Created
August 11, 2021 11:59
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#include <sys/types.h> | |
#include <sys/socket.h> | |
#include <netdb.h> | |
#include <sys/socket.h> | |
#include <netinet/in.h> | |
#include <arpa/inet.h> | |
#include <stdio.h> | |
#include <string.h> | |
#define __USE_GNU | |
#include <dlfcn.h> | |
/* | |
gcc -c -Wall -Wpedantic getaddrinfo.c -o getaddrinfo.o && gcc -ldl -fPIC getaddrinfo.c -shared -o getaddrinfo.so | |
*/ | |
static void get_ip_str(const struct sockaddr *sa, char *s, size_t maxlen) | |
{ | |
switch(sa->sa_family) { | |
case AF_INET: | |
inet_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr), s, maxlen); | |
break; | |
case AF_INET6: | |
inet_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr), s, maxlen); | |
break; | |
} | |
} | |
int (*real_getaddrinfo)(const char*, const char*, const struct addrinfo*, struct addrinfo**); | |
extern int getaddrinfo(const char *node, const char *service, | |
const struct addrinfo *hints, | |
struct addrinfo **res) | |
{ | |
*(void **)(&real_getaddrinfo) = dlsym(RTLD_NEXT, "getaddrinfo"); | |
int ret = real_getaddrinfo(node, service, hints, res); | |
char* res_or_err = NULL; | |
if (ret == 0) { | |
char ip_str[INET6_ADDRSTRLEN] = "\0"; | |
get_ip_str((*res)->ai_addr, ip_str, sizeof(ip_str)); | |
res_or_err = ip_str; | |
} else { | |
res_or_err = strerror(ret); | |
} | |
fprintf(stdout, "$$$ getaddrinfo(\"%s\", \"%s\"): %d -> %s\n", node, service, ret, res_or_err); | |
return ret; | |
} |
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