */
> int Fflag; /* fdpass sock to stdout */
> @@ -112,6 +118,8 @@ void set_common_sockopts(int);
> int map_tos(char *, int *);
> void report_connect(const struct sockaddr *, socklen_t);
> void usage(int);
> +ssize_t drainbuf(int, unsigned char *, size_t *);
> +ssize_t fillbuf(int, unsigned char *, size_t *);
>
> int
> main(int argc, char *argv[])
> @@ -608,7 +616,7 @@ remote_connect(const char *host, const c
>
> if (bind(s, (struct sockaddr *)ares->ai_addr,
> ares->ai_addrlen) < 0)
> - err(1, "bind failed");
> + errx(1, "bind failed: %s", strerror(errno));
> freeaddrinfo(ares);
> }
>
> @@ -640,7 +648,7 @@ timeout_connect(int s, const struct sock
> if (timeout != -1) {
> flags = fcntl(s, F_GETFL, 0);
> if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1)
> - err(1, "set non-blocking mode");
> + warn("unable to set non-blocking mode");
> }
>
> if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) {
> @@ -730,67 +738,229 @@ local_listen(char *host, char *port, str
> * Loop that polls on the network file descriptor and stdin.
> */
> void
> -readwrite(int nfd)
> +readwrite(int net_fd)
> {
> - struct pollfd pfd[2];
> - unsigned char buf[16 * 1024];
> - int n, wfd = fileno(stdin);
> - int lfd = fileno(stdout);
> - int plen;
> -
> - plen = sizeof(buf);
> -
> - /* Setup Network FD */
> - pfd[0].fd = nfd;
> - pfd[0].events = POLLIN;
> + struct pollfd pfd[4];
> + int stdin_fd = STDIN_FILENO;
> + int stdout_fd = STDOUT_FILENO;
> + unsigned char netinbuf[BUFSIZE];
> + size_t netinbufpos = 0;
> + unsigned char stdinbuf[BUFSIZE];
> + size_t stdinbufpos = 0;
> + int n, num_fds, flags;
> + ssize_t ret;
> +
> + /* don't read from stdin if requested */
> + if (dflag)
> + stdin_fd = -1;
> +
> + /* stdin */
> + pfd[POLL_STDIN].fd = stdin_fd;
> + pfd[POLL_STDIN].events = POLLIN;
> +
> + /* network out */
> + pfd[POLL_NETOUT].fd = net_fd;
> + pfd[POLL_NETOUT].events = 0;
> +
> + /* network in */
> + pfd[POLL_NETIN].fd = net_fd;
> + pfd[POLL_NETIN].events = POLLIN;
> +
> + /* stdout */
> + pfd[POLL_STDOUT].fd = stdout_fd;
> + pfd[POLL_STDOUT].events = 0;
> +
> +
> + /* make all fds non-blocking */
> + for (n = 0; n < 4; n++) {
> + if (pfd[n].fd == -1)
> + continue;
> + flags = fcntl(pfd[n].fd, F_GETFL, 0);
> + /*
> + * For sockets and pipes, we want non-block, but setting it
> + * might fail for files or devices, so we ignore the return
> + * code.
> + */
> + fcntl(pfd[n].fd, F_SETFL, flags | O_NONBLOCK);
> + }
>
> - /* Set up STDIN FD. */
> - pfd[1].fd = wfd;
> - pfd[1].events = POLLIN;
> + while (1) {
> + /* both inputs are gone, buffers are empty, we are done */
> + if (pfd[POLL_STDIN].fd == -1 && pfd[POLL_NETIN].fd == -1
> + && stdinbufpos == 0 && netinbufpos == 0) {
> + close(net_fd);
> + return;
> + }
> + /* both outputs are gone, we can't continue */
> + if (pfd[POLL_NETOUT].fd == -1 && pfd[POLL_STDOUT].fd == -1) {
> + close(net_fd);
> + return;
> + }
> + /* listen and net in gone, queues empty, done */
> + if (lflag && pfd[POLL_NETIN].fd == -1
lflag ???
