TCP Server client implemention in C
* main.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h> /* read(), write(), close() */
#include <errno.h>
#include <pthread.h>
#define CLTBUFSZ 256
static int sockfd;
static off_t get_line(FILE *f, char *b) {
off_t off = 0;
fgets(b, 255, f);
while (off < 255 && b[off]!=0x0d && b[off]!=0x0a) {
off++;
}
b[off] = 0x00;
return off;
}
// Function designed for chat between client and server.
int client_handler(int clt_fd, char *clt_ip)
{
char buff[CLTBUFSZ];
FILE *is = fdopen(clt_fd, "r");
off_t off;
char body[256];
if (!is) {return -1;}
bzero(buff, CLTBUFSZ);
while (!feof(is)) {
off = get_line(is, buff);
if (off < 3) { break; }
printf("%s\n", buff); /* Print client request message */
}
strcpy(buff, "HTTP/1.1 200 OK\r\n");
send(clt_fd, buff, strlen(buff), 0);
strcpy(buff, "Date: Sun, 12 May 2024 05:41:07 GMT\r\n");
send(clt_fd, buff, strlen(buff), 0);
sprintf(body, "<h1>TCP Server IPv6 demo.</h1><p>Your IP address: %s</p>\n", clt_ip);
sprintf(buff, "Content-Length: %lu\r\n", strlen(body));
send(clt_fd, buff, strlen(buff), 0);
strcpy(buff, "Content-Type: text/html; charset=utf-8\r\n\r\n");
send(clt_fd, buff, strlen(buff), 0);
send(clt_fd, body, strlen(body), 0);
return 0;
}
#define IPv6_CHUNK \
*s++ = cvt[ t[i]>>4 ]; \
*s++ = cvt[ t[i] & 0x0f ]; \
i++; \
*s++ = cvt[ t[i]>>4 ]; \
*s++ = cvt[ t[i] & 0x0f ]; \
i++
char *inet6_to_s(struct in6_addr addr6) {
char *s_addr = malloc(40);
char *s = s_addr;
uint8_t *t = (uint8_t *)addr6.__in6_u.__u6_addr8;
int i = 0;
char cvt[] = "0123456789abcdef";
IPv6_CHUNK;
while (i < 16) {
*s++ = ':';
IPv6_CHUNK;
}
*s = 0x00;
return s_addr;
}
unsigned short atos(const char s[]) {
int i;
unsigned short us = 0;
for (i = 0; i < 6 && s[i]; i++) {
if (s[i] < 0x30 || s[i] > 0x3a) {
break;
}
us *= 10;
us += s[i] - 0x30;
}
return us;
}
void *work_rt(void *params) {
int ret;
char *s_addr = NULL;
socklen_t len;
int connfd;
struct sockaddr_in6 cli;
connfd = accept(sockfd, (struct sockaddr *)&cli, &len);
if (connfd < 0) {
printf("server accept failed...\n");
return NULL;
}
struct timeval timeout;
timeout.tv_sec = 5;
timeout.tv_usec = 0;
if (setsockopt (connfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof timeout) < 0) {
printf("setsockopt failed\n");
return NULL;
}
s_addr = inet6_to_s(cli.sin6_addr);
if (0 == strncmp(s_addr, "0000:0000:0000:0000:0000:0000:0000:0000", 39)) {
return NULL;
}
printf("server accept the client#%d [%s]:%d\n", connfd, s_addr, ntohs(cli.sin6_port));
ret = client_handler(connfd, s_addr);
if (ret != 0) {
printf("client_handler error %d:%s\n", errno, strerror(errno));
}
free(s_addr);
close(connfd);
return NULL;
}
/*
* http://[2408:8940:0:974a:368c:700c:????:????]:8080/
* curl -i "http://\[2408:8940:0:974a:368c:700c:????:????\]:8080"
*/
int main(int argc, char *argv[])
{
struct sockaddr_in6 servaddr;
char s_port[6];
pthread_t t1;
if (argc < 2) {
printf("Usage: %s port\n", argv[0]);
return 0;
}
strncpy(s_port, argv[1], 6);
sockfd = socket(AF_INET6, SOCK_STREAM, 0);
if (sockfd == -1) {
printf("socket creation failed %d:%s\n", errno, strerror(errno));
return errno;
}
printf("server sockfd=%d\n", sockfd);
/* atexit(clean_handler); */
bzero(&servaddr, sizeof(servaddr));
servaddr.sin6_family = AF_INET6;
servaddr.sin6_addr = in6addr_any;
servaddr.sin6_port = htons(atos(s_port));
/*
> netstat -ano | findstr 8080
TCP 192.168.0.104:15515 157.148.54.168:8080 ESTABLISHED 24680
TCP [2408:8940:0:974a:b0db:b3d9:????:????]:17234 [2408:80f1:21:4080::28]:8080 ESTABLISHED 11092
> taskkill /F /PID 11092
> taskkill /F /PID 24680
*/
if ((bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr))) != 0) {
printf("socket bind failed:%d:%s\n", errno, strerror(errno));
return errno;
}
printf("Socket bound ipaddr.\n");
// Now server is ready to listen and verification
if ((listen(sockfd, 16)) != 0) {
printf("Listen failed...\n");
return errno;
}
printf("Server listening [::]:%d\n", ntohs(servaddr.sin6_port));
/* Accept the data packet from client and verification */
for (;;) {
pthread_create(&t1, NULL, work_rt, NULL);
pthread_join(t1, 0);
}
}
* CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
project(tcpsvr C)
set(CMAKE_C_STANDARD 90)
add_executable(tcpsvr main.c)
target_link_libraries(tcpsvr pthread)
* Makefile
CC=gcc
CFLAGS=-g -static -Wl,-s,--stack=67108864
TARGETS=tcpsvr
all: ${TARGETS}
${TARGETS}: main.o
${CC} main.o -lpthread -o $@
main.o: main.c
${CC} ${CFLAGS} -c main.c -o $@
clean:
rm -f ${TARGETS} main.o core.*
test:
./tcpsvr 8080
make
make test
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netsh interface ipv6 show neighbors