翻译了那么多章《Beej’s Guide Network to Programming》我们有必要自己动手写一个简单的客户端和服务器端的程序！

Client Side:

getaddrinfo() -> socket() -> connect() -> recv()

code:
#include
#include
#include
#include
#include
#include

#define SERVIP "192.168.56.112"
#define SERVPORT "2349"

int main(int argc, char *argv[])
{
struct addrinfo hints, *res;
int status;
int sockfd;
int connSta;

int recvSta;
char buffer[1024];
int len;

char ipstr[INET_ADDRSTRLEN];
void *addr;

if (argc != 3) {
fprintf(stderr, "Usage: Not Server IP And Port!");
return 1;
}

memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;

status = getaddrinfo(argv[1], argv[2], &hints, &res);

if (status != 0) {
fprintf(stderr, "Error, Server IP And Port!");
return 2;
}

sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);

if (sockfd == 0) {
fprintf(stderr, "Create, socket fail!");
return 3;
}

connSta = connect(sockfd, res->ai_addr, res->ai_addrlen);

if (connSta != 0) {
fprintf(stderr, "Connect, Remote Host fail!");
return 4;
}
else {
struct sockaddr_in *ipv4 = (struct sockaddr_in *)res->ai_addr;
addr = &(ipv4->sin_addr);

inet_ntop(res->ai_family, addr, ipstr, sizeof(ipstr));

printf("Linked: Host = %s, Port = %d\n", ipstr, ntohs(ipv4->sin_port));
}


recvSta = recv(sockfd, buffer, sizeof(buffer), 0);

printf("\n%s\n", buffer);

freeaddrinfo(res);
close(sockfd);

return 0;
}
#include
#include
#include
#include
#include
#include

#define SERVIP "192.168.56.112"
#define SERVPORT "2349"

int main(int argc, char *argv[])
{
struct addrinfo hints, *res;
int status;
int sockfd;
int connSta;

int recvSta;
char buffer[1024];
int len;

char ipstr[INET_ADDRSTRLEN];
void *addr;

if (argc != 3) {
fprintf(stderr, "Usage: Not Server IP And Port!");
return 1;
}

memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;

status = getaddrinfo(argv[1], argv[2], &hints, &res);

if (status != 0) {
fprintf(stderr, "Error, Server IP And Port!");
return 2;
}

sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);

if (sockfd == 0) {
fprintf(stderr, "Create, socket fail!");
return 3;
}

connSta = connect(sockfd, res->ai_addr, res->ai_addrlen);

if (connSta != 0) {
fprintf(stderr, "Connect, Remote Host fail!");
return 4;
}
else {
struct sockaddr_in *ipv4 = (struct sockaddr_in *)res->ai_addr;
addr = &(ipv4->sin_addr);

inet_ntop(res->ai_family, addr, ipstr, sizeof(ipstr));

printf("Linked: Host = %s, Port = %d\n", ipstr, ntohs(ipv4->sin_port));
}


recvSta = recv(sockfd, buffer, sizeof(buffer), 0);

printf("\n%s\n", buffer);

freeaddrinfo(res);
close(sockfd);

return 0;
}

Server Side:

getaddrinfo() -> socket() -> bind() -> listen() -> accept() -> send()

code: