From de0b74b1ab6c43ee5c2e4c19c07ae4e20730fbd5 Mon Sep 17 00:00:00 2001
From: Christopher Bohn <bohn@unl.edu>
Date: Wed, 17 Jun 2020 21:53:23 -0500
Subject: [PATCH] Made human entry & display of IP addresses using unsigned
values
---
assignment/.gitignore | 1 +
assignment/Makefile | 9 +++
.../socket_chat--patterns-and-testing.md | 2 +-
.../edu/unl/cse/csce361/socket_chat/Chat.java | 69 ++++++++++++++++---
4 files changed, 70 insertions(+), 11 deletions(-)
create mode 100644 assignment/.gitignore
create mode 100644 assignment/Makefile
diff --git a/assignment/.gitignore b/assignment/.gitignore
new file mode 100644
index 0000000..2d19fc7
--- /dev/null
+++ b/assignment/.gitignore
@@ -0,0 +1 @@
+*.html
diff --git a/assignment/Makefile b/assignment/Makefile
new file mode 100644
index 0000000..0df9cec
--- /dev/null
+++ b/assignment/Makefile
@@ -0,0 +1,9 @@
+ASSIGNMENTS = $(wildcard *.md)
+ASSIGNMENT_HTML = $(ASSIGNMENTS:%.md=%.html)
+
+all: $(ASSIGNMENT_HTML)
+
+%.html: %.md
+ pandoc -o $@ $<
+ sed "s/’/'/g" $@ | sed "s/‘/'/g" | sed 's/”/"/g' | sed 's/“/"/g' > temp
+ mv temp $@
diff --git a/assignment/socket_chat--patterns-and-testing.md b/assignment/socket_chat--patterns-and-testing.md
index fd6df5b..6c38999 100644
--- a/assignment/socket_chat--patterns-and-testing.md
+++ b/assignment/socket_chat--patterns-and-testing.md
@@ -127,7 +127,7 @@ feel for how the program works.
chatters
- When launching SocketChat, both chatters should select the option to be
the client
- - IP address: `-127.93.-91.26` <!--`129.93.165.26`-->, Port: `361NN`,
+ - IP address: <!--`-127.93.-91.26`--> `129.93.165.26`, Port: `361NN`,
where *NN* is your team number
- The two chatters alternate turns sending Strings to each other over the
socket
diff --git a/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java b/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java
index 478514a..95e3f6d 100644
--- a/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java
+++ b/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java
@@ -21,6 +21,15 @@ public class Chat {
socket = null;
}
+ /**
+ * Provides a test hook to test that the program terminates.
+ *
+ * @param exitCode the code passed to the shell indicating (ab)normal termination
+ */
+ protected void exit(int exitCode) {
+ System.exit(exitCode);
+ }
+
/**
* Overrides the system's default Locale.
*
@@ -90,9 +99,10 @@ public class Chat {
*/
private Socket connectAsServer(Scanner userInput) throws IOException {
byte[] address = InetAddress.getLocalHost().getAddress();
+ short[] humanReadableAddress = signedToUnsignedAddress(address);
// "Host address: ..."
System.out.println(MessageFormat.format(bundle.getString("connection.info.hostAddress.0.1.2.3"),
- address[0], address[1], address[2], address[3]));
+ humanReadableAddress[0], humanReadableAddress[1], humanReadableAddress[2], humanReadableAddress[3]));
int port;
ServerSocket serverSocket;
do {
@@ -119,9 +129,10 @@ public class Chat {
*/
private Socket connectAsClient(Scanner userInput) throws IOException {
byte[] address = getRemoteHostAddress(userInput);
+ short[] humanReadableAddress = signedToUnsignedAddress(address);
// "Enter port host is opening at ..."
