421e64ceeb
Take almost all warnings into use except `format-overflow` and `unused-function`. format-overflow needs to be handled in a separate commit.
60 lines
1.3 KiB
C++
60 lines
1.3 KiB
C++
/*
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* Find local ip used as source ip in ip packets.
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* Use getsockname and a udp connection
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*/
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#include<stdio.h> //printf
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#include<string.h> //memset
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#include<errno.h> //errno
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#include<sys/socket.h> //socket
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#include<netinet/in.h> //sockaddr_in
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#include<arpa/inet.h> //getsockname
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#include<unistd.h> //close
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#include "get_my_ip.h"
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int get_my_ip(char * remote_ip, char * my_ip )
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{
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int dns_port = 53;
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struct sockaddr_in serv;
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int sock = socket ( AF_INET, SOCK_DGRAM, 0);
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//Socket could not be created
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if (sock < 0)
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{
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return 1;
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}
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memset( &serv, 0, sizeof(serv) );
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serv.sin_family = AF_INET;
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serv.sin_addr.s_addr = inet_addr( remote_ip );
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serv.sin_port = htons( dns_port );
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connect( sock , (const struct sockaddr*) &serv , sizeof(serv) );
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struct sockaddr_in name;
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socklen_t namelen = sizeof(name);
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getsockname(sock, (struct sockaddr*) &name, &namelen);
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char buffer[100];
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const char* p = inet_ntop(AF_INET, &name.sin_addr, buffer, 100);
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if (p != NULL)
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{
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//printf("Local ip is : %s \n" , buffer);
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strcpy(my_ip, buffer);
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close(sock);
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return 0;
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}
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else
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{
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//Some error
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printf ("Error number : %d . Error message : %s \n" , errno , strerror(errno));
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close(sock);
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return 2;
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}
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}
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