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#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <stdint.h> | |
#include <unistd.h> | |
#include <sys/types.h> | |
#include <sys/socket.h> | |
#include <arpa/inet.h> | |
#include <netinet/in.h> | |
#include <netdb.h> | |
#include <errno.h> | |
#include <unistd.h> | |
#include <fcntl.h> | |
#include <netinet/tcp.h> | |
#include <arpa/inet.h> | |
#include <stdbool.h> | |
int main() | |
{ | |
struct addrinfo hints; | |
memset(&hints, 0, sizeof(hints)); | |
hints.ai_family = AF_UNSPEC; | |
hints.ai_socktype = SOCK_DGRAM; | |
hints.ai_flags = AI_NUMERICHOST; | |
struct addrinfo * addr_1111 = NULL; | |
getaddrinfo("1.1.1.1", "53", &hints, &addr_1111); | |
struct addrinfo * addr_8888 = NULL; | |
getaddrinfo("8.8.8.8", "53", &hints, &addr_8888); | |
int fd_1111 = socket(addr_1111->ai_family, addr_1111->ai_socktype, addr_1111->ai_protocol); | |
int fd_8888 = socket(addr_8888->ai_family, addr_8888->ai_socktype, addr_8888->ai_protocol); | |
connect(fd_8888, addr_8888->ai_addr, addr_8888->ai_addrlen); | |
while (true) | |
{ | |
static const uint8_t dns_google[] = { | |
0x12,0x34, 1,0, 0,1, 0,0, 0,0, 0,0, 6,'g','o','o','g','l','e',3,'c','o','m',0, 0,1, 0,1 | |
}; | |
static const uint8_t dns_cloudflare[] = { | |
0x12,0x34, 1,0, 0,1, 0,0, 0,0, 0,0, 10,'c','l','o','u','d','f','l','a','r','e',3,'c','o','m',0, 0,1, 0,1 | |
}; | |
sendto(fd_1111, dns_cloudflare, sizeof(dns_cloudflare), MSG_NOSIGNAL, addr_1111->ai_addr, addr_1111->ai_addrlen); | |
sendto(fd_8888, dns_google, sizeof(dns_google), MSG_NOSIGNAL, addr_8888->ai_addr, addr_8888->ai_addrlen); | |
usleep(1000000); | |
for (int nsock=0;nsock<2;nsock++) | |
{ | |
while (true) | |
{ | |
char buf[1024]; | |
int ret = recvfrom(nsock ? fd_1111 : fd_8888, buf, sizeof(buf), MSG_DONTWAIT, NULL, NULL); | |
if (ret < 0) break; | |
for (int i=0;i<ret;i++) | |
printf("%.2x ", buf[i]&0xff); | |
puts(""); | |
} | |
} | |
} | |
} | |
/* | |
#define PORT 8080 | |
#define MAXLINE 1024 | |
// Driver code | |
int main() { | |
int sockfd; | |
char buffer[MAXLINE]; | |
char *hello = "Hello from client"; | |
struct sockaddr_in servaddr; | |
// Creating socket file descriptor | |
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) { | |
perror("socket creation failed"); | |
exit(EXIT_FAILURE); | |
} | |
memset(&servaddr, 0, sizeof(servaddr)); | |
// Filling server information | |
servaddr.sin_family = AF_INET; | |
servaddr.sin_port = htons(PORT); | |
servaddr.sin_addr.s_addr = INADDR_ANY; | |
int n, len; | |
sendto(sockfd, (const char *)hello, strlen(hello), | |
MSG_CONFIRM, (const struct sockaddr *) &servaddr, | |
sizeof(servaddr)); | |
printf("Hello message sent.\n"); | |
n = recvfrom(sockfd, (char *)buffer, MAXLINE, | |
MSG_WAITALL, (struct sockaddr *) &servaddr, | |
&len); | |
buffer[n] = '\0'; | |
printf("Server : %s\n", buffer); | |
close(sockfd); | |
return 0; | |
} | |
*/ |
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