Builtin macros for sha3-hash and ed25519-signing support

[exim.git] / src / src / dkim.c

diff --git a/src/src/dkim.c b/src/src/dkim.c
index 746a7a6b757612536b0f55aae3d219539480e434..c7bf641527822a7fecc97fe383ca7c548a5ea2f1 100644 (file)
--- a/src/src/dkim.c
+++ b/src/src/dkim.c
@@ -36,19 +36,19 @@ static const uschar * dkim_collect_error = NULL;
 
 
 /*XXX the caller only uses the first record if we return multiple.
-Could we hand back an allocated string?
 */
 
-static int
-dkim_exim_query_dns_txt(char *name, char *answer)
+static uschar *
+dkim_exim_query_dns_txt(char * name)
 {
 dns_answer dnsa;
 dns_scan dnss;
 dns_record *rr;
+gstring * g = NULL;
 
 lookup_dnssec_authenticated = NULL;
 if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED)
-  return PDKIM_FAIL;   /*XXX better error detail?  logging? */
+  return NULL; /*XXX better error detail?  logging? */
 
 /* Search for TXT record */
 
@@ -58,28 +58,33 @@ for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
   if (rr->type == T_TXT)
     {
     int rr_offset = 0;
-    int answer_offset = 0;
 
     /* Copy record content to the answer buffer */
 
     while (rr_offset < rr->size)
       {
       uschar len = rr->data[rr_offset++];
-      snprintf(answer + answer_offset,
-               PDKIM_DNS_TXT_MAX_RECLEN - answer_offset,
-               "%.*s", (int)len, CS  (rr->data + rr_offset));
+
+      g = string_catn(g, US(rr->data + rr_offset), len);
+      if (g->ptr >= PDKIM_DNS_TXT_MAX_RECLEN)
+       goto bad;
+
       rr_offset += len;
-      answer_offset += len;
-      if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN)
-       return PDKIM_FAIL;      /*XXX better error detail?  logging? */
       }
 
     /* check if this looks like a DKIM record */
-    if (strncasecmp(answer, "v=dkim", 6) != 0) continue;
-    return PDKIM_OK;
+    if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0)
+      {
+      store_reset(g->s + g->ptr + 1);
+      return string_from_gstring(g);
+      }
+
+    if (g) g->ptr = 0;         /* overwrite previous record */
     }
 
-return PDKIM_FAIL;     /*XXX better error detail?  logging? */
+bad:
+if (g) store_reset(g);
+return NULL;   /*XXX better error detail?  logging? */
 }
 
 
@@ -263,7 +268,7 @@ dkim_exim_verify_finish(void)
 pdkim_signature * sig;
 int rc;
 gstring * g = NULL;
-const uschar * errstr;
+const uschar * errstr = NULL;
 
 store_pool = POOL_PERM;
 
@@ -286,12 +291,8 @@ dkim_collect_input = FALSE;
 /* Finish DKIM operation and fetch link to signatures chain */
 
 rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr);
-if (rc != PDKIM_OK)
-  {
-  log_write(0, LOG_MAIN, "DKIM: validation error: %.100s%s%s", pdkim_errstr(rc),
-           errstr ? ": " : "", errstr ? errstr : US"");
-  goto out;
-  }
+if (rc != PDKIM_OK && errstr)
+  log_write(0, LOG_MAIN, "DKIM: validation error: %s", errstr);
 
 /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
 
@@ -540,8 +541,12 @@ switch (what)
 }
 
 
-/* Generate signatures for the given file, returning a string.
+/* Generate signatures for the given file.
 If a prefix is given, prepend it to the file for the calculations.
+
+Return:
+  NULL:                error; error string written
+  string:      signature header(s), or a zero-length string (not an error)
 */
 
 gstring *
@@ -701,6 +706,9 @@ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0)))
                        pdkim_canon,
                        pdkim_canon, -1, 0, 0);
 
+    if (!pdkim_set_bodyhash(&ctx, sig))
+      goto bad;
+
     if (!ctx.sig)              /* link sig to context chain */
       ctx.sig = sig;
     else
@@ -711,9 +719,15 @@ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0)))
       }
     }
   }
+if (!ctx.sig)
+  {
+  DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n");
+  sigbuf = string_get(1);      /* return a zero-len string */
+  goto CLEANUP;
+  }
 
-if (prefix)
-  pdkim_feed(&ctx, prefix, Ustrlen(prefix));
+if (prefix && (pdkim_rc = pdkim_feed(&ctx, prefix, Ustrlen(prefix))) != PDKIM_OK)
+  goto pk_bad;
 
 if (lseek(fd, off, SEEK_SET) < 0)
   sread = -1;
@@ -738,9 +752,8 @@ if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK)
 for (sigbuf = NULL; sig; sig = sig->next)
   sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n");
 
-(void) string_from_gstring(sigbuf);
-
 CLEANUP:
+  (void) string_from_gstring(sigbuf);
   store_pool = old_pool;
   errno = save_errno;
   return sigbuf;