openssh unix dev - Mar 2007 - Proposed patch: ssh-keygen allows writing to stdout for moduli generation

Hello all,

I propose the following patch to ssh-keygen.c for openssh version 4.5.
It allows to redirect output of the moduli operations to stdout, to do
something like e.g.:

$ ssh-keygen -G - -b 2048 | ssh-keygen -T - -f - >moduli

Best regards,

Christian

--- ssh/ssh-keygen.c.old	2007-03-01 12:43:06.000000000 +0100
+++ ssh/ssh-keygen.c	2007-03-01 12:47:32.000000000 +0100
@@ -1270,13 +1270,16 @@ main(int ac, char **av)
 	}
 
 	if (do_gen_candidates) {
-		FILE *out = fopen(out_file, "w");
-
-		if (out == NULL) {
-			error("Couldn't open modulus candidate file \"%s\":
%s",
-			    out_file, strerror(errno));
-			return (1);
-		}
+		FILE *out;
+		
+		if (strcmp(out_file, "-") != 0) {
+			if ((out = fopen(out_file, "w")) == NULL) {
+				fatal("Couldn't open modulus candidate file \"%s\":
%s",
+				      out_file, strerror(errno));
+			}
+		} else 
+			out = stdout;
+		
 		if (bits == 0)
 			bits = DEFAULT_BITS;
 		if (gen_candidates(out, memory, bits, start) != 0)
@@ -1287,8 +1290,16 @@ main(int ac, char **av)
 
 	if (do_screen_candidates) {
 		FILE *in;
-		FILE *out = fopen(out_file, "w");
+		FILE *out;
 
+		if (strcmp(out_file, "-") != 0) {
+			if ((out = fopen(out_file, "w")) == NULL) {
+				fatal("Couldn't open moduli file \"%s\": %s",
+				      out_file, strerror(errno));
+			}
+		} else 
+			out = stdout;
+		
 		if (have_identity && strcmp(identity_file, "-") != 0) {
 			if ((in = fopen(identity_file, "r")) == NULL) {
 				fatal("Couldn't open modulus candidate "
@@ -1298,10 +1309,6 @@ main(int ac, char **av)
 		} else
 			in = stdin;
 
-		if (out == NULL) {
-			fatal("Couldn't open moduli file \"%s\": %s",
-			    out_file, strerror(errno));
-		}
 		if (prime_test(in, out, trials, generator_wanted) != 0)
 			fatal("modulus screening failed");
 		return (0);

Christian Pfaffel-Janser wrote:
> I propose the following patch to ssh-keygen.c for openssh version 4.5.
> It allows to redirect output of the moduli operations to stdout, to do
> something like e.g.:
> 
> $ ssh-keygen -G - -b 2048 | ssh-keygen -T - -f - >moduli
If your platform has it you can use /dev/stdout for this:

ssh-keygen -b 2048 -G /dev/stdout | ssh-keygen -T - -f - >moduli

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
     Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.