Make errors human readable

Change error messages from numeric codes to human readable strings. This makes debugging failures much easier.

src/ffi.rs

@@ -272,6 +272,10 @@ extern "C" {
 
     pub fn ERR_get_error() -> c_ulong;
 
+    pub fn ERR_lib_error_string(err: c_ulong) -> *const c_char;
+    pub fn ERR_func_error_string(err: c_ulong) -> *const c_char;
+    pub fn ERR_reason_error_string(err: c_ulong) -> *const c_char;
+
     pub fn EVP_md5() -> *const EVP_MD;
     pub fn EVP_ripemd160() -> *const EVP_MD;
     pub fn EVP_sha1() -> *const EVP_MD;
@@ -345,6 +349,8 @@ extern "C" {
 
     pub fn SSL_library_init() -> c_int;
 
+    pub fn SSL_load_error_strings();
+
     #[cfg(feature = "sslv2")]
     pub fn SSLv2_method() -> *const SSL_METHOD;
     pub fn SSLv3_method() -> *const SSL_METHOD;

src/ssl/error.rs

@@ -1,5 +1,6 @@
 use libc::c_ulong;
 use std::io::IoError;
+use std::c_str::CString;
 
 use ffi;
 
@@ -20,24 +21,24 @@ pub enum OpensslError {
     /// An unknown error
     UnknownError {
         /// The library reporting the error
-        library: u8,
+        library: CString,
         /// The function reporting the error
-        function: u16,
+        function: CString,
         /// The reason for the error
-        reason: u16
+        reason: CString
     }
 }
 
-fn get_lib(err: c_ulong) -> u8 {
-    ((err >> 24) & 0xff) as u8
+fn get_lib(err: c_ulong) -> CString {
+    unsafe { CString::new(ffi::ERR_lib_error_string(err), false) }
 }
 
-fn get_func(err: c_ulong) -> u16 {
-    ((err >> 12) & 0xfff) as u16
+fn get_func(err: c_ulong) -> CString {
+    unsafe { CString::new(ffi::ERR_func_error_string(err), false) }
 }
 
-fn get_reason(err: c_ulong) -> u16 {
-    (err & 0xfff) as u16
+fn get_reason(err: c_ulong) -> CString {
+    unsafe { CString::new(ffi::ERR_reason_error_string(err), false) }
 }
 
 impl SslError {

src/ssl/mod.rs

@@ -24,6 +24,7 @@ fn init() {
     unsafe {
         INIT.doit(|| {
             ffi::SSL_library_init();
+            ffi::SSL_load_error_strings(); // maybe add err_load_crypto_strings?
             let verify_idx = ffi::SSL_CTX_get_ex_new_index(0, ptr::null(), None,
                                                            None, None);
             assert!(verify_idx >= 0);