C 仅使用插座实现单个工艺管道
我想为单个进程实现一个非阻塞套接字，但我也没有，但我可以使用非阻塞套接字。以下是我现在拥有的：C 仅使用插座实现单个工艺管道,c,sockets,pipe,freebsd,C,Sockets,Pipe,Freebsd,我想为单个进程实现一个非阻塞套接字，但我也没有，但我可以使用非阻塞套接字。以下是我现在拥有的： #include <stdint.h> #include <stdio.h> #include <fcntl.h> #include <string.h> #include <arpa/inet.h> int main(void) { // Wannabe server struct sockaddr_in addr;
#include <stdint.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <arpa/inet.h>
int main(void)
{
// Wannabe server
struct sockaddr_in addr;
int fd;
fd = socket(AF_INET, SOCK_STREAM, 0);
if(fd == -1)
{
printf("Error opening socket\n");
return -1;
}
addr.sin_port = htons(0);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_family = AF_INET;
if(bind(fd, (struct sockaddr *)&addr,sizeof(struct sockaddr_in) ) == -1)
{
printf("Error binding socket\n");
return -1;
}
if (fcntl(fd, F_SETFL, O_NONBLOCK))
{
printf("Unable to make socket non-blocking");
return -1;
}
socklen_t socklen = sizeof(addr);
getsockname(fd, &addr, &socklen);
const uint16_t port = ntohs(addr.sin_port);
printf("Successfully bound to port %u\n", ntohs(addr.sin_port));
// Accept the data packet from client and verification
struct sockaddr_in cli;
size_t cli_size = sizeof(cli);
accept(fd, &cli, &cli_size);
// Wannabe client
int sockfd;
struct sockaddr_in servaddr;
// socket create and varification
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
printf("socket creation failed...\n");
return -1;
}
else
printf("Socket successfully created..\n");
memset(&servaddr, 0, sizeof(servaddr));
// assign IP, PORT
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
servaddr.sin_port = addr.sin_port;
// connect the client socket to server socket
if (connect(sockfd, &servaddr, sizeof(servaddr)) != 0)
printf("connection with the server failed...\n");
else
printf("connected to the server..\n");
return 0;
}
我一定是客户端套接字出错了，或者accept调用可能有问题。操作系统很奇怪，但它是FreeBSD fork，根本不支持进程调用。任何帮助都将不胜感激 OPs发布的代码编译不干净 编译时，始终启用警告，然后修复这些警告 以下是编译器的输出：
gcc -ggdb -Wall -Wextra -Wconversion -pedantic -std=gnu11 -c "untitled.c"
untitled.c: In function ‘main’:
untitled.c:38:21: warning: passing argument 2 of ‘getsockname’ from incompatible pointer type [-Wincompatible-pointer-types]
getsockname(fd, &addr, &socklen);
^
In file included from /usr/include/netinet/in.h:23:0,
from /usr/include/arpa/inet.h:22,
from untitled.c:5:
/usr/include/x86_64-linux-gnu/sys/socket.h:116:12: note: expected ‘struct sockaddr * restrict’ but argument is of type ‘struct sockaddr_in *’
extern int getsockname (int __fd, __SOCKADDR_ARG __addr,
^~~~~~~~~~~
untitled.c:47:16: warning: passing argument 2 of ‘accept’ from incompatible pointer type [-Wincompatible-pointer-types]
accept(fd, &cli, &cli_size);
^
In file included from /usr/include/netinet/in.h:23:0,
from /usr/include/arpa/inet.h:22,
from untitled.c:5:
/usr/include/x86_64-linux-gnu/sys/socket.h:232:12: note: expected ‘struct sockaddr * restrict’ but argument is of type ‘struct sockaddr_in *’
extern int accept (int __fd, __SOCKADDR_ARG __addr,
^~~~~~
untitled.c:47:22: warning: passing argument 3 of ‘accept’ from incompatible pointer type [-Wincompatible-pointer-types]
accept(fd, &cli, &cli_size);
^
In file included from /usr/include/netinet/in.h:23:0,
from /usr/include/arpa/inet.h:22,
from untitled.c:5:
/usr/include/x86_64-linux-gnu/sys/socket.h:232:12: note: expected ‘socklen_t * restrict {aka unsigned int * restrict}’ but argument is of type ‘size_t * {aka long unsigned int *}’
extern int accept (int __fd, __SOCKADDR_ARG __addr,
^~~~~~
untitled.c:71:25: warning: passing argument 2 of ‘connect’ from incompatible pointer type [-Wincompatible-pointer-types]
if (connect(sockfd, &servaddr, sizeof(servaddr)) != 0)
^
In file included from /usr/include/netinet/in.h:23:0,
from /usr/include/arpa/inet.h:22,
from untitled.c:5:
/usr/include/x86_64-linux-gnu/sys/socket.h:126:12: note: expected ‘const struct sockaddr *’ but argument is of type ‘struct sockaddr_in *’
extern int connect (int __fd, __CONST_SOCKADDR_ARG __addr, socklen_t __len);
^~~~~~~
untitled.c:40:20: warning: unused variable ‘port’ [-Wunused-variable]
const uint16_t port = ntohs(addr.sin_port);
^~~~
Compilation finished successfully.
