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ivan47
n00b
Joined: 27 Jan 2008
Posts: 7
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 Posted: Thu Feb 21, 2008 10:28 pm Post subject: unable to listen for udp packets at specific ip [SOLVED] |
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Hi all, I'm trying to run a UDP-listener, but also want to set my IP, rather than have it automatically filled. I'm getting the following error when I try to set the IP manually - "bind: cannot assign requested address". This depends on setting the s_addr struct. I've commented out a couple of the other things I've tried.
| Code: |
int sockfd;
struct sockaddr_in my_addr; //my address info
struct sockaddr_in their_addr; // connector's address information
socklen_t addr_len;
int numbytes;
char buf[MAXBUFLEN];
// create a socket
if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
perror("socket");
exit(1);
}
my_addr.sin_family = AF_INET; // host byte order
my_addr.sin_port = htons(MYPORT); // short, network byte order
/******************** PROBLEM CODE ***********************/
my_addr.sin_addr.s_addr = inet_addr("192.168.0.125");
//OTHER THINGS I'VE TRIED:
// inet_pton(AF_INET,"192.168.0.125",&my_addr.sin_addr.s_addr);
// though the following doesn't error, it doesn't accomplish what i want since
//i want to set the listener to listen for packets sent to 192.168.0.125
// my_addr.sin_addr.s_addr=INADDR_ANY;
/********************END PROBLEM CODE ***********************/
printf("hex s_addr = %x\n",my_addr.sin_addr.s_addr);
memset(my_addr.sin_zero, '\0', sizeof my_addr.sin_zero);
// bind the socket to the port
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof my_addr) == -1) {
perror("bind");
exit(1);
}
addr_len = sizeof their_addr;
if ((numbytes = recvfrom(sockfd, &buf, MAXBUFLEN-1 , 0,
(struct sockaddr *)&their_addr, &addr_len)) == -1) {
perror("recvfrom");
exit(1);
}
buf[numbytes] = '\0';
close(sockfd);
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Help would be much appreciated.
_________________
--ivan
Last edited by ivan47 on Fri Feb 22, 2008 11:54 pm; edited 1 time in total |
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UberLord
Retired Dev
Joined: 18 Sep 2003
Posts: 6835
Location: Blighty
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ivan47
n00b
Joined: 27 Jan 2008
Posts: 7
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| Posted: Fri Feb 22, 2008 9:12 pm Post subject: |
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thanks, but it didn't work either. i tried the inet_aton with setting SO_REUSEADDR. any other ideas?
i should be able to set it to whatever ip i want, right? it shouldn't fail to bind the socket if i do something like:
| Code: |
inet_aton("111.111.111.111",&my_addr.sin_addr)
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That's not what I did, I did 192.168.0.130, but still, even with a garbage address it shouldn't break, right?
_________________
--ivan |
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ivan47
n00b
Joined: 27 Jan 2008
Posts: 7
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| Posted: Fri Feb 22, 2008 11:54 pm Post subject: |
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So, as it turns out, i have no idea what i'm doing. I guess your network card needs to be set to the IP address you're trying to listen at...who woulda guessed.
| Code: |
ifconfig(IPADDRESS)
then inet_aton(IPADDRESS,&my_addr.sin_addr) |
now it works...
_________________
--ivan |
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