看來IPv4與IPv6在Socket軟體的寫作上有些不太一樣的地方。
1. gethostbyname(argv[1]);是在IPv4上使用。
gethostbyname2(argv[1], AF_INET6);是在IPv6上使用。
2. struct sockaddr_in server; 是在IPv4上使用的結構
struct sockaddr_in6 server;是在IPv6上使用的結構
3.細部分的不同就參考下面的程式吧！
4.如果軟體在寫作上有明顯的不同參數設定，即表示協構上相同，但是指令上應該是不相容吧！
Porting IPv6 -- examples
Consider the following IPv4 code examples:
IPv4 client code
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
...
main(argc, argv) /* client side */
int argc;
char *argv[];
{
struct sockaddr_in server;
struct servent *sp;
struct hostent *hp;
int s;
...
sp = getservbyname("login", "tcp");
if (sp == NULL) {
fprintf(stderr, "rlogin: tcp/login: unknown service\n");
exit(1);
}
hp = gethostbyname(argv[1]);
if (hp == NULL) {
fprintf(stderr, "rlogin: %s: unknown host\n", argv[1]);
exit(2);
}
memset((char *)&server, 0, sizeof(server));
memcpy((char *)&server.sin_addr, hp->h_addr, hp->h_length);
server.sin_len = sizeof(server);
server.sin_family = hp->h_addrtype;
server.sin_port = sp->s_port;
s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0) {
perror("rlogin: socket");
exit(3);
}
...
/* Connect does the bind for us */
if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0) {
perror("rlogin: connect");
exit(5);
}
...
exit(0);
}
IPv4 server code
#include <sys/types.h>This code can be ported to IPv6 with only a small number of changes.
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
...
main(argc, argv) /* server side */
int argc;
char *argv[];
{
int f;
struct sockaddr_in from;
struct sockaddr_in sin;
struct servent *sp;
sp = getservbyname("login", "tcp");
if (sp == NULL) {
fprintf(stderr,
"rlogind: tcp/login: unknown service\n");
exit(1);
}
...
#ifndef DEBUG
/* Disassociate server from controlling terminal. */
...
#endif
memset((char *)&sin, 0, sizeof(sin));
sin.sin_len = sizeof(sockaddr_in);
sin.sin_port = sp->s_port; /* Restricted port */
sin.sin_addr.s_addr = INADDR_ANY;
...
f = socket(AF_INET, SOCK_STREAM, 0);
...
if (bind(f, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
...
}
...
listen(f, 5);
for (;;) {
int g, len = sizeof(from);
g = accept(f, (struct sockaddr *) &from, &len);
if (g < 0) {
if (errno != EINTR)
syslog(LOG_ERR, "rlogind: accept: %m");
continue;
}
if (fork() == 0) {
close(f);
doit(g, &from);
}
close(g);
}
exit(0);
}
These changes are highlighted in the examples below by comments in the code.
IPv4 client code ported to IPv6
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
...
main(argc, argv) /* client side */
int argc;
char *argv[];
{
/* */
/* OLD code: struct sockaddr_in server; */
/* */
/* Change structure to sockaddr_in6 from sockaddr_in. */
/* */
struct sockaddr_in6 server;
struct servent *sp;
struct hostent *hp;
int s;
...
sp = getservbyname("login", "tcp");
if (sp == NULL) {
fprintf(stderr, "rlogin: tcp/login: unknown service\n");
exit(1);
}
/* */
/* OLD code: hp = gethostbyname(argv[1]); */
/* */
/* Use gethostbyname2 instead of gethostbyname. */
/* */
hp = gethostbyname2(argv[1], AF_INET6);
if (hp == NULL) {
fprintf(stderr, "rlogin: %s: unknown host\n", argv[1]);
exit(2);
}
memset((char *)&server, 0, sizeof(server));
/* */
/* OLD code: Not applicable. */
/* */
/* If the len member was not in the original IPv4 code*/
/* add it now and make sure it is sin6_len for IPv6. */
/* */
server.sin6_len = sizeof(server);
/* */
/* OLD code: memcpy((char *)&server.sin_addr, ... */
/* OLD code: server.sin_family = hp->h_addrtype; */
/* OLD code: server.sin_port = sp->s_port; */
/* */
/* Make sure you are using sockaddr_in6 members. */
/* */
memcpy((char *)&server.sin6_addr, hp->h_addr, hp->h_length);
server.sin6_family = hp->h_addrtype;
server.sin6_port = sp->s_port;
/* */
/* OLD code: s = socket(AF_INET, SOCK_STREAM, 0); */
/* */
/* Use the correct address family for IPv6. */
/* */
s = socket(AF_INET6, SOCK_STREAM, 0);
if (s < 0) {
perror("rlogin: socket");
exit(3);
}
...
/* Connect does the bind for us */
if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0) {
perror("rlogin: connect");
exit(5);
}
...
exit(0);
}
NOTE: In the assignments to
server.sin6_addr andserver.sin6_family hp->h_length will always beequal to sizeof(struct in6addr) and
hp->h_addrtype willalways be equal to AF_INET6.