warning only one ref in the diff
> + && stdinbufpos == 0 && netinbufpos == 0) {
> + close(net_fd);
> + return;
> + }
>
> - while (pfd[0].fd != -1) {
> + /* help says -i is for "wait between lines sent". We read and
> + * write arbitray amounts of data, and we don't want to start
> + * scanning for newlines, so this is as good as it gets */
> if (iflag)
> sleep(iflag);
>
> - if ((n = poll(pfd, 2 - dflag, timeout)) < 0) {
> - close(nfd);
> - err(1, "Polling Error");
> + /* poll */
> + num_fds = poll(pfd, 4, timeout);
> +
> + /* treat poll errors */
> + if (num_fds == -1) {
> + close(net_fd);
> + err(1, "polling error");
> }
>
> - if (n == 0)
> + /* timeout happened */
> + if (num_fds == 0)
> return;
>
> - if (pfd[0].revents & POLLIN) {
> - if ((n = read(nfd, buf, plen)) < 0)
> - return;
> - else if (n == 0) {
> - shutdown(nfd, SHUT_RD);
> - pfd[0].fd = -1;
> - pfd[0].events = 0;
> - } else {
> - if (tflag)
> - atelnet(nfd, buf, n);
> - if (atomicio(vwrite, lfd, buf, n) != n)
> - return;
> + /* treat socket error conditions */
> + for (n = 0; n < 4; n++) {
> + if (pfd[n].revents & (POLLERR|POLLNVAL)) {
> + pfd[n].fd = -1;
> + continue;
> }
> }
> + /* only treat the fds used for writing, because
> + * reading is always possible even after HUP */
> + if (pfd[POLL_NETOUT].revents & POLLHUP) {
> + if (Nflag)
> + shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
> + pfd[POLL_NETOUT].fd = -1;
> + }
> + /* if HUP, stop watching stdout */
> + if (pfd[POLL_STDOUT].revents & POLLHUP)
> + pfd[POLL_STDOUT].fd = -1;
> + /* if no net out, stop watching stdin */
> + if (pfd[POLL_NETOUT].fd == -1)
> + pfd[POLL_STDIN].fd = -1;
> + /* if no stdout, stop watching net in */
> + if (pfd[POLL_STDOUT].fd == -1) {
> + if (pfd[POLL_NETIN].fd != -1)
> + shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
> + pfd[POLL_NETIN].fd = -1;
> + }
>
> - if (!dflag && pfd[1].revents & POLLIN) {
> - if ((n = read(wfd, buf, plen)) < 0)
> - return;
> - else if (n == 0) {
> - if (Nflag)
> - shutdown(nfd, SHUT_WR);
> - pfd[1].fd = -1;
> - pfd[1].events = 0;
> - } else {
> - if (atomicio(vwrite, nfd, buf, n) != n)
> - return;
> + /* try to read from stdin */
> + if (pfd[POLL_STDIN].revents & POLLIN && stdinbufpos <
> BUFSIZE) {
> + ret = fillbuf(pfd[POLL_STDIN].fd, stdinbuf,
> + &stdinbufpos);
> + /* error or eof on stdin - remove from pfd */
> + if (ret == 0 || ret == -1)
> + pfd[POLL_STDIN].fd = -1;
> + /* read something - poll net out */
> + if (stdinbufpos > 0)
> + pfd[POLL_NETOUT].events = POLLOUT;
> + /* filled buffer - remove self from polling */
> + if (stdinbufpos == BUFSIZE)
> + pfd[POLL_STDIN].events = 0;
> + }
> + /* try to write to network */
> + if (pfd[POLL_NETOUT].revents & POLLOUT && stdinbufpos > 0) {
> + ret = drainbuf(pfd[POLL_NETOUT].fd, stdinbuf,
> + &stdinbufpos);
> + if (ret == -1)
> + pfd[POLL_NETOUT].fd = -1;
> + /* buffer empty - remove self from polling */
> + if (stdinbufpos == 0)
> + pfd[POLL_NETOUT].events = 0;
> + /* buffer no longer full - poll stdin again */
> + if (stdinbufpos < BUFSIZE)
> + pfd[POLL_STDIN].events = POLLIN;
> + }
> + /* try to read from network */
