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-rw-r--r--networking/fakeidentd.c346
1 files changed, 167 insertions, 179 deletions
diff --git a/networking/fakeidentd.c b/networking/fakeidentd.c
index 7eac480..8c07082 100644
--- a/networking/fakeidentd.c
+++ b/networking/fakeidentd.c
@@ -9,12 +9,62 @@
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
+/* Ident crash course
+ *
+ * Incoming requests are of form "6191, 23\r\n" - peer asks us
+ * "which user connected from your port 6191 to my port 23?"
+ * We should answer:
+ * "6193, 23 : USERID : UNIX : username\r\n"
+ * and close the connection.
+ * We can also reply:
+ * "6195, 23 : USERID : OTHER[,US-ASCII] : username\r\n"
+ * "6195, 23 : ERROR : INVALID-PORT/NO-USER/HIDDEN-USER/UNKNOWN-ERROR\r\n"
+ * but we probably will never want that.
+ */
+
#include "busybox.h"
+
+#define SANE_INETD_ONLY_VERSION
+
+#ifdef SANE_INETD_ONLY_VERSION
+
+int fakeidentd_main(int argc, char **argv)
+{
+ char buf[64];
+ const char *bogouser = "nobody";
+ char *cur = buf;
+ int rem = sizeof(buf)-1;
+
+ if (argv[1])
+ bogouser = argv[1];
+
+ alarm(30);
+ while (1) {
+ char *p;
+ int sz = safe_read(0, cur, rem);
+ if (sz < 0) return 1;
+ cur[sz] = '\0';
+ p = strpbrk(cur, "\r\n");
+ if (p) {
+ *p = '\0';
+ break;
+ }
+ cur += sz;
+ rem -= sz;
+ if (!rem || !sz)
+ break;
+ }
+ printf("%s : USERID : UNIX : %s\r\n", buf, bogouser);
+ return 0;
+}
+
+#else
+
+/* Welcome to the bloaty horrors */
+
#include <sys/syslog.h>
#include <sys/uio.h>
-
-#define IDENT_PORT 113
#define MAXCONNS 20
#define MAXIDLETIME 45
@@ -43,9 +93,9 @@ enum { ident_substr_len = sizeof(ident_substr) - 1 };
* in `conns' array + FCS
*/
static struct {
- char buf[20];
- int len;
time_t lasttime;
+ int len;
+ char buf[20];
} conns[MAXCONNS];
/* When using global variables, bind those at least to a structure. */
@@ -55,111 +105,92 @@ static struct {
int conncnt;
} G;
-/*
- * Prototypes
- */
-static void reply(int s, char *buf);
-static void replyError(int s, char *buf);
+static char *bind_ip_address;
-static const char *nobodystr = "nobody"; /* this needs to be declared like this */
-static char *bind_ip_address = "0.0.0.0";
+static int chmatch(char c, char *chars)
+{
+ for (; *chars; chars++)
+ if (c == *chars)
+ return 1;
+ return 0;
+}
-static void movefd(int from, int to)
+static int skipchars(char **p, char *chars)
{
- if (from != to) {
- dup2(from, to);
- close(from);
- }
+ while (chmatch(**p, chars))
+ (*p)++;
+ if (**p == '\r' || **p == '\n')
+ return 0;
+ return 1;
}
-static void inetbind(void)
+static int parseAddrs(char *ptr, char **myaddr, char **heraddr)
{
- int s, port;
- struct sockaddr_in addr;
- int len = sizeof(addr);
- struct servent *se;
+ /* parse <port-on-server> , <port-on-client> */
- se = getservbyname("identd", "tcp");
- port = IDENT_PORT;
- if (se)
- port = se->s_port;
+ if (!skipchars(&ptr, " \t"))
+ return -1;
- s = xsocket(AF_INET, SOCK_STREAM, 0);
+ *myaddr = ptr;
- setsockopt_reuseaddr(s);
+ if (!skipchars(&ptr, "1234567890"))
+ return -1;
- memset(&addr, 0, sizeof(addr));
- addr.sin_addr.s_addr = inet_addr(bind_ip_address);
- addr.sin_family = AF_INET;
- addr.sin_port = htons(port);
+ if (!chmatch(*ptr, " \t,"))
+ return -1;
- xbind(s, (struct sockaddr *)&addr, len);
- xlisten(s, 5);
+ *ptr++ = '\0';
- movefd(s, 0);
-}
+ if (!skipchars(&ptr, " \t,") )
+ return -1;
-static void handlexitsigs(int signum)
