URGENT | How to implement HTTP in Linux with C and C++, without socket.
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Homework? Or at least this is what it sounds like. Please see the LQ Rules.
What have you tried so far? Please post your code. If you have questions about how best to pose updates to enhance your question, please see our Site FAQ and add some more to your question to allow others to help you with your problem. Whether or not it is homework, it seems to be an important project for you, therefore your level of C or C++ knowledge will be helpful for others to understand when they consider how to advise you with your problem.
I do also agree with the earlier comments of NevemTeve and audriusk, it is really not possible to perform network programming without using the System V sockets layer, and that this is a forum of volunteers, you asking an "urgent" question, while providing few, and also unclear details, makes it very difficult for people to be able to help you.
But note that people WILL help you, and help you a lot, however you really need to show some initiative on your part to show what you're trying.
A final thought is that there are plenty of client and server programming examples on the web. Unfortunately I honestly have always searched using strings such as: "server socket C source example", or "client socked C source example".
Best Regards. Once again, welcome, and we look forward to any updates you can provide.
Good points Jamison20000e! Occurred to me upon seeing that, that I recently had referred the Beej's Guide to Network Programming on a different thread.
You don't have to "implement" something, as in "from scratch." Nor should you feel that you owe particular allegiance to any particular programming language in order to get the job done. For all languages, there is now a very considerable depth of pre-existing, highly tested code, in binary form and otherwise, which you can simply use to assemble your new solution.
"HTML Rendering," even "a complete web server," all of this stuff has already been done, and done very well, and you don't have to pay a dime to get it.
Can you tell us more about the "without socket" requirement?
My searches for socket alternatives got me NetBIOS, IPX/SPX, networking over a serial port (thought of this myself), and "X/Open Transport Interface" (that's the name of the Wikipedia article).
The only thing that came to my mind with "without socket" is that may be your solution wants to by pass the kernel and go directly by programming ip/tcp layers, also this option will require a socket raw. Anyway, a bit of more detail about you want to achieve will help
Possible Example with classical method, using conventional socket. This may guide you to using sockets. If you don't want this, you may be having to search. I am not aware so far that it could be possible. Experienced programmers may give you some code tiny example or help on that matter.
// 20170419-220634
Edit, I can't find an old http programme I had some day.
Anyhow, there is here a quick possible way to look at-
This code can oriente you.
Let's try to hack google:
Code:
gcc code.c -o httpaccess
./httpaccess www.google.com index.html
and tada, you can view export.html
leafpad export.html or vim export.html
Code:
#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <netdb.h>
#include <string.h>
int create_tcp_socket();
char *get_ip(char *host);
char *build_get_query(char *host, char *page);
void usage();
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <dirent.h> //
// for fexist
#include <ctype.h>
#include <sys/stat.h>
#include <dirent.h>
#include <sys/types.h>
#include <unistd.h>
// time
#include <time.h>
#include <ncurses.h>
#define HOST "coding.debuntu.org"
#define PAGE "/"
#define PORT 80
#define USERAGENT "HTMLGET 1.0"
FILE *fpout;
int main(int argc, char **argv)
{
struct sockaddr_in *remote;
int sock;
int tmpres;
char *ip;
char *get;
char buf[BUFSIZ+1];
char *host;
char *page;
if(argc == 1){
usage();
exit(2);
}
host = argv[1];
if(argc > 2){
page = argv[2];
}else{
page = PAGE;
}
sock = create_tcp_socket();
ip = get_ip(host);
fprintf(stderr, "IP is %s\n", ip);
remote = (struct sockaddr_in *)malloc(sizeof(struct sockaddr_in *));
remote->sin_family = AF_INET;
tmpres = inet_pton(AF_INET, ip, (void *)(&(remote->sin_addr.s_addr)));
if( tmpres < 0)
{
perror("Can't set remote->sin_addr.s_addr");
exit(1);
}else if(tmpres == 0)
{
fprintf(stderr, "%s is not a valid IP address\n", ip);
exit(1);
}
remote->sin_port = htons(PORT);
if(connect(sock, (struct sockaddr *)remote, sizeof(struct sockaddr)) < 0){
perror("Could not connect");
exit(1);
}
get = build_get_query(host, page);
fprintf(stderr, "Query is:\n<<START>>\n%s<<END>>\n", get);
//Send the query to the server
int sent = 0;
while(sent < strlen(get))
{
tmpres = send(sock, get+sent, strlen(get)-sent, 0);
if(tmpres == -1){
perror("Can't send query");
exit(1);
}
sent += tmpres;
}
//now it is time to receive the page
memset(buf, 0, sizeof(buf));
int htmlstart = 0;
char * htmlcontent;
while((tmpres = recv(sock, buf, BUFSIZ, 0)) > 0){
if(htmlstart == 0)
{
/* Under certain conditions this will not work.
