套接字编程：sendto 总是失败，错误号 22 (EINVAL)
使用此代码，我总是没有收到任何字节发送，错误号为 22（EINVAL，无效参数）。 destination_host 在其他地方设置并且已知是有效的，所以我真的不明白发生了什么。 MAXMSGSIZE 为 1000。没有错误或警告。我正在使用 -Wall -Werror -pedantic 进行编译
char *data_rec;
u_int data_len;
int sockfd;
uint16_t *ns;
struct sockaddr_in address;
struct sockaddr *addr;
char *ip;
int i;
int errno;
int bytes_sent;
data_len = MAXMSGSIZE;
data_rec = malloc(sizeof(char)*MAXMSGSIZE);
ns = malloc(MAXMSGSIZE*sizeof(uint16_t));
ip = malloc(MAXMSGSIZE*sizeof(char));
data_rec = "some random test stuff";
sockfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(sockfd<0) {
printf("socket() failed\n");
}
inet_ntop(AF_INET,destination_host->h_addr,ip,MAXMSGSIZE);
memset(&address, 0, sizeof(address));
address.sin_family = AF_INET;
address.sin_port = htons(theirPort);
address.sin_addr.s_addr = (unsigned long)ip;
addr = (struct sockaddr*)&address;
bind(sockfd,addr,sizeof(address));
/*Convert the message to uint16_t*/
for(i=0; i<MAXMSGSIZE; i++) {
ns[i] = htons(data_rec[i]);
}
/* send the message */
bytes_sent = sendto(sockfd, ns, data_len, MSG_DONTWAIT, addr, sizeof(addr));
if(bytes_sent == -1) {
printf("Error sending: %i\n",errno);
}
I am always getting no bytes sent, with an errno of 22 (EINVAL, Invalid Argument) with this code. The destination_host is set elsewhere and known to be valid, so I really don't see what is going on. MAXMSGSIZE is 1000. No errors, or warnings. I am compiling with -Wall -Werror -pedantic
char *data_rec;
u_int data_len;
int sockfd;
uint16_t *ns;
struct sockaddr_in address;
struct sockaddr *addr;
char *ip;
int i;
int errno;
int bytes_sent;
data_len = MAXMSGSIZE;
data_rec = malloc(sizeof(char)*MAXMSGSIZE);
ns = malloc(MAXMSGSIZE*sizeof(uint16_t));
ip = malloc(MAXMSGSIZE*sizeof(char));
data_rec = "some random test stuff";
sockfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(sockfd<0) {
printf("socket() failed\n");
}
inet_ntop(AF_INET,destination_host->h_addr,ip,MAXMSGSIZE);
memset(&address, 0, sizeof(address));
address.sin_family = AF_INET;
address.sin_port = htons(theirPort);
address.sin_addr.s_addr = (unsigned long)ip;
addr = (struct sockaddr*)&address;
bind(sockfd,addr,sizeof(address));
/*Convert the message to uint16_t*/
for(i=0; i<MAXMSGSIZE; i++) {
ns[i] = htons(data_rec[i]);
}
/* send the message */
bytes_sent = sendto(sockfd, ns, data_len, MSG_DONTWAIT, addr, sizeof(addr));
if(bytes_sent == -1) {
printf("Error sending: %i\n",errno);
}
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评论（3）
您提供的地址大小错误。
addr实际上是一个struct sockaddr_in，而不是struct sockaddr。将sendto的最后一个参数更改为
sizeof(address)You're giving the wrong size for the address.
addris really astruct sockaddr_in, not astruct sockaddr.Change the last parameter of sendto to
sizeof(address)inet_ntop可能不是您想要的 - 它从网络（即有线）格式转换为演示格式（即“1.2.3.4”） 。尝试：inet_ntopprobably isn't what you want - it converts from network (i.e. wire) format into presentation format (i.e. "1.2.3.4"). Try:您有：
因为
sizeof(addr) == 4（或 8），所以使用sizeof(*addr)。You have:
Because
sizeof(addr) == 4(or 8), usesizeof(*addr).