socket.c

本人收集整理的一份c/c++跨平台网络库

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netinet/ip.h>
#include <arpa/inet.h>

#include "socket.h"
#include "tun.h"

extern int debug;

int
udp_socket(struct sockaddr_in *laddr, struct sockaddr_in *raddr) {
	int fd;
	
	if ( (fd = socket(AF_INET, SOCK_DGRAM, 0)) == -1 ) {
		if (debug) perror("socket()");
		return -1;
	}
	
	if ( bind(fd, (struct sockaddr *)laddr, sizeof(struct sockaddr_in)) == -1 ) {
		if (debug) perror("bind()");
		return -1;
	}
	
	return fd;
}


void *
udp_read_tun_write( void *args ) {
	struct udp_tun *foo;
	foo = (struct udp_tun *)args;
	int bytes = 0;
	size_t fromlen;
	char buf[1500];
	
	while (1) {
		if ( (bytes = recvfrom(foo->skfd, buf, sizeof(buf), 0, (struct sockaddr *)foo->addr, &fromlen)) == -1) {
			if (debug) perror("recvfrom()");
		}
		else { 
			if (debug) printf("recv(): %d\n", bytes);
		}
		
		if ( (bytes = tun_write(foo->tunfd, buf, bytes) ) < 0)
			fprintf(stderr, "tun_write(): %d\n", bytes);
	}
	
	return 0;
}


//---------------------------------------------------

char tmp[64];
char *bits = "01";

char *int_bits(unsigned int n, int n_bits) {
	tmp[63] = '\0';
	int i = 62;
	int c;
	for (c = 0; c < n_bits; c++) {	
		tmp[i] = bits[n & 1];
		i--;
		n = n >> 1;
	}
	return &tmp[i + 1];
}

char *inaddr_txt(u_int32_t address) {
	struct in_addr addr;
	addr.s_addr = (in_addr_t)address;
	return(inet_ntoa(addr));
}

void analizar_buffer(char buffer[], int size) {
	struct iphdr *ip_hdr = (struct iphdr *)buffer;
	int ip_header_length = htons(ip_hdr->ihl);

	if (ip_header_length > size) {
		printf(" !!!!! error al analizar ihl\n");
		return;
	}

	printf("ihl: %d\n", 		ip_header_length);
	printf("version: %d\n", 	htons(ip_hdr->version));
	printf("tos: %s\n", 		int_bits(ip_hdr->tos, 8));
	printf("tot_len: %d\n", 	htons(ip_hdr->tot_len));
	printf("id: %d\n", 			htons(ip_hdr->id));
	printf("frag_off: %d\n",	htons(ip_hdr->frag_off));
	printf("ttl: %d\n",			htons(ip_hdr->ttl));
	printf("protocol: %d\n",	htons(ip_hdr->protocol));
	printf("check: %d\n",		htons(ip_hdr->check));
	printf("saddr: %s\n",		inaddr_txt(ip_hdr->saddr));
	printf("daddr: %s\n",		inaddr_txt(ip_hdr->daddr));

	struct tcphdr *tcp = (struct tcphdr *)&buffer[ip_header_length];
	printf("s_port: %d\n",		htons(tcp->source));
	printf("dest: %d\n",		htons(tcp->dest));
	printf("seq: %d\n",			htonl(tcp->seq));
	printf("ack_seq: %d\n",		htonl(tcp->ack_seq));
	printf("doff: %d\n",		htons(tcp->doff));
	printf("flags: ");
		if (tcp->urg) printf("|URG");
		if (tcp->ack) printf("|ACK");
		if (tcp->psh) printf("|PSH");
		if (tcp->rst) printf("|RST");
		if (tcp->syn) printf("|SYN");
		if (tcp->fin) printf("|FIN");
	printf("|\n");
}


//----------------------------------------------------

void *
tun_read_udp_write( void *args ) {
	struct udp_tun *foo;
	foo = (struct udp_tun *)args;
	int bytes = 0;
	char buf[1500];
	
	while (1) {
		if ( (bytes = read(foo->tunfd, buf, sizeof(buf))) < 0 ) {
			if (debug) perror("read()");
		}
		else {
			if (debug) printf("read(): %d\n", bytes);
		}
		
		analizar_buffer(buf, bytes);

		if ( (bytes = sendto(foo->skfd, buf, bytes, 0, (struct sockaddr *)foo->addr, sizeof(struct sockaddr_in))) == -1) {
			if (debug) perror("sendto()");
		}
		else {
			if (debug) printf("send(): %d\n", bytes);
		}
		fflush(stdout);
	}		
	
	return 0;
}