87 lines
1.8 KiB
C
87 lines
1.8 KiB
C
#define _GNU_SOURCE
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#include <sys/socket.h>
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#include <dlfcn.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <netinet/in.h>
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int
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connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
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{
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unsigned short port;
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static int (*next_connect)(int, const struct sockaddr *, socklen_t);
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if (next_connect == NULL) {
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next_connect = dlsym(RTLD_NEXT, "connect");
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if (next_connect == NULL) {
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errno = ENOSYS;
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return -1;
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}
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}
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if (getenv("NOPORT53") == NULL) {
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return next_connect(sockfd, addr, addrlen);
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}
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switch (addr->sa_family) {
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case AF_INET:
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port = ntohs(((struct sockaddr_in *)addr)->sin_port);
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if (port == 53) {
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errno = ECONNREFUSED;
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return -1;
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}
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break;
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case AF_INET6:
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port = ntohs(((struct sockaddr_in6 *)addr)->sin6_port);
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if (port == 53) {
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errno = ECONNREFUSED;
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return -1;
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}
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break;
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default:
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break;
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}
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return next_connect(sockfd, addr, addrlen);
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}
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ssize_t
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sendto(int sockfd, const void *buf, size_t len, int flags,
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const struct sockaddr *dest_addr, socklen_t addrlen)
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{
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unsigned short port;
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static int (*next_sendto)(int, const void *, size_t, int,
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const struct sockaddr *, socklen_t);
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if (next_sendto == NULL) {
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next_sendto = dlsym(RTLD_NEXT, "sendto");
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if (next_sendto == NULL) {
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errno = ENOSYS;
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return -1;
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}
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}
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if (getenv("NOPORT53") == NULL) {
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return next_sendto(sockfd, buf, len, flags, dest_addr, addrlen);
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}
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switch (dest_addr->sa_family) {
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case AF_INET:
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port = ntohs(((struct sockaddr_in *)dest_addr)->sin_port);
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if (port == 53) {
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errno = ECONNREFUSED;
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return -1;
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}
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break;
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case AF_INET6:
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port = ntohs(((struct sockaddr_in6 *)dest_addr)->sin6_port);
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if (port == 53) {
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errno = ECONNREFUSED;
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return -1;
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}
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break;
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default:
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break;
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}
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return next_sendto(sockfd, buf, len, flags, dest_addr, addrlen);
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}
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