1 files changed, 144 insertions, 0 deletions

diff --git a/networking/isrv_identd.c b/networking/isrv_identd.c
new file mode 100644
index 000000000..b9481f8d3
--- /dev/null
+++ b/networking/isrv_identd.c
@@ -0,0 +1,144 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Fake identd server.
+ *
+ * Copyright (C) 2007 Denis Vlasenko
+ *
+ * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ */
+
+#include <syslog.h>
+#include "busybox.h"
+#include "isrv.h"
+
+enum { TIMEOUT = 20 };
+
+/* Why use alarm(TIMEOUT-1)?
+ * isrv's internal select() will run with timeout=TIMEOUT.
+ * If nothing happens during TIMEOUT-1 seconds (no accept/read),
+ * then ALL sessions timed out by now. Instead of closing them one-by-one
+ * (isrv calls do_timeout for each 'stale' session),
+ * SIGALRM triggered by alarm(TIMEOUT-1) will kill us, terminating them all.
+ */
+
+typedef struct identd_buf_t {
+        int pos;
+        int fd_flag;
+        char buf[64 - 2*sizeof(int)];
+} identd_buf_t;
+
+static const char *bogouser = "nobody";
+
+static int new_peer(isrv_state_t *state, int fd)
+{
+        int peer;
+        identd_buf_t *buf = xzalloc(sizeof(*buf));
+
+        alarm(TIMEOUT - 1);
+
+        peer = isrv_register_peer(state, buf);
+        if (peer < 0)
+                return 0; /* failure */
+        if (isrv_register_fd(state, peer, fd) < 0)
+                return peer; /* failure, unregister peer */
+
+        buf->fd_flag = fcntl(fd, F_GETFL, 0) | O_NONBLOCK;
+        isrv_want_rd(state, fd);
+        return 0;
+}
+
+static int do_rd(int fd, void **paramp)
+{
+        identd_buf_t *buf = *paramp;
+        char *cur, *p;
+        int sz;
+
+        alarm(TIMEOUT - 1);
+
+        cur = buf->buf + buf->pos;
+
+        fcntl(fd, F_SETFL, buf->fd_flag | O_NONBLOCK);
+        sz = safe_read(fd, cur, sizeof(buf->buf) - buf->pos);
+
+        if (sz < 0) {
+                if (errno != EAGAIN)
+                        goto term; /* terminate this session if !EAGAIN */
+                goto ok;
+        }
+
+        buf->pos += sz;
+        buf->buf[buf->pos] = '\0';
+        p = strpbrk(cur, "\r\n");
+        if (p)
+                *p = '\0';
+        if (p || !sz || buf->pos == sizeof(buf->buf)) {
+                /* fd is still in nonblocking mode - we never block here */
+                fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
+                goto term;
+        }
+ ok:
+        fcntl(fd, F_SETFL, buf->fd_flag & ~O_NONBLOCK);
+        return 0;
+ term:
+        fcntl(fd, F_SETFL, buf->fd_flag & ~O_NONBLOCK);
+        free(buf);
+        return 1;
+}
+
+static int do_timeout(void **paramp)
+{
+        return 1; /* terminate session */
+}
+
+static void inetd_mode(void)
+{
+        identd_buf_t *buf = xzalloc(sizeof(*buf));
+        /* We do NOT want nonblocking I/O here! */
+        buf->fd_flag = fcntl(0, F_GETFL, 0);
+        while (do_rd(0, (void*)&buf) == 0) /* repeat */;
+}
+
+int fakeidentd_main(int argc, char **argv)
+{
+        enum {
+                OPT_foreground = 0x1,
+                OPT_inetd      = 0x2,
+                OPT_inetdwait  = 0x4,
+                OPT_nodeamon   = 0x7,
+                OPT_bindaddr   = 0x8,
+        };
+
+        const char *bind_address = NULL;
+        unsigned opt;
+        int fd;
+
+        opt = getopt32(argc, argv, "fiwb:", &bind_address);
+        if (optind < argc)
+                bogouser = argv[optind];
+
+        /* Daemonize if no -f or -i or -w */
+        bb_sanitize_stdio(!(opt & OPT_nodeamon));
+        if (!(opt & OPT_nodeamon)) {
+                openlog(applet_name, 0, LOG_DAEMON);
+                logmode = LOGMODE_SYSLOG;
+        }
+
+        if (opt & OPT_inetd) {
+                inetd_mode();
+                return 0;
+        }
+
+        /* Ignore closed connections when writing */
+        signal(SIGPIPE, SIG_IGN);
+
+        if (opt & OPT_inetdwait) {
+                fd = 0;
+        } else {
+                fd = create_and_bind_stream_or_die(bind_address,
+                                bb_lookup_port("identd", "tcp", 113));
+                xlisten(fd, 5);
+        }
+
+        isrv_run(fd, new_peer, do_rd, NULL, do_timeout, TIMEOUT, 1);
+        return 0;
+}