/* $OpenBSD: rfc931.c,v 1.13 2013/11/13 22:37:15 deraadt Exp $ */ /* rfc1413 does an attempt at an ident query to a client. Originally written * by Wietse Venema, rewritten by Bob Beck to avoid * potential longjmp problems and get rid of stdio usage on sockets. */ #include #include #include #include #include #include #include #include #include #include #include /* Local stuff for tcpd. */ #include "tcpd.h" #define IDENT_PORT 113 static volatile sig_atomic_t ident_timeout; int rfc931_timeout = RFC931_TIMEOUT; /* global, legacy from tcpwrapper stuff */ /*ARGSUSED*/ static void timeout(int s) { ident_timeout = 1; } /* * The old rfc931 from original libwrap for compatibility. Now it calls * rfc1413 with the default global parameters, but puts in the string * "unknown" (from global unknown) on failure just like the original. */ void rfc931(rmt_sin, our_sin, dest) struct sockaddr *rmt_sin; struct sockaddr *our_sin; char *dest; { if (rfc1413(rmt_sin, our_sin, dest, STRING_LENGTH, rfc931_timeout) == -1) strlcpy(dest, unknown, STRING_LENGTH); } /* * rfc1413, an rfc1413 client request for user name given a socket * structure, with a timeout in seconds on the whole operation. On * success returns 0 and saves dsize-1 characters of the username * provided by remote ident daemon into "dest", stripping off any * terminating CRLF, and terminating with a nul byte. Returns -1 on * failure (timeout, remote daemon didn't answer, etc). */ int rfc1413(rmt_sin, our_sin, dest, dsize, ident_timeout_time) struct sockaddr *rmt_sin; struct sockaddr *our_sin; char *dest; size_t dsize; int ident_timeout_time; { in_port_t rmt_port, our_port; int s, i, gotit, salen; char *cp; in_port_t *rmt_portp; in_port_t *our_portp; fd_set *readfds = NULL; fd_set *writefds = NULL; struct sockaddr_storage rmt_query_sin; struct sockaddr_storage our_query_sin; struct sigaction new_sa, old_sa; char user[256]; char tbuf[1024]; size_t rsize, wsize; gotit = 0; s = -1; /* address family must be the same */ if (rmt_sin->sa_family != our_sin->sa_family) goto out1; switch (rmt_sin->sa_family) { case AF_INET: salen = sizeof(struct sockaddr_in); rmt_portp = &(((struct sockaddr_in *)rmt_sin)->sin_port); break; #ifdef INET6 case AF_INET6: salen = sizeof(struct sockaddr_in6); rmt_portp = &(((struct sockaddr_in6 *)rmt_sin)->sin6_port); break; #endif default: goto out1; } switch (our_sin->sa_family) { case AF_INET: our_portp = &(((struct sockaddr_in *)our_sin)->sin_port); break; #ifdef INET6 case AF_INET6: our_portp = &(((struct sockaddr_in6 *)our_sin)->sin6_port); break; #endif default: goto out1; } if ((s = socket(rmt_sin->sa_family, SOCK_STREAM, 0)) == -1) goto out1; /* * Set up a timer so we won't get stuck while waiting for the server. * timer sets volatile sig_atomic_t ident_timeout when it fires. * this has to be checked after system calls in case we timed out. */ ident_timeout = 0; memset(&new_sa, 0, sizeof(new_sa)); new_sa.sa_handler = timeout; new_sa.sa_flags = SA_RESTART; if (sigemptyset(&new_sa.sa_mask) == -1) goto out1; if (sigaction(SIGALRM, &new_sa, &old_sa) == -1) goto out1; alarm(ident_timeout_time); /* * Bind the local and remote ends of the query socket to the same * IP addresses as the connection under investigation. We go * through all this trouble because the local or remote system * might have more than one network address. The IDENT etc. * client sends only port numbers; the server takes the IP * addresses from the query socket. */ memcpy(&our_query_sin, our_sin, salen); switch (our_query_sin.ss_family) { case AF_INET: ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(0); break; #ifdef INET6 case AF_INET6: ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(0); break; #endif } memcpy(&rmt_query_sin, rmt_sin, salen); switch (rmt_query_sin.ss_family) { case AF_INET: ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(IDENT_PORT); break; #ifdef INET6 case AF_INET6: ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(IDENT_PORT); break; #endif } if (bind(s, (struct sockaddr *) & our_query_sin, salen) == -1) goto out; if ((connect(s, (struct sockaddr *) & rmt_query_sin, salen) == -1) || ident_timeout) goto out; /* We are connected, build an ident query and send it. */ rsize = howmany(s+1, NFDBITS); readfds = calloc(rsize, sizeof(fd_mask)); if (readfds == NULL) goto out; wsize = howmany(s+1, NFDBITS); writefds = calloc(wsize, sizeof(fd_mask)); if (writefds == NULL) goto out; snprintf(tbuf, sizeof(tbuf), "%u,%u\r\n", ntohs(*rmt_portp), ntohs(*our_portp)); i = 0; while (i < strlen(tbuf)) { int j; memset(writefds, 0, wsize * sizeof(fd_mask)); FD_SET(s, writefds); do { j = select(s + 1, NULL, writefds, NULL, NULL); if (ident_timeout) goto out; } while ( j == -1 && (errno == EAGAIN || errno == EINTR )); if (j == -1) goto out; if (FD_ISSET(s, writefds)) { j = write(s, tbuf + i, strlen(tbuf + i)); if ((j == -1 && errno != EAGAIN && errno != EINTR) || ident_timeout) goto out; if (j != -1) i += j; } else goto out; } /* Read the answer back. */ i = 0; tbuf[0] = '\0'; while ((cp = strchr(tbuf, '\n')) == NULL && i < sizeof(tbuf) - 1) { int j; memset(readfds, 0, rsize * sizeof(fd_mask)); FD_SET(s, readfds); do { j = select(s + 1, readfds, NULL, NULL, NULL); if (ident_timeout) goto out; } while ( j == -1 && (errno == EAGAIN || errno == EINTR )); if (j == -1) goto out; if (FD_ISSET(s, readfds)) { j = read(s, tbuf + i, sizeof(tbuf) - 1 - i); if ((j == -1 && errno != EAGAIN && errno != EINTR) || j == 0 || ident_timeout) goto out; if (j != -1) i += j; tbuf[i] = '\0'; } else goto out; } if ((sscanf(tbuf,"%hu , %hu : USERID :%*[^:]:%255s", &rmt_port, &our_port, user) == 3) && (ntohs(*rmt_portp) == rmt_port) && (ntohs(*our_portp) == our_port)) { if ((cp = strchr(user, '\r')) != NULL) *cp = '\0'; gotit = 1; } out: alarm(0); sigaction(SIGALRM, &old_sa, NULL); if (readfds != NULL) free(readfds); if (writefds != NULL) free(writefds); out1: if (s != -1) close(s); if (gotit) { strlcpy(dest, user, dsize); return(0); } return(-1); }