Path: wupost!unlinfo.unl.edu!moe.ksu.ksu.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!ira.uka.de!math.fu-berlin.de!mailgzrz!mailgzrz.tu-berlin.de!nickel From: nickel@cs.tu-berlin.de (Juergen Nickelsen) Newsgroups: alt.sources Subject: nslook -- simple Domain Name Service lookup Message-ID: Date: 10 Sep 91 17:45:19 GMT Sender: news@mailgzrz.tu-berlin.de Reply-To: nickel@cs.tu-berlin.de Distribution: world Organization: STONE Project, Technical University of Berlin, Germany Lines: 381 Nntp-Posting-Host: desaster.cs.tu-berlin.de From the README file: nslook is a simple form of nslookup. It only gives you what you want to see: The IP address of a host, or the hostname of an IP address. Usage: nslook [-l] hostname to give you an IP address from a name nslook [-l] -a IP-address to give you a name from an IP address The flag "-l" gives a long output. If you have any comments, suggestions, complaints, improvements, please send them to me: Juergen Nickelsen . #! /bin/sh # This is a shell archive, meaning: # 1. Remove everything above the #! /bin/sh line. # 2. Save the resulting text in a file. # 3. Execute the file with /bin/sh (not csh) to create: # README # nslook.1 # Makefile # nslook.c # This archive created: Tue Sep 10 18:32:30 1991 export PATH; PATH=/bin:/usr/bin:$PATH if test -f 'README' then echo shar: "will not over-write existing file 'README'" else cat << \SHAR_EOF > 'README' To build nslook, type "make" on BSD Systems or "make sysv" on System V. It is tested on ISC 386/ix (sysv), BSD 4.3 and SunOS 4.1.1. I don't know anything about other systems, but: If ld complains about missing gethostbyname, gethostbyaddr, and h_errno, you probably have to link with libresolv.a or some other library containing these, if you have it. nslook is a simple form of nslookup. It only gives you what you want to see: The IP address of a host, or the hostname of an IP address. Usage: nslook [-l] hostname to give you an IP address from a name nslook [-l] -a IP-address to give you a name from an IP address The flag "-l" gives a long output. Some examples of use: coma: /u/nickel) nslook ucbvax.berkeley.edu 128.32.133.1 coma: /u/nickel) nslook -l ucbvax.berkeley.edu Official name: ucbvax.berkeley.edu Address: 128.32.133.1 Address: 128.32.130.12 Address: 128.32.149.36 Address: 128.32.137.3 coma: /u/nickel) nslook -a 128.32.133.1 ucbvax.Berkeley.EDU coma: /u/nickel) nslook -al 128.32.133.1 Official name: ucbvax.Berkeley.EDU Address: 128.32.133.1 coma: /u/nickel) nslook -l ftp.informatik.uni-dortmund.de Official name: walhalla.informatik.uni-dortmund.de Alias: ftp.informatik.uni-dortmund.de Address: 129.217.64.63 If you have any comments, suggestions, complaints, improvements, please send them to me: Juergen Nickelsen . Copyrights? what Copyrights? SHAR_EOF fi if test -f 'nslook.1' then echo shar: "will not over-write existing file 'nslook.1'" else cat << \SHAR_EOF > 'nslook.1' ..TH NSLOOK 1 "Sep 10, 1991" ..UC 4 ..SH NAME nslook \- name server lookup ..SH SYNOPSIS ..B nslook [ ..B \-l ] ..I hostname ..br ..B nslook [ ..B \-l ] ..B \-a ..I IP-address ..br ..SH DESCRIPTION ..B Nslook provides a simple way to retrieve an IP address or a host name from the Domain Name Service. The command ..PP ..ti +10n \fC nslook \fP ..I hostname ..PP prints the IP address of ..I hostname on standard output (and nothing else). The command ..PP ..ti +10n \fC nslook \-a \fP ..I IP-address ..PP prints the official name of the Internet host with the specified ..I IP-address on standard output. ..PP If the ..B \-l flag is given, ..B nslook gives a long format display, showing the hosts official name, zero or more aliases, and one or more IP addresses. ..PP ..SH DIAGNOSTICS The diagnostics of ..B nslook correspond to the errors signalled by gethostbyname(3) and gethostbyaddr(3). ..TP \fC unknown host \fP ..TP \fC temporary error -- try again later \fP This usually indicates that the local server did not receive a response from an authoritative server. A retry at some later time may succeed. ..TP \fC unrecoverable error \fP Some unexpected server failure was encountered. ..TP \fC no IP address \fP The requested name is valid but does not have an IP address; this is not a temporary error. This means that the name is known to the name server but there is no address associated