sendmsg

send，sendto以及sendmsg系统调用用于发送消息到另一个套接字。send函数在套接字处于连接状态时方可使用。而sendto和sendmsg在任何时候都可使用 era。

基本信息

外文名
sendmsg
含义
发送消息到另一个套接字
使用方法
在套接字处于连接状态时
性质
函数

基本内容

send,sendto,sendmsg方法用于从套接字发送消息。

ssize_t send (int s, const void *msg, size_t len, int flags); ssize_t sendto (int s, const void *msg, size_t len, int flags, const struct sockaddr *to, socklen_t tolen); ssize_t sendmsg (int s, const struct msghdr *msg, int flags);

send，sendto以及sendmsg系统调用用于发送消息到另一个套接字。send函数在套接字处于连接状态时方可使用。

而sendto和sendmsg在任何时候都可使用。

下面的代码片段演示了send，sendto，sendmsg函数的用法：

#include <sys/socket.h>#include <netinet/in.h>#include <unistd.h> void Recv() { struct sockaddr_in serv_addr; int sock_fd; char line = "Hello world!"; int size = 13; serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); serv_addr.sin_port = htons(5000); sock_fd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); connect(sock_fd,(struct sockaddr*)&serv_addr,sizeof(serv_addr)); send(sock_fd, line, size, 0); close(sock_fd); }

#include <sys/socket.h> #include <netinet/in.h> #include <unistd.h> void Sendto() { sockaddr_in receiver_addr; int sock_fd; char line = "Hello World!"; sock_fd = socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP); receiver_addr.sin_family = AF_INET; receiver_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); receiver_addr.sin_port = htons(5000); sendto(sock_fd, line, 13, 0,(struct sockaddr*)&receiver_addr,sizeof(receiver_addr)); close(sock_fd); }

#include <sys/socket.h> #include <netinet/in.h> #include <unistd.h> void sendmsg() { struct sockaddr_in receiver_addr; int sock_fd; char line = "Hello World!"; struct msghdr msg; struct iovec iov; sock_fd = socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP); receiver_addr.sin_family = AF_INET; receiver_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); receiver_addr.sin_port = htons(5000); msg.msg_name = &receiver_addr; msg.msg_namelen = sizeof(receiver_addr); msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_iov->iov_base = line; msg.msg_iov->iov_len = 13; msg.msg_control = 0; msg.msg_controllen = 0; msg.msg_flags = 0; sendmsg(sock_fd,&msg,0); close(sock_fd); }