made more robust and commented my code.
diff --git a/networking/nslookup.c b/networking/nslookup.c
index 0a2a574..82d3b36 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -32,14 +32,24 @@
#include <sys/types.h>
#include <netinet/in.h>
+/*
+ | I'm only implementing non-interactive mode;
+ | I totally forgot nslookup even had an interactive mode.
+ |
+ | [ TODO ]
+ | + find out how to use non-default name servers
+ | + find out how the real nslookup gets the default name server
+ */
static const char nslookup_usage[] =
-"only implementing non-interactive mode\n"
-"I totally forgot nslookup even had an interactive mode\n"
+ "nslookup [HOST]\n\n"
;
-/* */
+/* I have to see how the real nslookup does this.
+ * I could dig through /etc/resolv.conf, but is there a
+ * better (programatic) way?
+ */
static void
server_fprint(FILE *dst)
{
@@ -67,7 +77,9 @@
return 0;
}
-/* */
+/* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
+ * into a uint32_t
+ */
static uint32_t
str_to_addr(const char *addr)
{
@@ -86,59 +98,63 @@
return htonl(ip);
}
-/* */
+/* takes the NULL-terminated array h_addr_list, and
+ * prints its contents appropriately
+ */
static int
addr_list_fprint(char **h_addr_list, FILE *dst)
{
- int i;
+ int i, j;
char *addr_string = (h_addr_list[1])
? "Addresses"
: "Address";
fprintf(dst, "%s: ", addr_string);
- for (i = 0; h_addr_list[i]; i++) {
+ for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
addr_fprint(h_addr_list[i], dst);
- if (h_addr_list[i+1]) {
- fprintf(dst, ", ");
+
+ /* real nslookup does this */
+ if (j == 4) {
+ if (h_addr_list[i+1]) {
+ fprintf(dst, "\n ");
+ }
+ j = 0;
+ } else {
+ if (h_addr_list[i+1]) {
+ fprintf(dst, ", ");
+ }
}
+
}
fprintf(dst,"\n");
return 0;
}
-/* */
+/* gethostbyaddr wrapper */
static struct hostent *
-lookup_by_name(const char *hostname)
+gethostbyaddr_wrapper(const char *address)
{
- struct hostent *host;
+ struct in_addr addr;
- host = gethostbyname(hostname);
+ addr.s_addr = str_to_addr(address);
+ return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
+}
+
+/* print the results as nslookup would */
+static struct hostent *
+hostent_fprint(struct hostent *host, FILE *dst)
+{
if (host) {
- fprintf(stdout, "Name: %s\n", host->h_name);
- addr_list_fprint(host->h_addr_list, stdout);
+ fprintf(dst, "Name: %s\n", host->h_name);
+ addr_list_fprint(host->h_addr_list, dst);
} else {
- herror("crap");
+ fprintf(dst, "*** %s\n", hstrerror(h_errno));
}
return host;
}
-/* */
-static struct hostent *
-lookup_by_addr(const char *addr)
-{
- struct hostent *host;
- host = gethostbyaddr(addr, 4, AF_INET); /* IPv4 only for now */
- if (host) {
- fprintf(stdout, "Name: %s\n", host->h_name);
- addr_list_fprint(host->h_addr_list, stdout);
- } else {
- herror("crap");
- }
- return host;
-}
-
-/* */
+/* naive function to check whether char *s is an ip address */
static int
is_ip_address(const char *s)
{
@@ -153,16 +169,20 @@
int
nslookup_main(int argc, char **argv)
{
- struct in_addr addr;
+ struct hostent *host;
+
+ if (argc < 2) {
+ usage(nslookup_usage);
+ }
server_fprint(stdout);
if (is_ip_address(argv[1])) {
- addr.s_addr = str_to_addr(argv[1]);
- lookup_by_addr((char *) &addr);
+ host = gethostbyaddr_wrapper(argv[1]);
} else {
- lookup_by_name(argv[1]);
+ host = gethostbyname(argv[1]);
}
+ hostent_fprint(host, stdout);
return 0;
}
-/* $Id: nslookup.c,v 1.1 2000/01/29 12:59:01 beppu Exp $ */
+/* $Id: nslookup.c,v 1.2 2000/01/30 09:47:16 beppu Exp $ */