String prompt = MessageFormat.format(bundle.getString("connection.prompt.getHostPort.0.1.2.3"),
- address[0], address[1], address[2], address[3]);
+ humanReadableAddress[0], humanReadableAddress[1], humanReadableAddress[2], humanReadableAddress[3]);
int port = getPort(prompt, userInput);
Socket socket = null;
int attemptCount = 0;
@@ -161,7 +172,7 @@ public class Chat {
private byte[] getRemoteHostAddress(Scanner userInput) {
// This assumes IPv4. Probably a good assumption.
boolean haveGoodAddress = false;
- byte[] address = new byte[4];
+ short[] address = new short[4];
while (!haveGoodAddress) {
// "Enter IP address of host <##.##.##.##>:"
System.out.print(bundle.getString("connection.prompt.getHostAddress") + " ");
@@ -170,7 +181,7 @@ public class Chat {
String[] tokens = addressString.split("\\.");
if (tokens.length == 4) {
for (int i = 0; i < 4; i++) {
- address[i] = Byte.parseByte(tokens[i]);
+ address[i] = Short.parseShort(tokens[i]);
}
haveGoodAddress = true;
} else {
@@ -179,9 +190,10 @@ public class Chat {
addressString));
haveGoodAddress = false;
}
- } catch (NumberFormatException nfException) {
+ } catch (NumberFormatException ignored) {
// "The IP address should be exactly as reported to the host user."
System.out.println(bundle.getString("connection.error.badNumberInAddress"));
+ /*
String message = nfException.getMessage();
// "Value out of range. Value"
if (message.startsWith(bundle.getString("exception.numberFormat.startOfValueOutOfRangeMessage"))) {
@@ -193,10 +205,11 @@ public class Chat {
"connection.error.userAttemptedUnsignedByte.0.1"), value, value - 256));
}
}
+ */
haveGoodAddress = false;
}
}
- return address;
+ return unsignedToSignedAddress(address);
}
/**
@@ -234,6 +247,46 @@ public class Chat {
return port;
}
+ /**
+ * Utility function necessary because Java does not have unsigned integer types. Converts from the signed bytes
+ * that Java uses for IP address fields and mimics unsigned values that humans are accustomed to.
+ *
+ * @param signedAddress IP address fields in the range -128..127
+ * @return IP address fields in the range 0..255
+ */
+ private short[] signedToUnsignedAddress(byte[] signedAddress) {
+ short offset = -2 * Byte.MIN_VALUE;
+ short[] unsignedAddress = new short[signedAddress.length];
+ for (int i = 0; i < signedAddress.length; i++) {
+ if (signedAddress[i] >= 0) {
+ unsignedAddress[i] = signedAddress[i];
+ } else {
+ unsignedAddress[i] = (short) (offset + signedAddress[i]);
+ }
+ }
+ return unsignedAddress;
+ }
+
+ /**
+ * Utility function necessary because Java does not have unsigned integer types. Converts from the unsigned values
+ * that humans are accustomed to and converts them to signed bytes that Java uses for IP address fields.
+ *
+ * @param unsignedAddress IP address fields in the range 0..255
+ * @return IP address fields in the range -128..127
+ */
+ private byte[] unsignedToSignedAddress(short[] unsignedAddress) {
+ short offset = -2 * Byte.MIN_VALUE;
+ byte[] signedAddress = new byte[unsignedAddress.length];
+ for (int i = 0; i < unsignedAddress.length; i++) {
+ if (unsignedAddress[i] <= Byte.MAX_VALUE) {
+ signedAddress[i] = (byte) unsignedAddress[i];
+ } else {
+ signedAddress[i] = (byte) (unsignedAddress[i] - offset);
+ }
+ }
+ return signedAddress;
+ }
+
/*
* THESE METHODS PERFORM CHAT AFTER CONNECTION IS SET UP
*/
@@ -363,10 +416,6 @@ public class Chat {
return true;
}
- protected void exit(int exitCode) {
- System.exit(exitCode);
- }
-
private String encipher(String plaintext) {
String ciphertext = plaintext; // Replace this with a call to cipherBehavior.encipher(plaintext)
return ciphertext;
--
GitLab