建议阅读
connect（）accept（）getsockname（）#include <stdint.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <errno.h>
#include <unistd.h>
int
main( int argc, char **argv )
{
// Wannabe server
struct sockaddr_in addr;
int fd;
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf( stderr, "Error opening socket 1: %s\n", strerror( errno ) );
return errno;
}
addr.sin_port = htons(0);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_family = AF_INET;
if (bind(fd, (struct sockaddr *)&addr,sizeof(struct sockaddr_in) ) == -1) {
fprintf( stderr, "Error binding socket 1: %s\n", strerror( errno ) );
return errno;
}
if (fcntl(fd, F_SETFL, O_NONBLOCK)) {
fprintf( stderr, "Error setting NONBLOCK socket 1: %s\n", strerror( errno ) );
return errno;
}
if (listen( fd, 5 )) {
fprintf( stderr, "Error listening socket 1: %s\n", strerror( errno ) );
return errno;
}
socklen_t socklen = sizeof(addr);
getsockname(fd, (struct sockaddr *)&addr, &socklen);
const uint16_t port = ntohs(addr.sin_port);
printf( "Successfully bound to port %u\n", ntohs(addr.sin_port));
struct sockaddr_in cli;
socklen_t cli_size = sizeof(cli);
errno = 0;
int result;
int srv2cli = accept( fd, (struct sockaddr *)&cli, &cli_size );
printf( "Non-blocking accept() returns %d: %s\n", srv2cli, strerror( errno ) );
// Wannabe client
int sockfd;
struct sockaddr_in servaddr;
// socket create and varification
if ((sockfd = socket( AF_INET, SOCK_STREAM, 0 )) == -1) {
fprintf( stderr, "Error opening socket 2: %s\n", strerror( errno ) );
return errno;
}
memset(&servaddr, 0, sizeof(servaddr));
// assign IP, PORT
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
servaddr.sin_port = addr.sin_port;
if (fcntl( sockfd, F_SETFL, O_NONBLOCK)) {
fprintf( stderr, "Error setting NONBLOCK socket 2: %s\n", strerror( errno ) );
return errno;
}
errno = 0;
result = connect( sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr) );
printf( "Non-blocking connect() returns %d: %s\n", result, strerror( errno ) );
for ( ; ; ) {
fd_set readfds;
fd_set writefds;
fd_set exceptfds;
struct timeval tv;
int maxfd = fd;
if (maxfd < sockfd) maxfd = sockfd;
if (maxfd < srv2cli) maxfd = srv2cli;
FD_ZERO( &readfds );
FD_ZERO( &writefds );
FD_ZERO( &exceptfds );
FD_SET( fd, &readfds );
FD_SET( fd, &writefds );
FD_SET( fd, &exceptfds );
FD_SET( sockfd, &readfds );
FD_SET( sockfd, &writefds );
FD_SET( sockfd, &exceptfds );
if (srv2cli >= 0) {
FD_SET( srv2cli, &readfds );
FD_SET( srv2cli, &writefds );
FD_SET( srv2cli, &exceptfds );
}
tv.tv_sec = 5;
tv.tv_usec = 0;
errno = 0;
result = select( maxfd, &readfds, &writefds, &exceptfds, &tv );
printf( "select returns %d : %s\n", result, strerror( errno ) );
if (FD_ISSET( fd, &readfds )) {
printf( "fd (%d) is ready to read (execute accept())\n", fd );
srv2cli = accept( fd, (struct sockaddr *)&cli, &cli_size );
printf( "\"Server\" accepted connection on fd %d (%s)\n", srv2cli, strerror( errno ) );
if (fcntl( srv2cli, F_SETFL, O_NONBLOCK)) {
fprintf( stderr, "Error setting NONBLOCK srv2cli socket : %s\n", strerror( errno ) );
return errno;
}
result = write( srv2cli, "Hello, world", 12 );
