Linux-客户端访问mjpeg-stream的web网站，保存图像

代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>

#define SERVER_IP "192.168.85.207"
#define PORT 8080
#define BUFFER_SIZE 1024

/*
 * Generate an HTTP GET request for a static snapshot.
 * This function creates a properly formatted HTTP GET request string
 * to retrieve a static snapshot from an mjpg - streamer server.
 * Return: A pointer to the generated request string.
 */
char* generate_get_request() {
    char* request = (char*)malloc(1024);
    if (request == NULL) {
        perror("malloc error");
        exit(EXIT_FAILURE);
    }
    sprintf(request, "GET /?action=snapshot HTTP/1.1\r\n"
                    "Host: %s:%d\r\n"
                    "User - Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0\r\n"
                    "Accept: image/jpeg\r\n"
                    "Connection: close\r\n\r\n", SERVER_IP, PORT);
    return request;
}

/*
 * Read data from the server and save it as a file.
 * This function handles receiving data from the server and writing it to a file.
 * It first skips the HTTP header information and then saves the image data.
 * Parameters:
 *      - sockfd: The socket file descriptor connected to the server.
 */
void save_image_from_server(int sockfd) {
    FILE *fp;
    char buffer[BUFFER_SIZE];
    size_t bytes_read;

    /* Open a file to write the image data */
    fp = fopen("received_image.jpg", "wb");
    if (fp == NULL) {
        perror("Error opening file");
        close(sockfd);
        exit(EXIT_FAILURE);
    }

    /* Skip the HTTP header information */
    char* http_header_end;
    do {
        bytes_read = recv(sockfd, buffer, BUFFER_SIZE, 0);
        if (bytes_read <= 0) {
            perror("Error receiving HTTP header");
            fclose(fp);
            close(sockfd);
            exit(EXIT_FAILURE);
        }
        printf("Received bytes in header loop: %zu\n", bytes_read);
        http_header_end = strstr(buffer, "\r\n\r\n");
    } while (http_header_end == NULL);

    /* Start writing the image data (skip the HTTP header) */
    fwrite(http_header_end + 4, 1, bytes_read - (http_header_end + 4 - buffer), fp);

    /* Continue receiving and saving the remaining image data */
    while ((bytes_read = recv(sockfd, buffer, BUFFER_SIZE, 0)) > 0) {
        printf("Received bytes of image data: %zu\n", bytes_read);
        fwrite(buffer, 1, bytes_read, fp);
    }

    if (bytes_read < 0) {
        perror("Error receiving image data");
    }

    fclose(fp);
}

int main() {
    int sockfd;
    struct sockaddr_in server_addr;
    char* request;

    /* Create a socket */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        perror("Error creating socket");
        exit(EXIT_FAILURE);
    }
    printf("Socket created.\n");

    /* Set up the server address structure */
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr(SERVER_IP);

    /* Connect to the server */
    if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("Error connecting to server");
        close(sockfd);
        exit(EXIT_FAILURE);
    }
    printf("Connected to the server.\n");

    /* Generate an HTTP GET request for a static snapshot */
    request = generate_get_request();

    /* Send the request */
    if (send(sockfd, request, strlen(request), 0) < 0) {
        perror("Error sending request");
        free(request);
        close(sockfd);
        exit(EXIT_FAILURE);
    }
    free(request);
    printf("Request sent.\n");

    /* Get and save the image from the server */
    save_image_from_server(sockfd);

    /* Close the socket connection */
    close(sockfd);
    printf("Socket closed.\n");

    return 0;
}