Simple C Sockets HTTP Program Can't Find Resource: 404

Question

I have spring-boot server that I am running in AWS. The server works fine. I can access it using chrome, postman, and curl with no issues. However, I have an embedded device that is running C and I am using sockets to try to connect to my server. The embedded device is running Linux so I can use curl to talk to the server with no issues. However, my C sockets code cannot seem to find the resource on the server. I keep getting 404's.

Here is my embedded client code,

 #include <stdarg.h>
 #include <stdio.h>
 #include <errno.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <resolv.h>
 #include <errno.h>


 int main() {

     // Define some parameters
     int sockfd, bytes_read;
     struct sockaddr_in dest;
     char buffer[4000];
     char hdr[1000];

     // Create Server Client Strings
     bzero(hdr, sizeof(hdr));
     strcpy(hdr, "GET /hello HTTP/1.1\r\n");
     strcat(hdr, "Host: 52.200.39.81\r\n\r\n");

     // Clean things up a bit before sarting
     printf("\n\n");

    // Create Socket
    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
          printf("Socket not created\n");
          return 0;
    }

    // Initialize server address/port struct
    bzero(&dest, sizeof(dest));

    // *** Added this line to fix the code ***
    dest.sin_addr.s_addr = inet_addr("52.200.39.81", &dest.sin_addr.s_addr);

    dest.sin_family = AF_INET;
    dest.sin_port = htons(8080);
    if ( inet_addr("52.200.39.81", &dest.sin_addr.s_addr) == 0 ) {
         printf("Incorrect Address Expression\n");
         return 0;
    }

    // Connect Socket
    if ( connect(sockfd, (struct sockaddr*)&dest, sizeof(dest)) != 0 ) {
         printf("Socket Connection Failed\n");
         close(sockfd);
         return 0;
    }

    // Send data
    if (send(sockfd, hdr, strlen(hdr), 0) < 0) {
         printf("Send Data Failed\n");
         return 0;
    }

    printf("Socket successfully sent\n");
    printf("\nSend Message - TxBufferSize = %d\n\n",strlen(hdr));
    printf("%s", hdr);

    bzero(buffer, sizeof(buffer));
    bytes_read = recv(sockfd, buffer, sizeof(buffer), 0);

    if (bytes_read < 0) {
         printf("Read Data Failed\n");
    }

    if (bytes_read > 0) {
        // Print out receive buffer
        printf("\n\nReceived Message -- RxSize = %d \n\n", strlen(buffer));
        printf("%s", buffer);
    }

    if (bytes_read == 0) {
        printf("No Read Bytes Received\n");
    }

    /*---Clean up---*/
    close(sockfd);
    return 0;
}

Here is what I get back,

debian@beaglebone:~$ ./helloworld


Socket successfully sent

***** Send Message -- TxBufferSize = 80 *****

GET http://52.200.39.81:8080/hello HTTP/1.1
Host: 52.200.39.81
accept: */*



***** Received Message -- RxBufferSize = 467 *****

HTTP/1.1 404 Not Found
Date: Sat, 02 Apr 2016 17:36:37 GMT
Server: Apache/2.2.22 (Debian)
Vary: Accept-Encoding
Content-Length: 283
Content-Type: text/html; charset=iso-8859-1

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>404 Not Found</title>
</head><body>
<h1>Not Found</h1>
<p>The requested URL /hello was not found on this server.</p>
<hr>
<address>Apache/2.2.22 (Debian) Server at 52.200.39.81 Port 8080</address>
</body></html>
debian@beaglebone:~$

If I use the curl command on the embedded device,

debian@beaglebone:~$ curl 52.200.39.81:8080/hello
Greetings WebServiceTest1 -- ServiceCount = 11
debian@beaglebone:~$

I get the correct response from the server. So I am confident that the embedded device is talking to my server. Just can't seem to get the sockets code to work. Any help would be appreciated.