printf( "Transmitted %d bytes to client\n", result );
}
if (FD_ISSET( fd, &writefds )) printf( "fd (%d) is ready to write\n", fd );
if (FD_ISSET( fd, &exceptfds )) printf( "fd (%d) is ready to except\n", fd );
if (FD_ISSET( sockfd, &readfds )) {
char buf[32];
result = read( sockfd, buf, sizeof(buf) );
printf( "sockfd(%d) is ready to read...got %d bytes\n", sockfd, result );
}
if (FD_ISSET( sockfd, &writefds )) {
result = write( sockfd, "Foobar", 6 );
printf( "sockfd (%d) is ready to write...sent %d bytes\n", sockfd, result );
}
if (FD_ISSET( sockfd, &exceptfds )) printf( "sockfd (%d) is ready to except\n", sockfd );
if (FD_ISSET( srv2cli, &readfds )) printf( "srv2cli (%d) is ready to read\n", srv2cli );
if (FD_ISSET( srv2cli, &writefds )) printf( "srv2cli (%d) is ready to write\n", srv2cli );
if (FD_ISSET( srv2cli, &exceptfds )) printf( "srv2cli (%d) is ready to except\n", srv2cli );
}
return 0;
}
（没有停止条件，所以你需要杀死它！）你的操作系统有
错误吗？如果没有，那就太过分了。如果是这样，你应该更好地利用它。请参见perror
@rici我确信它有！很抱歉没有出现这种情况：connect
上的错误显示“连接被拒绝”，我已经升级了，因为尽管我开发了多个服务器端或客户端应用程序，但我从未见过它们具有相同的功能。然后：1）在哪里是listen（）
？2） 是我错了还是客户端的connect（）只有在服务器接受后才成功？@Cubo78谢谢你的关注，好像我错过了！我将尝试修复此问题并更新此问题。我怀疑这里的挑战是从同一线程执行connect（）
和accept（）
。这些都是阻塞调用，除非你设置了NONBLOCK，所以一旦你做了一个，你就不能做另一个。（如果这是一个家庭作业问题，这可能是练习的重点。）我想你可以通过在两个插座上都设置NONBLOCK，然后同时执行connect
和accept
，最后使用select
在各个插座准备就绪时继续操作。
#include <stdint.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <errno.h>
#include <unistd.h>
int
main( int argc, char **argv )
{
// Wannabe server
struct sockaddr_in addr;
int fd;
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf( stderr, "Error opening socket 1: %s\n", strerror( errno ) );
return errno;
}
addr.sin_port = htons(0);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_family = AF_INET;
if (bind(fd, (struct sockaddr *)&addr,sizeof(struct sockaddr_in) ) == -1) {
fprintf( stderr, "Error binding socket 1: %s\n", strerror( errno ) );
return errno;
}
if (fcntl(fd, F_SETFL, O_NONBLOCK)) {
fprintf( stderr, "Error setting NONBLOCK socket 1: %s\n", strerror( errno ) );
return errno;
}
if (listen( fd, 5 )) {
fprintf( stderr, "Error listening socket 1: %s\n", strerror( errno ) );
return errno;
}
socklen_t socklen = sizeof(addr);
getsockname(fd, (struct sockaddr *)&addr, &socklen);
const uint16_t port = ntohs(addr.sin_port);
printf( "Successfully bound to port %u\n", ntohs(addr.sin_port));
struct sockaddr_in cli;
socklen_t cli_size = sizeof(cli);
errno = 0;
int result;
int srv2cli = accept( fd, (struct sockaddr *)&cli, &cli_size );
printf( "Non-blocking accept() returns %d: %s\n", srv2cli, strerror( errno ) );
// Wannabe client
int sockfd;
struct sockaddr_in servaddr;
// socket create and varification
if ((sockfd = socket( AF_INET, SOCK_STREAM, 0 )) == -1) {
fprintf( stderr, "Error opening socket 2: %s\n", strerror( errno ) );
return errno;
}
memset(&servaddr, 0, sizeof(servaddr));
// assign IP, PORT
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
servaddr.sin_port = addr.sin_port;
if (fcntl( sockfd, F_SETFL, O_NONBLOCK)) {
fprintf( stderr, "Error setting NONBLOCK socket 2: %s\n", strerror( errno ) );
