made more robust and commented my code.

diff --git a/networking/nslookup.c b/networking/nslookup.c
index 0a2a57437b164775d3d8f863d2880417843538ae..82d3b3690a83a3f29ac409dcdebc51a04a7b8df1 100644 (file)
--- 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 @@ addr_fprint(char *addr, FILE *dst)
     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 @@ str_to_addr(const char *addr)
     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);
-    if (host) {
-       fprintf(stdout, "Name:    %s\n", host->h_name);
-       addr_list_fprint(host->h_addr_list, stdout);
-    } else {
-       herror("crap");
-    }
-    return host;
+    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 *
-lookup_by_addr(const char *addr)
+hostent_fprint(struct hostent *host, FILE *dst)
 {
-    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);
+       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;
 }
 
-/* */
+
+/* naive function to check whether char *s is an ip address */
 static int
 is_ip_address(const char *s)
 {
@@ -153,16 +169,20 @@ is_ip_address(const char *s)
 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 $ */

diff --git a/nslookup.c b/nslookup.c
index 0a2a57437b164775d3d8f863d2880417843538ae..82d3b3690a83a3f29ac409dcdebc51a04a7b8df1 100644 (file)
--- a/nslookup.c
+++ b/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 @@ addr_fprint(char *addr, FILE *dst)
     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 @@ str_to_addr(const char *addr)
     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);
-    if (host) {
-       fprintf(stdout, "Name:    %s\n", host->h_name);
-       addr_list_fprint(host->h_addr_list, stdout);
-    } else {
-       herror("crap");
-    }
-    return host;
+    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 *
-lookup_by_addr(const char *addr)
+hostent_fprint(struct hostent *host, FILE *dst)
 {
-    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);
+       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;
 }
 
-/* */
+
+/* naive function to check whether char *s is an ip address */
 static int
 is_ip_address(const char *s)
 {
@@ -153,16 +169,20 @@ is_ip_address(const char *s)
 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 $ */