Merge remote-tracking branch 'origin/pr/2539' into development

Resolve conflicts by performing the following:
  - Ensure calls to mbedtls_x509_crt_verify_* are made with callbacks

* origin/pr/2539:
  Make CRT callback tests more robust
  Rename constant in client2.c
  Fix typo
  Add test for configuration specific CRT callback
  Fix doxygen documentation of mbedtls_ssl_set_verify()
  Add test exercising context-specific CRT callback to ssl-opt.sh
  Add cmd to use context-specific CRT callback in ssl_client2
  Implement context-specific verification callbacks
  Add context-specific CRT verification callbacks
  Improve documentation of mbedtls_ssl_conf_verify()

tests/ssl-opt.sh

@@ -1031,6 +1031,27 @@ run_test    "Unique IV in GCM" \
             -u "IV used" \
             -U "IV used"
 
+# Tests for certificate verification callback
+run_test    "Configuration-specific CRT verification callback" \
+            "$P_SRV debug_level=3" \
+            "$P_CLI context_crt_cb=0 debug_level=3" \
+            0 \
+            -S "error" \
+            -c "Verify requested for " \
+            -c "Use configuration-specific verification callback" \
+            -C "Use context-specific verification callback" \
+            -C "error"
+
+run_test    "Context-specific CRT verification callback" \
+            "$P_SRV debug_level=3" \
+            "$P_CLI context_crt_cb=1 debug_level=3" \
+            0 \
+            -S "error" \
+            -c "Verify requested for " \
+            -c "Use context-specific verification callback" \
+            -C "Use configuration-specific verification callback" \
+            -C "error"
+
 # Tests for rc4 option
 
 requires_config_enabled MBEDTLS_REMOVE_ARC4_CIPHERSUITES