* If the \r\n\r\n part is splitted into two messages
* it will fail to detect the beginning of HTML content
*/
htmlcontent = strstr(buf, "\r\n\r\n");
if(htmlcontent != NULL){
htmlstart = 1;
htmlcontent += 4;
}
}else{
htmlcontent = buf;
}
if(htmlstart)
{
fprintf(stdout, htmlcontent);
// export
fpout = fopen( "export.html", "ab+" );
fputs( htmlcontent, fpout );
fclose( fpout );
}
memset(buf, 0, tmpres);
}
if(tmpres < 0)
{
perror("Error receiving data");
}
free(get);
free(remote);
free(ip);
close(sock);
return 0;
}
void usage()
{
fprintf(stderr, "USAGE: htmlget host [page]\n\
\thost: the website hostname. ex: coding.debuntu.org\n\
\tpage: the page to retrieve. ex: index.html, default: /\n");
}
int create_tcp_socket()
{
int sock;
if((sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0){
perror("Can't create TCP socket");
exit(1);
}
return sock;
}
char *get_ip(char *host)
{
struct hostent *hent;
int iplen = 15; //XXX.XXX.XXX.XXX
char *ip = (char *)malloc(iplen+1);
memset(ip, 0, iplen+1);
if((hent = gethostbyname(host)) == NULL)
{
herror("Can't get IP");
exit(1);
}
if(inet_ntop(AF_INET, (void *)hent->h_addr_list[0], ip, iplen) == NULL)
{
perror("Can't resolve host");
exit(1);
}
return ip;
}
char *build_get_query(char *host, char *page)
{
char *query;
char *getpage = page;
char *tpl = "GET /%s HTTP/1.0\r\nHost: %s\r\nUser-Agent: %s\r\n\r\n";
if(getpage[0] == '/'){
getpage = getpage + 1;
fprintf(stderr,"Removing leading \"/\", converting %s to %s\n", page, getpage);
}
// -5 is to consider the %s %s %s in tpl and the ending \0
query = (char *)malloc(strlen(host)+strlen(getpage)+strlen(USERAGENT)+strlen(tpl)-5);
sprintf(query, tpl, getpage, host, USERAGENT);
return query;
}
- on simple question, all those posts and no one will give a single hint of information so far about libraries,... -
Not that any of us aren't guilty of this from time to time, but referring to:
Quote:
Do not post if you do not have anything constructive to say in the post.
And as dugan points out, many have said that this is not possible under Linux using the System V programming model. There are a few reference links provided earlier in the thread. If you disagree with other members' assessments and do have a solution, I, along with the OP would like to see it posted. What libraries are you referring to?
2 Minutes,..., you post much faster than me I was looking my old programm, but I could not find it. Then I gave an example of code. I have quite a lot of small utilities for such things on my disk.
Despite the fact that it took me less than 5 min to find possible helpful code only, you post even faster. - @Rtmistler, how can you post so fast?
Quote:
Do not post if you do not have anything constructive to say in the post.
Thank you.
Without socket, that might indeed quite hard lol.
Actually it is a kinda strange question, don't you think?
After so much answers, the OP didnt give a response. I even don't know if we'll get one.
You gave him a nice info, other users too, and I completed with a possible code that uses the Linux way.
I believe that it is important to give him the solution, by directly giving possible minimalist code source or libraries, so that he can have a look in the right direction. You know for any beginner, Sockets are not easy at all. You could try to remember yourself, when you had to understand those pointers in C. Pointers are at first sight not an easy thing for many programmers. I am still at early beginning, and sometimes there are some black magic in C/C++ language. So, to said, an example is a good start and we ought to help in constructive manner.
I have no idea how to do this under Windows, actually. But really no single idea. It could be with I/o things. For http, I know only the linux way. Hopefully, he can see a bit more the possibilities we have under linux.
Let's wait and see what the OP will answers, or maybe hopefully he will give additional information that will give a more concrete, adapted, answer/solution.
// 22:22:50: Done I did, - I believe, a great help for the OP. He has some interesting code for http access.
