Peter,

Remove the semicolon at the end of the below if condition. By the
semicolon, you are mandating the printf and exit statement. Otherwise
it is perfect.

if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0);

Rgds,
Nabeel

Peter wrote:
> Hi all,
>
> I am new to network programming and am trying to work my way through
> this book, admittedly i haven't gotten very far.
>
> The book uses it's own header file (unp.h) to include lots of the
> usual headers and set various constants necessary in many networking
> programs.
>
> I thought I would try to write the same programs without using the
> author's header file to make sure i understood what was going on.
>
> I am trying to connect my daytimeclient to the books intro/
> daytimetcpsrv.c
>
> Unfortunately I get a socket error when trying to connect but no
> problems when compiling.
>
> Here is my daytimeclient:
>
> #include /* error handling stuff */
> #include /* stdout, fputs */
> #include /* exit */
> #include /* bzero */
> #include /* read */
> #include /* sockaddr_in{}, htons and other Internet
> defns */
> #include /* sockaddr_in, socket, connect, read */
> #include /* inet_pton */
>
> #define MAXLINE 4096 /* max text line length */
>
> int
> main(int argc, char **argv)
> {
> int err; // for errors
> int sockfd, n;
> char recvline[MAXLINE + 1];
> struct sockaddr_in servaddr;
>
> if (argc != 2)
> {
> printf("Usage: %s \n", argv[0]);
> exit(1);
> }
>
> // create a socket
> if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0);
> {
> printf("Socket creation error!\n");
> exit(1);
> }
>
> bzero(&servaddr, sizeof(servaddr));
> servaddr.sin_family = AF_INET;
> servaddr.sin_port = htons(13); /* daytime server */
>
> // convert ascii command line arg into proper format
> if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0);
> {
> printf("inet_pton error for %s", argv[1]);
> exit(1);
> }
>
> if (connect(sockfd, (struct sockaddr *) &servaddr,
> sizeof(servaddr)) < 0)
> {
> printf("connect error\n");
> exit(1);
> }
>
> while ( (n = read(sockfd, recvline, MAXLINE)) > 0)
> {
> recvline[n] = 0; /* null terminate */
> if (fputs(recvline, stdout) == EOF)
> {
> printf("fputs error\n");
> exit(1);
> }
> }
> if (n < 0)
> {
> printf("read error\n");
> exit(1);
> }
> exit(0);
> }
>
>
> I compile the above code using:
>
> $ g++ Mydaytimetcpcli.c
>
> I fire up the daytimetcpsrv in a terminal and then try connecting with
> my daytimeclient as per:
>
> $ ./a.out 127.0.0.1
>
> Output:
> Socket creation error!
>
> Can someone tell me what I might be doing wrong?
>
> Am I including the wrong headers? Is there some flag I should be
> using with the compiler? I am lost.
>
> I am doing this on:
> $ uname -a
> Linux unko 2.6.15-29-386 #1 PREEMPT Mon Sep 24 17:18:25 UTC 2007 i686
> GNU/Linux
> (Ubuntu - Dapper Drake)
>
> Many thanks,
>
> Peter.

On Nov 3, 7:14 pm, Nabeel wrote:
> Peter,
>
> Remove the semicolon at the end of the below if condition. By the
> semicolon, you are mandating the printf and exit statement. Otherwise
> it is perfect.
>
> if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0);

Nabeel,

Thank you so much. Turns out I had another one at:

if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)

Must be addicted to them.

Thanks again,

Peter.