with this name. Another type of request to the name server using this domain name will result in an answer; for example, a mail-forwarder may be registered for this domain. ..PP If one of these errors occurs, ..B nslook returns an exit code of 1. ..SH "SEE ALSO" nslookup(1), gethostbyaddr(3), gethostbyname(3) ..SH BUGS Normally ..B nslook does not list alias hostnames since it only uses the information given by gethostbyname(3) or gethostbyaddr(3). ..PP If ..B nslook tries to find the address of a non-existent host in the local domain, the error ``no IP address'' is signalled. This is due to the return code of gethostbyname(3). ..PP ..SH AUTHOR Juergen Nickelsen SHAR_EOF fi if test -f 'Makefile' then echo shar: "will not over-write existing file 'Makefile'" else cat << \SHAR_EOF > 'Makefile' CC = gcc # CFLAGS = -g CFLAGS = -O SYSTYPE = bsd # SYSTYPE = sysv all : $(SYSTYPE) bsd : ; make nslook DEFINES=-DBSD CC=$(CC) CFLAGS=$(CFLAGS) sysv : ; make nslook DEFINES=-DSYSV CC=$(CC) CFLAGS=$(CFLAGS) LIBS=-linet nslook : nslook.c Makefile $(CC) $(CFLAGS) $(DEFINES) -o nslook nslook.c $(LIBS) SHAR_EOF fi if test -f 'nslook.c' then echo shar: "will not over-write existing file 'nslook.c'" else cat << \SHAR_EOF > 'nslook.c' #include #include #ifdef SYSV #include #include #endif #include #include char *progname ; extern struct hostent *gethostbyname(), *gethostbyaddr() ; extern int errno ; main(argc, argv) int argc ; char **argv ; { extern int optind ; /* from getopt */ int opt ; /* option character */ int aflg = 0 ; /* address is given if non-zero, else name */ int lflg = 0 ; /* long output format */ int errflg = 0 ; /* usage error encountered */ char *cp, *strrchr() ; progname = argv[0] ; if (cp = strrchr(progname, '/')) progname = cp + 1 ; while ((opt = getopt(argc, argv, "la")) != -1) { switch (opt) { case 'l': lflg = 1 ; break ; case 'a': aflg = 1 ; break ; case '?': errflg++ ; } } if (errflg || optind != argc - 1) { usage() ; exit(1) ; } if (aflg) { from_address(argv[optind], lflg) ; } else { from_name(argv[optind], lflg) ; } return 0 ; } from_address(astring, lflg) char *astring ; int lflg ; { unsigned long addr ; /* address in host order */ unsigned long norder ; /* address in network order */ struct hostent *host ; /* structure returned by gethostbyaddr() */ int octet[4] ; /* the four bytes of the address */ if (sscanf(astring, "%d.%d.%d.%d", octet, octet+1, octet+2, octet+3) != 4 || octet[0] > 255 || octet [0] < 0 || octet[1] > 255 || octet [1] < 0 || octet[2] > 255 || octet [2] < 0 || octet[3] > 255 || octet [3] < 0) { usage() ; exit(1) ; } norder = (octet[0] << 24) | (octet[1] << 16) | (octet[2] << 8) | octet[3] ; addr = ntohl(norder) ; if ((host = gethostbyaddr(&addr, 4, AF_INET)) == NULL) { herror(progname) ; exit(1) ; } if (lflg) { print_long(host) ; } else { puts(host->h_name) ; } } from_name(name, lflg) char *name ; int lflg ; { struct hostent *host ; if ((host = gethostbyname(name)) == NULL) { herror(progname) ; exit(1) ; } if (lflg) { print_long(host) ; } else { paddress(*host->h_addr_list) ; } } print_long(host) struct hostent *host ; { int i ; unsigned long horder ; printf("Official name: %s\n", host->h_name) ; while (*host->h_aliases) { printf("Alias: %s\n", *host->h_aliases++) ; } while (*host->h_addr_list) { printf("Address: ") ; paddress(*host->h_addr_list++) ; } } paddress(paddr) unsigned long *paddr ; { unsigned long horder ; horder = ntohl(*paddr) ; printf("%u.%u.%u.%u\n", horder >> 24, (horder >> 16) & 0xff, (horder >> 8) & 0xff, horder & 0xff) ; } usage() { fprintf(stderr, "Usage: %s [-l] hostname\n %s [-l] -a IP-address\n", progname, progname) ; } herror(s) char *s ; { #ifdef BSD extern int h_errno ; #endif if (s && *s) { fputs(s, stderr) ; fputs(": ", stderr) ; } switch (h_errno) { case HOST_NOT_FOUND: fputs("unknown host\n", stderr) ; break ; case TRY_AGAIN: fputs("temporary error -- try again later\n", stderr) ; break ; case NO_RECOVERY: fputs("unrecoverable error\n", stderr) ; break ; #ifdef BSD case NO_DATA: #else #ifdef SYSV case NO_ADDRESS: #else you must define SYSV or BSD #endif /* SYSV */ #endif /* BSD */ fputs("no IP address\n", stderr) ; break ; default: fprintf(stderr, "unknown error number %d\n", h_errno) ; } } SHAR_EOF fi exit 0 # End of shell archive -- Juergen Nickelsen nickel@cs.tu-berlin.de