Handle truncated message authentication codes.

[tinc] / src / openssl / digest.c

diff --git a/src/openssl/digest.c b/src/openssl/digest.c
index 1e2557d..e1db934 100644 (file)
--- a/src/openssl/digest.c
+++ b/src/openssl/digest.c
@@ -26,26 +26,43 @@
 #include "digest.h"
 #include "logger.h"
 
-bool digest_open_by_name(digest_t *digest, const char *name) {
+static void set_maclength(digest_t *digest, int maclength) {
+       int digestlen = EVP_MD_size(digest->digest);
+
+       if(maclength > digestlen || maclength < 0)
+               digest->maclength = digestlen;
+       else
+               digest->maclength = maclength;
+}
+
+bool digest_open_by_name(digest_t *digest, const char *name, int maclength) {
        digest->digest = EVP_get_digestbyname(name);
-       if(digest->digest)
-               return true;
 
-       logger(LOG_DEBUG, _("Unknown digest name '%s'!"), name);
-       return false;
+       if(!digest->digest) {
+               logger(LOG_DEBUG, _("Unknown digest name '%s'!"), name);
+               return false;
+       }
+
+       set_maclength(digest, maclength);
+       return true;
 }
 
-bool digest_open_by_nid(digest_t *digest, int nid) {
+bool digest_open_by_nid(digest_t *digest, int nid, int maclength) {
        digest->digest = EVP_get_digestbynid(nid);
-       if(digest->digest)
-               return true;
 
-       logger(LOG_DEBUG, _("Unknown digest nid %d!"), nid);
-       return false;
+       if(!digest->digest) {
+               logger(LOG_DEBUG, _("Unknown digest nid %d!"), nid);
+               return false;
+       }
+
+       set_maclength(digest, maclength);
+       return true;
 }
 
-bool digest_open_sha1(digest_t *digest) {
+bool digest_open_sha1(digest_t *digest, int maclength) {
        digest->digest = EVP_sha1();
+
+       set_maclength(digest, maclength);
        return true;
 }
 
@@ -53,22 +70,27 @@ void digest_close(digest_t *digest) {
 }
 
 bool digest_create(digest_t *digest, const void *indata, size_t inlen, void *outdata) {
+       size_t len = EVP_MD_size(digest->digest);
+       unsigned char tmpdata[len];
+
        EVP_MD_CTX ctx;
 
-       if(EVP_DigestInit(&ctx, digest->digest)
-                       && EVP_DigestUpdate(&ctx, indata, inlen)
-                       && EVP_DigestFinal(&ctx, outdata, NULL))
-               return true;
-       
-       logger(LOG_DEBUG, _("Error creating digest: %s"), ERR_error_string(ERR_get_error(), NULL));
-       return false;
+       if(!EVP_DigestInit(&ctx, digest->digest)
+                       || !EVP_DigestUpdate(&ctx, indata, inlen)
+                       || !EVP_DigestFinal(&ctx, tmpdata, NULL)) {
+               logger(LOG_DEBUG, _("Error creating digest: %s"), ERR_error_string(ERR_get_error(), NULL));
+               return false;
+       }
+
+       memcpy(outdata, tmpdata, digest->maclength);
+       return true;
 }
 
 bool digest_verify(digest_t *digest, const void *indata, size_t inlen, const void *cmpdata) {
        size_t len = EVP_MD_size(digest->digest);
-       char outdata[len];
+       unsigned char outdata[len];
 
-       return digest_create(digest, indata, inlen, outdata) && !memcmp(cmpdata, outdata, len);
+       return digest_create(digest, indata, inlen, outdata) && !memcmp(cmpdata, outdata, digest->maclength);
 }
 
 int digest_get_nid(const digest_t *digest) {
@@ -76,7 +98,7 @@ int digest_get_nid(const digest_t *digest) {
 }
 
 size_t digest_length(const digest_t *digest) {
-       return EVP_MD_size(digest->digest);
+       return digest->maclength;
 }
 
 bool digest_active(const digest_t *digest) {