> + if (pfd[POLL_NETIN].revents & POLLIN && netinbufpos <
> BUFSIZE) {
> + ret = fillbuf(pfd[POLL_NETIN].fd, netinbuf,
> + &netinbufpos);
> + if (ret == -1)
> + pfd[POLL_NETIN].fd = -1;
> + /* eof on net in - remove from pfd */
> + if (ret == 0) {
> + shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
> + pfd[POLL_NETIN].fd = -1;
> }
> + /* read something - poll stdout */
> + if (netinbufpos > 0)
> + pfd[POLL_STDOUT].events = POLLOUT;
> + /* filled buffer - remove self from polling */
> + if (netinbufpos == BUFSIZE)
> + pfd[POLL_NETIN].events = 0;
> + /* handle telnet */
> + if (tflag)
> + atelnet(pfd[POLL_NETIN].fd, netinbuf,
> + netinbufpos);
> + }
> + /* try to write to stdout */
> + if (pfd[POLL_STDOUT].revents & POLLOUT && netinbufpos > 0) {
> + ret = drainbuf(pfd[POLL_STDOUT].fd, netinbuf,
> + &netinbufpos);
> + if (ret == -1)
> + pfd[POLL_STDOUT].fd = -1;
> + /* buffer empty - remove self from polling */
> + if (netinbufpos == 0)
> + pfd[POLL_STDOUT].events = 0;
> + /* buffer no longer full - poll net in again */
> + if (netinbufpos < BUFSIZE)
> + pfd[POLL_NETIN].events = POLLIN;
> + }
> +
> + /* stdin gone and queue empty? */
> + if (pfd[POLL_STDIN].fd == -1 && stdinbufpos == 0) {
> + if (pfd[POLL_NETOUT].fd != -1 && Nflag)
> + shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
> + pfd[POLL_NETOUT].fd = -1;
> }
> + /* net in gone and queue empty? */
> + if (pfd[POLL_NETIN].fd == -1 && netinbufpos == 0)
> + pfd[POLL_STDOUT].fd = -1;
> }
> }
>
> +ssize_t
> +drainbuf(int fd, unsigned char *buf, size_t *bufpos)
> +{
> + ssize_t n;
> + ssize_t adjust;
> +
> + n = write(fd, buf, *bufpos);
> + /* don't treat EAGAIN, EINTR as error */
> + if (n == -1 && (errno == EAGAIN || errno == EINTR))
> + n = -2;
> + if (n <= 0)
> + return n;
> + /* adjust buffer */
> + adjust = *bufpos - n;
> + if (adjust > 0)
> + memmove(buf, buf + n, adjust);
> + *bufpos -= n;
> + return n;
> +}
> +
> +
> +ssize_t
> +fillbuf(int fd, unsigned char *buf, size_t *bufpos)
> +{
> + size_t num = BUFSIZE - *bufpos;
> + ssize_t n;
> +
> + n = read(fd, buf + *bufpos, num);
> + /* don't treat EAGAIN, EINTR as error */
> + if (n == -1 && (errno == EAGAIN || errno == EINTR))
> + n = -2;
> + if (n <= 0)
> + return n;
> + *bufpos += n;
> + return n;
> +}
> +
> /*
> * fdpass()
> * Pass the connected file descriptor to stdout and exit.
> @@ -857,6 +1027,8 @@ atelnet(int nfd, unsigned char *buf, uns
> {
> unsigned char *p, *end;
> unsigned char obuf[4];
> + int flags;
> + int blocking = 0;
>
> if (size < 3)
> return;
> @@ -877,8 +1049,20 @@ atelnet(int nfd, unsigned char *buf, uns
>
> p++;
> obuf[2] = *p;
> +
> + if (!blocking) {
> + flags = fcntl(nfd, F_GETFL, 0);
> + if (fcntl(nfd, F_SETFL, flags & ~O_NONBLOCK) == -1)
> + warn("unable to set blocking mode");
> + blocking = 1;
> + }
> if (atomicio(vwrite, nfd, obuf, 3) != 3)
> warn("Write Error!");
> + }
> + if (blocking) {
> + flags = fcntl(nfd, F_GETFL, 0);
> + if (fcntl(nfd, F_SETFL, flags | O_NONBLOCK) == -1)
> + warn("unable to set non-blocking mode");
> }
> }
>
--
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