Change SRP functions to use EVP_EncodeUpdate/EVP_DecodeUpdate functions

Previously they were using EVP_EncodeBlock/EVP_DecodeBlock. These are low
level functions that do not handle padding characters. This was causing
the SRP code to fail. One side effect of using EVP_EncodeUpdate is that
it inserts newlines which is not what we need in SRP so we add a flag to
avoid that.

Reviewed-by: Andy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5925)

2 files changed, 22 insertions, 8 deletions

diff --git a/crypto/evp/encode.c b/crypto/evp/encode.c
index 17198ff6be..a43755ab17 100644
--- a/crypto/evp/encode.c
+++ b/crypto/evp/encode.c
@@ -12,6 +12,7 @@
 #include "internal/cryptlib.h"
 #include <openssl/evp.h>
 #include "evp_locl.h"
+#include "internal/evp_int.h"
 
 static unsigned char conv_ascii2bin(unsigned char a);
 #ifndef CHARSET_EBCDIC
@@ -115,11 +116,17 @@ int EVP_ENCODE_CTX_num(EVP_ENCODE_CTX *ctx)
     return ctx->num;
 }
 
+void evp_encode_ctx_set_flags(EVP_ENCODE_CTX *ctx, unsigned int flags)
+{
+    ctx->flags = flags;
+}
+
 void EVP_EncodeInit(EVP_ENCODE_CTX *ctx)
 {
     ctx->length = 48;
     ctx->num = 0;
     ctx->line_num = 0;
+    ctx->flags = 0;
 }
 
 int EVP_EncodeUpdate(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl,
@@ -145,18 +152,24 @@ int EVP_EncodeUpdate(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl,
         j = EVP_EncodeBlock(out, ctx->enc_data, ctx->length);
         ctx->num = 0;
         out += j;
-        *(out++) = '\n';
+        total = j;
+        if ((ctx->flags & EVP_ENCODE_CTX_NO_NEWLINES) == 0) {
+            *(out++) = '\n';
+            total++;
+        }
         *out = '\0';
-        total = j + 1;
     }
     while (inl >= ctx->length && total <= INT_MAX) {
         j = EVP_EncodeBlock(out, in, ctx->length);
         in += ctx->length;
         inl -= ctx->length;
         out += j;
-        *(out++) = '\n';
+        total += j;
+        if ((ctx->flags & EVP_ENCODE_CTX_NO_NEWLINES) == 0) {
+            *(out++) = '\n';
+            total++;
+        }
         *out = '\0';
-        total += j + 1;
     }
     if (total > INT_MAX) {
         /* Too much output data! */
@@ -177,7 +190,8 @@ void EVP_EncodeFinal(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl)
 
     if (ctx->num != 0) {
         ret = EVP_EncodeBlock(out, ctx->enc_data, ctx->num);
-        out[ret++] = '\n';
+        if ((ctx->flags & EVP_ENCODE_CTX_NO_NEWLINES) == 0)
+            out[ret++] = '\n';
         out[ret] = '\0';
         ctx->num = 0;
     }
@@ -217,11 +231,11 @@ int EVP_EncodeBlock(unsigned char *t, const unsigned char *f, int dlen)
 
 void EVP_DecodeInit(EVP_ENCODE_CTX *ctx)
 {
-    /* Only ctx->num is used during decoding. */
+    /* Only ctx->num and ctx->flags are used during decoding. */
     ctx->num = 0;
     ctx->length = 0;
     ctx->line_num = 0;
-    ctx->expect_nl = 0;
+    ctx->flags = 0;
 }
 
 /*-
diff --git a/crypto/evp/evp_locl.h b/crypto/evp/evp_locl.h
index 209577b7c2..d5dbbeb0da 100644
--- a/crypto/evp/evp_locl.h
+++ b/crypto/evp/evp_locl.h
@@ -59,7 +59,7 @@ struct evp_Encode_Ctx_st {
     unsigned char enc_data[80];
     /* number read on current line */
     int line_num;
-    int expect_nl;
+    unsigned int flags;
 };
 
 typedef struct evp_pbe_st EVP_PBE_CTL;