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POConverting uint32_t to network byte order
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  1. POConverting uint32_t to network byte order
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    copied!<p>i'm doing stuff for my studies, so yeah, it's <em>homework</em>.</p> <p>First: I got a working Java Server Application, i also had this client application i'm writing in c now working in java. Simple as is, i fail at sending the uint32_t to my java server.</p> <p>So let's show off some code:</p> <pre><code>char* callString(char func, char* str, uint32_t anz) { uint32_t packageLength, funcLength, strLength; funcLength = htonl(sizeof(func)); strLength = htonl(strlen(str)); uint32_t byte = htonl(4); uint32_t trailing = htonl(1); anz = htonl(anz); packageLength = byte + byte + funcLength + byte + strLength + byte + byte + trailing; /*packageLength = htonl(packageLength);*/ char byteBuffer[ntohl(packageLength)]; printf("%i\n", packageLength); printf("%i\n", htonl(packageLength)); printf("%i\n", ntohl(packageLength)); sprintf(byteBuffer, "%i%i%c%i%s%i%i%c", packageLength, byte, func, byte, str, byte, anz, '\0'); printf("%s\n", byteBuffer); if(write(sock, byteBuffer, packageLength) &lt; 0) { printf("write: Konnte keine Daten zum gegenüber senden.\n"); exit(EXIT_FAILURE); } char* retVal = "hallo"; return retVal; } </code></pre> <p>Simple as is, i call this function with func = 'v', str = "hallo" and anz = 2 which will give me a packageLength of 27 bytes.</p> <p>Package is build like this:<br /> = packageLength (int) which is 4 byte<br /> + length of function descriptor (funcLength) which is 4 byte<br /> + func descriptor (func) which is funcLength<br /> + length of param1 (strLength) which is 4 byte<br /> + length of value of param1 (str) which is strLength<br /> + length of param2 which is 4 byte<br /> + length of value of param2 (anz) which is 4 byte<br /> + NULL Byte (\0) which is 1 byte<br /></p> <p>I assume the conversion i do is wrong maybe i'm using the wrong datatype. On server-side i use the Java ByteBuffer to collect the data. At first i read the 4 byte packagelength from the network which will give me the information of how long i have to read until i get the whole data package:</p> <pre><code>byte[] msgLength = new byte[4]; try { handle.getInputStream().read(msgLength); } catch (IOException ex) { System.out.println("could not receive byte stream: msgLength"); break; } ByteBuffer receive; receive = ByteBuffer.wrap(msgLength); int packageLength = receive.getInt(); System.out.println("packageLength" + packageLength); </code></pre> <p>The last println will give me the following output:</p> <blockquote> <p>packageLength875901497</p> </blockquote> <p>So does anyone now where my problem is? I can provide you with more code if necessary but i think the error is either the datatype (uint32_t) or the conversion.</p> <p>Help is appriciated. Thanks in advance.</p> <p>Cheers Daniel</p>
 

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