fix: Set correct index for limit in book_offers CLI (#6043)

This change fixes an indexing typo in the `book_offers` CLI processing, and does not affect the HTTPS/WS RPC processing.

Author: mvadari

src/test/rpc/RPCCall_test.cpp

@@ -1584,8 +1584,6 @@ static RPCCallTestData const rpcCallTestArray[] = {
          "EUR/rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
          "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
          "ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789",
-         "junk",  // Note: indexing bug in parseBookOffers() requires junk
-                  // param.
          "200",
      },
      RPCCallTestData::no_exception,
@@ -1597,7 +1595,6 @@ static RPCCallTestData const rpcCallTestArray[] = {
          "issuer" : "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
          "ledger_hash" : "ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789",
          "limit" : 200,
-         "proof" : true,
          "taker_gets" : {
             "currency" : "EUR",
             "issuer" : "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA"
@@ -1617,8 +1614,8 @@ static RPCCallTestData const rpcCallTestArray[] = {
       "EUR/rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
       "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
       "ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789",
-      "junk",  // Note: indexing bug in parseBookOffers() requires junk param.
       "200",
+      "0",
       "MyMarker"},
      RPCCallTestData::no_exception,
      R"({
@@ -1630,7 +1627,6 @@ static RPCCallTestData const rpcCallTestArray[] = {
          "ledger_hash" : "ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789",
          "limit" : 200,
          "marker" : "MyMarker",
-         "proof" : true,
          "taker_gets" : {
             "currency" : "EUR",
             "issuer" : "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA"
@@ -1665,8 +1661,8 @@ static RPCCallTestData const rpcCallTestArray[] = {
       "EUR/rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
       "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
       "ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789",
-      "junk",  // Note: indexing bug in parseBookOffers() requires junk param.
       "200",
+      "0",
       "MyMarker",
       "extra"},
      RPCCallTestData::no_exception,
@@ -1770,12 +1766,19 @@ static RPCCallTestData const rpcCallTestArray[] = {
          "EUR/rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
          "rnUy2SHTrB9DubsPmkJZUXTf5FcNDGrYEA",
          "ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789",
-         "junk",  // Note: indexing bug in parseBookOffers() requires junk
-                  // param.
          "not_a_number",
      },
-     RPCCallTestData::bad_cast,
-     R"()"},
+     RPCCallTestData::no_exception,
+     R"({
+    "method" : "book_offers",
+    "params" : [
+      {
+         "error" : "invalidParams",
+         "error_code" : 31,
+         "error_message" : "Invalid field 'limit'."
+      }
+    ]
+    })"},
 
     // can_delete
     // ------------------------------------------------------------------

src/xrpld/rpc/detail/RPCCall.cpp

@@ -332,15 +332,31 @@ class RPCParser
 
         if (jvParams.size() >= 5)
         {
-            int iLimit = jvParams[5u].asInt();
+            try
+            {
+                int iLimit = jvParams[4u].asInt();
 
-            if (iLimit > 0)
-                jvRequest[jss::limit] = iLimit;
+                if (iLimit > 0)
+                    jvRequest[jss::limit] = iLimit;
+            }
+            catch (std::exception const&)
+            {
+                return RPC::invalid_field_error(jss::limit);
+            }
         }
 
-        if (jvParams.size() >= 6 && jvParams[5u].asInt())
+        if (jvParams.size() >= 6)
         {
-            jvRequest[jss::proof] = true;
+            try
+            {
+                int bProof = jvParams[5u].asInt();
+                if (bProof)
+                    jvRequest[jss::proof] = true;
+            }
+            catch (std::exception const&)
+            {
+                return RPC::invalid_field_error(jss::proof);
+            }
         }
 
         if (jvParams.size() == 7)