Warn if a pre RAR 3 file is detected

[claudioandre-br]

Closes #5271

Closes the bug, we can keep the issue open as an "enhancement" to request to implement the "new format".

[magnumripper]

I came up with a slightly different patch before I saw this PR:

diff --git a/src/rar2john.c b/src/rar2john.c
index c7a4ae78b..290ba18d0 100644
--- a/src/rar2john.c
+++ b/src/rar2john.c
@@ -562,6 +562,10 @@ next_file_header:
 			fprintf(stderr, "! not encrypted, skipping\n");
 			jtr_fseek64(fp, file_hdr_pack_size, SEEK_CUR);
 			goto next_file_header;
+		} else if (file_hdr_block[24] < 29) {
+			fprintf(stderr, "! %s: Too old RAR file version (v%0.1f encryption), not supported.\n",
+			        archive_name, (float)file_hdr_block[24] / 10.);
+			goto err;
 		}
 
 		method = file_hdr_block[25];

The reason I chose v2.9 is our unpack code is called rar_unpack29(). I tested the above patch against our samples and it seems fine - but I'm not sure mine is better or worse.

[claudioandre-br]

I was confused whether to go to err or BailOut. anyway, Please feel free to choose

[magnumripper]

I'll do some more testing real quick.

[magnumripper]

OK so yours and mine version handle all samples the same. I'm not quite sure but I think we should go with my version - I'm pretty sure the version (archive format version, not RAR version) where it changed was v2.9.

I'll make a PR with that, then let's sleep on it.

[magnumripper]

I was confused whether to go to err or BailOut. anyway, Please feel free to choose

I amended my patch to do neither - it now skips to next file in the archive. In the (remote) case there are a mix of format versions in the archive, we might be able to handle some later file.