Add a -sigalgs option to bssl client.

Change-Id: I6247e02c6a9a9cc6ff5005eafe96f89f864cb12c
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/39846
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

tool/client.cc

@@ -47,6 +47,11 @@ static const struct argument kArguments[] = {
         "-curves", kOptionalArgument,
         "An OpenSSL-style ECDH curves list that configures the offered curves",
     },
+    {
+        "-sigalgs", kOptionalArgument,
+        "An OpenSSL-style signature algorithms list that configures the "
+        "signature algorithm preferences",
+    },
     {
         "-max-version", kOptionalArgument,
         "The maximum acceptable protocol version",
@@ -380,6 +385,12 @@ bool Client(const std::vector<std::string> &args) {
     return false;
   }
 
+  if (args_map.count("-sigalgs") != 0 &&
+      !SSL_CTX_set1_sigalgs_list(ctx.get(), args_map["-sigalgs"].c_str())) {
+    fprintf(stderr, "Failed setting signature algorithms list\n");
+    return false;
+  }
+
   uint16_t max_version = TLS1_3_VERSION;
   if (args_map.count("-max-version") != 0 &&
       !VersionFromString(&max_version, args_map["-max-version"])) {