IPv4 server code ported to IPv6
#include <sys/types.h>As can be seen in the two IPv6 ported examples, there are only a few
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
...
main(argc, argv) /* server side */
int argc;
char *argv[];
{
int f;
/* */
/* OLD code: struct sockaddr_in from; */
/* OLD code: struct sockaddr_in sin; */
/* */
/* Change structure to sockaddr_in6 from sockaddr_in. */
/* */
struct sockaddr_in6 from;
struct sockaddr_in6 sin;
struct servent *sp;
sp = getservbyname("login", "tcp");
if (sp == NULL) {
fprintf(stderr,
"rlogind: tcp/login: unknown service\n");
exit(1);
}
...
#ifndef DEBUG
/* Disassociate server from controlling terminal. */
...
#endif
memset((char *)&sin, 0, sizeof(sin));
/* */
/* OLD code: Not applicable. */
/* */
/* If the len member was not in the original IPv4 code*/
/* add it now and make sure it is sin6_len for IPv6. */
/* */
sin.sin6_len = sizeof(sin);
/* */
/* OLD code: sin.sin_port = sp->s_port; */
/* */
/* Make sure you are using sockaddr_in6 members. */
/* */
sin.sin6_port = sp->s_port; /* Restricted port */
/* */
/* OLD code: sin.sin_addr.s_addr = INADDR_ANY; */
/* */
/* Make the modifications for assigning in6addr_any to*/
/* sin6_addr. */
/* */
sin.sin6_addr = in6addr_any;
...
/* */
/* OLD code: f = socket(AF_INET, SOCK_STREAM, 0); */
/* */
/* Use the correct address family for IPv6. */
/* */
f = socket(AF_INET6, SOCK_STREAM, 0);
...
if (bind(f, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
...
}
...
listen(f, 5);
for (;;) {
int g, len = sizeof(from);
g = accept(f, (struct sockaddr *) &from, &len);
if (g < 0) {
if (errno != EINTR)
syslog(LOG_ERR, "rlogind: accept: %m");
continue;
}
if (fork() == 0) {
close(f);
doit(g, &from);
}
close(g);
}
exit(0);
}
changes required to port IPv4 applications to IPv6. You may want to go one step
further and use the new getaddrinfo(3N)
and getnameinfo(3N)
functions to make your IPv6 application more portable. The following examples
show how you could modify the client and server examples to use getaddrinfo(3N).
IPv6 client code using getaddrinfo
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
main(argc, argv) /* client side */
int argc;
char *argv[];
{
struct addrinfo req, *ans;
int code, s;
req.ai_flags = 0;
req.ai_family = PF_INET6; /* Same as AF_INET6. */
req.ai_socktype = SOCK_STREAM;
/* */
/* Use default protocol (in this case tcp) */
/* */
req.ai_protocol = 0;
if ((code = getaddrinfo(argv[1], "login", &req, &ans)) != 0) {
fprintf(stderr, "rlogin: getaddrinfo failed code %d\n",
code);
exit(1);
}
/* */
/* ans must contain at least one addrinfo, use */
/* the first. */
/* */
s = socket(ans->ai_family, ans->ai_socktype, ans->ai_protocol);
if (s < 0) {
perror("rlogin: socket");
exit(3);
}
...
/* Connect does the bind for us */
if (connect (s, ans->ai_addr, ans->ai_addrlen) < 0) {
perror("rlogin: connect");
exit(5);
}
...
/* */
/* Free answers after use */
/* */
freeaddrinfo(ans);
/* ... */
exit(0);
}
IPv6 server code using getaddrinfo
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
main(argc, argv) /* server side */
int argc;
char *argv[];
{
struct sockaddr_in6 from;
struct addrinfo req, *ans;
int code, f, len;
/* */
/* Set ai_flags to AI_PASSIVE to indicate that return */
/* address is suitable for bind() */
/* */
req.ai_flags = AI_PASSIVE;
req.ai_family = PF_INET6; /* Same as AF_INET6. */
req.ai_socktype = SOCK_STREAM;
req.ai_protocol = 0;
if ((code = getaddrinfo(NULL, "login", &req, &ans)) != 0) {
fprintf(stderr, "rlogind: getaddrinfo failed code %d\n",
code);
exit(1);
}
...
#ifndef DEBUG
/* Disassociate server from controlling terminal. */
...
#endif
/* */
/* ans must contain at least one addrinfo, use */
/* the first. */
/* */
f = socket(ans->ai_family, ans->ai_socktype, ans->ai_protocol);
...
if (bind(f, ans->ai_addr, ans->ai_addrlen) < 0) {
...
}
listen(f, 5);
for (;;) {
int g, len = sizeof(from);
g = accept(f, (struct sockaddr *) &from, &len);
if (g < 0) {
if (errno != EINTR)
syslog(LOG_ERR, "rlogind: accept: %m");
continue;
}
if (fork() == 0) {
close(f);
doit(g, &from);
}
close(g);
}
/* */
/* Free answers after use */
/* */
freeaddrinfo(ans);
exit(0);
}
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