Another cool programme which does give a nice example of using sockets, but in the other direction.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define VERSION 23
#define BUFSIZE 8096
#define ERROR 42
#define LOG 44
#define FORBIDDEN 403
#define NOTFOUND 404
struct {
char *ext;
char *filetype;
} extensions [] = {
{"gif", "image/gif" },
{"jpg", "image/jpg" },
{"jpeg","image/jpeg"},
{"png", "image/png" },
{"ico", "image/ico" },
{"zip", "image/zip" },
{"gz", "image/gz" },
{"tar", "image/tar" },
{"htm", "text/html" },
{"html","text/html" },
{"json","application/json" },
{0,0} };
void logger(int type, char *s1, char *s2, int socket_fd)
{
int fd ;
char logbuffer[BUFSIZE*2];
switch (type) {
case ERROR: (void)sprintf(logbuffer,"ERROR: %s:%s Errno=%d exiting pid=%d",s1, s2, errno,getpid());
break;
case FORBIDDEN:
(void)write(socket_fd, "HTTP/1.1 403 Forbidden\nContent-Length: 185\nConnection: close\nContent-Type: text/html\n\n<html><head>\n<title>403 Forbidden</title>\n</head><body>\n<h1>Forbidden</h1>\nThe requested URL, file type or operation is not allowed on this simple static file webserver.\n</body></html>\n",271);
(void)sprintf(logbuffer,"FORBIDDEN: %s:%s",s1, s2);
break;
case NOTFOUND:
(void)write(socket_fd, "HTTP/1.1 404 Not Found\nContent-Length: 136\nConnection: close\nContent-Type: text/html\n\n<html><head>\n<title>404 Not Found</title>\n</head><body>\n<h1>Not Found</h1>\nThe requested URL was not found on this server.\n</body></html>\n",224);
(void)sprintf(logbuffer,"NOT FOUND: %s:%s",s1, s2);
break;
case LOG: (void)sprintf(logbuffer," INFO: %s:%s:%d",s1, s2,socket_fd); break;
}
/* No checks here, nothing can be done with a failure anyway */
if((fd = open("nweb.log", O_CREAT| O_WRONLY | O_APPEND,0644)) >= 0) {
(void)write(fd,logbuffer,strlen(logbuffer));
(void)write(fd,"\n",1);
(void)close(fd);
}
if(type == ERROR || type == NOTFOUND || type == FORBIDDEN) exit(3);
}
/* this is a child web server process, so we can exit on errors */
void web(int fd, int hit)
{
int j, file_fd, buflen;
long i, ret, len;
char * fstr;
static char buffer[BUFSIZE+1]; /* static so zero filled */
ret =read(fd,buffer,BUFSIZE); /* read Web request in one go */
if(ret == 0 || ret == -1) { /* read failure stop now */
logger(FORBIDDEN,"failed to read browser request","",fd);
}
if(ret > 0 && ret < BUFSIZE) /* return code is valid chars */
buffer[ret]=0; /* terminate the buffer */
else buffer[0]=0;
for(i=0;i<ret;i++) /* remove CF and LF characters */
if(buffer[i] == '\r' || buffer[i] == '\n')
buffer[i]='*';
logger(LOG,"request",buffer,hit);
if( strncmp(buffer,"GET ",4) && strncmp(buffer,"get ",4) ) {
logger(FORBIDDEN,"Only simple GET operation supported",buffer,fd);
}
for(i=4;i<BUFSIZE;i++) { /* null terminate after the second space to ignore extra stuff */
if(buffer[i] == ' ') { /* string is "GET URL " +lots of other stuff */
buffer[i] = 0;
break;
}
}
for(j=0;j<i-1;j++) /* check for illegal parent directory use .. */
if(buffer[j] == '.' && buffer[j+1] == '.') {
logger(FORBIDDEN,"Parent directory (..) path names not supported",buffer,fd);
}
if( !strncmp(&buffer[0],"GET /\0",6) || !strncmp(&buffer[0],"get /\0",6) ) /* convert no filename to index file */
(void)strcpy(buffer,"GET /index.html");
/* work out the file type and check we support it */
buflen=strlen(buffer);
fstr = (char *)0;
for(i=0;extensions[i].ext != 0;i++) {
len = strlen(extensions[i].ext);
if( !strncmp(&buffer[buflen-len], extensions[i].ext, len)) {
fstr =extensions[i].filetype;
break;
}
}
if(fstr == 0) logger(FORBIDDEN,"file extension type not supported",buffer,fd);
if(( file_fd = open(&buffer[5],O_RDONLY)) == -1) { /* open the file for reading */
logger(NOTFOUND, "failed to open file",&buffer[5],fd);
}
logger(LOG,"SEND",&buffer[5],hit);
len = (long)lseek(file_fd, (off_t)0, SEEK_END); /* lseek to the file end to find the length */
