Hi Amy, I would propose an alternate solution would be to add the key extension string onto the method kex prefs string _after_ it’s been filtered, instead of before, so the rest of the preferences wouldn’t be subject to this test which would be a bit confusing. I’ll work up an MR with this change.
Cheers, Will > On Feb 27, 2025, at 11:10 AM, Amy Lin via libssh2-devel > <libssh2-devel@lists.haxx.se> wrote: > > Hello Team, > > We are upgrading from Libssh2 1.10 to 1.11.1. We found that calling kex.c: > libssh2_session_method_pref() with bad method names did not throw an error. > > It looks like key extension indicators were added with the new update, but > the error handling for LIBSSH2_ERROR_METHOD_NOT_SUPPORTED continues to check > for empty string. > https://github.com/libssh2/libssh2/commit/00e2a07e824db8798d94809156e9fb4e70a42f89 > > What do folks think about this update in error handling? > > In https://github.com/libssh2/libssh2/blob/master/src/kex.c: 4310 > - if(!*newprefs) { > + // ignore trailing comma in kex_extensions when comparing > + if((strlen(newprefs) == (kex_extensions_len-1)) && > + (strncmp(newprefs, kex_extensions, (kex_extensions_len-1)) == > 0)) { > LIBSSH2_FREE(session, newprefs); > return _libssh2_error(session, LIBSSH2_ERROR_METHOD_NOT_SUPPORTED, > "The requested method(s) are not currently " > "supported"); > } > > Thanks, > Amy > -- > libssh2-devel mailing list > libssh2-devel@lists.haxx.se <mailto:libssh2-devel@lists.haxx.se> > https://lists.haxx.se/mailman/listinfo/libssh2-devel
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