-{
- if (unlink(PIDFILE) < 0)
- close(open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0644));
- exit(0);
-}
+ *heraddr = ptr;
-/* May succeed. If not, won't care. */
-static void writepid(uid_t nobody, uid_t nogrp)
-{
- char buf[sizeof(int)*3 + 2];
- int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
+ skipchars(&ptr, "1234567890");
- if (fd < 0)
- return;
+ if (!chmatch(*ptr, " \n\r"))
+ return -1;
- sprintf(buf, "%d\n", getpid());
- write(fd, buf, strlen(buf));
- fchown(fd, nobody, nogrp);
- close(fd);
+ *ptr = '\0';
- /* should this handle ILL, ... (see signal(7)) */
- signal(SIGTERM, handlexitsigs);
- signal(SIGINT, handlexitsigs);
- signal(SIGQUIT, handlexitsigs);
+ return 0;
}
-/* return 0 as parent, 1 as child */
-static int godaemon(void)
+static void replyError(int s, char *buf)
{
- uid_t nobody, nogrp;
- struct passwd *pw;
-
- switch (fork()) {
- case -1:
- bb_perror_msg_and_die("fork");
-
- case 0:
- pw = getpwnam(nobodystr);
- if (pw == NULL)
- bb_error_msg_and_die("cannot find uid/gid of user '%s'", nobodystr);
- nobody = pw->pw_uid;
- nogrp = pw->pw_gid;
- writepid(nobody, nogrp);
-
- close(0);
- inetbind();
- xsetgid(nogrp);
- xsetuid(nobody);
- close(1);
- close(2);
+ struct iovec iv[3];
+ iv[0].iov_base = "0, 0 : ERROR : "; iv[0].iov_len = 15;
+ iv[1].iov_base = buf; iv[1].iov_len = strlen(buf);
+ iv[2].iov_base = "\r\n"; iv[2].iov_len = 2;
+ writev(s, iv, 3);
+}
- signal(SIGHUP, SIG_IGN);
- signal(SIGPIPE, SIG_IGN); /* connection closed when writing (raises ???) */
+static void reply(int s, char *buf)
+{
+ char *myaddr, *heraddr;
- setsid();
+ myaddr = heraddr = NULL;
- return 1;
+ if (parseAddrs(buf, &myaddr, &heraddr))
+ replyError(s, "X-INVALID-REQUEST");
+ else {
+ struct iovec iv[6];
+ iv[0].iov_base = myaddr; iv[0].iov_len = strlen(myaddr);
+ iv[1].iov_base = ", "; iv[1].iov_len = 2;
+ iv[2].iov_base = heraddr; iv[2].iov_len = strlen(heraddr);
+ iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
+ iv[4].iov_base = (void *)G.identuser; iv[4].iov_len = strlen(G.identuser);
+ iv[5].iov_base = "\r\n"; iv[5].iov_len = 2;
+ writev(s, iv, 6);
}
+}
- return 0;
+static void movefd(int from, int to)
+{
+ if (from != to) {
+ dup2(from, to);
+ close(from);
+ }
}
static void deleteConn(int s)
@@ -215,15 +246,32 @@ static int checkInput(char *buf, int len, int l)
return 0;
}
+/* May succeed. If not, won't care. */
+static const char *to_unlink;
+static void writepid(void)
+{
+ int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
+ if (fd < 0)
+ return;
+ to_unlink = PIDFILE;
+ fdprintf(fd, "%d\n", getpid());
+ close(fd);
+}
+
+static void handlexitsigs(int signum)
+{
+ if (to_unlink)
+ if (unlink(to_unlink) < 0)
+ close(open(to_unlink, O_WRONLY|O_CREAT|O_TRUNC, 0644));
+ exit(0);
+}
+
int fakeidentd_main(int argc, char **argv)
{
- /* This applet is an inetd-style daemon */
- openlog(applet_name, 0, LOG_DAEMON);
- logmode = LOGMODE_SYSLOG;
+ int fd;
+ pid_t pid;
- memset(conns, 0, sizeof(conns));
- memset(&G, 0, sizeof(G));
- FD_ZERO(&G.readfds);
+ /* FD_ZERO(&G.readfds); - in bss, already zeroed */
FD_SET(0, &G.readfds);
/* handle -b <ip> parameter */
@@ -232,11 +280,30 @@ int fakeidentd_main(int argc, char **argv)
if (optind < argc)
G.identuser = argv[optind];
else
- G.identuser = nobodystr;
+ G.identuser = "nobody";
- /* daemonize and have the parent return */
- if (godaemon() == 0)