return errno;
}
errno = 0;
result = connect( sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr) );
printf( "Non-blocking connect() returns %d: %s\n", result, strerror( errno ) );
for ( ; ; ) {
fd_set readfds;
fd_set writefds;
fd_set exceptfds;
struct timeval tv;
int maxfd = fd;
if (maxfd < sockfd) maxfd = sockfd;
if (maxfd < srv2cli) maxfd = srv2cli;
FD_ZERO( &readfds );
FD_ZERO( &writefds );
FD_ZERO( &exceptfds );
FD_SET( fd, &readfds );
FD_SET( fd, &writefds );
FD_SET( fd, &exceptfds );
FD_SET( sockfd, &readfds );
FD_SET( sockfd, &writefds );
FD_SET( sockfd, &exceptfds );
if (srv2cli >= 0) {
FD_SET( srv2cli, &readfds );
FD_SET( srv2cli, &writefds );
FD_SET( srv2cli, &exceptfds );
}
tv.tv_sec = 5;
tv.tv_usec = 0;
errno = 0;
result = select( maxfd, &readfds, &writefds, &exceptfds, &tv );
printf( "select returns %d : %s\n", result, strerror( errno ) );
if (FD_ISSET( fd, &readfds )) {
printf( "fd (%d) is ready to read (execute accept())\n", fd );
srv2cli = accept( fd, (struct sockaddr *)&cli, &cli_size );
printf( "\"Server\" accepted connection on fd %d (%s)\n", srv2cli, strerror( errno ) );
if (fcntl( srv2cli, F_SETFL, O_NONBLOCK)) {
fprintf( stderr, "Error setting NONBLOCK srv2cli socket : %s\n", strerror( errno ) );
return errno;
}
result = write( srv2cli, "Hello, world", 12 );
printf( "Transmitted %d bytes to client\n", result );
}
if (FD_ISSET( fd, &writefds )) printf( "fd (%d) is ready to write\n", fd );
if (FD_ISSET( fd, &exceptfds )) printf( "fd (%d) is ready to except\n", fd );
if (FD_ISSET( sockfd, &readfds )) {
char buf[32];
result = read( sockfd, buf, sizeof(buf) );
printf( "sockfd(%d) is ready to read...got %d bytes\n", sockfd, result );
}
if (FD_ISSET( sockfd, &writefds )) {
result = write( sockfd, "Foobar", 6 );
printf( "sockfd (%d) is ready to write...sent %d bytes\n", sockfd, result );
}
if (FD_ISSET( sockfd, &exceptfds )) printf( "sockfd (%d) is ready to except\n", sockfd );
if (FD_ISSET( srv2cli, &readfds )) printf( "srv2cli (%d) is ready to read\n", srv2cli );
if (FD_ISSET( srv2cli, &writefds )) printf( "srv2cli (%d) is ready to write\n", srv2cli );
if (FD_ISSET( srv2cli, &exceptfds )) printf( "srv2cli (%d) is ready to except\n", srv2cli );
}
return 0;
}
dhm@rubidium-debian:~/code/nettest$ ./a.out 2>&1 | head -20
Successfully bound to port 60219
Non-blocking accept() returns -1: Resource temporarily unavailable
Non-blocking connect() returns -1: Operation now in progress
select returns 1 : Success
fd (3) is ready to read (execute accept())
"Server" accepted connection on fd 5 (Success)
Transmitted 12 bytes to client
select returns 2 : Success
sockfd(4) is ready to read...got 12 bytes
sockfd (4) is ready to write...sent 6 bytes
select returns 1 : Success
sockfd (4) is ready to write...sent 6 bytes
select returns 1 : Success
sockfd (4) is ready to write...sent 6 bytes
select returns 1 : Success
sockfd (4) is ready to write...sent 6 bytes
select returns 1 : Success
sockfd (4) is ready to write...sent 6 bytes
select returns 1 : Success
sockfd (4) is ready to write...sent 6 bytes