If you execute curl with the verbose flag: curl -v 52.200.39.81:8080/hello, you can see the header it sent. Try using "GET /hello HTTP/1.1\r\n" instead of "GET http://52.200.39.81:8080/hello HTTP/1.1\r\n" — Lilás, Apr 02 '16 at 19:07
I tried "Get /hello HTTP/1.1\r\n" with no luck. Good recommendation with curl -v ... I tried it and copied the header exactly into my program with no luck. This is very troubling. I have done this exact process before on other platforms. — skmansfield, Apr 02 '16 at 19:29
I modified the code in this question http://stackoverflow.com/questions/11208299/http-get-request-using-c-without-libcurl. Try this code: http://pastebin.com/MNHLS77c, make hello, ./hello 52.200.39.81, it works, you can search now what is going wrong with your code by comparing — Lilás, Apr 02 '16 at 19:34
I downloaded your code and included my url's. It worked fine. Let me spend a few minutes trying to figure out what I did wrong. I will get back to you with what I find. — skmansfield, Apr 02 '16 at 19:48

score 0 · Accepted Answer · answered Apr 03 '16 at 15:32

Ok, I found out what the problem was. I did not set the socket address. A very simple omission but that what the problem was. I have updated the code and it is now working. I added gethostbyname to make the code more standardized. The new lines of code are in the comment section "// Initialize server address/port struct". I would like to thank Lilas for providing me the reference code that led me to the omission of the dest.sin_addr.s_addr line. Below is the corrected code.

#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>

int main() {

     // Define some parameters
     int sockfd, bytes_read;
     struct sockaddr_in dest;
     char *hostname = "skmdev1.net";
     struct hostent *hostent;
     char buffer[4000];
     char hdr[1000];

     // Create Server Client Strings
     bzero(hdr, sizeof(hdr));
     strcpy(hdr, "GET /hello HTTP/1.1\r\n");
     strcat(hdr, "Host: skmdev1.net\r\n\r\n");

     // Clean things up a bit before sarting
     printf("\n\n");

     // Build the address
     hostent = gethostbyname(hostname);
     if (hostent == NULL) {
        printf("error: gethostbyname(\"%s\")\n", hostname);
        return 0;
    }

    // Create Socket
    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
          printf("Socket not created\n");
          return 0;
    }

    // Initialize server address/port struct
    bzero(&dest, sizeof(dest));
    dest.sin_family = AF_INET;
    dest.sin_port = htons(8080);
    dest.sin_addr.s_addr = inet_addr(inet_ntoa(*(struct in_addr*)hostent->h_addr));

    if ( dest.sin_addr.s_addr == INADDR_NONE ) {
        printf("Incorrect Address Expression\n");
        return 0;
    }

    // Connect Socket
    if ( connect(sockfd, (struct sockaddr*)&dest, sizeof(dest)) != 0 ) {
         printf("Socket Connection Failed\n");
         close(sockfd);
         return 0;
    }

    // Send data
    if (send(sockfd, hdr, strlen(hdr), 0) < 0) {
         printf("Send Data Failed\n");
         return 0;
    }

    printf("Socket successfully sent\n");
    printf("\nSend Message - TxBufferSize = %d\n\n",strlen(hdr));
    printf("%s", hdr);

    bzero(buffer, sizeof(buffer));
    bytes_read = recv(sockfd, buffer, sizeof(buffer), 0);

    if (bytes_read < 0) {
         printf("Read Data Failed\n");
    }

    if (bytes_read > 0) {
        // Print out receive buffer
        printf("\n\nReceived Message -- RxSize = %d \n\n", strlen(buffer));
        printf("%s\n\n", buffer);
    }

    if (bytes_read == 0) {
        printf("No Read Bytes Received\n");
    }

    /*---Clean up---*/
    close(sockfd);
    return 0;
}

Simple C Sockets HTTP Program Can't Find Resource: 404

1 Answers1