(void)lseek(file_fd, (off_t)0, SEEK_SET); /* lseek back to the file start ready for reading */
(void)sprintf(buffer,"HTTP/1.1 200 OK\nServer: nweb/%d.0\nContent-Length: %ld\nConnection: close\nContent-Type: %s\n\n", VERSION, len, fstr); /* Header + a blank line */
logger(LOG,"Header",buffer,hit);
(void)write(fd,buffer,strlen(buffer));
/* send file in 8KB block - last block may be smaller */
while ( (ret = read(file_fd, buffer, BUFSIZE)) > 0 ) {
(void)write(fd,buffer,ret);
}
sleep(1); /* allow socket to drain before signalling the socket is closed */
close(fd);
exit(1);
}
int main(int argc, char **argv)
{
int i, port, pid, listenfd, socketfd, hit;
socklen_t length;
static struct sockaddr_in cli_addr; /* static = initialised to zeros */
static struct sockaddr_in serv_addr; /* static = initialised to zeros */
if( argc < 3 || argc > 3 || !strcmp(argv[1], "-?") ) {
(void)printf("hint: nweb Port-Number Top-Directory\t\tversion %d\n\n"
"\tnweb is a small and very safe mini web server\n"
"\tnweb only servers out file/web pages with extensions named below\n"
"\t and only from the named directory or its sub-directories.\n"
"\tThere is no fancy features = safe and secure.\n\n"
"\tExample: nweb 8181 /home/nwebdir &\n\n"
"\tOnly Supports:", VERSION);
for(i=0;extensions[i].ext != 0;i++)
(void)printf(" %s",extensions[i].ext);
(void)printf("\n\tNot Supported: URLs including \"..\", Java, Javascript, CGI\n"
"\tNot Supported: directories / /etc /bin /lib /tmp /usr /dev /sbin \n"
"\tNo warranty given or implied\n\tNigel Griffiths nag@uk.ibm.com\n" );
exit(0);
}
if( !strncmp(argv[2],"/" ,2 ) || !strncmp(argv[2],"/etc", 5 ) ||
!strncmp(argv[2],"/bin",5 ) || !strncmp(argv[2],"/lib", 5 ) ||
!strncmp(argv[2],"/tmp",5 ) || !strncmp(argv[2],"/usr", 5 ) ||
!strncmp(argv[2],"/dev",5 ) || !strncmp(argv[2],"/sbin",6) ){
(void)printf("ERROR: Bad top directory %s, see nweb -?\n",argv[2]);
exit(3);
}
if(chdir(argv[2]) == -1){
(void)printf("ERROR: Can't Change to directory %s\n",argv[2]);
exit(4);
}
/* Become deamon + unstopable and no zombies children (= no wait()) */
if(fork() != 0)
return 0; /* parent returns OK to shell */
(void)signal(SIGCHLD, SIG_IGN); /* ignore child death */
(void)signal(SIGHUP, SIG_IGN); /* ignore terminal hangups */
for(i=0;i<32;i++)
(void)close(i); /* close open files */
(void)setpgrp(); /* break away from process group */
logger(LOG,"nweb starting",argv[1],getpid());
/* setup the network socket */
if((listenfd = socket(AF_INET, SOCK_STREAM,0)) <0)
logger(ERROR, "system call","socket",0);
port = atoi(argv[1]);
if(port < 0 || port >60000)
logger(ERROR,"Invalid port number (try 1->60000)",argv[1],0);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(port);
if(bind(listenfd, (struct sockaddr *)&serv_addr,sizeof(serv_addr)) <0)
logger(ERROR,"system call","bind",0);
if( listen(listenfd,64) <0)
logger(ERROR,"system call","listen",0);
for(hit=1; ;hit++) {
length = sizeof(cli_addr);
if((socketfd = accept(listenfd, (struct sockaddr *)&cli_addr, &length)) < 0)
logger(ERROR,"system call","accept",0);
if((pid = fork()) < 0) {
logger(ERROR,"system call","fork",0);
}
else {
if(pid == 0) { /* child */
(void)close(listenfd);
web(socketfd,hit); /* never returns */
} else { /* parent */
(void)close(socketfd);
}
}
}
}
To give this link http://www.sc.edu/beaufort/library/p...es/bones.shtml (above), might make the OP thinking that his issue is not listened seriously. Over looked, the OP took time to post on this forum and did got the answer, how to search using "Google"
Finally, at this moment and in my opinion, considering the problem/question of the OP, the most constructive answer is this one. This answer is full of compassion and gives also impression that people care about his problem, and that they want to help him constructively. Thank you Dugan.
Code:
Can you tell us more about the "without socket" requirement?
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