- return 0;
+ writepid();
+ signal(SIGTERM, handlexitsigs);
+ signal(SIGINT, handlexitsigs);
+ signal(SIGQUIT, handlexitsigs);
+ signal(SIGHUP, SIG_IGN);
+ signal(SIGPIPE, SIG_IGN); /* ignore closed connections when writing */
+
+ fd = create_and_bind_stream_or_die(bind_ip_address, bb_lookup_port("identd", "tcp", 113));
+ xlisten(fd, 5);
+
+ pid = fork();
+ if (pid < 0)
+ bb_perror_msg_and_die("fork");
+ if (pid != 0) /* parent */
+ exit(0);
+ /* child */
+ setsid();
+ movefd(fd, 0);
+ while (fd)
+ close(fd--);
+ openlog(applet_name, 0, LOG_DAEMON);
+ logmode = LOGMODE_SYSLOG;
/* main loop where we process all events and never exit */
while (1) {
@@ -252,10 +319,11 @@ int fakeidentd_main(int argc, char **argv)
if (FD_ISSET(s, &rfds)) {
char *buf = conns[i].buf;
- unsigned int len = conns[i].len;
- unsigned int l;
+ unsigned len = conns[i].len;
+ unsigned l;
- if ((l = read(s, buf + len, sizeof(conns[0].buf) - len)) > 0) {
+ l = read(s, buf + len, sizeof(conns[0].buf) - len);
+ if (l > 0) {
if (checkInput(buf, len, l)) {
reply(s, buf);
goto deleteconn;
@@ -268,10 +336,8 @@ int fakeidentd_main(int argc, char **argv)
} else {
goto deleteconn;
}
-
conns[i].lasttime = tim;
continue;
-
deleteconn:
deleteConn(s);
} else {
@@ -287,7 +353,7 @@ deleteconn:
int s = accept(0, NULL, 0);
if (s < 0) {
- if (errno != EINTR) /* EINTR */
+ if (errno != EINTR)
bb_perror_msg("accept");
} else {
if (G.conncnt == MAXCONNS)
@@ -297,7 +363,6 @@ deleteconn:
movefd(s, i + FCS); /* move if not already there */
FD_SET(i + FCS, &G.readfds);
-
conns[i].len = 0;
conns[i].lasttime = time(NULL);
}
@@ -307,81 +372,4 @@ deleteconn:
return 0;
}
-static int parseAddrs(char *ptr, char **myaddr, char **heraddr);
-static void reply(int s, char *buf)
-{
- char *myaddr, *heraddr;
-
- myaddr = heraddr = NULL;
-
- if (parseAddrs(buf, &myaddr, &heraddr))
- replyError(s, "X-INVALID-REQUEST");
- else {
- struct iovec iv[6];
- iv[0].iov_base = myaddr; iv[0].iov_len = strlen(myaddr);
- iv[1].iov_base = ", "; iv[1].iov_len = 2;
- iv[2].iov_base = heraddr; iv[2].iov_len = strlen(heraddr);
- iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
- iv[4].iov_base = (void *)G.identuser; iv[4].iov_len = strlen(G.identuser);
- iv[5].iov_base = "\r\n"; iv[5].iov_len = 2;
- writev(s, iv, 6);
- }
-}
-
-static void replyError(int s, char *buf)
-{
- struct iovec iv[3];
- iv[0].iov_base = "0, 0 : ERROR : "; iv[0].iov_len = 15;
- iv[1].iov_base = buf; iv[1].iov_len = strlen(buf);
- iv[2].iov_base = "\r\n"; iv[2].iov_len = 2;
- writev(s, iv, 3);
-}
-
-static int chmatch(char c, char *chars)
-{
- for (; *chars; chars++)
- if (c == *chars)
- return 1;
- return 0;
-}
-
-static int skipchars(char **p, char *chars)
-{
- while (chmatch(**p, chars))
- (*p)++;
- if (**p == '\r' || **p == '\n')
- return 0;
- return 1;
-}
-
-static int parseAddrs(char *ptr, char **myaddr, char **heraddr)
-{
- /* parse <port-on-server> , <port-on-client> */
-
- if (!skipchars(&ptr, " \t"))
- return -1;
-
- *myaddr = ptr;
-
- if (!skipchars(&ptr, "1234567890"))
- return -1;
-
- if (!chmatch(*ptr, " \t,"))
- return -1;
-
- *ptr++ = '\0';
-
- if (!skipchars(&ptr, " \t,") )
- return -1;
-
- *heraddr = ptr;
-
- skipchars(&ptr, "1234567890");
-
- if (!chmatch(*ptr, " \n\r"))
- return -1;
-
- *ptr = '\0';
-
- return 0;
-}
+#endif /* !SANE_INETD_ONLY_VERSION */
generated by cgit v1.1 at 2024-12-27 12:44:52 +0000